Big Brake Kit Troubleshooting help.
 

Hi Folks with Wilwood BBK or BBKs, need your help troubleshooting an issue.

I got Wilwood 6Pot front and 4 Pot rear Drilled and Slotted rotors with B10 pads installed last weekend. Brakes were also bled, converted from DOT 3 OEM Fluid to DOT 4 ATE.

Been driving them with 100 miles on them and in the pedal, since brand new, I've experienced rumbling and vibration in the pedal and in the car.

When I lightly brake from 65 -> 40, the entire car vibrates like the brakes are catching on the slots on the rotors. There is pulsating in the brake pedal. The car pulls slightly right while braking.

From 40-30, there is still vibration in the car chassis but not as much as from 65-40. There is also a pulsating feel in the pedal like I am hitting ABS but I am not hitting ABS. The car pulls slightly right while braking.

From 30-0, it the brakes feel like normal brakes, smooth.


Thing's I've tried so far:

1) Re-Bed Brakes by doing stops from 30-5, 40-5, 50-5, 65 - 5 and coasting to cool the brakes off.

2) Inspected the brakes, I have noticed that the front driver side inner pad slightly sticks out 1/2mm while the outer pad is completely flush. Checked Passenger Front Side and both pads are flush.

3) Noticed that the wheels now sit on the brake hat and not the actual hub anymore. Wheels are 18X9.5 +38 Work Emotion Kiwami with 255 35 R18 MPS4. I don't have hub rings since I've read that once the wheels are torqued with lug nuts, the clamping force of the lug nuts do the work while the hub ring just goes along for the ride.

4) Considering re-bleeding the brakes. I doubt there is an air bubble since the brake pedal is very stiff and there is no brake fade.

5) Lug nuts have been retorqued many times from inspecting.

6) No leaks of brake fluid, brake fluid level is the same.


Is this vibration going to go away after more mileage? Or did Wilwood send me some non-true rotors? Possibility of a brake piston not returning or uneven brake pressure from the pistons? Ideas of how to check that?

check to find out why one pad is different.
bed by going 70-5 in 3 sec. ie at ABS limit. several times to get things warmed up.
big brakes are meant for hard stopping.

So I tried this, the vibration went away slightly but the brakes started to make a grinding noise. It's not a brake squeal at all...? Went away as soon as the brakes cooled down. Still getting some vibrations.

3) Noticed that the wheels now sit on the brake hat and not the actual hub anymore. Wheels are 18X9.5 +38 Work Emotion Kiwami with 255 35 R18 MPS4. I don't have hub rings since I've read that once the wheels are torqued with lug nuts, the clamping force of the lug nuts do the work while the hub ring just goes along for the ride.

Not sure what you mean by "sitting on the brakes hat" means but wheels and breaks should not touch at all. If your wheels are hitting the your brakes that's your problem.

Try buying some spacers if it does hit. You can buy cheap-o's at any auto parts store.

As far as the hub rings, it does help.

Are you able to go on the side with extended pad and dissassemble the caliper and make sure the pad is seated properly?

The "hat" is what is commonly referenced as the inner part of a two piece rotor.

OP.

Double check that assembly is correct, then go and bed the brakes in hard. at least 10 stops from 70-30, then drive around without touching the brakes for 10-15 minutes. You get some slight pulsation from the slotted rotors, but any more then that is not normal.

I had a similar issue when I first went BBK, it takes a lot more heat to bed them in then the stock brakes.

For two piece rotors there is a "hat" which is the part where you put it on the hub. The contact piece of where the actual brake pads meet and contact the rotor, is replaceable.

Yes, the pad is seated correctly, even try to hit the bracket to push it closer to the rotor. Might be a QC issue with Wilwood.

I will try to bed them in....with higher speeds and more times.

I know you'd like to fix this DIY, but you could also find a shop close to you that handles wilwood and brembo BBK installs to look at it and find the issue just in case the bedding process doesn't work out. It's very possible you could accidentally wear something incorrectly if it's got a QA issue.

https://www.wilwood.com/Tech/Index
https://www.wilwood.com/TechTip/TechContact

Ah. Brake hat got me confused, should have wrote as rotor hat.

You mention an ABS-like pulsing in the brake pedal when the car pulls to one side. Are you sure you didn't damage one of the ABS/wheel speed sensor wires, or rings during the install somehow? It almost sounds like you're having ABS issues when braking from higher speeds.

You aren't getting any lights on the dash, are you? You might want to pull your ABS fuse(s) and try braking without it just to see if that has any effect on the pulsing pedal and the pulling to one side. I know you said that the whole car was ALSO shaking, which ABS shouldn't cause, but it doesn't hurt to rule out any ABS issues.

I don't have any ABS lights on the dash. If I brake harder, then I can feel additional pulsating through the pedal.

I did do some more hard braking and it seemed to help a little bit in terms of vibration, but light braking still vibrates really bad.

Ah ok. That sounds like it's just mechanical vibration from the brakes, then. Have you identified what is causing one pad to sit differently from the rest?

I'm pretty sure it's the bracket. But it's only 1/2mm so I dont think that would make a huge difference?

These are huge brakes for a street car with lots of cooling. It will be very difficult to get them up to proper operating temperature on the street. Might suggest a street pad for daily and save those pads for track.
Still think a check of install is in order to determine miss aligned pad.
Some track pads make a grinding noise when cold, but a check of surfaces for a rub is in order.