Joshboody

Looking for some advice. My brakes are pretty consistent, but pedal isn't as hard as I'd like. And longer than I’d like. I can’t remember how it was before tracking it though. After a track day its softer/longer and gets harder with street driving, but not optimal IMO.

The feeling is that harder I press seems pedal will continue moving but with increasing pressure… there’s no “stopping point”. But I don’t give it too much force in testing.

My taper is only about 0.5mm in the front and I do not regularly check the rear as they don’t seem to taper the few times I’ve checked.

I believe I’m fairly easy on brakes and the local tracks are slower <120mph straights, getting about 7+days out of my front rotors… rears much longer.

*BUT when I'm in ABS, it's a very hard pedal*

- Stock C5 brakes, ST43 pads, steel lines, DRM cooling
- hardware is good… pins and pistons. Stoptech brake lines seem fine.
- NO leaks
- removed speed bleeders and now pressure bleed... but no noticeable change

Potential Actions… what do you think?
- tech 2 ABS bleed.
- maybe calipers are spreading, but seems this would be unlikely
- change master… but no leaks and seems consistent braking performance.

Been bugging me for awhile and with harder pedal think my late braking confidence would increase. So thought I detail my thoughts looking for any input. Thanks!

ps. My DD is Infiniti and has a much harder pedal.

oharal

Sealbeams

I have noticed a similar softness in my brakes at the end of a track session. Have not noticed any degradation in performance though. The brakes seem to go back to normal after 20 minutes or so. The basics are good to the best of my knowledge: fresh Wilwood Exp 600+ fluid, SS brake lines, good pads (carbotech HP10 fronts, HP8 rears). Looking forward to suggestions.

FASTFATBOY

Checked wheel bearings and slide pins?

Joshboody

Pins are good and no play in wheel bearings.
My observations can be duplicated static in the driveway.

its pretty consistent, just doesn't seem optimal.

Potentially just don't get my pads completely flat (no taper) after tracking and this is just the norm... BUT I only taper about 0.5mm and will hit the brakes hard on the street, which does improve it but not as I would expect. Unfortunately I don't have a new pad set, which would be good test... next set was purchased used and has slight taper also.

spdislife

The C5 is prone to getting a long pedal as the pads wear.

Would you say more of your issue is a long pedal, or soft spongy pedal?

One technique I used especially after a long straight is to roll my left foot over to the brake pedal and tap it while under throttle just before the braking zone. This removes the excess gap that develops between the pad and rotor that's a result of vibrations in the drive train, especially on a bumpy track. It worked well when I ran the OEM calipers on my Z. Since then I've switched to a Wilwood 6 piston caliper and that's delivered a more consistent pedal.

555ss

I have had the long pedal issue many times the biggest help was to go to SKF race bearings even though the stock ones feel ok when hot they move alot and very prone to failure ( I have killed a new GM bearing in 1 weekend with a7 's) the next is Pad taper I flip them after every event going to ap fronts helped huge.

It is the taper / knock back that give the long pedal and the hard abs pedal is because you have already used up the gap between the pads and the rotors, if it stayed kinda soft on abs then it has air in the system.
A tapered pad will feel long even if the car does not move due to the taper causing the caliper /mount to flex.

0Anthony @ LGMotorsports

Check the basics first.

Make sure you do not have a leak....at a fitting, at a bleeder, or at a piston seal. Might be small enough that it just causes a sweat but it can allow air in the system.

Make sure you do not have a vacuum leak at the booster

Make sure the wheel bearings are good and not causing any knock back

Make sure all mounting bolts are tight and not moving.

Check pads...are these the same pads you have always used? Are they very thin? Swap a known good set, or if it is a different brand, go back to the others. It might sound a little odd but we have had issues with different pads giving a soft pedal before in the past on the race cars.

Have you made any recent changes to the system that might cause this?

How old are the calipers? A OEM caliper is not going to last forever. Even with cooling ducts on it, years of heat and abuse can cause them to start to flex and will give you this feeling as well. Might just be time for new calipers or an upgrade.

Joshboody

Thanks for all the feedback. As stated these observations are in the driveway, static… so its not knockback.

Even though taper was minimal, I’ll flip them to guarantee a flat pad after some spirited street driving… and see if I notice improvement.

Again its not bad and my brakes are pretty consistent on the track… just not optimal IMO compared to other cars when pressing the pedal while stationary.

