tmak26b

I don't have a lot of seat time with the C6. In my short time with the car, I do notice the following. Can someone tell me if I am indeed feeling what the car normally does or do I need to work on my car?

I have a 05 Z51 with 7000 miles

#1 The brake bias seem to be extremely front heavy. I can feel most of the brake pressure going to the front. It might be perhaps the tires are cold, but I can feel the heavy front pressure is creating a lot of brake lockup situation (ABS). Is that the case with the C6?

#2 ABS on this car can be a joke sometimes. It would sometimes go in and out of ice mode. If you want to ride ABS to a complete stop, I could feel the car really slowing down. It would then do nothing and slow down again (not the normal pulse, I am talking about pressure and no pressure at all)

#3 Despite how clean the fluids and how new the pads are. There seems to be a lot of pedal travel with the brake pedal?

#4 Lastly, I don't know if it is because of my aggressive alignment, but high speed heavy braking results in a very very nervous car. It doesnt matter if i am on race or stock pads, I can snap the car sideways easily under initial braking. It's not exactly confident when you are going into a turn with that kind of brakes. Is that the way it is with other people's C6 too?

Just need some opinions from C6 owners, thanks

gkmccready

1. I don't find the bias issues you do. Even when running PFC01 front and PFC-Z rear compound pads. I did notice running Wilwood H pads in the rear gave the car a better feel under braking than the PFC-Z pads, though.

2. Haven't seen ice mode or weird ABS behaviour.

3. Nope. I have a nice high, hard pedal.

4. I had this with initial turn-in, but not so much under braking. More rear toe-in made all the difference in the world.

I rarely get myself in to ABS. This is my first car with ABS so I'm learning as I go... used to be a lockup on track would be expensive on tires... and, FWIW, I've been getting about 280 minutes of track time to a set of front PFC01 pads.

0Randy@DRM

WOW you have some issues but nothing that can't be fixed or lived with.
1. Front heavy bias is a issue, it is all done by computers and is something that can be corrected mechnically or mentally. Possible fix, switching up pads.
2. Does the ice mode come on the dash? If so get your abs checked out. If not it sounds like it could be boiling the fuild. The way you described pressure then no pressure? Is it during one stop or from braking point to braking point?
3. Pedal travel is something that is tricking to get right. Running stock calipers you can get into "caliper flex", or it could be a rubber line flexing. Pull off all the wheels and have someone push hard on the pedal. Do you see things flexing a lot? Fix what moves more then it should or the time you checked before. If you had aftermarket brakes then one of our masters would help alot.
4. Under braking the suspension is under extreme force. Something just smells like a toe-out situation atleast under braking. Check out bushings and alinment specs. Also check out the tie rod end. Or it could be from a shock bottoming out, nothing will snap a car faster.

Randy

MattW_VA

I also have an 05 C6. I find the car behaves better with staggered pad compounds front/rear. i.e. something with less bite in the rear. You definitely need some toe in in the rear as has been mentioned.

I have a great brake pedal with stock calipers and brake lines, good fluid and pads.

Do you track it with all the electronic nannies off? I've forgotten to turn them off a couple times and the car absolutely refuses to stop, it is bizarre and more than a little scary.

AU N EGL

Damn Matt that is scary especially when your use to braking late and deep into the brake zone.

davidfarmer

some of this could also be related to other cars you've driven. If you are coming out of Porsches/BMW's, then the Corvette could just be different. Those of us who almost always driver Vettes find the C5/C6 braking systems to be just fine, and the ABS system is amazing (until it fails completely).

I find our Z06 can be nervous at braking zones, but it's usually because I'm going 170mph, and off-line passing people. I've also found that "racing" pads have such a high torque level that it makes the car feel extremely nervous, and that's why I often use HP+ pads at the track.....car takes a little longer to slow down, but the pads are cheaper, last longer, and are quite a bit easier to modulate.

I would hook up with some other Vette drivers and compare issues. If you are on the east, there several events coming up that will be full of Vettes. I for one will be at VIR 3 times in the next two months, as well as Rd Atlanta and maybe even CMP.

Hope you get it working to your expectations.

MattW_VA

It'll get your attention going into roller coaster!

rustyguns

I do not have a C6 Z51 but i run with a C6 guy. we usually are braking very close to the same time and he complains of his ABS coming on. And mine is not. He was running the stock Z51 pads. I was running Hawk HP plus pads in front and C6 z51 pads in the rear ( a bit softer). maybe C6 ABS more sensitive? i do not know

I drove a porsche before the Z06 and the dynamics are not comparable. I do think Porsches stop so much better because the engine is in the back. and I believe they transition into the turns from braking because of the rear motor also. I did love my Porsche but now I am a torque Addict with the C5 Z06! it is a blast!

