Brake Recommendations Please
 

I've got a 65K mile 91' ZR-1. And it's been sitting in the garage for way too long.
We're waking it up, changing all fluids, and trying to freshen it up overall for the summer.

The brakes are all original. Only one pad replacement since the car was new. Front rotors look o.k., but the rears are worn.

While bleeding the brakes we found that the front caliper was clogged and wouldn't bleed. We're going to pull it off today and see what's up.
I'm wondering what you guys have done to rehab the brakes on your car, and who offers the best deal on parts.

Before you tell me to go out and get a set of drilled or slotted rotors and three or four piston calipers, I've got to say that I'm generally happy with the stock brakes, and their performance. And I really like the bone stock look, no flash.
The only thing I would do to change it is possibly put on stainless braided hoses, as they might give a firmer pedal. (Do they?).

I'm thinking, rehab or replace the calipers if they need it, new rotors for sure, (stock), fresh pads (what kind for normal driving?).

I do like to drag race, but don't spend a lot of time at top-end, or slamming through the twisties, (there aren't any here in Fla.) No track days either.
Who offers the best, cost effective package for the ZR-1. Cost is a factor here.
What do you think? :confused:

Thanks in advance. :handshak:

Re: Brake Recommendations Please
 

The C5 brake upgrade may be of interest , being most of the brake system is in need of replacement already.

Re: Brake Recommendations Please
 

Thanks Frank. Who has the best write-up on that? Video?
It might be the way to go if new calipers are required anyway.

Re: Brake Recommendations Please
 

Stainless lines are bling only - they do not make a difference in pedal feel - however after all these years, you should think about replacing the stock hoses.

Any OEM-style pad should be fine.

Re: Brake Recommendations Please
 

That's what I wondered. Does anybody have a different take on that? I've read in a number of brake co. ads that it provides a firmer pedal feel.
Direct experience? You put them on and it didn't seem to make any difference?

Re: Brake Recommendations Please
 

Steel braided brake lines can help give a stiffer pedal but only very slightly (unless you have very bad lines on the car). New stock hoses would help that, too.

Steel braided lines (made for brake systems) usually have Teflon in place of rubber, which expands less, but most people wouldn't feel that, and it would not shorten braking differences. The steel braid is mostly for protecting the hoses from being cut or chafed.

Re: Brake Recommendations Please
 

Rockauto has HD loaded calipers pretty darn reasonably. Looks like that's your best bet for making it easy, and it would probably come with new retaining pins, which in my world are wear items and seem to have dried up (at least there). In the old days you would hone the cylinders and clean everything up, maybe replace the pistons, new seals & pads and off you go. Nowadays you just replace with reman stuff.

Russ has the tech on the stainless lines, I found they gave a 5% improvement where a 20% was hoped for, but they do give worthwhile robustness and your stock lines are almost certainly aging out. Plus if you do juggle various wheel sizes etc they'll be more immune to a stray tire rub.

The 91 pedal ratio with the stock M/C and front caliper piston combo will never give what I would call a firm brake pedal. Brake upgrades usually just increase the heat capacity (ie for track use), the stock brakes are perfectly able to hit ABS and that is the real stopping power indication. You could argue that C5 parts are more readily available for future maintenance but I've not had a problem with C4 J55 parts - yet.

Cheers,
- Jeff

Re: Brake Recommendations Please
 

The stock lines have steel braiding too - cut one apart some time. If you use any aftermarket part, make sure it is DOT compliant. The ones on my 91 are TUV compliant (European) and that is equal to or better than DOT as I was advised.

CORRECTION: I cut open a stock rear line and there are two layers of braided fabric instead of one braid of steel like the aftermarket stuff.

Re: Brake Recommendations Please
 

I love my C6Z brakes both from a performance and aesthetic point of view. However, the upgrade requires wheel and tire upgrade as well, which may probably be more than your interested in doing.

Re: Brake Recommendations Please
 

The C5-6 brake upgrade requires A-mold wheels. C5-6 calipers and rotors can be found on E-Bay cheap enough. Conversion brackets can be found for @ 150.00 complete.

Re: Brake Recommendations Please
 

I will go into what I did a bit ago.

http://www.zr1.net/forum/showthread....=brakes&page=3

I cleaned up my calipers really good, and painted them red. I like the White and Red theme of my car. I used Hawk HPS+ pads from Advance Auto Parts(coupon deal), and I used Drilled and Slotted Rotors bought from RockAuto. My calipers worked fine so I just flushed the entire system with fresh fluid. Last I upgraded to stainless steel lines, speed bleeders. I have been very happy with my brakes performance. A lot of people talk about dismal performance of the stock brakes, but mine have slowed me down pretty well from Triple Digit speeds.

