Getting Ready to Pull the Trigger - Some last ditch Questions

[BrewCityCobra]

I'm probably a month or so away from pulling the trigger on a MK4 complete kit. Been scouring the boards for a few years now and it has been extremely helpful in nailing down some of the details. That said, I have a few questions I keep going back and forth on and would love to hear the board's opinions.

Some quick background - I suspect this car will be driven regularly through the summers (to work every sunny day and on the weekends with the wife) so daily driving capabilities are a must. That said, I've recently gotten into Autocross and HPDE (with an old 944) and am hoping the roadster will be able to take over those duties once it is complete. Basically I'm trying to take the steps needed to make sure the car will perform and be safe on the track.

So the big questions (drum roll):

1) Suspension

I'm beyond torn right now on suspension. I'd prefer the IRS over straight axle but am having difficulty determining how much more it would cost to make the upgrade. IRS upgrade from FF is about $2500 and it looks like I can get a used Mustang IRS on Ebay for about $800. Does that sound about right? Am I forgetting anything else I may need to buy to make that change? Also for track use what rear ratio are people running? (assuming I run a TKO600 w/ .64 5th).

2) Engine

I'm all but set on going with a Forte 427W setup. I just love the look and feel of those engines. That said, for track, is that going to be a mistake? My thoughts here are that, if anything, a Dart block 427W would actually be a bit more durable than a Coyote, but that is pure speculation.

3) Brakes

I ultimately want to go with Wilwoods but, as is typically the case, budget comes into question. My big question here is - is it worth giving up Wilwoods to get IRS? My thought is that I can always upgrade the brakes later but my suspension is locked in so I should worry about that now. I also figure the stock brakes provided by FF should be able to hold up fine to tracking duties until that upgrade is made.

4) Roll Bars

First off, I plan on going with two roll bars for safety. That said, I prefer the look of the Breeze roll bars but am wondering from a safety standpoint, with tracking the car, if that is a mistake. Would I even be able to pass safety with the breeze bars? Should I just bite the bullet and go with FFR bars? Any avice/experience in the area would be greatly appreciated.

Looking forward to hopefully joining the builders ranks soon.

-Brew

[q4stix]

With #1, did you include the cost of the rear axle parts and things for the 3/4/5 link setup? I think that cost will offset some of the IRS setup if you haven't already considered that. When you buy a takeout or dropout IRS setup from a Mustang, you typically get the rear brakes included. This will also offset cost relative to a solid axle that typically won't come with brakes.

When I bought my Mustang IRS, it was a 3.73 Torsen while many others listed were the 3.55 or 3.31 which have the Tac-Loc but that made mine cost more because of the torsen diff. Every once and a while you can find a performance pack diff listed at the same price. With the torque output of a 427, I'm not sure what final drive would suit you best or what speeds your auto-x and HPDE runs will go.

#2 If you like the 427, go for it. I like the tuning ability and upgrades I can do with the Coyote so I went with that. They're both popular (and 351/363)

#3 As stated above, I'm starting with Mustang GT rear brakes but I bought the Wilwood fronts. I figure I can change the master cylinder diameter to get the right brake bias. That may be an incremental step for you too.

[nuhale]

Brew,

I'm in gurnee just over the border from the "Chedder Curtian" if you want to ride down and take a look. I have a older MK4 with pre 2015 IRS, Gen 2 Coyote, standard Fox Mustang brakes + Hydroboost power brakes/power steering. I'm in the finishing steps of my build.

PM me if you wish to connect.

[delta0014]

Not a ton of experience, just built mine but...


1) IRS would be a must have for me, drives great. Can't help you with track gear ratios.
2) I was debating between the blueprint 427 and coyote also. Went with the Coyote to have the new modern power, and so far no complaints, its a beast. Although the 427 would look better with the hood up.
3) I'd choose IRS over wilwoods. Although for track maybe Wilwoods would be worth it to keep them cooler, but the regular brakes shouldn't have a problem on the street with a light car.
4) I thought about the breeze roll bars too, but ultimately just put dual FFR roll bars on. They look good, i think they look taller in pictures then they do in person.

[GoDadGo]

Brew,

Welcome Aboard But More Importantly, Welcome To The Family!
What is your primary intention for the use of this car is the first thing you need to determine.
What kind of tracking are you planning to do because the street versions don't usually pass most inspections?

> Drag Racing
> Auto Crossing
> Open Track Days Lite (Follow The Leader)
> Open Track Days Heavy (Allowed To Pass)
> True Road Racing & Class Driving Events

Think about HP to weight ratio because a peppy 302 (5.0 Litre) will push the car pretty well.
A 427 (7.0 Litre) will be able to boil the tires in nearly every gear.
Something in between may be a better option.

Steve

[Desert Cobra]

IRS costs a lot more than the performance difference you will actually feel during an autocross.A brake buster will do more than slightly better calipers. Pads are pads. A 427 will overpower these cars during autocross or HPDE. Having had a 944 you will not be able to handle the power to weight ratio. Roll bars should comply with whatever organization runs the HPDE events you go to. Check the regulations (wall thickness, type of steel. etc.) Then get proof your bars meet that standard from the maker. My 2 cents.

