J55's Really are Worthless
02-12-2007, 10:22 PM
#1
Melting Slicks
Thread Starter
J55's Really are Worthless
After spending the last three years band-aiding these brakes(cooling ducts, SS pistons, Motul 600, air deflectors) I finally had brake failure at Laguna Seca today when the caliper spread to such an extent that the pistons extended to a degree that I lost fluid. My first indication was extreme outside pad taper that wore a new pad to the backing plate in two sessions. When I changed the pad, the pistons didn't seem entirely perpendicular to the rotor. Luckily, I did turn a 1:48.4 before the brakes packed it up. No damage was done other than a blistered finger from changing pads, I shoved the pistons back in, put in new pads and drove it with a very soft pedal home 100 miles. I only wish I had gone the Wilwood route three years ago.
02-13-2007, 12:22 PM
#2
Burning Brakes
After spending the last three years band-aiding these brakes(cooling ducts, SS pistons, Motul 600, air deflectors) I finally had brake failure at Laguna Seca today when the caliper spread to such an extent that the pistons extended to a degree that I lost fluid. My first indication was extreme outside pad taper that wore a new pad to the backing plate in two sessions. When I changed the pad, the pistons didn't seem entirely perpendicular to the rotor. Luckily, I did turn a 1:48.4 before the brakes packed it up. No damage was done other than a blistered finger from changing pads, I shoved the pistons back in, put in new pads and drove it with a very soft pedal home 100 miles. I only wish I had gone the Wilwood route three years ago.
02-14-2007, 10:19 AM
#4
Melting Slicks
You can put reinforcing rods in the calipers. Also run plates, either old pad backing and or heat sheilds to keep the pistons retracted. But if you run the brakes hard, you should really upgrade. The C5 calipers are far superior at a low cost. The Wilwood GN isnt pretty, but are the best for the cost. Awesome 1 3/8" rotors. It only important to have them at the front if cost is a concern. I think the SL6 is also available thats a bit superior.
02-14-2007, 02:56 PM
#8
Team Owner
Are the calipers original equipment? Over the years, the stress placed on them could have caused a gradual tapering and they finally got too wide to work.
I replace my stock C4 calipers every three years to avoid problems. But I agree that going to a C5 caliper setup would be a big improvement and at a lower cost than Wildwood or race-specific equipment. Some tracks are much harder on brakes so that has to be taken into account too.
I replace my stock C4 calipers every three years to avoid problems. But I agree that going to a C5 caliper setup would be a big improvement and at a lower cost than Wildwood or race-specific equipment. Some tracks are much harder on brakes so that has to be taken into account too.
02-14-2007, 04:09 PM
#9
Team Owner
Member Since: Mar 2001
Location: Boston, Dallas, Detroit, SoCal, back to Boston MA
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The J55's are a good street and autocross caliper. Light weight for the stopping power. But, they really start showing their limits at long track sessions.
The C5's are better, but they're still a sliding caliper design.
You're really better off with the Wilwoods.
The funny thing is the C3's came with 4pot calipers.
The C5's are better, but they're still a sliding caliper design.
You're really better off with the Wilwoods.
The funny thing is the C3's came with 4pot calipers.
02-14-2007, 08:32 PM
#11
Racer
Member Since: May 2005
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You can put reinforcing rods in the calipers. Also run plates, either old pad backing and or heat sheilds to keep the pistons retracted. But if you run the brakes hard, you should really upgrade. The C5 calipers are far superior at a low cost. The Wilwood GN isnt pretty, but are the best for the cost. Awesome 1 3/8" rotors. It only important to have them at the front if cost is a concern. I think the SL6 is also available thats a bit superior.
The SL6 is superior, unfortunately after contacting Wilwood they told me for a C4 you can only fit the 1.10 rotor under that caliper. 1.10 is the stock J55 size... not much of a heat sync. I think the 1 3/8 rotor is the better way to go with the GNIII caliper just not sure how much modification is needed for it to fit. Now if you can get the 1 3/8 under the SL6 That I would at least consider.
Another consideration is the less known Brakeman set up which I heard some good things about, the system uses a 4 piston caliper which has a Cro-moly bridge connecting the 2 aluminum 1/2s. 1 3/8 rotor also can be had for the C4 even though not listed on the web page. The steel will not spread therefore the calipers do not use differential size pistons, just 4 large pistons. Aluminum will start to spread at anything over 500 degrees I beleive, therefore the need for the different size pistons in the SL6.... it prevents pad taper.
Some "A" sedan & guys run Brakeman & love them! Some Northeast Iron Guys picked the brakeman over the Wilwood & Brembo. At $2,700.00 its not cheap. Anyone using brakeman set up for racing a C4?
Decisions, decisions.
Last edited by fmrfast; 02-14-2007 at 08:36 PM.
02-14-2007, 10:00 PM
#12
Drifting
We pound the crap out of our car and GS brakes work very well.
02-14-2007, 10:40 PM
#13
Melting Slicks
Thread Starter
It was a J55 using KFP Purple race pads. It had about 4 or 5 events on it. Previously, I had GS calipers on it, which lasted 3 years(20+ events) but eventually the pad taper became excessive and consumed too many expensive pads. Any pictures of the reinforcing rods? Also, how do install pad backings with new pads; aren't the pistons fully retracted? I wanted to burn through my inventory of race pads before ditching this setup. Thanks for all the input.
