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LOL we're are looking at how small of brakes we need to stuff 15" wheels on the front... considering going down to 10" rotors. But, we autox, so we aren't too worried about heat. A lot of the CSP Miata's are down to 9.25" front rotors to save on unsprung weight.
Yeah, you autox guys can run some stupidly light/small rotors. I've seen some that look like Swiss cheese. I mean seriously? This:
http://www.autocross.us/forums/uploa...1262268326.jpg
Those wouldn't last a single session at Road America.
-j
OK, perhaps a little hyperbole, but there are other fancy pedal boxes out there. The brake specialist said they were sweet and are gentler on the cylinders since they push straight. Lol. Perhaps money could be better spent.
I was also told (please no eye-rolling just yet) that there is the three inch rule for calipers and wheels. A "good" 12" rotor and caliper should fit in a 15 inch wheel. However, I could not find a 17" wheel for my 14" BBK due to offset issues and cost.
The comment about auto X was about the issue of mass of a larger rotor. Not only unsprung weight but the rotational mass and the gyroscopic resistance effect. I think there is a technical automotive term for it. Quick transitions would see more resistance to turning, the larger the rotor and the faster it is spinning. When I asked about the trade offs of large brakes he said it was worth it in road racing in most instances.
On my OEM Subaru wheels and rims. The 11.5" rotors/brakes barely fit in 16" rims. So for OEM Subaru it is more like a 4.5" rule.Quote:
Originally Posted by Scargo
I would warp that on the street, never mind a racetrack. hole-lee crap.Quote:
Originally Posted by Santiago
Fun baby steps. Finished overhauling and beautifying the rear uprights. Made aluminum inserts to replace the rubber bushings.
I mounted a wheel from my STi. That's a 18x10.5" Enkei RPF-01, (38ET) and BFG 275-35's, the equivalent of a Hoosier 285. What you can't see is a 10mm spacer. Just about absolute minimum for this setup to make things clear. Wheel has too much offset to the inside to work. Baby needs new shoes! Body needs flares.
Caveat: No alignment has been done; just eyeballing angles and axles are not in. There's some droop in this mockup.
Now I have to buy the proper length bolts and thinner Heim joint spacers or go back to the lathe. That's high-performance rattle-can enamel I baked on. All new bearings and seals. There's some Rasmus OCD engineering going on too.
Attachment 35950Attachment 35951
Looks good, what size wheel and tire is that?
not running any e-brakes?Quote:
Originally Posted by Scargo
That there is an R-car... :cool:
No real need for an e-brake on a dedicated track car that will never see the street. I'm not running one on mine either.
Best,
-j
I thought so... that's what he was referring to with the Rasmus OCD engineering ;)
What do you do if you lose brake hydraulics on track?Quote:
Originally Posted by Santiago
Jerome, you pray and downshift for all it's worth.
I think you're yanking our chain. You've been on the track.
I don't think the E brake is going to help you going 100 mph into turn eleven at Sonoma
The real question is, how are you going to drift it around a parking garage in Tokyo?
No to mention all the wood blocks you'll have to lug around to keep the thing from rolling down hills when parked.
If only you could park it in gear..Quote:
Originally Posted by STiPWRD
Our miata has a sticky ebrake. We haven't used it in a year. Hasn't been an issue for us..
Touche, I had remote start so leaving the car in gear is something I hadn't done in a very long time and had all but forgotten about it.Quote:
Originally Posted by xxguitarist
Racing is a different world. You have to warm things up. Tires brakes, oil must be warmed. Once I spun out on a new set of greasy R compound tires on the first turn! It was if I was on ice.Quote:
Originally Posted by STiPWRD
Then you do the reverse. When you come off the track you should have done a cool-off lap, or a minute or so at a slow pace...
When you stop you do not engage a parking brake or sit on your brakes. The pads can stick to the rotors!
Hopefully you are cooled down enough that you can kill the motor and have it in gear. Otherwise, you need a level spot, a crew to chock your wheels or you jump out and do it yourself, without setting the handbrake,(again, IF you have one).
I'm not sure that I would drive a car on track without an e-brake... Too much there to go wrong. Admittedly, it's not going to STOP you in the event of a brake failure... But, it can slow things down enough or give you an extra moment to point at something else...Quote:
Originally Posted by Scargo
Time to take a step back and think about it:
When using the brakes at a track, you wait till the last possible second and use them HARD, just like you accelerate hard. Deceleration is as or even more important than acceleration to lap times. By the time you realize you have no brakes something else is reducing your velocity at a very rapid rate. :(
I thought this was a joke, but apparently not. Plenty of us don't ever use the e-brake with dedicated track vehicles. This is because they're not really "emergency" brakes, they're parking brakes and you don't use them for the reasons Glyn mentioned.
