Transmissions for 600 hp

[SteveP]

I'm rethinking a choice I made before my kit arrived. I bought a used t-5 transmission for a good price and assumed it would handle the power of a 351 because the tires would spin before the transmission broke or the Mustang GT clutch burned up. Then my engine project got away from me. The displacement grew to 427, the heads and cam improved, TBI was added, compression raised. Now I wonder if I have enough transmission and I realize I don't have any real world experience to make the right choice. I don't plan to race but I would like to light up the tires occasionally. I might even want to use the Nitto 555R tires in back some time so I have a better chance of keeping up with my wife's Tesla. Is it inevitable the T-5 will break? Do I need to go to a TKO 500 or 600? If I need to change, now is the best time because the engine isn't installed yet. Maybe someone on the forum has used a T-5 in similar circumstances. If so I would really like to hear the results before I spend another $3,500 on a transmission and clutch I might not need.

[TrevorP]

Yes, once you pass 300 or so ft. lbs, the T5 will not do well. I raced for years with a 500hp 347 and a modified T5 with super alloy gears. Levy did the work. Even with those gears I would have a failure, I think it was 3rd that broke. It took a while though, and racing conditions are far worse than the street. If you want the lighter weight and easy shifting, modify the T5. The TKOs are truck transmissions and do not shift as nice as the T5. Later, I switched to a race Gforce GF5R dog box, that is bulletproof and doesn't work well for a street car.

[edwardb]

For that much HP, you will probably break a standard T5, including the world class version. Best to do the TKO. Having said that, 500-600 HP for street use will likely not get fully used. Or maybe better said, shouldn't be. You can "light up the tires occasionally" with half that, or less. Curious, have you driven one of these before? If that 500-600 isn't friendly, it won't be particularly fun to drive. Just my opinion.

[KDubU]

TKO600 would be my choice.

[Derald Rice]

If you are looking for peace of mind, go with the 600 from the start, and don't look back.

I was one of those who tried a TKO many years ago, and it's truck heritage was very obvious. Hard to shift and very rough to drive, especially when cold. But when I changed the motor, I had the same second thoughts that you are going through, so I had Bob Hanlon at HanlonMotorsports.com go through a TKO 600 for me with his improved blocker rings, and what ever else he does. That was 2 years ago, and this TKO 600 is every bit as smooth as a T5, maybe even better. TKO's are also known for fluid leaks, but mine has been totally dry from day one. Some of the members here say it is "smooth as butter", and I do agree.

Bob is a stand-up guy, and all he does is TKO's.

[GoDadGo]

Steve's Stupid Question From The Dark Dart Side:

Has anybody successfully used a Richmond Gear 5-Speed?

https://www.richmondgear.com/wp-content/uploads/pdfs/richmond/RG22.pdf

It is similar in size to my ZF 6-Speed Gearbox, which also has the shifter hanging off the left side, but the shifter for the Richmond is 4-5 inches further forward.

[SteveP]

Sounds like the t-5 might work for my use but it is risky and maybe not long term. The engine is built for the street with a cam designed for low and mid range power and an Edelbrock Performer manifold which I understand doesn't take high rpm's to make lower rpm power. I sincerely hope it is fun and easy shifting would be a plus. If I break the transmission, how hard is it to change after the chassis is fully assembled and the body on? Is it so difficult I shouldn't experiment with the T-5?

[GFX2043mtu]

If you have 500+ ft/lbs of torque you’ll kill any gear set you can get for a T5 box regardless of the series. Don’t bother with a TKO500 either as the 600 is the same price and dimensionally the same. If your worried about smoothness like some have suggested Liberty’s Gears makes carbon lined synchronizer rings and a shift shaft modification kit that will smooth out the box by a good amount. If your going to be getting a new box you may want to talk to them first any ways about the motor and what needs you’ll have for a transmission.

[BEAR-AvHistory]

Have a TKO-600 & am happy with it. Not unlike the Muncie Rock Crushers from the muscle car era in feel. FWIW the car is so light it has no trouble spinning 315 NITTO 555R at 1800 RPM in 1st.