[Jeff Kleiner]

Power steering if you have any thoughts of track or autocross. Trust me on this...you really won't be able to hustle and keep up with the car otherwise ;) Breeze roll bars are likely to raise eyebrows for HPDE use for two reasons; first because of the height...unless you're short in the torso and mount the seat flat on the floor your helmeted head likely won't pass the "broomstick test". Secondly because they have a slip joint (albeit with a through bolt) on all three legs. The FFR bars are such that even if the bolts were to shear compression would bottom the tubes on the chassis rather than allowing them to telescope like the Breeze bars. I tend to think of the Wilwoods as eye candy or jewelry. The Mustang derived brakes with aggressive pads and the Wilwood pedal box which allows for adjusting bias will haul the car down with eyeball popping authority. If you reach a point where you're able to over drive them you can add bigger brakes later but that threshold is pretty high!

Cheers,
Jeff

[RRussellTx]

Brew,

I have the Forte 427W and the IRS setup.

I'm very happy with my engine choice, but I don't drive mine as much as you will. The 427W DART setup from Forte is not cheap or polite compared to the Coyote. The 427W from Forte is smelly, snotty and obnoxious sounding and I love it. I haven't checked prices lately but you can probably pay for much of your other upgrades going with the Coyote (and your wife might like it more - mine would have). There are LOTS of other Pros and Cons to each option so good luck making up your mind.

As for the IRS setup, I know you will also need the spindles in addition to the center section. That should be it.

I'm running a 3.31 with the TKO600 and its pretty tall. Great for highway cruising with the .64, but it hates running under 15 mph in first. I've never tracked it or really even pushed it too hard so I'm not sure about the 'trackability' of the setup.

[KDubU]

Welcome aboard! As the SBF vs Coyote debate, to me comes down to looks and sound more than anything. Fuel mileage too I guess but most don’t drive there for mpg so that point is moot IMHO. There are arguments on both sides but truly I don’t think any matter. Some say from a cold start, “I just turn the key and go” with a yote, okay I guess one is in a rush. I would start my 351 and would sit for a bit but not long before taking off. I used to drive mine for the experience even if it just to go grab milk, I’ll use my DD otherwise. The yote has modern tech which can be good but is it needed in these cars, nope but nothing wrong with it. A well built SBF will last as long as a yote so longevity is even IMHO. So now the question is looks and sound, the sbf wins mostly however the yote can be made to look good although there is still a lot of plastic. Sound cannot be duplicated with a yote however I understand there is a setting to make it sound more aggressive.

There you go! Thought I would put this out there for a little fun! ;) I am sure Paul will chime in and others.

[CFranks]

Hi. I have the exact setup that you're steering away from for each of your points, and I can say it's awesome! I have 3-Link, Forte 427W, Stock Brakes (with power booster) and FFR bars.

#1 - Regarding the 3-link, unless going over a crazy bump, I find it very smooth, in fact my passengers usually comment on how smooth it is (i've never driven IRS which i assume would be much better... just never drive one with IRS and you'll never miss it!).

#2 The 427W is actually incredibly driveable, I have the X-heads though - 450 hp; 550ish torque... if you go with more aggressive heads that may change. It sounds awesome and has so much torque as long as you manage your right foot, it's very easy to drive.

#3 I have the mustang pedal box with stock brakes and pads and added a basic vacuum booster ($65). My brakes are awesome, i wouldn't change a thing and they're cheap. If you get the Wilwood pedal box upgrading to power is a little more difficult so I can't speak to how they feel manually in the wilwood box.

#4 As others have indicated, FFR bars don't look that bad in person. They are a little too tall for the eye so I looked into Breeze which do look better, but when you factor in cost of bars, welding, chroming as well as the height concern you mention... I opted to stay with FFR.

Have fun!

[chmhasy]

This may help in the parts search www.car-parts.com

for the "Select parts" drop down box use Carrier, Differential, or Axle Assy Rear(w housing)

each search will yield different inventory's of parts but still same parts

[Bob Cowan]

1. Doesn't matter what the IRS costs - get it. It's a huge improvement in performance and ride. Worth every penny. I wouldn't even consider owning a Cobra with a solid axle.

2. The Dart block has some significant advantages to a Coyote. It is a little heavier, but it is also much stronger. You can easily get 500 rwhp out it without it being too radical. For a Coyote, you almost have to have a blower for that kind of power. Blowers are often not track friendly. Also, a Dart block is much easier to repair if something bad happens. I had this repaired and running again in 8 days.
https://i.imgur.com/CV8DdWI.jpg

3. If you're going to track the car, Wilwoods are a must have. You'll burn up stock Mustang brakes in no time at all. For track use, you want slotted, but no holes or dimples. And you should also have some 3" brake duct hose directed at the center of the disk.
https://i.imgur.com/XHFZ1a4.jpg

4. Not sure. I would contact Mark and ask him.

[rich grsc]

1) IRS, IRS IRS, if you're unsure get the IRS.
2) Coyote, you said you're getting into Autocross, and I hate it when the coyote guy's show up. That damn thing redlines at 8000, it hard to run against that, and my opinion is it has a more manageable power delivery.
3) Get the Wilwoods as a later up grade, or even do Baer brakes.
4) No questions, stick with the FFR bars. Don't care what anyone says, they look better, or better yet have someone build you a fullwidth single bar.

