C4 Brake upgrade
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Originally Posted by FELNGR8
I believe GM engineered the car for the 90% of drivers who can't handle race car precision.
Melting Slicks
Joined: Feb 2006
Posts: 2,753
Likes: 15
From: backwoods upstate ny
Originally Posted by CentralCoaster
Since we're both guessing, I believe GM hired an underpaid, undereducated intern to size the bias spring and caliper pistons.
i'm not tryin to hose down playing with your brakes, but if you let anybody drive your car who might not be in the top 5% of drivers,don't get them in over their head.
and i'm not guessing when i tell you that its a real thrill to be sitting in turn one, facing the wrong way, with 30 guys coming at me at over 120 mph, cause i turned the prop valve up a little too much
Last edited by redrose; May 6, 2006 at 08:49 AM.
Racer
Joined: Feb 2005
Posts: 381
Likes: 0
From: Daytona Beach Florida
The C4-5 brake upgrade is a total F*ckin nightmare!
My C4 has been on a lift at Tire Kingdom for the last 28 days.... I am doing the C4-C5 brake upgrade and this is the biggest pain in the a$$ I have ever experienced bar none!
I will never, ever upgrade or change anything mechanical on a car again.
Bear's 2-piece Eradispeed rotors (C5's) did not fit right, sent them back, I paid shipping! Had my front C5 calipers powdercoated by Mike (a bang up job) then the greasy monkey mechanic chipped the powdercoat off as he installed my new TT2 wheels. The front TT2 wheels did not allow enough room for the C5 caliper! Damn! Now I am asking myself "what the f*ck am I doing?". I could be in the tropics!
Now, the front calipers are rubbing! Tomorrow I grab take my sorry a$$ to the f*ckin' dealer to figure this bullsh*t out, then I take one side apart again and send the caliper back to Mike the powdercoater to correct what the Tire Kingdom mechanic grease monkey did.
Do it yourself! Or take it to someone your trust!
One more thing, some of you guys don't know sh*t from shiola, now get with the program and start advising your fellow vette brother correctly.
I will never, ever upgrade or change anything mechanical on a car again.
Bear's 2-piece Eradispeed rotors (C5's) did not fit right, sent them back, I paid shipping! Had my front C5 calipers powdercoated by Mike (a bang up job) then the greasy monkey mechanic chipped the powdercoat off as he installed my new TT2 wheels. The front TT2 wheels did not allow enough room for the C5 caliper! Damn! Now I am asking myself "what the f*ck am I doing?". I could be in the tropics!
Now, the front calipers are rubbing! Tomorrow I grab take my sorry a$$ to the f*ckin' dealer to figure this bullsh*t out, then I take one side apart again and send the caliper back to Mike the powdercoater to correct what the Tire Kingdom mechanic grease monkey did.
Do it yourself! Or take it to someone your trust!
One more thing, some of you guys don't know sh*t from shiola, now get with the program and start advising your fellow vette brother correctly.
Last edited by gringoray; May 12, 2006 at 01:18 AM.
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Originally Posted by gringoray
I will never, ever upgrade or change anything mechanical on a car again.
...
One more thing, some of you guys don't know sh*t from shiola, now get with the program and start advising your fellow vette brother correctly.
...
One more thing, some of you guys don't know sh*t from shiola, now get with the program and start advising your fellow vette brother correctly.
I got nothing but naysayers when I asked about the c5 adapters working with my Wilwoods. Funny though, how none of those people had actually tried the work I was asking about. I went ahead and got some cnc'd and they bolted right up. This forum is 90% regurgitation and 5% bogus guesswork. The rest is first hand experience.
So what's shiola?
Racer
Joined: Feb 2005
Posts: 381
Likes: 0
From: Daytona Beach Florida
The biggest problem was the Bear rotors, those expensive one's, they did not fit the front spindle, then the C5 caliper brackets was rubbing my new rotors I got from VBP, I shimmed that down, then I got the wrong size TT2 wheel. I got the 9.5 size and the spokes hit the caliper. I could send the wheels back and get front 11x17’s but that’s more $$$ for storage and shipping etc.
Pep boys sells spacers and they did work for now but I'm worried the spacers might break or something - they're not exactly high tensil steel. The spacers allow the 9.5 TT2 wheel to strick out more - no hitting of the calipers now.
After all this, the pads are making a lot of noise - factory pads no less. The worst part is the mechanic chipping the newly powdercoated calipers. Now I fell like going to Sears and buying a f*ckin jack, stands and torq wrench and do this bullsh*t myself.
