Wobble during high speed braking

benjj · **Posted:** Fri Nov 14, 2014 9:56 am

Gents,

I've got some time to address a few issues on the 944 over the weekend. The first thing is to sort the wobble.

Anyone got any ideas where best to start diagnosing the issue?

Issue: big wobble felt through wheel when hitting the brakes (hard or medium) from higher speeds. No wobble without brakes applied. No wobble on brakes at lower speeds (pottering in town etc.)

I'm pretty sure it isn't a warped disc or issues with the brakes themselves.

The majority of the front suspension is Powerflex polybushed so unlikely a warn bush.

Am thinking along the lines of a failed balljoint.

Any suggestions most welcome.

Cheers,

Ben

EDDIE · **Posted:** Fri Nov 14, 2014 10:25 am

discs or stuck/sticking pots in calipers.

Hope you get it sorted.

Nick

tr7v8 · **Posted:** Fri Nov 14, 2014 11:04 am

EDDIE wrote:

discs or stuck/sticking pots in calipers.

Hope you get it sorted.

Nick

This, quite common on 944s. Make sure that the hubs are 100% clean before you replace the discs

benjj · **Posted:** Fri Nov 14, 2014 11:13 am

Thanks chaps, will have a good poke around.

Calipers had a full rebuild before last rally, could be a sticking piston though. Will get under there and have a look see.

scam75 · **Posted:** Fri Nov 14, 2014 11:24 am

As they have all said. I had the same issue, new discs and a good clean of the mating surfaces sorted it eventually.

Stuart

broady_6 · **Posted:** Sat Nov 15, 2014 9:44 am

Wheels gone out of balance? A lock up during braking can cause that

Brett928S2 · **Posted:** Sat Nov 15, 2014 7:52 pm

Hi

Agree with the above post...... Brakes OR Wheel balance.....

All the best Brett

white944 · **Posted:** Sat Nov 15, 2014 8:22 pm

Almost certainly brake discs. Wheel balance would not cause shake under braking only.

Brett928S2 · **Posted:** Sat Nov 15, 2014 10:04 pm

white944 wrote:

Almost certainly brake discs. Wheel balance would not cause shake under braking only.

Hi

As an ex race mechanic, I can assure you it can.....

Also easy to check and fix BEFORE expensive brakes.....

Imagine he changes the discs and pads and its still there.....

If he has the same size wheels front/back... he just swaps them....if problem vanishes...its balance..if still there...brakes or suspension....

All the best Brett

944 Man · **Posted:** Sun Nov 16, 2014 2:20 pm

Untrue discs (fitting, not the discs themselves which don't warp) - less likely.

Build up of material on pads, probably due to incorrect bedding in - quite likely.

benjj · **Posted:** Sun Nov 16, 2014 5:52 pm

Cheers gents.

Might go and put them through a spirited cycle to confirm or write off pad deposits.

Have the knobber winter wheels going on shortly so that'll count in/out balance.

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Wobble during high speed braking

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