[edwardb]

Can't add too much to what's already written. IRS over the Wilwoods all day long. You have one shot to get the suspension right. Brakes (and MC's and pads) can be adjusted and swapped. I've had both solid axle and IRS. The difference is significant and won't go back. Power steering all the way. Jeff beat me to that one. I too like the look of the Breeze roll bar. Did one on #7750. But for height and construction, as already pointed out, probably not want you want for your purposes. After two small block builds, have done two Coyotes and am a big convert. Some can't get past the look or the non-tradition. I get that. But what a pleasure to drive. Mild or wild as you want. I've gotten past it needing to rattle and shake at idle. (no age comments please) With side pipes, sounds different than a traditional engine. But it's not a bad sound and certainly doesn't sound like a Mustang. Which is a good thing. For these cars anyway. The value is there compared to the HP and torque you get. Don't think you can make a claim either way for long term reliability. Though with a 100K mile maintenance cycle, my money's on the Coyote. But the small block 427 is a great choice. Almost went that way on my 20th Anniversary build before jumping to the Coyote. I'd do a DART block for sure. For the rear diff, 3.55 is by far the most common. For IRS anyway. But you need to look at all the aspects -- engine, trans, tires, intended use -- before deciding. Good luck and welcome aboard.

[Papa]

You've got a lot of replies already, so I won't specifically answer your questions. What I will offer is this. If you think you want something, but the budget isn't quite there, keep saving and order when you can get what you want. I really regret not going with IRS, and at the time I ordered my kit, the IRS was about $5,000 vs. $3,000 for the Moser 3-link (new). I could have easily saved that additional $2,000 in another couple of months and had what I really wanted. I also toyed with the idea of going with standard brakes and upgrading to the Wilwoods later, but the cost difference to do that is pretty steep. I also like the 18" Halibrands that FFR offers, but settled for the 17" based on the cost difference. Well guess what? Before my car was even completely finished I ordered a set of 18" wheels. The moral of this story is do it once and do it the way you see the car in your dreams. If that means waiting a bit longer to place your order, then wait and order when you can get what you really want.

[BrewCityCobra]

With #1, did you include the cost of the rear axle parts and things for the 3/4/5 link setup? I think that cost will offset some of the IRS setup if you haven't already considered that. When you buy a takeout or dropout IRS setup from a Mustang, you typically get the rear brakes included. This will also offset cost relative to a solid axle that typically won't come with brakes.

When I bought my Mustang IRS, it was a 3.73 Torsen while many others listed were the 3.55 or 3.31 which have the Tac-Loc but that made mine cost more because of the torsen diff. Every once and a while you can find a performance pack diff listed at the same price. With the torque output of a 427, I'm not sure what final drive would suit you best or what speeds your auto-x and HPDE runs will go.

#2 If you like the 427, go for it. I like the tuning ability and upgrades I can do with the Coyote so I went with that. They're both popular (and 351/363)

#3 As stated above, I'm starting with Mustang GT rear brakes but I bought the Wilwood fronts. I figure I can change the master cylinder diameter to get the right brake bias. That may be an incremental step for you too.

I did generally but not sure I appreciated the fact the brakes are typically included with an IRS. I'll have to update my calculations accordingly. Thanks!

[BrewCityCobra]

Brew,

Welcome Aboard But More Importantly, Welcome To The Family!
What is your primary intention for the use of this car is the first thing you need to determine.
What kind of tracking are you planning to do because the street versions don't usually pass most inspections?

> Drag Racing
> Auto Crossing
> Open Track Days Lite (Follow The Leader)
> Open Track Days Heavy (Allowed To Pass)
> True Road Racing & Class Driving Events

Think about HP to weight ratio because a peppy 302 (5.0 Litre) will push the car pretty well.
A 427 (7.0 Litre) will be able to boil the tires in nearly every gear.
Something in between may be a better option.

Steve

Definitely wouldn't be going wheel to wheel with it. I'd say autocross for sure - very likely heavy open track days - absolute max would be a time trial if I ever develop my skills far enough and it wouldn't require major changes to the car (although TT would probably be a stretch).

[Traveller]

For #2 - very much a personal choice and I considered the 427W, but ended up going the coyote route. I enjoyed this video of the factory five guys sharing their thoughts on various engines:

https://youtu.be/fpjwKZEgzj8

[BrewCityCobra]

Power steering if you have any thoughts of track or autocross. Trust me on this...you really won't be able to hustle and keep up with the car otherwise ;) Breeze roll bars are likely to raise eyebrows for HPDE use for two reasons; first because of the height...unless you're short in the torso and mount the seat flat on the floor your helmeted head likely won't pass the "broomstick test". Secondly because they have a slip joint (albeit with a through bolt) on all three legs. The FFR bars are such that even if the bolts were to shear compression would bottom the tubes on the chassis rather than allowing them to telescope like the Breeze bars. I tend to think of the Wilwoods as eye candy or jewelry. The Mustang derived brakes with aggressive pads and the Wilwood pedal box which allows for adjusting bias will haul the car down with eyeball popping authority. If you reach a point where you're able to over drive them you can add bigger brakes later but that threshold is pretty high!

Cheers,
Jeff

Power steering was definitely on the "must have list" for this build!

On the brakes front. If I do end up going with the standard FF/Mustang brakes. Is it a mistake to keep them manual without a booster (in anticipation of ultimately switching to wilwoods) or will the brake feel / pedal force be prohibitive?