[NAZ]

Go with a TKO 600, forget the T5 & TKO 500. Don't expect the T5 to be durable enough for a moderately powered engine like one you appear to be thinking of. And the TKO 500 is rated for 500 lb ft of torque because of the very low 1st gear which is also not the best choice for a light car. The TKO 600 is rated for 600 lb ft of torque and can be made to handle over 700 lb ft (Liberty Gear). And if you buy one from Liberty Gear you can have them work their magic to make the TKO shift much better than the standard TKO.

Buy cheap -- buy twice. And increase your workload -- install, break, remove, install again.

But don't just listen to us, do your own research on transmission choices and torque ratings. Include in that research the RPM in 1st gear and think about that.

https://www.tremec.com/menu/tko/

[boat737]

...FWIW the car is so light it has no trouble spinning 315 NITTO 555R at 1800 RPM in 1st.

Or 2nd. Or...

[mike223]

Curious, have you driven one of these before? If that 500-600 isn't friendly, it won't be particularly fun to drive. Just my opinion.




Make that a pretty common opinion, if you ask exactly the right question.

~500hp/550ftlbs here, NT05 tires - Started with a 3.55 rear gear, now at 3.15 rear gear - Still "dangerous" in third gear, but with the 3.55 rear gear it was "routinely" lighting up the tires at a very gentle half throttle in third gear (be careful what you wish for).


The car is no faster to 100mph on street tires than it would have been with 400hp/400ftlbs - it's simply more tricky to drive well.


If I had known this when I started, I would have built a 9:1 351w instead of a 10.5:1 393w - and the 9:1 would certainly average faster to 100mph on street tires, without all the hazards associated with accidentally scaring hell out of yourself in the 50+mph speed range (and that is the best possible outcome - the rest are usually fatal mistakes).


Just my experience - but your experience isn't going to vary much.

[SteveP]

Thank you everyone. Based on your experienced input and even my wife's advice, I'm going with the TKO 600. NAZ, I'm glad you told me why the 600 is preferable. Unless there is some reason not to, I'll get the higher 5th gear ratio. Edwardb, I read your previous posts about the shifter location and the reverse rear looks like it will work for me. You had a different shifter and I have the FFR. Will the FFR shifter work in the rear reversed position? Is that something I can do easily after delivery without additional parts or do I need to plan ahead? Other than cutting a piece off, is there any other reason I would need to buy the transmission from a vendor knowledgeable about FFR roadsters? Free shipping is tempting.
I guess I'll need a different bellhousing and driveline. Anything else? Hopefully FFR will be able to open as expected so I can trade drivelines.

[mike223]

To the original clutch + transmission question - I have a T56 that handles it and I can't speak to the T5 (except I wouldn't try it).

I am running an OEMish Mustang GT clutch with no problems - you will overwhelm any street tire before you overwhelm the clutch - but drag slicks might change that equation.

[SteveP]

Mike223, now you make it harder with another option. I have a 351 block all machined and ready to go. I can probably finish it at 400hp for about the same price as a TKO 600 setup, maybe even less if I take the induction parts off the 427. Edwardb, you raised the issue of drivability, is 400hp better than 600?

[edwardb]

Edwardb, I read your previous posts about the shifter location and the reverse rear looks like it will work for me. You had a different shifter and I have the FFR. Will the FFR shifter work in the rear reversed position? Is that something I can do easily after delivery without additional parts or do I need to plan ahead? Other than cutting a piece off, is there any other reason I would need to buy the transmission from a vendor knowledgeable about FFR roadsters? Free shipping is tempting.
I guess I'll need a different bellhousing and driveline. Anything else? Hopefully FFR will be able to open as expected so I can trade drivelines.

The shifter you saw was this one: https://www.**********accessories.com/p-150-shifter-handle-427-t5.aspx. No reason the FFR shifter wouldn't bolt into place, but I haven't tried it so can't cite any experience. What I have seen is guys drilling a different hole location in at least one of the FFR holes and changing the angle of the shifter. Perhaps something like that would work. Trimming the rear mount so it clears the cross tube in the frame can be done yourself if whoever you buy it from doesn't know about it. X3 (or whatever) on Liberty Gears. Both TKO's I've used were from them with their shift mods and shift just nicely. I've heard both positive and negative about how a stock TKO shifts. Can't cite any personal experience there. Liberty knows about the trim on the mount BTW, and will take care of it. They machine it (vs. a Sawzall...) and looks like it was mfg that way. Only downside with Liberty is they may have a leadtime to work through. Seems their work is popular. Only change to FFR would be the driveshaft. Length and spline count is different between a T5 and TKO.

