I've been having an ongoing problem with my Wilwood SL6 front brakes dragging/locking up. I thought it was a caliper piston problem, rebuilt them, still had the problem, and sent them back to Wilwood and they rebuilt them and said they are perfectly within spec. I reinstalled them and still had a brake lock-up problem.

I took the car over to a local dealership, and the mechanic there thought the calipers were mounted/shimmed wrong, so he corrected that and said the brakes were fine. I picked the car up Saturday and guess what? The brakes are still dragging. And it is both front wheels, not just one.

I'm trying to figure out what the likely causes could be. I have two thoughts at this point:

1. The master cylinder for the front circuit is bad (the rears are fine by the way).
2. The stainless braided flex lines to the front brakes are defective.

I can't see any other culprits. All the lines from the master cylinder to the wheel wells are metal tubing, so it seems unlikely they could be the problem. Plus, it is both front wheels, not just one.

Could it be something in the ABS module? I'm not at all familiar with how the ABS module works, so no idea if it could be holding pressure steadily on the front brake calipers.

I'm running out of time to get the car ready to take to Watkins Glen later this week. I am considering changing the front flex lines and the master cylinder, but don't want to waste time and money if it could be something else rather obvious that I'm overlooking.

Has anyone run into this type of problem? If so, what was the cause and the fix? Thanks gang. Really need some help here!!!

 

My first guess would be the flex lines. How old are your braided lines. Did the kit come with new ones? I had a problem with the lines colapsing and the brakes were dragging. new lines - no problem (on original calipers).

 

Hi Steve,

There are a few issues to look at one.

- A bad master cylinder.

- Brake pedal not returning all of the way ? Maybe the brake switch under neath by the pedal has turned a few times ?

Tony

 

My guess is not as good as yours but I had heard w/respect to stainless lines that they should be avoided because of maintenance. The source said they had a place in an all out race car where they would be replaced/maintained frequently.

My guess is to change them out; it's pretty easy for a DIY guy like you!

 

Picked up a new set of brake lines today, will install them. Talked to the dealership and will take the car back over and they will hook it up to the techII equipment and test the whole system. Hopefully, will get to the bottom of this before the end of the day tomorrow, as I'm supposed to leave Thursday for the Glen.

Argh. This has been an annoyance from almost day one with this car. Thought it was solved several times. I've installed the DRM brake ducts and Quantum spindle ducts, so cooling should no longer be an issue. But the brake drag IS a drag, and want it solved NOW.

 

Im not too familiar with wildwood but,,,,most calipers float/slide on metal pins to center them selves on the rotor. Are your calipers free to slide side to side? The pins need to be greased with a SPECIAL synthetic grease. Regular grease will get hard and stiff when exposed to heat. check those sliding pins and ,make sure that the calipers are free to slide.

When you release the brake peddle the fluid that expands the pistons must be able to return to the master cylinder. Can you depress the pistons on one caliper and does the fluid go back into the master cylinder?

BC

 

Hi Bill,

The Wilwoods are fixed caliper and there are no sliders like the stock C5 brake calipers.

I'm pretty sure it's not the brake lines since both front brakes are not working right.

The only other time that I have seen this kind of problem was a master cylinder and a bad brake booster that was leaking and locking all four of the calipers not just the front two.

Since the vettes have seperate lines for both the front and rear brakes my best guest is the master cylinder.

 

I don't think the front brakes are on the same circuit. Judging by the way the brakes are bled, I think the LF and RR are on one circuit, and the LR/RF are together.

I have had flex lines look perfect from the outside, but collapse on the inside, effectively forming a check valve. The caliper cannot release the pressure and the brake stays locked. If both brake hoses are the same age, it is possible they have both deteriorated internally.
You may have to loosen the hose connecting and see if the brake releases. Or just take them off and see if you can blow air through them.

 

There are two lines running out of the master into the ABS. You are talking about the ABS unit and I'm refering to the Brake master cylinder.

 

That is probably where the lines split, but the point was that if you lose half the master cylinder, you lose a front brake and a rear brake, but not both front brakes. Is that not correct?

 

Don't think so, since when you install a line lock you only have to install one unit from the master down to the ABS block.