As for using them as a legitimate emergency measure, I think it's definitely time to think about that. So here's the scene: you're deep into the entry of a corner when you realize you are have catastrophic brake failure (I say that because you have two independent hydraulic lines that would have to fail simultaneously; but that's another matter). Now you decide to pull the e-brake as a way to stay safe? Not only is it not going to stop you, it's almost certainly going to spin you unless you're going straight on. The move is just as likely to make things worse as it is to help - and I suspect it's really more likely to make things worse. You've just locked up your rear tires right when you're in a mood to take evasive measures...I'd rather not.
Best,
-j
All joking aside, is the argument against e-brakes (in a racing application) basically the weight penalty and the tendency to spin out when trying to use it in a turn? Or maybe the lack of reaction time between realizing the hydraulic brakes have failed to pulling the e-brake? What about emergency braking in a straight line if space will allow?
Regarding the cool down period, I can see how the brake pads could stick but wouldn't the e-brake shows be ok to use for parking since they would have been relatively unused during the racing? Or would the rotors still be too hot?
I don't have much road racing experience to this is all educational for me, I appreciate everyone's input. One of these years I'd like to get more into racing.
It is a weight penalty and a complexity you do not need or want in road racing. In autocross there might be a need for the handbrake, but in my last few years of doing auto-X I never saw a lone cone, where you had to do a "Uey" or a 360 around it. Rally or drifting might use them but not in road racing. Maybe in the movies...
Regardless of whether it's used on a road circuit or not, which it's not, you can have it get stuck. I was explicitly warned about this several times by my Subie buddy (ex-SCCA racer and driving instructor of eight or more years). It may be the shoe material and the heat built up in the drum and/or the contraction of the drum as it cools.
With the stock or add-on brake systems (I believe the Wilwood is this way), you will need some or all of the backing plate to hold the caliper. I will not even use the backing plate unless I decide to use some of it to hold a cooling duct in place.
This ebrake thing is cracking me up. I have never needed an ebrake, no race car I have driven has had an ebrake, if brakes fail on the track, you won't know until it's too late, and you won't be thinking "ebrake".
People have been watching too much Fast and Furious.....
It's added weight, ditch them.
We won't use our E-brake for the pin turns, but for Pro-SOLO (a drag race that suddenly turns into auto-x) there are some staging zones with a slope, so many will use the e-brake to hold staging position while the tree drops.Quote:
Originally Posted by Scargo
This is why you do not have 1 hydraulic system on the brakes.. you have two. The front and rear units are completely separate, linked only by the shaft within the master cyl.Quote:
Originally Posted by JeromeS13
That said, if BOTH went out and you had to stop within the distance of the PARKING brake, you can downshift to 1st and use the clutch.
I know I've been quiet about my build. I've been restoring a Logan 200 lathe.
Attachment 36439
I just purchased a comprehensive set of Subaru specialty tools for less than half price.
Company 23 tools:
AVCS Int Cam Sprocket Tool
Dual AVCS Exh Cam Sprocket Tool
Camlock Tool 1
AVCS Security Socket
Axle Pin Tool
Grimmspeed - crank pulley tool
Snap On - Subaru ball joint removal tool
If anyone in the area needs to borrow any of these you are welcome to use them. I'll have them in a couple of days.
I should have axles on the car in a week. I'm trying to find someone to help me with the front suspension design. I just Received "Competition Car Suspension by Allan Staniforth. I hope to learn from it.
My current plan is to use these spindles and 13" Stoptech Trophy brakes front and rear. Working with Zeckhausen, I have submitted a "race car data sheet" on the 818. Through them, Stoptech is evaluating my needs and I should have their opinion soon.
I made more parts acquisitions, including a MAC four-port valve for the turbo.
Posted this elsewhere:
https://fbcdn-sphotos-g-a.akamaihd.n...38f6c1d12c4a34https://scontent-a-ord.xx.fbcdn.net/...5b&oe=55130523
My 275 Goodrich R1s on 10.5"x 18 with 38 ET wheels and 10mm offset.
I received my heavy-duty CV joints from The Driveshaft Shop yesterday and I found time to get one mounted. This is an all STi rear with an STi rear axle. Shown is the hub at 3.25 inch ride height. My hubs are 62.4 inches apart. Basic alignment is done for camber and toe.
With my 10.5 inch wide wheels and spaced to the equivalent of a 28ET I barely clear the arms. A 10 inch rim would fix everything.
Attachment 36570Attachment 36571Attachment 36572
A question I have is about the axle offset. Look at the third picture of the axle and lateral arms. It's over an inch and a half and perhaps as much as two inches. Is this normal?
1.5" is normal AFAIK. What were you expecting, exactly?
You should see mines, not only I will get 2x that, but they are offset back of the axle centres on the tranny! :)
Don't know what to expect. Wheels farther back so it's squarer? I haven't seen any pictures of the axle in relationship to the Lateral links and outer hub on other people's cars.
I am adapting 2006 Honda S2000 front spindles (some may call them knuckles) to my car. Major brake options are available and the geometry looks good. Thought this is not a "money is no object" solution, they are beefy and light and well-designed. I'm thinking that I will have to move the steering rack mounts up or remake them.
Looks like four-pot Stoptech Trophy 12.9" brakes front and rear. Actual piston size combo TBD. I'm working on the LCA design and should have something mocked up soon.