Granted my 944 turbo had better brakes, but it had 4 piston Brembo calipers all the way around.

Re: Brake Recommendations Please
 

For people who upgrade their front brakes (to C5-6), do they sometimes move the stock C4 front brakes to the rear?

What are the upgrade options if the stock sawblade wheels will be used?

Re: Brake Recommendations Please
 

Some have moved the front calipers to the rear. Not worth moving fronts to the rear it IMO. Bias will be a problem too.

See Billys post above.

Re: Brake Recommendations Please
 

Billy,
What brand of paint did you use for your calibers?
They really look good.
Nelson007

Re: Brake Recommendations Please
 

What would u do for eBrake?

Re: Brake Recommendations Please
 

http://www.amazon.com/Dupli-Color-BC.../dp/B000B6AF80

I used this, but got it from Advance Auto Parts.

I wanted to use the paint brush route as I feel the coverage was better. I did about 3-4 coats. Brake fluid will still ruin the finish so be careful.

Re: Brake Recommendations Please
 

I have the Hawk HPS with GS calipers & SS Brake lines. Between the lines and the calipers, the pedal is slightly firmer than originally. I see no difference at all between the Hawk pads and the originals which was quite disappointing, ditto for using the Hawk pads on our Expedition. Does anyone have any other pad recommendations?

Re: Brake Recommendations Please
 

Hello Bob

Allowe me please to tell you something about brakes.
I understand when it's about a brake update, many ZR-1 owners don't want or can't afford to invest money in driving security. But keep certain facts in mind:

When you want a firmer pedal, with new stock or stainless braided hoses you won't get it. The reason is, especially due aging the caliper use to spread a bit more than new ones.

Some low-budget drivers suppose when they install a C5 upgrade it will become significant better, but it also isn't the case. The reason here is the C5 caliper pistons have a bigger diameter and also a bigger volume. The pedal can't become firmer due to a volume imbalance between the main brake cylinder and the caliper volume. Another point is, the C5 calipers also do spread a bit.

I have customers who did a C5 upgrade on their ZR-1 but soon changed back to stock because the result wasn't satisfying.

The solution is to go with 4 or 6 piston brakes when you consider a upgrade, and I am not talking about the C6 Z06 brakes because its piston volume is adjusted for the C5 and C6 brake system but not for the C4. These brakes are mainly good for a nice show behind big open rims.

Porsche recommend to go in high performing cars up to 500 hp at least with 4 piston brakes at the front and over 500 hp with 6 piston calipers. Additionaly a update at the rear can also be installed but that is something for those who race or have money to spend.

I wonder how people can spend alot of money in big cubic inch motor upgrades but don't care about a significant better stoping performance. Today's middle class cars have even better brakes than our ZR-1's. In my opinion it's like a playing with the fire. Some guys believe they are experienced drivers and can handle with the very most traffic situations. But the unexptected is often unpredictable and it can depend in a emergency case on just some feet or inches. The stock brakes are good for 1-2 hard stops from 60-0 and that was it.

I do work together with the german brake manufacturer Mov'it (take a look at:http://www.movitcars.com/rahmen/corvette.htm) and we developped for the C4 a fit bolt on brake system for all 3 different stock 17 inch rim designs. You can install the 4 or 6 piston brakes without to have to replace the stock rims.

By the way: One of my clients run with sawblade rims and want to sell his black 4 caliper 322 x 32mm Porsche front brakes with about 4'500 miles on including all holders, screws and stainless braided hoses.
He is going to upgrade his brakes to 6 piston calipers (with 342 x 32 mm rotors) at the front and 4 piston calipers (with 322 x 28 mm rotors) at the rear for his new 427 engine.

If you or anybody else is interested in this kit, let me know.

Re: Brake Recommendations Please
 

Sam, PM sent. I might want them before driving at Road Atlanta in 3 weeks.

Thank you.

Re: Brake Recommendations Please
 

I couldn't believe that even a C5Z06 only comes with 2 piston calipers.

How did such a high performance car like the ZR1 only have 2 piston calipers? Crazy. What did they do on factory race cars.

Re: Brake Recommendations Please
 

Sam,

Would you explain further what you mean by the C6Z brake piston volume adjusted for C5-6 but not C4?
I have the C6Z brakes, front and rears and using stock master/booster. In the 2 years of driving I have not sensed any inadequacy from them. I first had just the fronts, then upgraded the rears last year including the eBrake. I don't track the car although I have hauled it down from 225km/h+ a few times with no drama. Having enough brake is the least of my concerns. Yes they do look nice behind 18"+ wheels. One of the reasons I did it was due to limited tire availability for 17s.

