In Defense of J55 Brakes

[LGAFF]

First, Big brakes look awesome... certainly over high speed repeated stops there is a clear advantage, I have 8 piston Brembos on my SL600, and 6 Pistons on 3 of my other cars. My 91 ZR1 at one point had Brembos from the Porsche 993 but the prior owner sold them... so I was looking for a brake upgrade.

I had landed a set of C6 Z51s cheap, so I thought throw them on the Z... well that didnt pan out the Z51s dont clear stock Amold sizes. As I started to look at options I did some checking on the J55's performance. From 70 it drew the LT5 down at 170ft... when I looked at the C6 Z51 the number was anywhere from 152-160+. So I asked myself, how much better is the C5/C6 caliper when its stopping a Z06/or C6 that weighs 200lbs less than a Z in just 5-15ft. I never noticed this but the standard c4 was the first corvette to hit below 110 from 60

Even the best braking cars in the world currently are in the mid 140s, some 130s for stops from 70.

So when you consider advancements in tire and pad compounds since the 90s, you could easily get your J55s into 150s with Hawks or EBC pads... better tires could even up the ante.... So the J55s no slouch..... I think Im staying with them.

[Ccmano]

I couldn't agree more. J55's are way under rated and with modern high performance pads they really perform well. When I installed my GS J55 calipers last year I opted for PowerStop Z26 Street Performance pads and rotors. The difference from stock pads is remarkable. C5/C6 Calipers have little advantage over a good J55 setup. Larger calipers like the C6 Z06 and other Brembo, Wilwood or Baer setups are good, but for the cost and installation headaches (parking brake) they are only an advantage if you track or autocross the car. But hey, if people like the look or feel the need for every ounce braking performance they can spend their money however they like! It's still a free country (for now).
H
:cheers:

https://farm66.staticflickr.com/65535/49868739617_d7a64ca022_c.jpg (https://flic.kr/p/2iYJjTt)

[1991 Corvette ZR-1]

I couldn't agree more. J55's are way under rated and with modern high performance pads they really perform well. When I installed my GS J55 calipers last year I opted for PowerStop Z26 Street Performance pads and rotors. The difference from stock pads is remarkable. C5/C6 Calipers have little advantage over a good J55 setup. Larger calipers like the C6 Z06 and other Brembo, Wilwood or Baer setups are good, but for the cost and installation headaches (parking brake) they are only an advantage if you track or autocross the car. But hey, if people like the look or feel the need for every ounce braking performance they can spend their money however they like! It's still a free country (for now).
H
:cheers:

https://farm66.staticflickr.com/65535/49868739617_d7a64ca022_c.jpg (https://flic.kr/p/2iYJjTt)

I went with the same brake pad/rotor set up from Power Stop, complete with a full fluid flush. I?ve found the Z still doesn?t shed the speed like I thought it would. I?ve been spoiled by of all things, an old 2000 F body a friend drove in college with factory braking system. I got to drive it a few times and if you just breathed on the brake pedal, you could feel the brakes really bite. With the Z, I feel like I have to roll into the brake pedal and apply a decent amount of pedal push to slow the car.

[LGAFF]

I think a lot of it is pedal feel vs actual results... electronic brakes make a huge difference in pedal feel

[LGAFF]

Car and Driver 2009 ZR1, Z06, Z51 Test

From 70

ZR1= 141
Z06= 150
Z51= 152

So a C4 ZR1 with the J55, EBC/Hawk pads and modern rubber would probably be right in the mid 150s

[Erik]

I never got the knock against the J55's. I can't imagine upgrading from them unless I was doing really serious track work.

[LGAFF]

I orderd some EBC red stuff pads, and will install the bias spring and see how they do

[tgonyaw]

I would be interested in seeing your results also. Road surface and tire configurations at play also. My car is mostly stock with full depth street tires. I think a well maintained J55 set up is all I need. Thanks doing the testing.

[1991 Corvette ZR-1]

I orderd some EBC red stuff pads, and will install the bias spring and see how they do

Interested in this result. I have stop tech pads but maybe trying out hawk pads might give me more of the grabby bite I?m anticipating in my head.

[LGAFF]

We put EBC red stuff pads on my wifes CLA45 it stops from 70 in 150ft stock, the pads have a lot more initial bite than the benz pads and zero dust

[conesare2seconds]

Pads make a big difference. When I autocrossed all the time, I put on new pads every year and once accidentally switched from Hawk HPS pads to HP+. I daily drove the car and the HP+ likes a little heat. The first stop or two of the morning commute the brakes were plain weak. After 6 months of scaring myself and a close call or two I gave up and switched back. The Plus pads technically had better specs but weren?t best for my application. The HPS pads didn?t stay hot in autox they way they would have for track day use and worked better than Plus at everyday temps Lately I?m using HPS 5.0 on the ZR-1 and am happy so far.