[GoDadGo]

Mike223, now you make it harder with another option. I have a 351 block all machined and ready to go. I can probably finish it at 400hp for about the same price as a TKO 600 setup, maybe even less if I take the induction parts off the 427. Edwardb, you raised the issue of drivability, is 400hp better than 600?

Steve,

Mike223 and I have often talked about the fact that a little less power would have been easier to drive on the street.

I'm making around 450 HP with similar torque numbers and on 300 TW tires, I can spin the tires at will in 1st, 2nd, and 3rd, but haven't tried it in 4th, 5th or 6th.
Yes I need softer tires to stick the power; however, my car is a cruiser and might hit the quarter mile once or twice each year and maybe the auto cross course too.
I actually took power out of the car with camshaft change, but it didn't help because I just created more bottom end torque.
My friend Heath put a peppy 351-Windsor in his car after going for a few short rides in my car.
My pal Dave went the opposite direction with a 517 HP 400 from Blueprint for his 33 HR.
You just need to decide what you want and go down the path you choose.

https://youtu.be/PCngiKoopkA

Good Luck, Happy Wrenching & Welcome Aboard!

Steve

[Jim1855]

I had 540hp / 530tq (flywheel) 427W in my Superformance cars. About 250 pounds heavier than a FFR roadster. Ran the same TKO-600, a 2004 version, for about 65,000 miles. No transmission problems although I did I did cause a few clutches to cry and had Liberty Gears redo syncros & shifting parts. Not a drag racer, most of my burnouts were with the throttle. Lots of roadtrack miles, plenty of high speed runs @ 140mph plus & 7,000 rpm.

Unless you do something nasty with the cam and too much carb I don't think you'll have drivability issues but you will need to learn how to modulate the skinny pedal.

Jim

[edwardb]

Edwardb, you raised the issue of drivability, is 400hp better than 600?

It's not just about the HP, which can be modulated with your right foot (and your brain...). It's just that often high powered engines have cams, heads, induction, etc. that provide high HP on the dyno but aren't friendly for less than track or strip driving. Don't like to idle, don't like to launch, don't like lower RPM's while cruising, and so on. I've talked to more than one owner (not just these cars) who regretted pushing the limits and then didn't enjoy driving the car. That plus honestly for street use you're just not going to hook up 600 hp. If you do, you probably shouldn't have. Like I said before. Don't want to go off topic, but that's one of the reasons I really like the Coyote. It's happy whether driven like grandma going to church on Sunday or pushed to the limit. Where it makes a bunch of power. Makes it really fun to drive. So I've appreciated this point more than ever since going that way. Interestingly, Dave Smith talked about this exact point in his daily live broadcast last Friday. Someone asked a question about what was the best power for the Roadster. He walked to the back of the showroom where they have a 5.2L Aluminator XS crate engine at 570 HP in the 25th Anniversary Roadster and his son's Roadster with a 300+ HP 306 small block. Said that both were crazy fast, but the small block was more fun and perhaps safer to drive. Talked exactly about the HP bragging race that many of us seem to get caught up in. Probably you could watch a replay on their Facebook page if you're interested.

[NAZ]

My car puts out 800 HP at the flywheel W/O any power adders, has a very lopy cam and weighs less than 2500 lbs with me in it and full of fuel. I had a very pleasant drive today, but it is a bit loud. Can floor it and no drama, no smoking tires just set you back in the seat acceleration.

It's not too much power but too little traction that makes a car hard to handle. You have to understand how to set-up the rear to hook when you start adding power. Really not that difficult.

[chuckster]

2 guys and I removed and reinstalled my TKO600,bell housing,clutch, pressure plate, and flywheel in 3 1/2 hours (on a lift). So IMHO if you have to replace the t5 at some point it’s no big deal.