Re: Brake Recommendations Please
 

Hi Sam

what is the 6 piston setup going for?

Re: Brake Recommendations Please
 

The C5 brakes are mounted on caliper slides and have a little bit more give and play resulting in a slightly less firm pedal. Although I have been in other C4's with J55's that weren't super great feeling- it does seem to vary from car to car.

You will have to spend more than a $1000 to do C5 brakes if you don't have the wheels already. I did mine only because I got a box of parts when I purchased the car. The rotors are cheaper (and thicker) plus you do get a lot more brake pad on the disc. My conclusion is not so much about the brakes, but the weak gain on the brake booster. Regular non ZR-1 C4's are especially weak feeling with only a single diaphragm booster.

Re: Brake Recommendations Please
 

of course don't forget to budget for a spare tire solution with big custom brakes.

Re: Brake Recommendations Please
 

Thanks a lot guys. this has been very instructive.

Though I'm the type that generally looks for an opportunity to upgrade, I think I'll stick with the stock setup.
Mostly for the impression that I get that the C5 upgrade will improve the car's ability to withstand repeated hard stops without fade, but would not give it that seriously shorter stopping power that I had wanted for the $$.

Also, Although I have A-Molds mounted now, I want the ability to go back to my perfect set of those beautiful original saw blades if I choose.

We're going with new stock type rotors, new brake lines and pads.

Thanks again. :cheers:

Re: Brake Recommendations Please
 

The brake systems of a C5 and C6 have the same piston volume. The C4 has another one.
The C5/C6 stock caliper pistons work with a 2 x 40.5 mm diameter, those from the C4 with 2 x 38 mm. The volume difference is about 14%.
When you install C5 brakes in a C4, the fluid volume ratio between the C4 main cylinder and the C5 calipers does not match. The consequence is the brake pedal become soft. With a Mov'it brake you have a hard pedal.

We wanted to open for C4 drivers the possibility to have a high performance brake without additional costs for the necessity to go with expensive 18 inch rims and tires. For the 17 inch stock rims exist the following brake upgrades:

Front:
322 x 32 mm with 4 pistons
342 x 32 mm with 4 pistons
342 x 32 mm with 6 pistons

Rear:
299 x 28 mm with 4 pistons and overtaking the stock C4 caliper for parking brake
342 x 28 mm with 4 pistons and a seperate small parking brake caliper

No spacers are required because the additional necessary offset is already in the 2 piece rotors implemented.

It also exist a 370 x 32 mm 4 and 6 piston upgrade but this set require 18 inch rims.

I don't want to say the C6 Z06 brake is bad but this system is just not calculated for the C4 and its about 400 lbs heavier car body. Running a C4 hard in the hills or a race track you will feel the difference between the Z06 and a Mov'it brake.

Re: Brake Recommendations Please
 

Sam,

How does the difference in "swept area" play into this? You are looking at front/rear rotors that are 1" larger than the stock ZR-1 rotors. Again, I don't race the car, but my experience has been that the pressure needed to slow/stop the car is noticeably less than w the Brembos I had up front. I see that u have a 90 and it's my understanding that the master/booster for the 90 is smaller than what was used for subsequent years. Some have used Camaro master/booster for use w Wilwoods for example. In my 92, the master feels more than adequate in terms of pedal feel and travel in combination w the Z brakes.
Just to clarify for others following this thread, my beginning objective was to use the Z06 wheels for the aesthetics and tire availability. Originally the car came w Brembo fronts under A molds. When I switched to Z06 wheels, the front tires protruded past the front fender noticeably. Part of the issue was the extra thickness of the Brembo rotor hat. Swapping in the Z06 calipers allowed use of the Z06 rotors, which are heavier, but they also reduced the offset putting the outer edge of the front tire almost virtually in line with the edge of the front fender.
The 19s, on the other hand, made the 12" stock rotors and caliper look rather puny. I do use 18mm spacers on the rears for the proper wheel/fender alignment.

Re: Brake Recommendations Please
 

Thanks Billy



[/B]QUOTE=Billy Mild;226004]http://www.amazon.com/Dupli-Color-BC.../dp/B000B6AF80

I used this, but got it from Advance Auto Parts.

