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I have J55 on my 96 and C5 on my 93. The braking is noticeably better with the C5 brakes. FWIW I have ceramic pads on both cars due to the low dusting and acceptable performance.
I just put J55's on the front of my 86. I designed and built my own custom brackets for the calipers. I was able to change the mounting points enough that I can run any 16" factory wheels. I have 3 different sets of factory wheels. There is the 9.5 wide Enkei wheels made in Japan, 9.5 Modern wheels made in USA and 8.5 wheels that don't say where they are made. There is quite a difference in the backside of the Enkei and Modern wheels.
The j55 is definitely worth the effort. I am running hawk blue pads all the way around. This car is used for autocross and track only. It stops on a dime and gives change but the dust is horrendous. I also installed the DRM bias spring.
I have used ceramic pads on other vehicles with great results. No loss of stopping power and very low dusting.
There aren't many choices for pads for early c4's. I am running Porterfield carbon kevlar pads on the front of my 85. They won't take prolonged track running but they are ok for the street. And they dust very little which is why I chose them.
wayyyyy old thread! However, you still have the specs on the adapter plates you made or even have a set lying around?
The PO of my 89 had used J55 calipers and brackets and brand new rotors. They were not installed but came with the car when I bought it. I needed to buy the pads and some hardware, I also did a caliper rebuild but probably didn't need to. So I am all in for about $150 with ceramic pads.
IS it worth it? - for what little I paid yes. The car has a lighter pedal with the bigger front disks. I don't think it stops any quicker on the street and to be honest I don't think any brake upgrade is going to improve cold stopping distance, but they do feel better than the stockers and it does feel like a more modern car as far as pedal feel. I am sure they fade less on the track too, but I don't track the car so I can't really compare.
If I did not have the hardware already I probably would not have got them, but they do improve feel and if that is worth it I would go for it.
I'll put my .02 in here on this brake thread even though it was originally from 2012 and got resurected. Ive tested and used standard 12" and J55 (13") for both autox and track. If you mainly autox or just run the street, the 12" is the way to go. Less weight and you will get the pad to heat up quicker to operating temp. 13" will be hard to get to temp in autox situations. With stock C4 calipers the 12" and 13" use the same brake pad, so there is not going to be any enhanced performance with a 13" rotor over a 12" except during track usage. The 12" will heat up quicker and possibly get too hot because it cannot dissipate heat quick enough. Really just depends on what pads are used and how long you will be on the track.
But what I think is the most important thing to consider to get the best brake performance will be the pads. You want to look at the brake temp range of the pads when selecting the best pads for your usage. That's what makes your brake system operate at its best. Along with good brake fluids and maintnenance.
For what it's worth I did this mod to my wife's 93, it got drilled and slotted rotors at the same time along with the braided SS hoses. For my own curiosity I told my wife it was all about the nicer looking rotors visible through the chrome ZR1 replica wheels. The first time she drove the car with the J55 brakes she came home and said "Wow, those rotors not only look nice the car stops WAY better than it did before! "
I completely rebuilt my J55, every clip, bore seal, parking brake etc, added track rated pads, acid washed and expoy coated front and rear (bare) and sanded and polished and clears the brackets with 2000 degree clear, just finsihed the rear today (not bled yet, parking brake reinstall was a pain, I won't lie) I plan one day to upgrade to C5 fronts but don't expect a lot better braking other than track work.
This are the rear on the car, fronts ont he counter - for tomorrow. Also new drilled and slotted rotors installed.
N
Another J55 fan here. As the car was ready for new friction materials, and the price difference between 12 inch and 13 front rotors is negligible, the only real expenditure was the calipers, which I got complete ( shout out to Mirrock Corvette) for a couple hun. My C4 is for street driving, but the improvement does show up on high speed braking, or , after spirited back road driving. No empirical data as before and after here, but my other braking points of reference are my 911 as well as the various motorcycles I ride. For me , it was worth it. Cheers
06-05-2012, 01:06 PM