[GoDadGo]

Brew,

The cool thing about building these cars is, in the end, your car will be exactly what you want.

It is what we all find when we started our journeys of building what we believe to be "The Perfect Factory Five" no matter what model we built.
Your vision, your dream, your ideas will be appreciated by us all, but the most important thing you will find is it will be uniquely yours.
For me, it was going down a path that went in a completely different direction of nearly everyone on the forum.
Your path will be just as unique because nobody will have a car that will be exactly like the one you will build.

We are all looking forward to your build and we will all cheer you on along the way.

Steve

[walt mckenna]

#2 Engine
Can't speak for Autocross, but if you are in HPDE 1-3, you are still getting instruction or logging seat time on your own. Tire scorching horsepower/torque is going to work against you. A road course is more about smoothness and rhythm then brute power. Even with 290 hp at the wheels, I have to be careful about when and where to apply power; I spend very little time at full throttle. I would choose an engine with smooth, linear power delivery and then focus on chassis setup and balance.

[RBachman]

I'll comment on the brakes only, and only my personal opinion. Take it or leave it, LOL. If I were to do it all again, I'd definitely avoid the Wilwoods and go elsewhere. There is ZERO warranty on the Wilwoods even right out of the box. Nothing, zilch! Blow a seal? Own your own. Bad paint? On your own. Leaks? on your own. Not even manufacturing defects are covered. Although FFR is good about helping out and going to bat for you, and they have some muscle to push around. They took care of me when a bracket broke off of brand new brakes due to a casting void...not even 2 miles on the thing for testing and still in go-cart. Wilwood was nice, and they have a great product (normally), but did nothing other than offer to sell me a new part.

[Papa]

I'll comment on the brakes only, and only my personal opinion. Take it or leave it, LOL. If I were to do it all again, I'd definitely avoid the Wilwoods and go elsewhere. There is ZERO warranty on the Wilwoods even right out of the box. Nothing, zilch! Blow a seal? Own your own. Bad paint? On your own. Leaks? on your own. Not even manufacturing defects are covered. Although FFR is good about helping out and going to bat for you, and they have some muscle to push around. They took care of me when a bracket broke off of brand new brakes due to a casting void...not even 2 miles on the thing for testing and still in go-cart. Wilwood was nice, and they have a great product (normally), but did nothing other than offer to sell me a new part.

Here is what is published on Wilwood's website regarding warranty:


Disclaimer of Warranty:
Purchasers recognize and understand that racing parts and equipment, such as disc brakes, hubs, etc. and all parts, inventory and services manufactured and/or sold by Wilwood Engineering, Inc. are exposed to many and varied conditions due to the manner in which they are installed and used. Purchasers and Wilwood Engineering, Inc. consciously desire to make their own bargain, irrespective of any court decision and purchasers agree upon good faith and in consideration for being allowed to purchase from Wilwood Engineering, Inc. said parts or services. Purchasers expressly acknowledge and understand that Wilwood Engineering, Inc. does not make any affirmation of fact or promise to purchaser, which relates to said parts, inventory, or services that becomes part of the basis of the bargain between Wilwood Engineering, Inc. and purchasers. Nor does Wilwood Engineering, Inc. make, or cause to be made to purchaser any description of the goods sold to purchaser, nor does Wilwood Engineering, Inc. make, or cause to be made, as part of the basis of the bargain with purchasers, any description or affirmation of fact concerning any sample or model of racing parts, and equipment inventory or service.

As further consideration for purchasers using Wilwood Engineering, Inc. racing parts and equipment any and all inventory and services, purchasers acknowledge that due to the differing conditions and circumstances under which all equipment and parts are installed and used, purchasers are not relying on Wilwood Engineering, Inc. skill or judgment to select or furnish the proper part or equipment. Purchasers expressly affirm they are relying upon their own skill or judgment to select and purchase suitable goods.

Wilwood Engineering, Inc. makes no warranties whatsoever, expressed or implied, oral or written, to purchasers. There is no warranty of merchantability made to purchasers. Wilwood Engineering, Inc. further excludes any implied warranty of fitness with respect to racing and equipment, any and all inventory and service.

It is expressly understood and agreed between purchasers and Wilwood Engineering, Inc. that as part of the bargain between Wilwood Engineering, Inc. and purchasers, and in consideration of doing business with each other, all purchasers take, select and purchase said racing parts, equipment, any and all inventory, or services from Wilwood Engineering, Inc. “as is” and “with all faults” and Wilwood Engineering, Inc. shall always provide purchasers with a full and complete opportunity to examine, at purchasers’ leisure and convenience, any racing parts and equipment, any and all inventory, or services when purchasing or contemplating purchasing from Wilwood Engineering, Inc.

If, and in the event that purchasers expressly or impliedly cause representations, or statements or affirmations of fact contrary to this disclaimer of all warranties, expressed or implied, then purchasers agree to indemnify and hold harmless Wilwood Engineering, Inc. in the event of any claim, demand, or legal action against Wilwood Engineering, Inc. by any purchaser.

Purchasers understand and agree that no officer, director, employee, or salesman of Wilwood Engineering, Inc. has any authority to make any statement contrary to the terms of this agreement. On the contrary, Wilwood Engineering, Inc. disavows any statement contrary to what is herein above written.

