medici78

We finished up the install of a Wilwood 6-piston setup. Everything seemed to be fine. On the way home, my friend noticed that the steering wheel shakes when applying brake pressure between 45-70mph. If you stand on it, it is not as noticeable. Does not pull to any direction, just shimmies through the steering wheel. Nothing in the brake pedal. The setup is brand new and only has 20-30 miles on it. is What could be causing this??

trackbird

iTrader: (4)

Make sure you got the oil cleaned off of the rotors (you did use plenty of brake clean, didn't you?). Otherwise, I'd go bed the pads (several stops from 35-5, cool them for a few miles and then a few from 60-5 mph). Once you do that, they should calm down. It's probably oil or uneven wear on the rotors as they are seating. Go put a little heat in them and let us know if they get better (I suspect they will).

medici78

Thanks for the tip, trackbird! I hate to sound like a redneck, but we didnt have brake cleaner, so we used carb cleaner. We then sanded the rotors down w/ fine grit sandpaper.

Foxxtron

iTrader: (1)

And if it still doesn't feel right, then you might have to find a way to temporarily install race pads and make a few passes to resurface the rotors (Don't keep the race pads installed any longer than necessary, because the agressive compund will eat the rotors in less than a week of street driving).

I hope this won't be necessary at this point, however I noticed you mentioned that you sanded the rotors down with a fine grit sandpaper, and I'm not too sure how much you did and what exact grain was it. By the statement, it probably wasn't enough to really make the surface uneven, but I just wanted to make sure.

trackbird

iTrader: (4)

Carb cleaner is oily and is very likely the source of your problems. I'd guess that you have "oil" on the rotors. If you go get them very hot, you should be able to burn that stuff off. Make sure you drive the car for a mile or two to cool the rotors before parking it to avoid any heat related problems. I'd go make a few hard stops (60-5mph) back to back until they smoke a bit (6 stops?) then cool them and see how they are.

Or, get a can of brake clean and hose them down good, then go make a few stops to make sure you get any "leftovers".

medici78

Update: The rotors were turned and the problem went away.

slayer6x6

iTrader: (2)

I have the same problem with my Wilwoods. Did you rotate the rotors from left to right, or did you just flip them around and keep them on the same hub?

Foxxtron

iTrader: (1)

Actually, what they meant by turned is not rotation by switching the rotors themselves from one side to the other, but resurfaced to make them smooth on each side of each rotor. Your vibration might be caused by improper bedding.

Before resurfacing, you might want to see if some hard braking will somewhat straighten out the pad bedding on the rotors. Which ever option you decide, make sure you're in a safe area away from traffic (I don't endorse performing this procedure on the public road).

Resurfacing performed on the Wilwoods would be to temporarily install racing pads and make a few passes (accelerating, then performing 60-10 MPH braking about 5 to 8 times), but not to the point where they heat up (pads beginning to emit gas or rotor beginning to glow). Once that is finished, you may then reinstall the old pads and being the bedding process again.

If you do decide to resurface, then you might want to check the friction ring width to see if it is still within safe specification.

If you didn't bed the pads in properly after you first installed them, then you get uneven pad deposition, which is one factor in vibration upon braking in new rotors.