AR10

You have to find and fix the reason for any looseness in the wheel bearings.

jeeper31

I replaced the wheel bearing and there is no play in either wheel now. Took it for a spirited ride today and upin hard turning the brake pedal still fades. Once again after the initial press it comes back to theproper height. What now?

aribop

...

jeeper31

BUMP

V2Rocket

Brake booster.

Van

rear wheel bearings

Van

And, don't always trust the "shake the tire" method of checking... A moderate cornering load can easily be .75 Gs (on the track 1+ Gs are common) -- which will put over 2000 lbs of force against the outside wheels. Last I checked, I can't push or pull on the wheels with that much force...

jeeper31

How can I check the rear wheel bearings then?

Van

By all means, jack it up and see if there is any wiggle in the wheel -- the point of my last post was to mean that even if it feels tight, it might move under more force... Of course, if you CAN move it by hand, then you have a problem -- its a good check to make, just don't put 100% of your faith into it.

So the first step would be to give the rear wheels a mighty shake... Can you hear any unsual noises when you corner in the "questionable" direction? The outside set of wheels will be taking most of the load.

Perhaps you should also check the torque of the stub axle nuts at the rear hub -- one could be loose (this you probably would NOT be able to detect by shaking the wheel). I believe it's a 32mm nut that gets torqued to something like 180 ft. lbs. (don't quote me on that).

If everything still checks out, then I'd remove the outer CV joint bolts (to disconnect the wheels from the transaxle) and then spin the wheels by hand -- hear any grinding? Does the movement feel a little gritty? These are signs that the bearing is drying out and starting to wear.

Good luck!

Van

If your wheel bearings are all good, then I'd be suspect of something between the brake disk and the hub... You just did the front bearings, right? Probably took the rotors off? If there was some little piece of foreign matter (like a wood chip) between the rotor and the hub, the wheel would also be a little misaligned... Under hard cornering, the foreign matter could compress and allow the rotor to push the caliper cylinders in a little extra -- giving you the extra pedal movement.

However, in this scenario, I'd also expect there would be some pedal vibration under braking.

M758

Bleed the brakes again and see what happens. It could also be a weak master cylinder.

jeeper31

I checked the rears and they are good. I readjusted the front bearings and they are tight now. The problem is still happening. To narrow down where it's coming from I let the car stand still idleing. I then turned the wheel all the way to the left, then all the way to the right then back to senter. I pressed on the brakes and the pedal was low again. Pressed it again and the height was fine. Turned the wheels again without moving and it was low again. Next press it was fine.

Any more ideas?

Van

Good diagnosing... Now you've limited it to the front wheels.

I have a hunch something is loose, and allowing the hub and/or rotor shift and pushing a caliper's pistons back. This is on your turbo?

If it is, this is what I'd do next:
start the car up, turn the steering wheel lock to lock a few times; do NOT step on the brake pedal; jack up one front wheel, remove the wheel, open the clamp on the brake caliper, and see if one or both of the pads are loose and ready to come out.

I have a hunch at least one side will show this condition -- meaning you can narrow down which side of the car to concentrate on.

This will proove that something is loose and flexing on that side. Could be caliper bolts, could be a rotor with a crack, or a hub with a crack. Perhaps a bearing race that didn't fully seat.

If it's not the turbo, you'll have to do a little more sleuthing to figure out which brake caliper "has the play"... You might be able to use a feeler gauge or maybe even a strip of paper to see if there is a gap between the pad and the rotor. The non-turbos have a floating, single piston caliper, so you won't really be able to tell which side of the caliper the pistons are being pushed in.

Good luck -- let us know what you find.

jeeper31

I cannot take credit for the diagnosing, it was Techno Duck's idea.

The problem is happening with my Turbo so I will do what you say hopefully tomorrow. Excited that I may finally be narrowing down the problem.

jeeper31

Brought car to mechanic and they told me it needed rotors. Replaced the rotors and problem still happening. Bringing it back tomorrow. Any other ideas I can tell him.