[mike223]

Mike223, now you make it harder with another option. I have a 351 block all machined and ready to go. I can probably finish it at 400hp for about the same price as a TKO 600 setup, maybe even less if I take the induction parts off the 427. Edwardb, you raised the issue of drivability, is 400hp better than 600?

My answer is I would have never known for certain if I hadn't overdone it.

Got started with these cars in a friends replica - he wanted to learn to autocross it - he knew I had round tracked + autocrossed.

I started out "terrified" of the car - they have a longstanding reputation (well deserved) for being a lot easier to make an azz out of yourself with - and exceptionally challenging to drive "well" approaching their capability on an autocross course.

That car was a 331w, and it took me at least a year (probably two) to learn to "drive it well" (autocross) - in the first three months I decided I was going to have to build one for myself (too much fun).


And you can never build one with "less".


Until you've "lived it", + learned that at some point - you actually can have too much of a great thing...


My next motor in this sort of a "street" replica will be a 9:1 351w - that's "plenty" for any "street" tire I'm aware of (and cheaper, less prone to catastrophic failure, and runs safely on regular unleaded too = bonus + bonus + bonus).

[TrevorP]

I've had 6 engines in my cobra with 3 while it was still a partial street car. I think my favorite engine was the 347 with AFR185s and 500hp. Pulled like a mother and hooked up nicely. Lots of low end grunt too. How large the head intake runners are and type of manifold you have make a big difference on the street manners.

You can pull the trans out with the car on the lift in a few hours. It is a little harder to get back in, but I have done that in about 3 hrs.

My last 2 motors were full race 363ci, 600hp, 7200 rpm, 13.8 to 1 CR, 110 race fuel, with nothing below 3000rpm. Perfect for the track, but terrible for the street.

[GoDadGo]

How large the head intake runners are and type of manifold you have make a big difference on the street manners.


Amen TrevorP,

215 CC Iron Eagle Tall Port Heads, A Team-G Single Plane Intake & Reasonable Camshaft Makes My 10-1 Dark Side 383 Barely Tolerable!

Great Insight You Bring To The Table As A Racer Having Multiple Motors!

Steve

[mike223]

It's not too much power but too little traction that makes a car hard to handle. You have to understand how to set-up the rear to hook when you start adding power. Really not that difficult.



According to my Speedhut GPS speedometer, I can and have repeatedly run 0-60 in 2.99 seconds @ ~140' on 200TW NT05s.

I will freely admit that 3.51 seconds @ ~180' is a lot more common.

Any noticeable mistake with the skinny pedal and it's going to be more like 3.76 to 4.01 in ~200'.

It's something I practice a lot.


Now, what specific modifications to the FFR roadster IRS do you think would hook that tire up better?

And are those modifications likely to screw me in autocross at the end of a straight coming off throttle fast and on the brake hard and then throw it into a corner?

[NAZ]

Traction is really a result of friction between the tire and the road surface. Friction is (almost) proportional (rubber’s coefficient of friction is not quite constant) to the force being applied to the tire holding it in contact with the road and the coefficient of friction of the road surface & tire compound. So, the way to increase traction is by applying more force holding the tire in contact with the road and or increasing the tire compound coefficient of friction (stickier tires).

Mike, you're definitely at a disadvantage using IRS as it can take significant anti-squat to plant the tires hard and make them hook with more than moderate torque & street tires. Doing so with IRS is more complicated than with a solid axle and can create some undesirable roll steer. It's a challenge to make a front engine IRS hook and still corner. You can do an internet search and find ideas on how to improve traction on your IRS.


The easiest way to increase traction on an IRS is through selection of tire compound. Weight distribution is a bit more challenging with a front engine car, especially a small car like the roadster.


It’s much easier with a solid rear axle. You can run lots of anti-squat with a solid axle and still achieve optimum roll center with minimum or zero roll steer. And even with lots of anti-squat there are ways to eliminate rear tire unloading during hard braking by using some dirt track suspension tricks. A solid axle can be set-up to handle great on a road course and will excel in planting big HP for straight line acceleration.