[BrewCityCobra]

IRS costs a lot more than the performance difference you will actually feel during an autocross.A brake buster will do more than slightly better calipers. Pads are pads. A 427 will overpower these cars during autocross or HPDE. Having had a 944 you will not be able to handle the power to weight ratio. Roll bars should comply with whatever organization runs the HPDE events you go to. Check the regulations (wall thickness, type of steel. etc.) Then get proof your bars meet that standard from the maker. My 2 cents.

I had to laugh at your 944 comment. Probably true that I couldn't have picked two more different cars to try to learn on.

[Avalanche325]

I have a 3-link, 347 with 500hp, TKO600 RR, 3.31:1 gears, and Wilwoods. I cruise, autocross, and track. My car does it all except for sitting still at a show.

These days, I would go with new IRS. Not so with the old IRS version when I was building. If you HAVE to choose, I would pick IRS over Wllwoods, because that leaves you an upgrade path. Personally, I wouldn't build one without Wilwoods. It would be cheaper to do them now in the long run. But you know your finances and you have to draw the line somewhere. But, when have you had a car that stops too fast?

I autocross with the SCCA, do Track Night in America and other track events. I have never been broom stick tested. But, I would stay with taller bars. We did have a Camaro go onto its roof at one autocross event. The roll bars are functional, not just cosmetic. At track events, your risk level is magnitudes higher than at autocross.

I completely agree that power steering is a MUST on an autocross and / or track car.

As far as the engine goes. For what you want to do, the only "mistake" would be a big block for handling reasons. A 302 based, 351 based, or Coyote will all make the car go like crazy and still turn well. I would pick the one that sings to you the most. If you just want it to have 427CI, then go for that. If you want modern, then go Coyote. I went with a 347 because I wanted light weight and a powerful tried and true combination. At 500hp, a 347 is snotty on the street, which I love, but it certainly isn't for everyone, INCLUDING 99% of wives (food for thought). A 427 at the same power would be tamer. A 427 weighs a little more and is a little more cramped. A 427 won't "overpower the car", however it will overpower a lot of drivers that don't have decent throttle control. A Blueprint 427 has 480HP. I use every bit of my 500hp, and sometimes wish for more. (I am not claiming to be Mario Andretti) Hopefully you have a realistic idea of your skills. DO NOT cheap out on tires. 200 TW is a great all around level.

As far as 944 vs Cobra. You are going from a momentum car to a HP car. There is a LOT of your experience that will cross over however. Things happen fast in the Cobra and jerky inputs are punished. You have to be smooth, but with the car dancing around on the ragged edge to be fast, which makes it fun. Accelerator control both on and off are key. Autocross is the best and safest way to learn the car. Do a season of that before you mess with track days.

I am happy with the 3.31 rear for my HP level and where I run. Any lower, and I would have to shift into 3rd more. Shifting is expensive in autocross.

[Jeff Kleiner]

Power steering was definitely on the "must have list" for this build!

On the brakes front. If I do end up going with the standard FF/Mustang brakes. Is it a mistake to keep them manual without a booster (in anticipation of ultimately switching to wilwoods) or will the brake feel / pedal force be prohibitive?

When using the Wilwood pedal box stay with manual. If you add a booster to the Wilwood box (or use a donor Mustang pedal box) you're locked into a single master cylinder and lose the ability to alter brake bias either by changing the individual master cylinder sizing or with adjustments to the balance bar. Obviously it will take a little more leg but once the pads are properly bedded it isn't excessive. I've built roadsters with vacuum boosters which works well on a street car but it does compromise feel and modulation on course/track.

Jeff

[GoDadGo]

The FFR bars are such that even if the bolts were to shear compression would bottom the tubes on the chassis rather than allowing them to telescope like the Breeze bars.

Brew,

I actually have my Factory Five Roll Bars bottomed out against the frame and cross-bolted on the main hoops with 3/8" Grade-8 bolts.
While the 3rd leg angle is off, I can deal with that issue knowing that my bolts aren't in a situation where they will likely shear off as Sir Jeffski described.
Shown below is what they looked like last summer:

https://youtu.be/CaRlqMmKIzk

Steve

NOTE:..Any advice you get from Jeff Kleiner, 65 Cobra Dude (Henry R.), Mike Everson or Edwardb (Paul B.) is going to be spot on.
............Also, consider looking at Edwardb's build threads because they supplement the manual very well plus his work is the best of all of the Hobbyist Builders.

[CraigS]

As you already know, an upgrade to IRS is tough although I have done it. So I'd sacrifice nearly anything to get that up front. I'd rather have a stock block 408 w/ IRS than a Dart 427 w/ solid axle. W/ a 427 nearly any of the common diff ratios will be fine. I'd stay w/ one of the taller ones because you will have plenty of power.I don't have all the #s in my head but be aware that not all the gears can be swapped for the others. Not like an old 8.8. Stay w/ a mild cam in the 427 because w/ a 315, 2000 rpm is 75 and 1500 is 55 so it's nice to be able to drive in 5th at 55. I had a 315 gear w/ a 408 in mine and kept thinking I'd like a 331 better but never quite got around to it. Definitely make sure to get brakes w/ your take out rear suspension and try to get the pk brake cables too. Hawk has most all of their pad compounds available for those brakes and they are larger than any of the other commonly used other than maybe Wilwoods. The Wilwood dual bias adjustable MC setup is good and will allow changes like if you decide later to get larger front brakes. Be sure to make your access plate large enough to change MCs. I can't comment on lasting on a track but the FFR front brakes, IRS rear brakes, Hawk HP+ pads all around, dual MC was a system that had a pedal effort just a little higher than my Tacoma truck and stopped crazy well. I suspect that setup w/ cool air ducted to the front brakes would be Ok for your first year of track days until you are really pushing the car.

