USA_Z

I have the following setup on my C5 Z06:

OEM Calipers all the way around
SS Lines on all four corners
SS Front caliper pistons
RBF 600 Fluid
Raybetos ST43 pads frt & rear
OEM Style blanks for rotors

I've used this setup for two events now and it is my first experience with track pads of any kind. My concern/issue is a constantly mushy pedal feel with very long travel. This does not inspire a whole lot of confidence in my brakes. I find that at speeds under 100mph there isn't much issue getting stopped but, I don't like the long travel or mushy feel. The pedal isn't that far from hitting the floor when the best braking finally takes place. At speeds over 100 I'm finding myself braking a lot earlier then I should be and I just don't trust them. There is never any real solid pedal feel like I get when I switch back to street pads.

From everything I have read I would have expected these track pads to squeal like a pig when cold. I've never heard a single peep out of them. It also seems that the hotter the brakes get the mushier things get. And that starts from my first session on. They stay like this for the entire event (5 or 6 30 minute sessions). Bleeding at the half way point of sessions made no difference in pedal feel at all.

After event 1 I put back on a different set of OEM like blanks for the street along with street pads. I also bleed the calipers but didn't find any air in the system. the pedal was rock hard with a very short pedal throw. I have not had the time to inspect and change the brakes out after this second event yet.

I just drove around the neighborhood to bedin the track pads. Perhaps I didn't do this step right and this has led to my issue??

There was barely any pad wear after the first event and from what I can tell they haven't worn much after this second event. (I have yet to inspect them though)

Does anyone have any idea why I'm experiencing this mushy pedal and long travel?

Thanks,

Sidney004

Pull the pads and check if they are longitudinally tapered. When mine are tapered, they feel just like that.

UstaB-GS549

I would check the pads for taper or bent backing plates.

I would also check for anything that would not allow the pads to slide in the brackets. With the caliper off and the pads in place, can you see an air gap between the rotor and pad?

JeremyGSU

Have you tried doubling pumping the brakes at all going into the braking zones to see if the pedal becomes firm on the second stab? That worked for me but I got tired of double pumping every corner.

Check out a thread I made not too long ago. I was having long pedal travel that didn't give me much confidence when I was tracking and it's probably a similiar feeling to what you're experiencing. The only thing that solved it for me was switching to SKF front racing hubs. Now I have a hard pedal all day.

http://forums.corvetteforum.com/auto...ck-c5-z06.html

sebdavid

Might be a bed-in issue. You're not going to bed brake pads in by driving around the neighborhood: http://www.essexparts.com/learning-c...ost/Bed-in?v=2

brkntrxn

Agree. Bed them properly.

Bills Z06

USA_Z

Thanks for the responses all. I thinks UsTa-B might be on to something. I should have known better, but I think my problem is with how the pads are fitting in the sliders. To say that some of them are tight would be an understatement when compared to how the street pads fit. I'm guessing that they are not moving very well. I won't be able to get to the car for a couple of days but, I'm going to take a look at that first along with checking for any tapering.

As for the bedding, I'm sure you guys are correct and thanks for the link. I did get out and do some hard 45mph stops as part of the bedding process. I pretty much followed the directions on the HAWK box I had for my old HPS pads. That's probably not good enough for track pads though. I'll check out the link and go from there.

JimbeauZ06

[QUOTE=JeremyGSU;1581690297] I was having long pedal travel that didn't give me much confidence when I was tracking and it's probably a similiar feeling to what you're experiencing. The only thing that solved it for me was switching to SKF front racing hubs. Now I have a hard pedal all day.

QUOTE]


Piston "knock back" causes a long pedal and SKFs will fix this to some extent.

If you didn't bleed correctly or completely and if you didn't clear out the ABS and re-bleed you may still have air or old/bad fluid in the lines causing a soft, spongey feel.

I doubt seriously that it's a "bedding" issue. I can't tell you the number of times I've replaced pads in the paddock and gone right back out on the track without bedding. Is it ideal? No. Does it cause a soft or long pedal. No worse than normal.

Here's the deal. Stock Corvette brakes have thin pads and a lot of heat transfer into the fluid. You've already done all the right basics with fluid and SS lines. It's taken me a while to get used to but even with SKF hubs and all the other upgrades to the stock system there's only so much you can do and this isn't going to go away completely without upgrading to Brembos and bigger wheels. This is just part of driving a 'vette at the track. So, run newer pads when you can, change your fluid often, bleed regularly and correctly, learn to brake less and get used to having some pedal travel when you're on the track.

JeremyGSU

I too highly doubt it's a bedding issue. I run XP12/XP10's and I have yet to bed my pads. I run street/track and have replaced pads at the track and just gone out the next session with no issues.