Also I will go with 17" wheels front and rear. My best-guess so far is 235's on 9" x 50 ET fronts and 255's or 275's on 10" x 28 ET rears.
Attachment 37091
Attachment 36867
Looks like what I'll run front and back.
Front: 328 x 35mm rotors and ST-40 calipers. Pistons sizes TBD.
Rear: Race-only (no parking brakes) rear ST-40 kit for the STi that uses 328 x 28mm rotors. That kit is p/n 87-838-0043. I have stripped the rear backing plates down to just the thick piece that holds the caliper. I will rotate it and run the caliper at the 7 to 9 o'clock position (if you are on the driver's side looking at the rear wheel).
Attachment 36868About a dozen spot-welds drilled and using a 5/8" drill bit rids me of the detritus. I can then rotate it 180 degrees and have a more racy mounting point (low and inside , as they say in BB).
Thanks to Zeckhausen Racing for the recommendations! I did a data sheet that went to Stoptech and then Dave took over.
What's the major advantage of the S2000 spindles over the Subaru ones? Just curious since I'm not familiar with them. We've pondered the idea of an S2000 steering rack since we love the quick steering response of the S2000, but that will likely be a next winter project if we do that.
I'm not going to show you the spindles just yet, as I am cleaning them. They weight 13-1/2 pounds. I can't remember the number... Perhaps someone else knows what the WRX setup weights. However, I want to say 19 pounds.
However, this is what got me started on them:
http://home.tiscali.nl/onlinestorage...nsionSmall.bmp
The lower ball-joint bolts on and the ball-shaft plugs into the LCA, like Subaru's. The bolt-on mount opens up all kinds of avenues for modification, as in spacers, offset and as shown below, really quick steering.
https://csgarage.files.wordpress.com...-800-copy1.jpg
Or...
http://image.nengun.com/catalogue/35...ng_knuckle.jpg
What's wrong with the Subaru upright/spindle/knuckle? I've been asked that a lot. Here's the summary:
It is a "one-size fits all" approach to a kit car suspension. Fine if you're building a DD or sunny day car.
The WRX upright is HEAVY. It's meant for a 3,500 pound car that can run rallys. Way too much unsprung weight.
The suspension is based on an AWD, McPhearson strut part that's adapted into unequal-length A arms. Just that conversion adds more unsprung weight and more pieces bolted together and something else to fail.
The steering is slow. I want something in the order of 12:1.
The WRX rack is heavy. You must de-power it and it has unnecessary bulk.
The LCA is very limited in its adjustability. Certainly not infinitely adjustable within a range that you would want with a race car.
Won't take tires over 24.5 OD. Some combos rub at full lock and hit at the corner of the chassis. While this may be workable, it is limiting in choices of wheels and tires.
It's too compromised for a real race car. It's based on an affordable donor car approach.
I contacted Anze Engineering, since they are nearby, offer Penske shocks and seem like a major player in suspension design in the NE. The prez, Angelo Zarra called me personally and I was impressed with what he can offer. He had done some homework on the 818R before calling. Previously he has done some FFR Cobra suspensions.
I will be sending him a front and rear red Koni for them to evaluate. Seems someone else had the red shocks dyno'd. I would sure like to know who that was/get those numbers for comparison.
In the meantime I have been learning CAD all over again and expect to be getting some brackets made shortly for the front suspension redesign. I'm looking for a shop that will cater to the DIY'er.
I'll have the S2000 uprights cleaned up and rebuilt in a few days. I've almost finished building a sandblasting cabinet out of our old AC heat exchanger box.
I'm also trying to settle on some rims. I may have a buddy with some Porsche staggered-sized take-off slicks that may be perfect for the first tire shodding iteration. Still puzzled why no-one else is running 17's in the rear.
Very cool man, I will stay tuned. I am plaining on building an R down the road so your front suspension ideas our great.
Stick shift84 is running 17's all aroundQuote:
Originally Posted by Scargo
I have 17's all around also.
Oops! Missed that. I can't find anything about stickshift's wheels/tires.
I am closing in on the sizes I want to run. I'm guessing (though I've been fitting some things so it's not a WAG) that it will be 9x17 50 ET front and 10x17 35 ET rear and 235x40 and 255x40 tires at first. I will have a bigger track based on the S2000 uprights and custom LCAs.
I have another oops. I misspoke about the spindle weight. With all pieces weighed they are more like 15 lbs, 14 ounces (with ARP long wheel studs).
We currently have 17x8 with a 45 offset on the rear, with 255/40/17 tires. I wouldn't want them to be any closer on the inside. Using this calculator here , to run a 17x10 wheel and have the same clearance, you would need an offset of 20. Of course this is not accounting for all factors and I don't know how your spindles change things.
We are planning on running different race wheels likely, 15's up front and 17's in the rear for the most tire choices. For dailies, these are Enkei Pfo1's, 17's all around.
Here's a photo of ours, alignment not yet set: http://i1374.photobucket.com/albums/...ps2cda8397.jpg