02-14-2007, 11:13 PM
#14
Safety Car
maybe you need a more agressive pad ????
more agressive pad = less pedal force = less strain on caliper.
at least in theory................. just more heat into the rotor.
try the GS calipers with a more serious pad, like PF01's.... Many have been sucessful with the GS setup.
It would actually be more cost effective to buy GS calipers every 3 years than a major brake upgrade.
(I never heard of that purple pad)
more agressive pad = less pedal force = less strain on caliper.
at least in theory................. just more heat into the rotor.
try the GS calipers with a more serious pad, like PF01's.... Many have been sucessful with the GS setup.
It would actually be more cost effective to buy GS calipers every 3 years than a major brake upgrade.
(I never heard of that purple pad)
Last edited by larryfs; 02-14-2007 at 11:15 PM.
02-14-2007, 11:39 PM
#15
Melting Slicks
Thread Starter
I agree Larry, but those GS calipers are hard to find and pricey. If I can find a used set that were street driven, I would gladly go back to the GS's. The KFP Purples are a carbon-kevlar race pad but I don't know what the CF is. I bought 10 sets off a former Corvette Challenge racer for $40 a piece. I actually have some PFC 83's and 93's as well as Hawk blue's in my stash. I was planning to use them when I polished off my Purples. Any spare calipers Larry?
02-14-2007, 11:50 PM
#16
Safety Car
Buy NEW GS calipers. DONE, move on to something else........
https://www.superchevyperformance.co...les.asp?ID=123
I really have zero trouble with the GS setup. You've seen the extent of the pad taper personally. The biggest problem is the price of the C4 rotors are $45 each now, otherwise I have no complaints.
https://www.superchevyperformance.co...les.asp?ID=123
I really have zero trouble with the GS setup. You've seen the extent of the pad taper personally. The biggest problem is the price of the C4 rotors are $45 each now, otherwise I have no complaints.
02-15-2007, 09:24 AM
#17
Melting Slicks
The rods help, DRM did that years ago.
The SL6 is superior, unfortunately after contacting Wilwood they told me for a C4 you can only fit the 1.10 rotor under that caliper. 1.10 is the stock J55 size... not much of a heat sync. I think the 1 3/8 rotor is the better way to go with the GNIII caliper just not sure how much modification is needed for it to fit. Now if you can get the 1 3/8 under the SL6 That I would at least consider.
Another consideration is the less known Brakeman set up which I heard some good things about, the system uses a 4 piston caliper which has a Cro-moly bridge connecting the 2 aluminum 1/2s. 1 3/8 rotor also can be had for the C4 even though not listed on the web page. The steel will not spread therefore the calipers do not use differential size pistons, just 4 large pistons. Aluminum will start to spread at anything over 500 degrees I beleive, therefore the need for the different size pistons in the SL6.... it prevents pad taper.
Some "A" sedan & guys run Brakeman & love them! Some Northeast Iron Guys picked the brakeman over the Wilwood & Brembo. At $2,700.00 its not cheap. Anyone using brakeman set up for racing a C4?
Decisions, decisions.
The SL6 is superior, unfortunately after contacting Wilwood they told me for a C4 you can only fit the 1.10 rotor under that caliper. 1.10 is the stock J55 size... not much of a heat sync. I think the 1 3/8 rotor is the better way to go with the GNIII caliper just not sure how much modification is needed for it to fit. Now if you can get the 1 3/8 under the SL6 That I would at least consider.
Another consideration is the less known Brakeman set up which I heard some good things about, the system uses a 4 piston caliper which has a Cro-moly bridge connecting the 2 aluminum 1/2s. 1 3/8 rotor also can be had for the C4 even though not listed on the web page. The steel will not spread therefore the calipers do not use differential size pistons, just 4 large pistons. Aluminum will start to spread at anything over 500 degrees I beleive, therefore the need for the different size pistons in the SL6.... it prevents pad taper.
Some "A" sedan & guys run Brakeman & love them! Some Northeast Iron Guys picked the brakeman over the Wilwood & Brembo. At $2,700.00 its not cheap. Anyone using brakeman set up for racing a C4?
Decisions, decisions.
02-15-2007, 09:47 AM
#18
Melting Slicks
It was a J55 using KFP Purple race pads. It had about 4 or 5 events on it. Previously, I had GS calipers on it, which lasted 3 years(20+ events) but eventually the pad taper became excessive and consumed too many expensive pads. Any pictures of the reinforcing rods? Also, how do install pad backings with new pads; aren't the pistons fully retracted? I wanted to burn through my inventory of race pads before ditching this setup. Thanks for all the input.
No pics of the rods, but I know someone out there will have them. Backing plates and heat shields get installed as you wear the pads, not in when new. Theres no room when new. They take up the wear keeping the pistons back and also serve as a heat barrier.
A GS caliper is marginally better than the J55 and not recommended. Especially after you results with the J55. Why did you go from GS to J55?
