greg1234

Hi all.

When I've been driving my 93 Turbo for a while around town, the wheels start making a sort of "chirping" or "squeaking" noise as they go round. I think it's the left hand front wheel - but it might be more than one. The sound gets worse whenever the steering wheel is turned slightly to the left.

I've also noticed that the brakes squeal a lot under the same conditions, but I'm assuming this is due to brake pad glazing with town use (which I used to get on the 928GTS).

What is likely to be the cause of the squeaking? Is it normal? Could it be the brake pads grabbing for some reason? Might it indicate warped discs or anything nasty?

It certainly doesn't sound sexy...

slant911

Wheel Bearings maybe? I had an old VW that did something like that. Turned out that one of the tie-rods was ready to let loose (and finally did). Replaced the tie-rod and never heard that noise again.

Is there a rhtymic sound to it (i.e it speeds up and slows down with your speed)? Does it happen once every rotation of the tire or less often?

These things can give clues as to what might be causing it.

It's a little hard to do, but, try finding a big open area where you can steer sort of crazy and go to the speed that it happens at and stick your head out the window to listen to the tire. This will help you determine some of the answers to above questions.

greg1234

It is definitely related to the speed of wheel rotation. It sounds like it's probably once per revolution. I should be able to do the maths but it's too late.. oh hell - assuming the circumference of an 18" wheel would be approx 140cm, at a speed of 5km/h the car is travelling approx 150cm per second which would equate to one wheel revolution, so one squeak per second.. yeah, I reckon it's once per wheel revolution.

My guess would be grabbing brakes (although why only once per revolution, unless the disc(s) is/are warped) or wheel bearing. Or, of course, some known fault with 964 Turbos that some kind person will tell me about so I don't have to worry...??? Anyone...?

MikeF

I'd definately have those wheel bearings looked at. If they're dry or worn, it's an inexpensive fix. If you ignore it, it can become a very expensive proposition (and possibly dangerous).

It is not likely that your rotors are causing this. Warped rotors will cause a pulsation in the brake pedal when applying the brake at high speed.

slant911

I agree with Mike. Brake issues do not usually show up as a grinding once every revolution. Warped or grooved rotors will give you a pulsating effect. Wheel bearings is the quickest/easiest thing to check/fix at this point. That's where I would start.

Jack your subject wheel up off the ground and tug back and forth os the wheel. DO it both top/bottom and side/side. There should be very little play.

Stephen Smith

In checking the wheel bearings, if one pushes and pulls side to side and top and bottom exactly how much free play should there to be for one to conclude that the bearings are still servicable or in need of replacement?
Regards
Stephen Smith
92 C2 Tip

greg1234

I think it's brake related for the following reasons:

1. When it happens, if I touch the brake pedal, the noise either changes or goes away.

2. With gentle application of the brake pedal I can get more than one wheel making the same noise - although it is hard to tell.

3. When it is at its worst, the brake squealing is also at its worst.

I noticed something else - I thought I'd try some heavy braking to wear off the pad glaze, and the first few times I tried to brake very hard from around 70mph I was getting ABS kicking in, despite being on a flat dry road with warm tyres. After three of four repetitions the ABS stopped kicking in and the car stopped a lot quicker. And the noise went away for a while. So I reckon it's brake related. Does this make sense..?

slant911

Sorry no scientific info here on the "how much play should there be" question. I've over the years have gotten the feel of what is right and what is not right. My experience is that if the wheel wobbles either side to side or top to bottom change the bearings. Everything should be tight. And I don't mean tight as in not freely moving in tire rotation, but, tight as in close tolerance.

Greg,

Do your brakes pull to one side or the other from a pretty good speed?

greg1234

I don't think there's a definite pull to one side or the other. I have noticed that when braking hard from speed I need to keep a grip on the wheel since the car squirms around a bit - but I'm not really surprised bearing in mind how quickly the car is decelerating under those conditions.

When I started the intense brake testing I think one of the wheels may have been locking up slightly early but that seemed to go away after a few attempts..

Bill Wagner

It could be bearings, but it could also be a sticking brake caliper. Brake noise often becomes worse the hotter the brakes are.

Just suggestions,

Bill Wagner

greg1234

I jacked the car up today and checked the play in the wheels. There's almost none in the rears, and in the front wheels there isn't much - less than a centimetre from one extreme to the other when holding the sides of the wheel. The amount of play is the same on both sides, and in both cases some of the free play is coming from movement in the shocks / struts / other suspension components.

So it doesn't look like there's too much play to me..

Jeff Curtis

Greg, I too experienced this noise in my car a few months ago. What it wound up being is the sheet metal guard behind the right front rotor was flexed/bent and rubbing against the inside of the rotor.

I muscled and twisted it one day when I had enough and wallah! Noise gone...just a suggestion to consider.