pewter82

I have a steering wheel shake under hard braking. Rotors right?
I look on Pelican parts and they list rotors and disc's. Wouldn't those be the same thing? But the Disc's are way more $$.

The car has a Ruf suspension, but I don't think that changed the rotors.

TIA

jason

malmasri

TT are heavy vehicles I recommend that you get Frozen rotors as they will last longer under heavy breaking...

Macster

Could be brake discs. How do the brakes/car feel under light braking?

Are you sure you're not triggering ABS? Has someone been at the braking balance?

Take a rotor off and put it on a brake rotor lathe and measure run out and see if there's any.

If you want to go to the trouble take a skin cut on both front rotors and see if this smooths up the braking.

If rotors undersized -- worn below the legal thickness threshold or will be under after a skin cut -- you'll have to replace them.

Be aware when I got my Turbo the brake rotor holes were plugged with stuff. (Rust mainly along with brake dust.) I used a car wash wand and rinse spray and blasted the holes clear on all 4 rotors.

But even before this brakes were smooth under all braking conditions.

I don't know the difference between rotors and discs. I was under the impression the terms could be used interchangeably. However, they might not be interchangeable.

Sincerely,

Macster.

adam_

Maybe try rebedding the brakes?

http://zeckhausen.com/bedding_in_brakes.htm

pewter82

Light braking no shake or very little. Hard brake its moving the wheel an inch back and forth.
Rotors look very clean, all holes look open. Brake thickness is good. DocPorsche noticed it needed rotors when he test drove the car, i am just unsure of what to buy or get them turned.

jason

Macster

That suggestion to attempt to bed in the brakes (again) is a good one. I'd give that a try before anything else.

For brake parts, I generally like stock parts but there are some good aftermarket brake hardware out there. I have no experience with any of it so I can't make a recommendation.

One thing you could do is get new stock front rotors (and maybe rears if new fronts don't "fix" the symptom) then use these to replace the ones currently on the car then take the old ones and have then skimmed. If the tech good he can tell you -- if you watch you may be able to see it -- if the rotors "warped" or something.

Actual warpage rare. Chances are the brakes just developed an inconsistent coefficient of friction. Happens if brakes not bedded in properly and an emergency stop done and hot pads left in contact with rotors for a while. Pad material remains "stuck" to rotors and this causes pulsing. This can also happen (at least my experience with my VW brakes) is if the brakes are rusty and they're not used sufficiently to remove the rust and an emergency stop done and the pads left in contact with the rotors. Even though the brakes bedded in the rust somehow causes problems..

If you're savvy and with the right measuring tools you can check brake rotor thickness and runout yourself.

Sincerely,

Macster.

Edgy01

Are you the original owner? Know the history of the car? I was test driving a Porsche several years ago with similar symptoms and discovered it had seriously warped rotors. (It had been a European car that had been massively abused overseas, hit something, and the front clip was replaced along with the front suspension and rotors. However, the rear rotors were left intact--and they were warped.)

Land Jet

New stock rotors are cheap and high quality. I'd go that way if you aren't tracking the car.

smithk993

My stock pads have a squeal when coming to a stop. Not loud, just a bit. Does a rebedding process serve any purpose after pads/rotors have been used? I've also tried a light steel wool sanding of rotors.

Thanks.

Keith

Macster

My Boxster's brakes sometimes develop a faint but still noticable squeal when being lightly used and what I found cures this is to take the car to a car wash and use the wand to thoroughly wash then rinse the brake calipers.

You can use the rinse setting or the "wash" (detergent is mixed with the water) setting.

Avoid jamming the wand tip right up close to avoid the possibility of forcing water past the piston seals.

After the wash cycle be sure to rinse the brake/wheel hardware throughly -- I use the no-spot rinse setting with its gentler pressure.

Lastly take the car for a drive and use the brakes sufficiently to get them warm enough to dry the brake hardware completely or the brake rotors will rust up if you park the car.

I don't believe -- can't remember anyhow -- my Turbo brakes have yet to do this but if they do I'll try this washing "trick" first.

If the washing trick doesn't help a mini-re-bedding in might be the cure. One maybe two hard brakes from speed to slow the car down very quickly without allowing the car to come to a complete stop performed back to back should suffice.

If the squeal is going to be eliminated by the bedding in it should happen quickly. If it is still present after 2 attempts I don't believe a 3rd would hold much chance for success.

Sincerely,

Macster.

TrackDays247.com

Chances are the rotors have pad deposits on them from some track use...I'd bet $5 on it ;-)

Land Jet

That's what I was going to say Craig.

Michael-Dallas

Also, don't discount that the wheels may be improperly torqued. If the [front] wheels are improperly torqued (i.e. unevenly), then it may also cause the steering wheel to shake under braking.

///Michael

pewter82

No squeal just a heavy wheel shake. The wheel has a small shake in it while driving, like a balance issue.

Mikelly

Brake cleaner on the rotors will remove the deposits... It's that simple... $5...

Mike