A Soft pedal is definitely fluid. Flush it with Castrol SRF and then you won't have that problem anymore.

davidfarmer

I have to disagree about the fluid definitely being the cause of a soft pedal. Pads that are of the incorrect temp range can "go off" just like street tires getting too hot. Pad fade, soft pedals, etc, can be caused by fluid, pads, or even flexing calipers. The GM Calipers only last about one season before the permanently deform.

rustyguns

yeah definitely was probably too strong of a word, sorry

but if he is using the original fluid that came in the car. Putting Castrol SRF sure won't hurt any. i know two low mileage C6 guys that got very spongy brakes after their first time at the track and went to better brake fluid and just love it of course then their pads wore out!

Never thought about the GM calipers deforming does the O ring fail then the piston gets warped ? or ? another needed mod..racing calipers

But Dave is the man ! Love your website! i learned a lot! thanks!

BEZ06

Wow!! You've got some weird sounding problems.

Do you have the OE wheels/tires on the car?

All I can think of is if the tires are different sizes than the stock sizes the ABS may be getting confused because the rotational speeds are different than the ABS expects so it's doing weird things.

Good luck,

Bob

tmak26b

Hi all, I think I might have confused you guys regarding my questions.

#1 Basically I feel the brake bias is too heavy toward the front. It creates a situation where the car has the tendency to lock up the fronts too easily. I just want to see if others feel the same. Someone mentioned about getting less grippy rear pads, I was actually thinking the opposite as I want the rears to do some work. I haven't tested it yet, but I believe if I do 80-0. The front brakes will probably get some heat in while the rears will probably just be warm. I could be wrong, it just felt like the brake bias has too much in the front.

#2 My problem with the ABS is that I get the same exact pressure. Instead of getting the pulse and have the car slow down like a normal car, I feel I get the pulse, then I get pulse that doesn't do anything (ice mode).

#3 I just have a long pedal that's all. The grabbing point is not at hte top on my car. I am just curious to see if that is the case.

#4 Car just felt nervous under heavy braking. The other poster might be right, I am doing a lot of speed, so any crazy things I do can magnify the problem. It just I am not sure if it is the alignment or the car itself that tends to do that.

No car is stock and I dont think there are any problems.

gkmccready

What alignment do you have on the car?

tmak26b

Off the top of my head, slightly more camber in F and R. zero toe in front and .06 toe in in the rear. THe car used to be a lot more stable, I think the potholes might have changed it. Now the car is a pain in the you know what to drive on teh highway

Bill Dearborn

These comments are from a C5 perspective:
1. The later C5s (2001 and newer) and the C6s have Dynamic Rear Proportioning. This means the EBCM can apply as much rear brake as the rear wheels will take.

2. A number of people have described Ice Mode on ABS systems but I haven't experienced it in 20 years of driving ABS equipped vehicles on or off track or autocross course so I can't provide any insight.

3. If I remember correctly from the few C6s I have driven the pedal feel is the same as on my C5s. With non-tapered pads the initial stroke on the pedal will drop the pedal to the same level as the gas pedal. If the pads start tapering the initial stroke gets longer and longer and longer until the pedal is slow low you can't heel toe properly as the gas pedal is too high. On the second stroke the pedal will come up to gas pedal level. Changing pads is the only way to get rid of the long pedal. You can bleed until the world comes to an end and you still won't get rid of it.

4. As for being nervous under braking it probably has more to do with alignment than anything else. Although you want some toe out in the front for better turn in actually using a very small amount of toe in seems to make C5s less nervous and tends to reduce wander on the street considerably.

Bill

tmak26b

The pedal goes down to about where the gas pedal is. There is a good 2" if i recall correctly. Some cars new pedals are right there, I just wantt o make sure mine is okay

Bill Dearborn

You should be. My 86 C4 did the same as well as my 97 C5 and current 03 Z06. That initial drop puts the pedal right where it should be for heel toe downshifting. I replaced the OEM front brakes with 6 piston Wilwoods on my Z and the pedal still drops the same amount but never goes lower no matter how hard I use the brakes as the Wilwood calipers aren't nearly as sensitive to pad taper as the OEM calipers. It gives a person a lot more confidence when running into a braking zone at 150 mph.

Bill

tmak26b

I just want to make sure its normal, makes no difference to me as long as I have a pedal!