[GoDadGo]

IRS vs 3-Link Rear

CraigS Made Some Great Points!

If you just like to embarrass folks from stoplight to stoplight or decide to head to the drag strip then the 3-link is a great option.
If you like to autocross or track the car on a road race course then know that the IRS is likely the best option.
Also, the 3-Link was the preferred set up prior to the current IRS coming on the scene.
Ride quality is the best with the IRS as you would well expect.
The biggest advantage of the 3-Link is its simplicity.

I went down the 3-Link this path because I'm a 1,320 guy, plus I was able to shorten the wheelbase to better center the rear wheels.

[Hoooper]

Highly recommend, if you are going to be seeing track use and end up with Wilwoods on the IRS, get the kit that is slotted and not drilled. Wilwood part 140-15138 (140-15138-R for red calipers).

For fronts, dont feel stuck with Wilwoods just because that is what FFR has to offer. Wilwood calipers are generally not very good for aftermarket calipers, they flex more than competitor calipers. IMO Wilwood big brake setups are generally street bling, they will perform well on track and are fine but are not as good as a setup that may not look as good. I would look at the CobraR setup for a budget option, Stoptech has an excellent standard street/track kit for a few hundred more, or the Stoptech trophy kit if you want the absolute best.

It was touched on earlier but if you are going to be tracking the car and sticking with manual brakes you should definitely go with the Wilwood pedal box for the adjustable bias dual master cylinders

[BrewCityCobra]

Highly recommend, if you are going to be seeing track use and end up with Wilwoods on the IRS, get the kit that is slotted and not drilled. Wilwood part 140-15138 (140-15138-R for red calipers).

For fronts, dont feel stuck with Wilwoods just because that is what FFR has to offer. Wilwood calipers are generally not very good for aftermarket calipers, they flex more than competitor calipers. IMO Wilwood big brake setups are generally street bling, they will perform well on track and are fine but are not as good as a setup that may not look as good. I would look at the CobraR setup for a budget option, Stoptech has an excellent standard street/track kit for a few hundred more, or the Stoptech trophy kit if you want the absolute best.

It was touched on earlier but if you are going to be tracking the car and sticking with manual brakes you should definitely go with the Wilwood pedal box for the adjustable bias dual master cylinders


The Wilwood pedal box is automatic with a complete kit right? Or is that something I need to make sure I order. I was planning on going with a hydraulic clutch on that setup as well.

Good point about looking at other brake companies. I kind of fell into the Wilwood trap since it was available and easy. I'll have to look around a bit.

[edwardb]

The Wilwood pedal box is automatic with a complete kit right? Or is that something I need to make sure I order. I was planning on going with a hydraulic clutch on that setup as well.

Good point about looking at other brake companies. I kind of fell into the Wilwood trap since it was available and easy. I'll have to look around a bit.

Yes, Wilwood pedal box is included with the complete kit. There are a number of hard core track guys on here (Gordon Levy, Bob Cowan, John George before he sold his just to name a few) that use Wilwood. Haven't seen anything posted about flexing calipers from them or anyone else. Don't know about your plans for the car, but I'd sure dig into that further if you're really concerned about it. Maybe call and talk to Gordon Levy. He seems to be very knowledgeable and available for discussion. Just hasn't been an issue on either forum. I use and like Wilwood. Other than the fact that they're way more expensive than OE style brakes, I've been very happy with them. Seem very high quality, instructions are top notch, and go together perfectly. Look good too. But them I'm just a street cruiser and don't push them very hard.

[BrewCityCobra]

1. Doesn't matter what the IRS costs - get it. It's a huge improvement in performance and ride. Worth every penny. I wouldn't even consider owning a Cobra with a solid axle.

2. The Dart block has some significant advantages to a Coyote. It is a little heavier, but it is also much stronger. You can easily get 500 rwhp out it without it being too radical. For a Coyote, you almost have to have a blower for that kind of power. Blowers are often not track friendly. Also, a Dart block is much easier to repair if something bad happens. I had this repaired and running again in 8 days.
https://i.imgur.com/CV8DdWI.jpg

3. If you're going to track the car, Wilwoods are a must have. You'll burn up stock Mustang brakes in no time at all. For track use, you want slotted, but no holes or dimples. And you should also have some 3" brake duct hose directed at the center of the disk.
https://i.imgur.com/XHFZ1a4.jpg

4. Not sure. I would contact Mark and ask him.

Random Question - If I go with the Wilwood kit at FFR, will that have the slotted rotors? It seems like the only option available is the drilled.

[Papa]

Random Question - If I go with the Wilwood kit at FFR, will that have the slotted rotors? It seems like the only option available is the drilled.

http://www.factoryfiveparts.com/12-88-front-wilwood-brake-kit/

I'd make sure you specify to FFR at order time that you want slotted, not drilled rotors.

[BrewCityCobra]

I have a 3-link, 347 with 500hp, TKO600 RR, 3.31:1 gears, and Wilwoods. I cruise, autocross, and track. My car does it all except for sitting still at a show.