[Ccmano]

We put EBC red stuff pads on my wifes CLA45 it stops from 70 in 150ft stock, the pads have a lot more initial bite than the benz pads and zero dust

Just be prepared to go through rotors faster. Benz uses soft rotors to begin with, which further enhances the braking performance.
H
:cheers:

[LGAFF]

Just be prepared to got through rotors faster. Benz uses soft rotors to begin with, which further enhances the braking performance.
H
:cheers:


I picked up some Brembos that are better

[sleazy rider]

when i put the brembo's and ccb rotors on my 2007 z06, i put the z06's brakes and wheel/tires on my 1991 zr-1. have not done any comparisons but they work.
#1 c6 z06 caliper vs c4 j55 caliper
#2 c6 z06 brake assy on c4
#3 rear z06 rotor vs c4 rotor

ps. how do i rotate a picture cw/ccw?

[Young1]

Be sure to install the DRM bias spring. It makes a noticeable difference.

[LGAFF]

when i put the brembo's and ccb rotors on my 2007 z06, i put the z06's brakes and wheel/tires on my 1991 zr-1. have not done any comparisons but they work.
#1 c6 z06 caliper vs c4 j55 caliper
#2 c6 z06 brake assy on c4
#3 rear z06 rotor vs c4 rotor

ps. how do i rotate a picture cw/ccw?


What wheels are you using

[Matt B]

As my Z still has the factory installed rotors and pads I'm thinking about some modernization, too, maintaining the stock setup. Powerstop Z26 would be the stuff of choice for me. Just one consideration: are these slotted and drilled disc's really anything as close to "quiet" as powerstop claims?
I used to have drilled rotors in the past in one of my Audi's and these were an awful choice as they caused buzzing/humming noises and even slight but noticeable vibrations up to the steering wheel.

When speaking about stock brakes also noise is a consideration as my Z is a Sunday Sunday afternoon bullet and not a track tool...

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[1991 Corvette ZR-1]

The Z26 package has been quiet as a mouse for me. I?ve been using it over a year now and no noise of any kind. The rotors are zinc plated, so it is a nice touch and good to know you don?t have to look at rusted parts of the rotor not in use. Low dust pads. The only thing that you might even consider an issue is on the rare cases there is enough pad dust accumulated that gets wet from say driving in the rain, it can run out onto the wheel and dry out. It requires some extra effort to remove from the wheel but a very minor issue.

[Matt B]

Great, thanks for that insight. Then I will order my set! Seems to be a wise upgrade.

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[XfireZ51]

when i put the brembo's and ccb rotors on my 2007 z06, i put the z06's brakes and wheel/tires on my 1991 zr-1. have not done any comparisons but they work.
#1 c6 z06 caliper vs c4 j55 caliper
#2 c6 z06 brake assy on c4
#3 rear z06 rotor vs c4 rotor

ps. how do i rotate a picture cw/ccw?

If u are going to go w 18/19? wheels like the OEM C6Z 5 spoke, the stock calipers and rotors look puny.
What I like about the bigger brake, beyond the aesthetics, is how light the pedal pressure needs to be to stop in typical driving situations. I end up stopping sooner than I think I will.

[dredgeguy]

The Z26 package has been quiet as a mouse for me. I?ve been using it over a year now and no noise of any kind. The rotors are zinc plated, so it is a nice touch and good to know you don?t have to look at rusted parts of the rotor not in use. Low dust pads. The only thing that you might even consider an issue is on the rare cases there is enough pad dust accumulated that gets wet from say driving in the rain, it can run out onto the wheel and dry out. It requires some extra effort to remove from the wheel but a very minor issue.
I used the same and no issues with noise or vibration. Used C5 brakes up front and stock in rear. Was a pain clearing my FM5's. If I were to do it again would have stayed with stock J55's as only time I get on a track is during our C4 gathering at BG. Other than that normal daily driver.

[sleazy rider]

What wheels are you using

i am using the corvette spyder wheels, 18 x 9.5 x 40mm in front and 19 x 12 x 59mm in the rear and the stock size tires but i am searching for some forged wheels to replace the spyders. stock wheel offset for the c4's is 57mm in the front. the spyders stick out of the wheel wells by about 3/4"in the front, which i hate the look, and i use a 1/2" spacer in the rear to place the tire in the middle of the wheel well to give me clearance on both sides. i looked at an aftermarket c6 zr1 wheel that had the correct offset in the front and cleared the z06's caliper but they weighed 35lbs in the front and 40lbs in the rear. each. and cleaning would be a b-otch with all those vanes to get thru.

