Wobbly front end

sirhal · 18-02-2006, 05:41 PM

Hi All,

A little while ago I changed the front discs and pads on my AUI Fairmont. They were shuddering under braking and I figured that it was just warped discs. I checked the thickness and they could of been machined, but the new discs were cheaper

However a couple of weeks later on a trip to Sydney (from Brisvegas), they started to wobble again.

: This was 4 months ago.
The strange thing is however, the wobble comes and goes. Sometimes it can go for a week without any vibration at all. But other days it is so bad that when you apply the brakes, the steering wheel shakes quite violently.

Any ideas???

You guys are pretty cluey. I thought I might check before I go pulling it all apart... again.

Cheers

AUIII XR8 MAN · 18-02-2006, 05:58 PM

Try takening both front wheels off & then spin the rotors around to see if there any warpping has started. Look carefully as it mite only small. Mine use to do the same thing, some times it wobbly & other times it was fine with the standard ones. Since i replace them with performance rotors (DBA) i haven't had the problem come back. Cheap rotors are well known to warp easy.

sirhal · 18-02-2006, 06:17 PM

Are warped discs the only thing than can cause this kind of wobble? Could we be talking calipers, bearings, faulty abs, steering, master cylinder, brake lines?

used:
If the discs are warped then why does the wobble come and go?

Cheers

EvilChief · 18-02-2006, 06:30 PM

lotsa things can cause a wobble in the front end one way or another ...

how is ur wheel balance and alignment?
tyres?
brakepads?
callpiers (pods)?
brakefluid?

sirhal · 18-02-2006, 06:38 PM

Quote:

Originally Posted by EvilChief

lotsa things can cause a wobble in the front end one way or another ...

how is ur wheel balance and alignment?
tyres?
brakepads?
callpiers (pods)?
brakefluid?

wheel balance? - not sure. was done with last tyres
tyres? - seem ok. even tread wear
brakepads? - changed with discs
calipers? - well last time I had them out of the rods were hard to remove. Needed to bang it out, sand it, lube it and put it back in.
brakefluid? - never replaced it. Thought about flushing the entire system.

Again however, it comes and goes! thats the most frustrating part. If it were constant it would be easier to diagnose.

Cheers

**Mechan1k** · 21-02-2006, 12:02 AM

Check to make sure your wheel nuts are on tight ... this could be another symptom.
Sounds simple .. but this can be the case as well.

JC · 21-02-2006, 12:46 AM

Quote:

Originally Posted by sirhal

calipers? - well last time I had them out of the rods were hard to remove. Needed to bang it out, sand it, lube it and put it back in.

I think you may find it's the callipers. If they are/were getting stuck, then they could be pushing the pad on at an angle causing vibration.

Try this (on a deserted street would be good, so you don't get rear-ended):
1. Accelerate to 60, then hit the brakes with moderate pressure - ie bring the car to a stop as fast as you can without enabling ABS. Did the brakes "wobble"? I doubt it.
2. Now accelerate back to 60, and hit the pedal softly, as if you are coming up to a set of red lights that are about to go green. Then slowly increase the pressure till you stop (pretend the lights stayed red). If at any point the wobble returns, I reckon it's the calliper slides.

If it is the callipers, when you pull them apart this time, use a polishing wheel/wire wheel to polish up the slides, and liberally spray WD40 into where the slides go and clean out all the rust and muck in there. Then check the rubber boots on the slides and make sure there are no holes. Holes = moisture = rust.

I had a similar issue on the front left of my XR8 (brakes wobbled) and after fixing the calliper slide, the wobble has disappeared.