These days, I would go with new IRS. Not so with the old IRS version when I was building. If you HAVE to choose, I would pick IRS over Wllwoods, because that leaves you an upgrade path. Personally, I wouldn't build one without Wilwoods. It would be cheaper to do them now in the long run. But you know your finances and you have to draw the line somewhere. But, when have you had a car that stops too fast?

I autocross with the SCCA, do Track Night in America and other track events. I have never been broom stick tested. But, I would stay with taller bars. We did have a Camaro go onto its roof at one autocross event. The roll bars are functional, not just cosmetic. At track events, your risk level is magnitudes higher than at autocross.

I completely agree that power steering is a MUST on an autocross and / or track car.

As far as the engine goes. For what you want to do, the only "mistake" would be a big block for handling reasons. A 302 based, 351 based, or Coyote will all make the car go like crazy and still turn well. I would pick the one that sings to you the most. If you just want it to have 427CI, then go for that. If you want modern, then go Coyote. I went with a 347 because I wanted light weight and a powerful tried and true combination. At 500hp, a 347 is snotty on the street, which I love, but it certainly isn't for everyone, INCLUDING 99% of wives (food for thought). A 427 at the same power would be tamer. A 427 weighs a little more and is a little more cramped. A 427 won't "overpower the car", however it will overpower a lot of drivers that don't have decent throttle control. A Blueprint 427 has 480HP. I use every bit of my 500hp, and sometimes wish for more. (I am not claiming to be Mario Andretti) Hopefully you have a realistic idea of your skills. DO NOT cheap out on tires. 200 TW is a great all around level.

As far as 944 vs Cobra. You are going from a momentum car to a HP car. There is a LOT of your experience that will cross over however. Things happen fast in the Cobra and jerky inputs are punished. You have to be smooth, but with the car dancing around on the ragged edge to be fast, which makes it fun. Accelerator control both on and off are key. Autocross is the best and safest way to learn the car. Do a season of that before you mess with track days.

I am happy with the 3.31 rear for my HP level and where I run. Any lower, and I would have to shift into 3rd more. Shifting is expensive in autocross.

Thanks or the tips. I'm certainly aware of my limitations behind the wheel - hopefully a few more summers of Autocross can start helping out.

Local-ish track is Road America, so I figure it is one of the places where a cobra can definitely use some serious brakes for the heavy braking zones, but actually allow you to put a 500HP 427W to work.

[RRussellTx]

allow you to put a 500HP 427W to work.

Like Kenny Roberts on a Yamaha TZ750
https://www.youtube.com/watch?v=8k8hJWKIVNs

[edwardb]

Random Question - If I go with the Wilwood kit at FFR, will that have the slotted rotors? It seems like the only option available is the drilled.

The FFR optional Wilwood brakes (6-piston front, 4-piston rear) are drilled and slotted. Have them on my 20th Anniversary Roadster and my recently finished Gen 3 Coupe.

https://hosting.photobucket.com/albums/ab234/edwardb123/Factory%20Five%2020th%20Anniversary%20Mark%204%20R oadster/Brakes/.highres/IMG_3686_zpsfr7cc8qa.jpg (https://app.photobucket.com/u/edwardb123/a/37aae101-f84e-4643-8779-c5d71efbfc65/p/c578ac21-5255-4470-baf4-15dbbb7f47a0)

https://thefactoryfiveforum.com/attachment.php?attachmentid=78320&d=1514591193

[Hoooper]

I suspect if you just ask FFR about it they can get you the just slotted rotors since Wilwood does offer it that way (kit 140-12048)

[Avalanche325]

"Local track is Road America".......NICE!

There is a track local to me called The FIRM. A nice technical track with a couple hard braking zones. I started the day with pads over 50% and took one down to the metal. The last little bit let go on the way home. Not a nice sound when a backing plate is digging into your rotor. Apparently, it is pretty common for the 2nd 50% to go away much quicker. Maybe less thermal mass? I was able to get the rotor turned. I am doing Daytona in a couple weeks. The full Rolex 24 course. Going to run out of cajones before anything else on this one.

When I did my build, you could order slotted only rotors or drilled / slotted. I would call. I haven't heard of anyone having cracking issues with the drilled ones, but if you are going to track a lot, you might as well play it safe.

[Jeff Kleiner]

...I am doing Daytona in a couple weeks. The full Rolex 24 course. Going to run out of cajones before anything else on this one...



Cool! My good buddy Bailey has run the full course in his various Backdrafts. Here's a quick couple of laps to get you psyched :cool: (Turn down the sound 'cause it's nothing but wind)


https://youtu.be/1Wvwcy18sTM

Jeff

[walt mckenna]

"Local track is Road America".......NICE!

There is a track local to me called The FIRM. A nice technical track with a couple hard braking zones. I started the day with pads over 50% and took one down to the metal. The last little bit let go on the way home. Not a nice sound when a backing plate is digging into your rotor. Apparently, it is pretty common for the 2nd 50% to go away much quicker. Maybe less thermal mass? I was able to get the rotor turned. I am doing Daytona in a couple weeks. The full Rolex 24 course. Going to run out of cajones before anything else on this one.