[LGAFF]

i am using the corvette spyder wheels, 18 x 9.5 x 40mm in front and 19 x 12 x 59mm in the rear and the stock size tires but i am searching for some forged wheels to replace the spyders. stock wheel offset for the c4's is 57mm in the front. the spyders stick out of the wheel wells by about 3/4"in the front, which i hate the look, and i use a 1/2" spacer in the rear to place the tire in the middle of the wheel well to give me clearance on both sides. i looked at an aftermarket c6 zr1 wheel that had the correct offset in the front and cleared the z06's caliper but they weighed 35lbs in the front and 40lbs in the rear. each. and cleaning would be a b-otch with all those vanes to get thru.


Those look awesome... not as awesome it would look with performance cams.... be pretty awesome :hello:

[LGAFF]

I got my EBC redstuff pads last weekend and installed the doug rippie bias spring in a new master cylinder might do the swap this weekend

[XfireZ51]

i am using the corvette spyder wheels, 18 x 9.5 x 40mm in front and 19 x 12 x 59mm in the rear and the stock size tires but i am searching for some forged wheels to replace the spyders. stock wheel offset for the c4's is 57mm in the front. the spyders stick out of the wheel wells by about 3/4"in the front, which i hate the look, and i use a 1/2" spacer in the rear to place the tire in the middle of the wheel well to give me clearance on both sides. i looked at an aftermarket c6 zr1 wheel that had the correct offset in the front and cleared the z06's caliper but they weighed 35lbs in the front and 40lbs in the rear. each. and cleaning would be a b-otch with all those vanes to get thru.

Part of the reason the fronts stick out as far as they do is the brake rotor. With my stock Z06 wheels over the stock brake rotors, the tire would protrude past the front fender opening as u describe. With the Z06 rotor, the tire receded into the wheel well further, and then w the 2piece Coleman rotors and aluminum hat, its nearly flush.
I?m using an 18mm spacer for the stock rear Z06 wheels.

[sleazy rider]

my issue is not the rotor but the c6 z06 caliper size. the caliper sticks out 2.22"/57mm from the hub mounting face. what i am looking for is a wheel that will clear the caliper and yet fit in the wheel well to give me a 57+/-mm offset.

[sleazy rider]

not as awesome it would look with performance cams.... :hello:

with the engine out of the car right now, i guess it would be the perfect time/opportunity to replace the cams, but $$ seems to be in short supply at this present time and i never budgeted for them. between you, jerry's, marc haibeck, zfdoc, stainless works and jet hot, i managed to spend over 6k and my paypal shows it. i need to sell some more parts...lots of them!

[LGAFF]

with the engine out of the car right now, i guess it would be the perfect time/opportunity to replace the cams, but $$ seems to be in short supply at this present time and i never budgeted for them. between you, jerry's, marc haibeck, zfdoc, stainless works and jet hot, i managed to spend over 6k and my paypal shows it. i need to sell some more parts...lots of them!

Just giving you a hard time, appreciate the support and buying parts!

[sleazy rider]

Just giving you a hard time

appreciate it! makes me feel as one of the pack...in my own warped mind. :cheers:

[XfireZ51]

my issue is not the rotor but the c6 z06 caliper size. the caliper sticks out 2.22"/57mm from the hub mounting face. what i am looking for is a wheel that will clear the caliper and yet fit in the wheel well to give me a 57+/-mm offset.

Of course I did not have that issue given the use of the stock Z06 wheel.

[bowtiguy]

We put EBC red stuff pads on my wifes CLA45 it stops from 70 in 150ft stock, the pads have a lot more initial bite than the benz pads and zero dust

Benz pads Are HORRIBLE! Short life and high dust rate. I had hawk make me up a set of HPS pads for the wife?s AMG GL63. Better initial bite.....ZERO dust!

[LGAFF]

First drive:

EBC Red Stuff Pads
New Master Cylinder
DRM Bias Spring


Initial bite is way better than stock, have to drive 200 miles before hard stops as the EBC pads use a break in compound. its 100% better than stock, Camaro master cylinder might make it about perfect from comments I have read

** I also changed my front coilovers to Aldan American from an old Carrera 525lb setup

[Erik]

First drive:

EBC Red Stuff Pads
New Master Cylinder
DRM Bias Spring


Initial bite is way better than stock, have to drive 200 miles before hard stops as the EBC pads use a break in compound. its 100% better than stock, Camaro master cylinder might make it about perfect from comments I have read

** I also changed my front coilovers to Aldan American from an old Carrera 525lb setup

Great update. Thanks!

Whats with this Camaro master cylinder thing?

[LGAFF]

4th Gen Camaro Master Cylinder has a much larger bore than the Corvette, supposedly it makes for a much firmer pedal feel.

requires some changes

[Matt B]

I recently installed my Powerstop Z26 package (all 4 corners) and can only say thanks for the advise. Whisper silent as indicated and good stopping power out of the box. Took her for a spin on the Autobahn last night with full confidence in my new brakes ;).

