SilverSmoke

Just curious as to what the potential issue could be. At high speed and trying to stop quickly, not stop on a dime, but a fairly quick decrease in speed, the ABS sensors activate the pedal gets stiff and all of the sudden the car is coasting forward rather than stopping.

Scenario 2: I'm going pretty fast, before entering a turn I hit the brakes fairly hard so I'm not braking too much if any during the turn. The ABS activates, the pedal gets stiff, and again the car coasts forward without slowing down, or at least slowing down like it need it to.

I did the Vette rotor upgrade in the front, and my wheels are different than stock, but the overall ride height of the wheels should be just about even if not dead on (9.5" 275 vs 10.5" 295 wide wheels).

If I were to autox this car, like I want and plan to, this could be a complete pain in the butt experience, and really could cause me to be afraid to manipulate the car in the manner I need to get around the track quickly but safely.

Any ideas? Do people put automatic ABS push button deletes when needed if there is such a thing?

mitchntx

iTrader: (14)

Sounds like brake fade and not ABS.

Which pads are you running?

VIP1

What about the fluid?
The pedal firmness change could indicate that its been cooked/boiled.

SilverSmoke

Oh No. Definitely not brake fade, and definitely not boiling the fluid. The ABS is activating, pushing the brake pedal back up at me.

00PewterSS

iTrader: (3)

You know, I have the same problem. My car is set up exactly like yours, vette calipers, rotors and pads, even the same tire and wheel package even.

I think it is an ABS proportioning problem. The car seems to hit the rear ABS when in a hard corner, makes it a bit unnerving. Someone suggested to me an adjustable ABS block, I have no idea who sells these.

I'm curious if someone has any better ideas.

Brian

mitchntx

iTrader: (14)

ABS engagement is a rapid pulse, not push back.

00PewterSS

iTrader: (3)

He may be interpretting what he is feeling slightly wrong. Mine is doing the same thing and it is the ABS coming on which gives you a different pedal feel. I am certain that I am not getting impending wheel lock-up and for some reason it is applying the ABS.

Brian

SilverSmoke

Exactly, I should just say the pedal gets dead stiff and feels a little gritty as you try to push harder down on it with not much affect on the braking.

mitchntx

iTrader: (14)

When I engage ABS, the pedal pulses or vibrates rapidly under my feet. And an associated loud banging noise follows along. It's unmistakeable.

It doesn't just get stiff.

No one has ever said what brake pads they are using and also what is considered a "high rate of speed"

SilverSmoke

It may pulse like that on a true hard stop going straight line, which is true, it will pulse, and make a bunch of noise. This is similar, but different because it is activated, but not in full force, like its there, and its not. The pedal gets stiff, you can hear the noise, though not that loud, and you can feel something going on with the brake pedal.

an example is speeding up to 60-70mph then hard braking before a turnoff onto another road approx 120* the other way. when I do the hard braking, the ABS is not activated, but when I go into the turn with my foot slightly on the brake for added drag to slow down, it gets activated, and this is when I have all the issues.

Not sure what the brake pads are anymore, too long ago (Green pad or something comes to mind?). They only have about 5k mi on them. it isn't brake fade, I start my car comming back from the gym, take one turn, hit it, then take the turnoff at the light. The brakes are warm by that time, but not fading away.

I hope this helps better expalin it. It's just really odd and very hard to describe, but it is definitely abs related. don't remember, but I think even the ABs lights up on the dash when activated.

11 Bravo

iTrader: (3)

I have the same problem, especially going into corners. I definatly don't have brake fade with my Baer Extreme+ setup. Thinking about deleting the abs and see how it is.

00PewterSS

iTrader: (3)

I have researched a bit more and I think this should help.

Here is a link to another forum where it linked to an article that talks about what we are experiencing and why.

http://web.camaross.com/forums/showthread.php?t=256527

Here is the link to the Wilwood brake proportioning valve.

http://www.wilwood.com/Products/006-...1-PV/index.asp

You simply put this in line with the rear brake line. Like I mentioned it seems the problem is that the ABS is putting too much rear pressure in and causing the rears to lock-up when they should not be. You can reduce the line pressure to the the rear and keep this from happening.

Oh, the thing appears to be about $40. I'm trying to find one of the sponsors that sells them.

SSBC sells valves too, even with a pressure gage, but I don't know the price.

Brian

SilverSmoke

Hmm, but if the rear was locking up on a turn, you would feel it start to kick out. I don't think mine has kicked out yet. Interesting post though. Makes you think about it some. Would be nice if there was an easy way to install it in the front, in the rear end, that is a pain in the butt big time!!

00PewterSS

iTrader: (3)

Mine doesn't kick out exactly... but it does induce an oversteer a bit when doing this. I really think this is what our cars are doing. It makes sense, the front brakes are more efficient and require less effort causing the rears to receive to high of a pressure.

I plan on ordering one and trying it out. I know it will need to be bled after, but it is still worth it if it works.

Is there are sponsor on here that sells them? Either Wilwood or SSBC?

Brian

00PewterSS

iTrader: (3)

Does anyone know if the proportioning valve will work with the ABS block? Or will the ABS compensate for the valve and still have the same issue?

Is there someone knows about this first hand before I buy something that does nothing?

Brian

mitchntx

iTrader: (14)

I don't understand why you are wanting to put a band-aid on the issue.

You have a problem that needs addressing.

I still think it's your brake pads. Green Stuffs are not known for their abilities to resist heat. They are a high dust version of stock at best.

00PewterSS

iTrader: (3)

Sorry to hijack this guys thread, but we have the same issue.

I don't have green stuff pads. I have Hawk HPS pads and I'm not experiencing fade. With my stock brakes I got fade, and that wasn't as bad as having ABS come on all the time! I'm not trying to band-aid an issue. I didn't have an issue (this issue) before installing larger front brakes, now my bias seems to be off. I'm open to solutions, and I have read elsewhere that an adjustable proportioning valve would work. I don't know, I'm looking for help!

Thanks,
Brian

mitchntx

iTrader: (14)

I guess I need to give some backstory ... I had C5 brakes on the front of my '98 TA and then went to 4 piston Brembos. So, I've been in this big-brake rodeo before.

I never experienced what you are describing as "ABS" or "bias". I know numerous folks who have made the change to C5 brakes and have no issues like being described.

To answer directly, I think a manual bias valve between the pump and rear brakes will cause more issues.

Your problem resides elsewhere.

Are you using C5 pads or F-Cars pads?

SilverSmoke

These are not stock replacement pads though. I've already ran them from 130mph to 40mph on a hard slow down, and the brakes loved it. No fade here.

If there was brake fade, the abs light wouldn't go on or get activated, I'd just keep rolling and pressing harder on the brake pedal.

VIP1

What about calipers?
C5, C6, or stock LS1 F-body?

That question goes to mitchintx, 00PewterSS, and SilverSmoke
(I think 00PewterSS said Corvette, but not which.)

If I remember correctly, the C5 calipers (and possibly C6 as well) have smaller cylinders which could push the brake bias rearward. Many on here have said that the stock brake bias is already too far rearward. If this is the case, then your calipers could be causing the brake bias and ABS issue.

Can the brackets and lines you have support the stock calipers? If so, try using the stock calipers (I don't know which pads to use, f-body or corvette).

I'm working off memory from what I've read on here, not experience. So if I'm wrong, let me know.