At any rate, tomorrow @ 7 I'm taking the piece if sh*t vette to f*ckin dealer.
I feel like I’ve just wasted a **** load of money.
Pep boys sells spacers and they did work for now but I'm worried the spacers might break or something - they're not exactly high tensil steel. The spacers allow the 9.5 TT2 wheel to strick out more - no hitting of the calipers now.
After all this, the pads are making a lot of noise - factory pads no less. The worst part is the mechanic chipping the newly powdercoated calipers. Now I fell like going to Sears and buying a f*ckin jack, stands and torq wrench and do this bullsh*t myself.
At any rate, tomorrow @ 7 I'm taking the piece if sh*t vette to f*ckin dealer.
I feel like I’ve just wasted a **** load of money.
Last edited by gringoray; May 12, 2006 at 01:41 AM.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
One more thing, some of you guys don't know sh*t from shiola, now get with the program and start advising your fellow vette brother correctly.
One more reason to not post advice unless you KNOW its correct and have spun the wrenches yourself. Guessing and requoting "internet and magazine reads" does nobody any favors.
Thread Starter
Burning Brakes
Joined: Jan 2005
Posts: 1,217
Likes: 0
From: Augusta GA
More info which is good to know. I got 17's in the front and when I do the upgrade I am going to start with 1 side first and make sure everything fits fine before I do the other. If things are not right I will put it back together then get whatever I need to make it right. 
Melting Slicks
Joined: Mar 2001
Posts: 2,149
Likes: 303
From: Timra, Sweden
I am working on another 'big brake' option for my 1984.
I am using BMW 540 front rotors. They have almost exaclty the same size as C5 rotors but much more 'offset' to help the caliper clear the spokes on the rim.
C5 rotors are 323mm in diameter and 32mm thick.
The BMW rotors are 324mm in diameter and 30mm thick.
With Wilwood forged superlite 4-piston calipers they clear my stock 1986 16"x9.5" wheels without any spacers.
I am using BMW 540 front rotors. They have almost exaclty the same size as C5 rotors but much more 'offset' to help the caliper clear the spokes on the rim.
C5 rotors are 323mm in diameter and 32mm thick.
The BMW rotors are 324mm in diameter and 30mm thick.
With Wilwood forged superlite 4-piston calipers they clear my stock 1986 16"x9.5" wheels without any spacers.
Last edited by JoBy; May 12, 2006 at 07:58 AM.
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Drifting
Joined: Sep 2004
Posts: 1,638
Likes: 3
Bigger Brake rotors = less HP to the track
You guys know alot more about brakes than I do - but I just wanted to remind anyone who doesn't remember - larger rotors = more rotating mass = less power available for speed. Stop fast = start slow.
someone here did the math in the past - and it was suprising how many ponies were being syphoned off. (I want to say 8 or 10 - but I'm old - I can't remember stuff anymore)
Carl Johansson
someone here did the math in the past - and it was suprising how many ponies were being syphoned off. (I want to say 8 or 10 - but I'm old - I can't remember stuff anymore)
Carl Johansson
Originally Posted by JoBy
I am working on another 'big brake' option for my 1984.
I am using BMW 540 front rotors. They have almost exaclty the same size as C5 rotors but much more 'offset' to help the caliper clear the spokes on the rim.
C5 rotors are 323mm in diameter and 32mm thick.
The BMW rotors are 324mm in diameter and 30mm thick.
With Wilwood forged superlite 4-piston calipers they clear my stock 1986 16"x9.5" wheels without any spacers.
I am using BMW 540 front rotors. They have almost exaclty the same size as C5 rotors but much more 'offset' to help the caliper clear the spokes on the rim.
C5 rotors are 323mm in diameter and 32mm thick.
The BMW rotors are 324mm in diameter and 30mm thick.
With Wilwood forged superlite 4-piston calipers they clear my stock 1986 16"x9.5" wheels without any spacers.
Melting Slicks
Joined: Mar 2001
Posts: 2,149
Likes: 303
From: Timra, Sweden
One pound extra on the rotor is worth about 1.3 pounds extra on the car if you compare acceleration performance.
Having installed a 4L80E that is about a 100 pounds more than the th700 ... the extra weight from the rotors does not matter much to me.
On a local race track the stock brakes did not even last one lap before overheating ... so I need brakes that can handle more heat.
Having installed a 4L80E that is about a 100 pounds more than the th700 ... the extra weight from the rotors does not matter much to me.