Let's see where they develop in terms of brake performance as I could not do much more as the break in procedure last night. And I hope that the low dust formula keeps its promise.

Anyway this seems like a good overall package. Thanks!15908

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[Vette Guy]

I'm a huge fan of J55s. Reference my article in issue 56 of the HotB, found on the Registry website. If I could ever take someone for a ride in my 1988 Challenge Car, you'd be overly astonished - I outbrake many other race cars, including NASCARs and Lolas. That said, I rebuild the calipers / master cylinder each year, run DRM pistons, love DBA rotors and Carbotech XP-12 pads. I run through a set of pads each event, and get about 3 events from a set of rotors. I've never cooked my brakes, but have cooling ducts and run high-temp fluid.

I did purchase a set of Baer 4-piston calipers for my 1991 ZR-1 with the intent of comparing stopping distance between J55s and them, working out the change in rear bias to minimize braking distance... and at least providing members an upgrade recipe if they wanted - unfortunately, that project is on the back burner for a while.

My 96 runs runs Coleman Series IIIs with custom rotors up front, with J55s/13" rotors on the rear. It does not stop anywhere near as good as the Challenge Car, even with an adjustable bias bar and same compound. I plan to replace all the flexible lines and start over with the brake system (Tilton, triple cylinder - no booster, recirculating valve and rear pressure dampener).

I've seen lots of 6-piston conversions with stock rear calipers, and think this is a recipe for disaster on the track, such as Bob Saveland experienced on the dragstrip with this setup. (Issue 21, HotB).

Even taking front & rears from a newer Corvette and retrofitting them on the C4 isn't a good option without adjusting bias. The cars are very different.

That said, if your Z isn't track driven, 6-piston fronts and stock rears (heavy front bias) may not matter much, but know the stock setup will stop better.

Mark

[Karl]

The Grand Sport brake calipers are a step up from the J55 calipers.

https://www.corvetteactioncenter.com/tech/knowledgebase/article/1988-1996-corvette-visual-differences-between-production-brakes-640.html

A little beefier and thicker than the J55 calipers.

[Ccmano]

The Grand Sport brake calipers are a step up from the J55 calipers.

https://www.corvetteactioncenter.com

A little beefier and thicker than the J55 calipers.

Agreed.... see page 1 of this thread.
H
:cheers:

[Norwegianmopar]

I recently installed my Powerstop Z26 package (all 4 corners) and can only say thanks for the advise. Whisper silent as indicated and good stopping power out of the box. Took her for a spin on the Autobahn last night with full confidence in my new brakes ;).

Let's see where they develop in terms of brake performance as I could not do much more as the break in procedure last night. And I hope that the low dust formula keeps its promise.

Anyway this seems like a good overall package. Thanks!15908

Sent from my SM-G991B using ZR-1 Net Registry mobile app (http://r.tapatalk.com/byo?rid=90383)Please update when you have tested them a bit more. I am going for Z26 too on our 94.

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[Matt B]

Sorry, should have done this earlier. It's for sure an upgrade to the stock pads and rotors. No noises or vibrations (which I really appreciate), very little brake dust (well, actually it is not "little" at all but it's light grey so wheels do look better. However, it's no comparison to ATE Ceramic pads I use on my Audis which produce extremely little dust that's nearly invisible) and a solid brake performance.
Compared to modern road use standards I'd still say it's a spongy old brake that is hard to modulate and provides rather little feedback and feel. Though ultimate stopping power with Z26 in combination with my Michelin tires (275 & 335) is pretty impressive. When you hammer it, it hammers back. I'd definitely add some braided hoses for more feel :)

[Norwegianmopar]

Sorry, should have done this earlier. It's for sure an upgrade to the stock pads and rotors. No noises or vibrations (which I really appreciate), very little brake dust (well, actually it is not "little" at all but it's light grey so wheels do look better. However, it's no comparison to ATE Ceramic pads I use on my Audis which produce extremely little dust that's nearly invisible) and a solid brake performance.
Compared to modern road use standards I'd still say it's a spongy old brake that is hard to modulate and provides rather little feedback and feel. Though ultimate stopping power with Z26 in combination with my Michelin tires (275 & 335) is pretty impressive. When you hammer it, it hammers back. I'd definitely add some braided hoses for more feel :)Thanks for the update.

I am getting the braided brake hoses and the bias spring from DRM too which I was recommended to do.

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[Matt B]

One thing that might be worth to be added is that both, rotors and pads are made in China. Quality seems okay, though. However personally I'd prefer parts made in the USA or somewhere on Europe.
Next time I'll look closer...

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