ZR1-Racer

Hi,

I'm wondering how good late model C4 calipers compare to C5/C6 calipers?

Aurora40

Maybe you should define what kind of comparison is relevant for you?

Personally I think the stock J55 setup works fine for the street and such. I never had a problem with back-to-back-to-back dragstrip stops from 115ish.

I also suspect the real gain in a C5 upgrade for road-race types is not the caliper as much as it is the substantial increase in rotor material. The C5 rotor is much thicker 1.25" vs 1.1".

ZR1-Racer

Well sort of driving i do would be aggrieve street driving and road race (think 120mph then stopping for a turn)

aboatguy

I hit triple digit speeds often...been doing it for years w/o issue braking issues with plain old stock J55 brakes. (think excess of 160 and then slowing for a turn...)

However, each generation of corvette brakes resulted in evolutionary improvement. So if you don't feel comfortable with your stopping power spend some $$$ and reduce your stopping distance.


Mike

Aardwolf

For road race use I would switch to C5/6 calipers or a BBK. I use the C5 setup on mine, mostly for the decreased cost of rotors and pads. It's easy to go through a set in a weekend or two. There have been many C4's raced on the stock calipers so it's possible and definitely okay for starting out.

The C4 caliper is much smaller, making it easier to spread under high heat. Use track pads, and brake ducts. If you're just starting out that will last awhile.

ZR1-Racer

okay so the only advantage C5 has is that they are run wider rotors than the C4 but the calipers aren't much better correct?

Aardwolf

The C5/6 calipers are larger and will handle heat better. That is good for racing! Plus the calipers, rotors, and pads, cost less. They aren't going to reduce your stopping distance. That is more of a function of your brake pad and tire.

dizwiz24

Also keep in mind the C5 brakes are larger, heavier, etc. than J55 brakes. And that is unsprung weight. the worst kind..

This is why I went with 13" 2-piece Baer Eradispeed rotors and stayed with the J55 setup. I also knwe I would be lightening my car in the future which would reduce demands on the braking system.

Also, use Hawk brand pads. I use HP Plus (I dont mind occasional squeaky stops on the street).

Sidney004

Take a look at post 93 to see what a J55 pad looks like after 40 minutes at Laguna Seca:
http://forums.corvetteforum.com/nort...-2010-a-5.html
The backing plate deformed from the heat and the pedal was long.
I think they are fine for the street however, it is just the extremes of a heavy braking circuit that overheats these poor brakes. I will be switching to the C5's shortly so we will see if they are better.

c4cruiser

What year C4 do you own (nothing listed in your profile)? "Late-model" C4's 95 and late had the J55 brakes as standard and were optional since 1989. All ZR-1's had the J55 brakes.

The J55 caliper is larger (wider) to accommodate the slightly wider 13" J55 rotor. There are a wide variety of performance pads available for the C4 brakes ranging from good HPDE pads to race-level stuff. Same with rotors; some people use a generic stock rotor and toss them when they wear out, some go for high-zoot rotors made for extreme braking.

I did a C5 brake upgrade on my 87 last summer and there was a marked improvement but the 87 front rotors were only 11.8" wide and relatively thin. With the C5 stuff in front, I now have a much wider range of brake components to use. I also added a Doug Rippie brake bias spring to help with the extra braking power up front. It's almost a necessity to keep from the ABS going nuts at even medium braking effort.

But adding C5 front brakes may require a different wheel. The OEM "salad-shooter" wheels do not work with C5 front brakes; the caliper is too large so something like a ZR-1 style wheel is needed.

The rear C4 brakes are very close in size to C5 rear brakes, so pad choice is the big factor out back. Add some good quality brake fluid with at least a DOT4 boiling point. cooling ducts to the front brakes, and stainless flex lines and you should be able to handle many tracks.

Bluewasp

if you are looking for a BBK I'm trying to setup a group purchase for a movit setup for the NASA CMC guys. Let me know. Send me a IM.

jaa1992

Last year my j55's developed a slight pull to the right when slowing for turn 10a at Road Atlanta (fastest straight to a sharp left).
I replaced all 4 calipers, master and booster. A couple weeks ago at CMP they worked great, I'll be back at Road Atl Mar 13& 14.

I've been using Carbotech, and EBC yellow. I'll never use the EBC pads again. I have them in my "if I burn thru the pads and have nothing left" box. I started with XP10 / AX pads and last year switched to xp12/xp8.
I like the xp12/xp8 combo, but I think I need xp10's on the rear.

I have some Hawk bucks and will try some dtc pads probably 70 F and 60 R later this year.

techvette

A great bang for your buck is a set of Hawk HPS brake pads, particularly if you already have J55 brakes.

Marv02

Kinda Hi Jacking this thread for a normal street car on my 1986 vette stock brake set up should work fine for it.

The reason I asking this I need to replace all 4 rotors rebuild the calipers new pads, the car was sitting out side for the last 7 years in a field and they look nasty.

Anouther reason after looking for tires for the stock 16 inch rims I have found out I dont have very many ways to go I mite as well go to the 17 inch wheel and tire combo, So doing the larger Brakes is anouther thing to look at for me.

As most projects I get my self into when I buy a cheep fixer upper after all done it not going to be cheep any more but at least I know what I have when I driving it a car thats been gone through.

c4cruiser

Don't forget new flex hoses too! And do a complete fluid flush. Hard to say if the master cylinder will need replacing, but you can get a rebuild kit for it. With any luck the vacuum booster will still work but be prepared to swap that out too. Not being used for so long can result in a rupture of the diaphragm and possible cracking of the vacuum line leading to the booster.

When you have the rear rotors off, check the condition of the parking brake shoes; clean everything and lube where specified.

1985 Corvette

Brakes are always an interesting topic on here. Guess it depends on what you're using them for. The C4 guys say all C4 brakes (even the J55s) suck. I toodle over to the C5 section to see topics like "C5 brakes suck". The C6 section isn't any better as I've seen lots of post of "The C6 brakes suck". Even the C6 Z06 owners say their brakes leave a little more to be desired.

The only Corvette I've yet to hear complaints from on brakes are the C6 ZR1 guys. Again all in what you're using them for. I think the J55s are pretty good.

Marv02

I have already flushed all the opld fuild out of tjhe old brake system out before I took the car for a spin after getting running after sitting in the same spot for the last 3.5 years.

I knew the rotors were rusty I was hoping after going around the block a couple time the rust would clean them selfs off with a couple cycles of the brakes but after taking a better look at them after the spin they need replacement.

Also the Anti Lock Brake lights on I think I need to clean the whell sending units should help But I do them when I do the Brake replacement.

Sure glad I have a Sand blasting booth at work makes life much easyer for me.

Toy90

I've driven the 12" rotors with hawk HP plus pads and R-compound tires on two different tracks in 90 degree heat and not had any issues unless I didn't put on cooling ducts in the front. I could lose brakes in a lap and a half without them! Extreme heat kills brakes and in my opinion if you are on a track and you want to push the car at all, even with good pads/rotors, you should have cooling ducts. Even if you don't think you need them, your pads/rotors/calipers will thank you. I made a set for $15 using dryer duct from Home Depot and they worked fine for several track days a year.

jaa1992

Sitting that long I'd go down to autozone and get all 4 rebuilt calipers.
There may be pitting in the bores and it would take more time to rebuild than to get rebuilt ones. You may want to replace the master cylinder as well.

JL9 brakes are adequate for the street, just rebuild the system and flush it with fresh fluid witn new hoses.

Marv02

Thanks for the info.