When I did my build, you could order slotted only rotors or drilled / slotted. I would call. I haven't heard of anyone having cracking issues with the drilled ones, but if you are going to track a lot, you might as well play it safe.

I was very surprised at how quickly your pads wore out and wondered what could be grinding the pad material away so quickly. I have stock mustang brakes with off-the-shelf rotors and ceramic pads that last me 2 years. I go to the track 4 times a year. I drive the car in one HPDE class and my son-in-law drives it in another, so the brakes see 2 hours and 40 minutes of track time each time out. We probably don't use the brakes as aggressively as you, but that kind of wear would concern me.

[Avalanche325]

The first 50% of the pads went through 22,000 miles including 5 seasons of autocross and a track day. The last 50% went away on a full day at the track. It is a 1.5 mile track that has a couple 120 - 40mph braking zones and I was pushing pretty hard. The track is known to be tough on brakes. The pedal was getting a little long in the last session and I literally had chunks of brake dust on the wheels. I still had a little pad left on 3, and one let go. I think it sheared off rather than wore all the way down. I will be checking for uneven wear. I wasn't the only one with fried brakes at the end of the day. There were two others.
132235

It was a fun day. 16 Cobras on a private track day.
132236

A couple guys that run Champ cars, and they said that they see the same thing on their race cars as far as the 2nd 50% goes quick.

[Rdone585]

I can't add much more to the wisdom already shared. The difference is I'm probably not to far from you. I agree in choosing a 408 versus a 427. That's what I did. With a Dart block and a good builder there is plenty of power on tap. Also went dry sump. I've been driving and tracking mine since 2003, started in Fl and now in WI. I don't have as much track wisdom as some of the others that have chimed in but I've been around many tracks more than I kept track of. Just did a body off restoration and new carpet and full body paint replacing the 18 year old paint. Now I'm back on the road and hoping to get the front end dialed in to go to Blackhawk this fall. Send me a PM if you want to talk or meet.

Robert

[NiceGuyEddie]

Keep in mind that people have spent up to $1,000 to align an IRS car, as opposed to $69 for front-end alignment only.

[Avalanche325]

Keep in mind that people have spent up to $1,000 to align an IRS car, as opposed to $69 for front-end alignment only.

Wow. That makes a FasTrax ($150), toe plates ($70) and a Sunday in the garage a pretty good deal. I think that anyone building a car can handle an alignment.

[Jeff Kleiner]

Keep in mind that people have spent up to $1,000 to align an IRS car, as opposed to $69 for front-end alignment only.

People have also paid $20K to have a roadster painted or $30K to have a Coupe done...but that doesn't make it real world. Just means that somebody saw a sucker walk through the door ;)

Jeff

[GoDadGo]

They charged me $75.00 (Plus Tax) to allign my solid axle MK-4.

They charged my friend Donnie $150.00 (Plus Tax) to allign his IRS MK-4.

Thank God The Tire Town Team Didn't View Us As A Pair Of Suckers!

[Papa]

Jeff aligned my front end using reference points and measurements while he had my car in his shop for paint. When I took it to get it aligned on a machine, it was nearly perfect; $49.00 for 15 minutes on the rack and done.

[rich grsc]

People have also paid $20K to have a roadster painted or $30K to have a Coupe done...but that doesn't make it real world. Just means that somebody saw a sucker walk through the door ;)

Jeff
DING DING DING, we have a winner here folks.

[CraigS]

Wow. That makes a FasTrax ($150), toe plates ($70) and a Sunday in the garage a pretty good deal. I think that anyone building a car can handle an alignment.
That is exactly right. Aligning these is tedious as can be but it is not hard to understand. The best plan is to do a perfect alignment when the car is in go kart stage w/o the body. Set the ride height and do the alignment. Now no matter what happens, body and other weight on, springs settle etc. set it back to the same ride height and the alignment will once again be perfect. If it happens to be off a little, or you decide you want to try another spec, it is much easier to do when it is perfect or close. One other thought, allow plenty of time; 4-5 hours for the initial and 2-3 hours for changes/touch ups. I enjoy doing alignments but it is NO fun at all if you are rushed. Longacre has some nice inexpensive tool also.
I use these;
http://www.longacreracing.com/products.aspx?itemid=1798&prodid=7219&pagetitle=Caster-%2f-Camber-Gauge-%26-case-only---NO-ADAPTER
a self made version of this
http://www.longacreracing.com/products.aspx?itemid=2445&prodid=7212&pagetitle=Toe-Bar

[BrewCityCobra]

"Local track is Road America".......NICE!

There is a track local to me called The FIRM. A nice technical track with a couple hard braking zones. I started the day with pads over 50% and took one down to the metal. The last little bit let go on the way home. Not a nice sound when a backing plate is digging into your rotor. Apparently, it is pretty common for the 2nd 50% to go away much quicker. Maybe less thermal mass? I was able to get the rotor turned. I am doing Daytona in a couple weeks. The full Rolex 24 course. Going to run out of cajones before anything else on this one.

When I did my build, you could order slotted only rotors or drilled / slotted. I would call. I haven't heard of anyone having cracking issues with the drilled ones, but if you are going to track a lot, you might as well play it safe.

I have to think it would pucker you up a bit going into that bus-top chicane at a buck-40, but I have to admit I'm jealous.

I was planing on calling FFR sometime next week to nail down a few details, I'll make sure to inquire about the slotted rotors.