If you read through my thread there were others having similiarly claimed issues and replacing the hubs fixed 90% of the problem. You're always going to get some pedal fade slightly just because you're going fast and the Corvette brakes aren't all that big. While most people say they are 13" I believe they are truly 12.8" and the calipers are small. That isn't all that big for the speeds you hit and the weight of the car.

USA_Z

I definitely find myself "double-pumping" the brakes as it were. I have plans to swap to SKF hubs over the winter. I just need to get through one more event this year. I don't feel that the extra pump to set the pistons is doing a whole lot for my condition but I do it anyways. I think there are a couple of factors at play here and this is surely one of them, just maybe not my biggest issue at the moment.

SouthernSon

[QUOTE=JimbeauZ06;1581693339] 100%. SKF's help a lot with knock back. And the looser the OEM bearings the worse the knock back.

JeremyGSU

I would also look at maybe switching pads. I haven't heard of many people running your pads.

Lots of people run Carbotech XP10/XP8's or XP12/XP10s with no issues.

Also, you need to add brake ducting if you haven't already. The brakes are small and there's not enough air flow. The ducts will help them stay cooler during sessions.

USA_Z

I'm sure I'll try different pads at some point. I'm not convinced that this issue is pad material related at this time though. The Hawks corrosive dust has me scarred off of them and the Carbotech's (my original thought on using) seem to have a very short pad life from what I've read. I talked with an individual at this past weekend's event that used to run the XP12/XP10 combo (non-corvette) and said that he could barely get a weekend out of them and has since stopped using them.

As for brake ducting, I have the DRM kit in the garage and it's on the list of winter projects to get done.

Sidney004

The only variable is the dimensional configuration of the pads.

If it were shot bearings, the street pads would of felt crappy as well. The bedding is a non factor because the brakes feel mushy when you press on them standing still or at very low speed, right?

IMO the Raybestos ST43's are excellent race pads(the only people who don't agree have never tried them) the real issue is the 2 piston PBR caliper, which is prone to tapering the pads. I measure the pads and calipers for taper after a track day. I've fought the same issue and this is what I found out: http://forums.corvetteforum.com/auto...rake-pads.html

Soloontario

I have had a similar issue using XP 10s up front and the Quantum brake ducts. The pedal would seem pretty long but actually came up as the temps increased and then would really drop down when they cooled. I had found this sort of thing to be a common issue with any kind of pad with cheaper cars with single piston brakes. The inner pad would hollow out under heat and pressure ( I assume due to some bending of the backing plate) and when the pad was cooled, only the outer edges of the pad were contacting the rotor producing a very low pedal. A number of street miles would bring the pedal back up.

Sure enough I looked at the XP10 pads off the vette and the inner pad was ever so slightly more worn in the middle than the outer edges and yes, some street miles have improved the pedal. It was pretty easy to see when you put the 2 pads together off the rotor that the inner pad was hollowed out.

Interesting side note is that I recently took the ducts off (really not happy with the makeshift seal I made to the OE fender well duct nor happy about the hose getting destroyed by any size tire bigger than stock) but I have only run on tracks that are easier on brakes since. This problem with what I assume to be a bending backing plate occured with the ducts in place.

My experience with returning to street pads is the same. The pedal immediately firms up (as the pads have never been used on the track and are not hollowed out)

BTW I agree, the raybestos are good pads (although a bit pricey) and I doubt this is a bedding issue.

USA_Z

I finally got around to looking at the brakes. Definitely not a slider problem. I was thinking they were tighter than they actually were. The problem is pad taper as many of you have mentioned. The rears are fine and the left front only has a slight taper to the pads. The right front, however, has a larger taper to both pads.

There is enough pad material left to get me through another event. I'll level the pads some, and swap sides. They be trashed after the next event anyways. I'll definitely be paying closer attention to this in the future. Thanks again everyone.

On another note: As of now I'm guessing I'll be staying with the stock 17" front wheels to keep costs down. It seems the only option I have for brakes is the Wilwood 13" SL6 kit. Have any of you run this setup? Is it worth investing in or should I save the money and bite the bullet on running 18" front wheels? A lot more options available then.

Lasco001

I'll give you a good tip. Free Get some money together, (Save).
Then buy yourself something really good, but you have something where you have your pleasure and fun.
Otherwise you buy just several times!

moespeeds

I like my Wilwood SL6's, but it's the only brakes I ever used so I'm not too objective. I use stock rears and run Wilwood H compound pads front and rear. The thicker pads work great, and last much longer.

Double check your hub bolts, make sure they are all torqued. I was having braking issues over the course of 3 weekends, until I finally lost them going into turn 1 at NJMP. Turned out to be pad knockback, I had a bolt completely fall out of my wheel hub, causing it to wobble. I had checked every single thing under there except those bolts. Fried an SKF hub, $350 mistake but it could have been much worse.