On a local race track the stock brakes did not even last one lap before overheating ... so I need brakes that can handle more heat.
Too bad.
Melting Slicks
Joined: May 2002
Posts: 2,670
Likes: 4
From: Severna Park MD
Originally Posted by cuisinartvette
One more reason to not post advice unless you KNOW its correct and have spun the wrenches yourself. Guessing and requoting "internet and magazine reads" does nobody any favors.
The only performance oddity I find is the ABS kicks in when braking hard while turning in to a corner. If I complete my braking before turn in then there is no ABS interference. It does serve to warn me when I'm at the limit of grip and should modulate the brakes carefully. All-in-all I find the J55 brakes to be more than good enough for hard road usage, but that goes against the collected wisdom of the gurus on here. So I'll leave it to the gurus to guide the masses on brake selection.
So long, and I'll keep my setup to myself thank you.
Race Director
Joined: May 2000
Posts: 17,101
Likes: 4
From: No more yankee my wankee, the Donger is tired!
Originally Posted by Carl Johansson
You guys know alot more about brakes than I do - but I just wanted to remind anyone who doesn't remember - larger rotors = more rotating mass = less power available for speed. Stop fast = start slow.
someone here did the math in the past - and it was suprising how many ponies were being syphoned off. (I want to say 8 or 10 - but I'm old - I can't remember stuff anymore)
someone here did the math in the past - and it was suprising how many ponies were being syphoned off. (I want to say 8 or 10 - but I'm old - I can't remember stuff anymore)
Yes because stopping is highly overrated
Le Mans Master
Joined: Oct 2004
Posts: 7,706
Likes: 485
From: Everett WA
C4 of Year Finalist (appearance mods) 2019
Originally Posted by gringoray
then I got the wrong size TT2 wheel. I got the 9.5 size and the spokes hit the caliper. I could send the wheels back and get front 11x17’s but that’s more $$$ for storage and shipping etc..
This is a silly question but, when you ordered the TT2's did you specify that you were going to be upgrading to a C5 setup?
I am not an expert but from what I have been told, using wheel spacers is something that should be avoided if at all possible because it places undue stress on the rest of the suspension. Jeff can you comment to this point?
Melting Slicks
Joined: Mar 2001
Posts: 2,149
Likes: 303
From: Timra, Sweden
Originally Posted by CentralCoaster
What is the hub bore on the BMW 540 rotors? I know the bolt pattern is close enough to fit.
Or are you using 2pc 540 rotors with corvette hats?
Or are you using 2pc 540 rotors with corvette hats?
Race Director
Joined: May 2000
Posts: 17,101
Likes: 4
From: No more yankee my wankee, the Donger is tired!
Originally Posted by Mr. Peabody
Jeff can you comment to this point?
Spacers are fine as long as they are used properly. Meaning, not to much, and if they are affixed to either the hub or the rim itself. Some rim manufacturors provide threaded holes in the back of the rim to apply a spacer if needed.
Racer
Joined: Feb 2005
Posts: 381
Likes: 0
From: Daytona Beach Florida
Yes, if I recall, I did mention to Luke (Tire Rack) that I was doing this upgrade, he said it would work. TT2's only come in one offset for the 9.5 wheel and I don't want to change to the next size up wheel now!
The spacers are between the rotor and the back of the TT2 wheels - fronts only, it's a round steel piece of metal with a bunch of holes (Pep Boys product) and today the local "Corvette specialist" at the dealer says everything looks okay.
I guess I could go back to stock or the J55/GS calipers, will they work without spacers?
The spacers are between the rotor and the back of the TT2 wheels - fronts only, it's a round steel piece of metal with a bunch of holes (Pep Boys product) and today the local "Corvette specialist" at the dealer says everything looks okay.
I guess I could go back to stock or the J55/GS calipers, will they work without spacers?
Melting Slicks
Joined: Mar 2001
Posts: 2,149
Likes: 303
From: Timra, Sweden
I took some pictures of the BMW rotor and Wilwood caliper.
The small rotor is the stock one. ( 290mm x 20mm )
The BMW rotor is 324mm X 30mm.
As you see I had to modify the BMW rotor in a lathe to clear the bolts for the caliper on the knockle.
( Click to enlarge )
The small rotor is the stock one. ( 290mm x 20mm )
The BMW rotor is 324mm X 30mm.
As you see I had to modify the BMW rotor in a lathe to clear the bolts for the caliper on the knockle.
( Click to enlarge )
Last edited by JoBy; May 13, 2006 at 03:09 PM.