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hello, I want to convert my standard 1985 brake to the J55 brake and ordered following parts: Rotors: StopTech 126-62047CSR + 126-62046CSL, calipers: from Eckler's: PART #: 25-341333-1 + PART #: 25-341337-1, brackets: from Corvette Central: PART #: 194126 (to mount the big calipers to 1984-1987 models).
The front suspension is stock 1985 with 1984 spring, matching shocks and stabilizer bar.
I painted the calipers and brackets, put the rotors to the hubs and secured them with the wheel nuts, so they are flat to the surface of the hubs.
Then I mounted the brackets and had to see: The rotors are not in the middle of the caliper-brackets, but touch them. Same on left + right.
rotor secured flat with nuts rotor is in contact with the bracket (inner side - to knuckle) - upper rotor is free (outer side - to wheel) - upper same to the lower same to the lower
Does anyone know what could be wrong with the parts combination or the assembly?
Of course, no color is applied to the surfaces of the caliper brackets where they contact the knuckle. As on the surfaces for the brake pads, that are visible on the photos.
If there was color on it, it would be a simple solution to the problem
Of course, no color is applied to the surfaces of the caliper brackets where they contact the knuckle. As on the surfaces for the brake pads, that are visible on the photos.
If there was color on it, it would be a simple solution to the problem
Usually is something simple.
I had that happen on a friends car. He was quick to bolt it up and didn't see they never took the paint off the mounting surface.
So in your case did you unbolt the bracket and put a straight edge on it to see if its parallel to the disc or outer part of bracket? Just a thought.
Curious to see your results as I was looking to go the same route next year. Good luck!!
Last edited by FostersPerformance; Jul 24, 2021 at 02:40 PM.
After painting, I noticed that the thickness of the calipers differ at the outer side. They are equal in width for the 13" rotors. Could this difference create problems?
That will be the next thing I will do. Next week I'll screw everything apart again and measure things. The sad thing is that except for the knuckle, everything is new. Corvette Central's caliper adapters were manufactured by or for SSBC.
I dont think calipers are an issue. Its the bracket that bolts to knuckle. Wondering if it was machined flat and parallel to rotor. ....any chance left to right makes a difference? Just my 2 cents
This morning, I began measuring: The hat/flange thickness of the 1985 rotor is 7,55mm and the 13" rotor has a thickness of just 7,00mm. When looking at the photos, 0,55mm would not be enough to center the rotor between the bracket. A 0,55mm shim or something between the rotor and hub would be needed to maintain the correct original track width. And the brackets would have to be machined to get the clearance....
OP - You've displayed everything except the 'brackets'! Where did they wander off to? If they were modified for resale by Corvette Central using J55 brackets they would have casting information on them and be mirrored images of one another!!
ChumpVette, that was also my thought: Do these holders even fit the early spindles? When I order something, I have to be able to rely on the supplier's description: At Corvette Central, the holders were advertised to fit the models from 1984 to 1987. Here is the link: https://www.corvettecentral.com/c4-8...-piston-194126
WVZR-1, I displayed photos of all 4 "corners" of the brackets, where they contact the rotors and where is play between. Here is a overview photo and also a photo of the unpainted brackets - from Corvette Central. There is no GM parts number, just "SSCB" and "2434 CM". They don't seem to be modified original parts.
I had the same problem using brackets from Vansteel and it turned out that they were marked incorrectly RH and LH so I was able to mount the left side bracket on the right spindle then everything fit properly.
I was mounting bigger brakes on my 92 Corvette
Last edited by jcarmichael; Jul 28, 2021 at 04:03 PM.
WVZR-1, I displayed photos of all 4 "corners" of the brackets, where they contact the rotors and where is play between. Here is a overview photo and also a photo of the unpainted brackets - from Corvette Central. There is no GM parts number, just "SSCB" and "2434 CM". They don't seem to be modified original parts.
You still haven't provided 'side by side' snapshots of anything to compare.
You need pieces 'side by side' and calipers to measure! That 'stick ain't doing a thing!
I don't like to snag info from other places and I'd have thought that 'you' having the issue and it's your $$$ you might have looked.
Here's a pretty good 'visual only' of JL9 and J55 bare calipers. The throats aren't dimensioned in these but they're pretty good for just visuals.
I ain't saying what your issue is BUT you ain't gong to figure it out the way you're going about it. I've seen 'a few' threads where people have mentioned issues. What were theirs? I had no interest at the time!
jcarmichael, the caliper guide pins must be at the bottom. If You mix up the sides, the guide pins would be up. I have the correct brackets, left and right fit with the guide pin below.
WVZR-1, there are no problems with the brake calipers, I'm just amazed at the way they are built. I know the GS calipers, the J55 calipers and the calipers for the 12" brake and some of their differences. But I have not yet seen a J55 caliper that has the somewhat weaker construction at the wheel side, like the 12" caliper - I already made the comments in the pictures, but has the correct width for the 13" rotors.
The problem/issue is still the distance between the rotors and the aftermarket brackets. Driver side and passenger side have the same problem - the rotor is too close to the brackets to the hub side. Today I put shims between the rotor and the hub. I figured out, the mounting flanges of the brackets are 2.5 mm too thick. With 2.5mm shims, I can center the rotor between the brackets. So I think, ChumpVette was right - these brackets were not made for the 1985 spindles, probably for newer C4 models. It is very annoying that they were declared by dealers as products for 1984-1989 models. Or the production was carried out with the wrong measurements. Or wrong machining.
WVZR-1, You're right, it is really not advisable to rely on the quality and accuracy of fit of aftermarket parts. Everything has to be pre-assembled first, in the hope that it will fit. Manufacturers should be ashamed. I should know better because I've already had some bad experiences with some aftermarket auto parts. But unfortunately I let myself be carried away again to the "paint first" ...
I doubt the knowlegde of anyone with the "JL9 - J55 - hybrid" caliper. But I like to be taught
Thanks for this information guys. I am getting ready to do this same conversion on my 1987 corvette. The parts I bought from our site here were off another c4 and I was told no other bracketry was needed . I hope the bolts that bolt the caliper bracket to the spindle are the same. As the J55 brakes I bought did not have the bolts.does anyone know if they are different?? thanks, gary
Thanks for this information guys. I am getting ready to do this same conversion on my 1987 corvette. The parts I bought from our site here were off another c4 and I was told no other bracketry was needed . I hope the bolts that bolt the caliper bracket to the spindle are the same. As the J55 brakes I bought did not have the bolts.does anyone know if they are different?? thanks, gary
Caliper bracket to knuckle bolts for the front are the same '85+ in the front. GM# 14084051.How about posting snapshots of your brackets. Have you done a trial fit of your purchase yet?
1985 C4 J55 conversion problem