We can add mass (increasing the car’s weight) over the rear tires to increase traction but adding weight is a performance killer. It's better to use weight transfer to load the rear tires as we are not adding mass to the car. To do this we can shift weight over the rear tires by physically moving components to the rear but this can also increase polar moment and have undesirable handling traits. Or we can shift weight to the rear using our suspension set-up. This is how I can couple >10,000 lb ft of torque through 3.90:1 rear gears from a standing stop and hook the tires. And anyone with a FFR Hot Rod or Roadster can do the same thing if using a solid rear axle. It takes some knowledge and fabrication skill -- knowledge of suspension set-up and skill to add brackets to facilitate adjusting the suspension to achieve optimal settings. And if a builder lacks the knowledge and skill, there are plenty of shops around the country that can do this work.

So, this is why I say of the tires are smoking look to the rear of the car for the solution not under the hood.

[Avalanche325]

I have a 500hp 347 and a TKO 600, I did the Liberty's gears upgrade after I tore up my 3rd gear synchro. It had to be the leak it had from day one, not my bad shifting. ;-)
It does shift better, especially over 6000 rpm.

The more HP you go for, the more important it is that you learn to properly handle it. On the street is not where you will learn. IMHO, autocross is the best place to learn your car and sharpen your own skills. If you do, and you should, plan on autocross or track, go with NT05s. Drag radials are for going straight.

If you wife beats you at the stop light, invite her to autocross or a track day.

[mike223]

You have to understand how to set-up the rear to hook when you start adding power. Really not that difficult.







Mike, you're definitely at a disadvantage using IRS as it can take significant anti-squat to plant the tires hard and make them hook with more than moderate torque & street tires. Doing so with IRS is more complicated than with a solid axle and can create some undesirable roll steer. It's a challenge to make a front engine IRS hook and still corner.

The easiest way to increase traction on an IRS is through selection of tire compound. Weight distribution is a bit more challenging with a front engine car, especially a small car like the roadster.




I already knew NAZ's answer - because we've discussed it rather specifically previously.

I just wanted both answers in one place so the OP can see that neither of us is misleading him.


For what I want out of my car - I'll take IRS + 2.99 on 200TW for now.

I'll probably try one of the 100TW tires next time....

[NAZ]

Mike is a sharp guy with experience -- he's not misleading anyone.

Like so many things out there, there are more than one way to do things -- and it's not a question of one way is right and the other is wrong. FFR provides a simple to build kit car that inherently performs well on the street. But the design is limited as it is intended to accept OEM drive train components that the average guy can install and go have fun with. And if you build it by the manual you are limiting your performance to the constraints of a high-production passenger car design. Not a bad thing, as they still scream. But Wait, There's More!

Some of us think that more power = more fun and go through some extra effort to optimize what FFR gave us to work with. If you're one of those ""hair on fire -- need for speed" you CAN run more power in these cars and still have a controllable street beast that is way more fun to drive. If you're the kind that can't leave anything "stock" and have to make it faster with more power like Tim The Toolman Taylor, it can be done and it's not really rocket science.

So build it like you want and don't let anyone tell you you can't have more -- it just takes some extra effort and $$.

[SteveP]

Ok, all you guys convinced me. Just ordered the TKO. Naz, thanks for the input. Some day I'll come and see your car. I usually spend Spring and Fall in Mesa but there are too many issues with the drive down now. Maybe May will work.

[NAZ]

Steve, swing by one of these days -- there's always cold adult beverages in the fridge.

[RoadRacer]

Steve's Stupid Question From The Dark Dart Side:

Has anybody successfully used a Richmond Gear 5-Speed?

https://www.richmondgear.com/wp-content/uploads/pdfs/richmond/RG22.pdf

It is similar in size to my ZF 6-Speed Gearbox, which also has the shifter hanging off the left side, but the shifter for the Richmond is 4-5 inches further forward.

I loved Doug Nash/Richmond, in a previous all-custom-built car.

[TrevorP]

I have a Gforce GF5R and it looks very similar to the richmond gear box. It has all the shifter controls on the left side using linkages. The case looks the same too. Can't find a good picture

https://www.jegs.com/i/G-Force+Transmissions/468/VN1000/10002/-1?msclkid=5dd2d8eacc0213c0fb1886690e1b2938&utm_source=bing&utm_medium=cpc&utm_campaign=BSC%20-%20All%20Products&utm_term=4579328492864333&utm_content=All%20Products