I wanted to use the paint brush route as I feel the coverage was better. I did about 3-4 coats. Brake fluid will still ruin the finish so be careful.[/QUOTE]

Re: Brake Recommendations Please
 

Bob, if anything you may want to consider finding C4 Grand Sport calipers, they are direct swap to yours but are a stronger caliper

Re: Brake Recommendations Please
 

Sam, you bring sound tech to the brake upgrade question but I have to take issue with this statement:

My car does nothing but autocross, which is basically several 1 minute long emergencies (20 to 70 to 30 to 60mph repeat 10 times) with 5-15 minutes in between. While I have managed to boil my fluid on a couple of occasions, that's been a combo of fluid age and over-braking - the J55 setup is not really the limit there, if you have pads that can take some temperature. The tradeoff part of pads that *can* take some heat is dust.

The PBR caliper is certainly not the best in the world but it is far from the worst. You will see some pad taper owing to the caliper flexing, but you have to work 'em pretty hard to get there.

There are a lot of different configurations of C4 brakes, with varying pedal ratios, different master cylinder piston sizes, different caliper piston sizes etc. All of these things, along with rotor diameter, can be thought of as levers. More lever equals more work per input.

My personal battle with the 91's brakes are due to the smaller pedal ratio, the small master cylinder piston size, and I believe the inability to bleed the ABS unit. Bear in mind my prior autocross car was a 99 Cobra with very similar calipers/rotors but a MUCH larger master cylinder piston. Long pedal travel is not a great answer in my use of the car, but I can see how it would be very beneficial at 150mph!

Cheers,
- Jeff

Re: Brake Recommendations Please
 

I suppose the Brembos didn't their work good because of not correct piston volumes. In my 1990 car I run a 6 piston Porsche brake with 330 x 34 mm rotors and sawblade rims and they do a good Job.
About 2 month ago I did install in a clients 1992 ZR-1 a Mov'it 6 Piston brake with 342 x 32 mm two piece rotors. It has now a hard pedal and the necessary pressure is low to stop the car fast.
The calipers work with different piston diameters. This combination provide a very fast braking reaction and a stable pedal pressure when you slow down from any speed. We did several stop tests from speeds of up to 280 km/h (like 175 miles) and the brakes had no fading and kept the car in line.

When you install in front and rear such brakes and slow down hard at high speed, it feels like somebody push the car down. It's a amazing feeling. A fit Mov'it outperform a Z06 or Wilwood or Bear brake.

The rotor offsets are calculated and designed for stock 9.5 x 17" rims with 56 mm offset. When you are going with bigger 18 or more inch rims you have to take that into your offset calculation. Otherwise the wheels can stand out of the car body.

Re: Brake Recommendations Please
 

I would think that '92+ cars would respond better to "bigger brake" packages because the pedal ratio was increased from 3.5 to 4.0 according to MVMA published specifications. The piston diameter of the master was also changed.

Adding the pedal and the pedal support from a '92+ car to a '90 or '91 isn't an issue (bolt on) but I'm not sure how the pedal push-rod is attached to the booster so whatever might be required there could be an issue.

I've not seen a '90/91 booster side by side with the '92+ either so is a modification to the push-rod to use possible?

If someone had access to some of the Corvette salvage yards they could likely do a "side by side" - to compare the push-rod length differences. It wouldn't need to be ZR-1 components TO COMPARE.

The correct ZR-1 push-rod was an available service part and the attaching to the booster I doubt changed.

Re: Brake Recommendations Please
 

WV,

Do you know if the pivot point changed from the 90-91 to 92+ on the brake pedal itself? I seem tot think that was something else too

Re: Brake Recommendations Please
 

You should need two pieces, the column support and the pedal for sure. Can the length of the push-rod be changed to accommodate? That's the only question I see. I've of course not done this but I've done similar changes when doing AT to MT swaps. The retention of the rod to the pedal is the same. The SLS bracket is the same '90 - '92 and was a bolt on. In '93 the SLS bracket changed but I can't see that being an issue.

Re: Brake Recommendations Please
 

SLS bracket?

Re: Brake Recommendations Please
 

Stop Light Switch

Re: Brake Recommendations Please
 

:cheers:

Re: Brake Recommendations Please
 

difficult to order/install? The website is tough to navigate and decipher for me.

Re: Brake Recommendations Please
 

Do you talk about the Mov'it webseite?

Re: Brake Recommendations Please
 

I want to keep my stock sawblades. What kind of caliper upgrades are there available? did the later 93-95 have bogger calipers? or could you guys recommend some brands/models? i do not want to change rims but on my next brake job i would like bigger calipers along witjh my pads. I like my sawblades too much to get larger wheels. In my opinion its the flagship rim of C4 and i love em.