Thinking about this more, I believe a master could leak internally not showing any visual signs of bad seal.

Joshboody

Actually if pedal is hard during ABS, potentially I can rule out master and air between ABS... thus no need for tech2 bleed. Just thinking through all possibilities.

0Anthony @ LGMotorsports

Other Corvettes or other cars?

Joshboody

I'm comparing to other cars... I rent a lot. Maybe there's a little play in the pedal before fluid starts moving compared to most cars.

I flipped both front and rear and drove for a few days. It does get better and I think even with minimal taper flipping will flatten them faster. Before my next event I plan to measure the pads again to compare before/after. Still not optimal for me, but don't think there's anything else going on other than the taper.

0Anthony @ LGMotorsports

Only other thing, if you didn't want to change calipers, would be to go to a bigger brake master cylinder...that would firm up the pedal.

Bill Dearborn

Your description mirrors the issues I had with my two C5s running stock brakes. I took the 97 to the track about 3 months after I took delivery with 2700 miles on the clock. After two twenty minute sessions with the stock pads the brake pedal was so low it was almost to the floor before it got hard. We bled and bled but to no avail. Took the car to the dealer and they replaced the pads under warranty claiming the pads not the rotors were warped. I found out later they really meant tapered.

These are my rules for C5 brake problems based on my experiences from 11 to 19 years ago. If the pedal is spongy bleed your brakes, if the pedal is long then flip the pads from one side of the car to the other: in other words the inside pad on the left becomes the outside pad on the right side. This starts to taper the pads in the opposite direction so you have overall less tapering. It also increased pad life. When engaging the pedal start softly to seat the pads against the rotor and then press hard. This tended to reduce the rate at which the pads tapered. If you start to get a long pedal use your left foot to reach over and tap the brake pedal a few times as you approach the braking zone to the next turn. Keep your right foot stuck to the floor.

The most important rule is get a fixed caliper brake kit such as the LG G Stop kit or something similar. Do not purchase the C6Z brakes.

If you do a search you will find plenty of discussion of this from 99 through 04. There was a now defunct Corvette Forum that ran for about 2 years before this forum began and there was a lot of feedback on it from GM Racing on how to survive the C5 long pedal.

Bill

blkbrd69

Good luck fixing it without reengineering the entire system.

As many things GM they have intentionally set up the fluid system softly.

I have found if you use both pressure pot and traditional pump bleeding its almost firm, but still has that mushy ratio first few inches.

Multiple vettes and brake systems. None of them come close to feeling like a normal sports car. While they grip great they are still missing the Feel.

FASTFATBOY

I don't have these issues unless I use pads I have already tracked and it clears up once they flatten to the rotor.

I bleed with this and have for years, the first ones were made from 16oz coke bottles then I stumbled on them surfing Amazon.





Put some fluid in the bottom to cover the straw, open the bleeder and pump the pedal sloooowly up and down, this keeps big bubbles big and not into hard to bleed little ones. When the fluid is clear of bubbles, close bleeder and move on.

My pedal in the C5 and the one in the Z28 were very good(to me anyway).

Joshboody

This is the first I've heard of a "soft system". Makes me feel better. I now test every car's pedal I'm in and vette is the softest so far. Haven't had a chance to check other vettes yet though.

I never see bubbles when pressure bleeding although just started... moved away from speed bleeders where I was in the cabin unable to see any bubbles.

I would still like to do 1 tech 2 ABS bleed to rule it out.

Joshboody

Thought I’d update

Done a bunch of changes, but not necessarily due to long pedal… pedal did kinda initiate changes early though.
- Used WW FNSL6 with 2pc 13.06 rotors
- New master
- SRF brake fluid
- Rebuilt all calipers including the WW

QUESTION for everyone
With car on but NOT moving, when you depress your brake pedal is it hard, meaning a definite stopping point (with reasonable pressure)?

Mine is still not very hard (relative to other cars), but maybe this is a vette thing. My pedal will move maybe 2” with reasonable force and seems would go further with additional force. Other cars are rock solid comparatively. Car off though, very solid now compared to past.

Street performance is very good, but track still TBD… had what I think was semi-bad new MC last outing.

ErnieN85

some what depends on the hardness of the pads,not all pads compress the same. remember there is a lot of force applied to them

Joshboody

I use ST43s. I thought about this and potentially some flex in the floating calipers... my pins aren't the tightest in the bores.