Brake shudder question - solved
 

Checking in with the brains-trust here - I have a brake shudder that is proving tricky to diagnose.

Light shuddering under brakes ONLY when at high speed (~100km/h) AND downhill.

Braking from high speed on the flat or uphill - smooth as silk.

Braking from low speeds (~50km/h) on flat or downhill - smooth as silk, no discernable shudder.

not much (if any) shudder felt through brake pedal - only through steering wheel and ears (very audible!).

Front control arm (tension strut) bushes are good, so I'm thinking it could be the lower control arms or the tension strut ball joints? Tempted to replace rotors to eliminate them but that is the priming of the parts cannon... :rolleyes:

At 270,000kms, the (original) lower control arms and tension strut ball joints are likley done anyway but there are no other symptoms that indicate these components need replacing. They are VERY expensive here so I'm not going to simply replace them "on spec". :(

*edit* tldr; turned out to be rotors - replaced with new Brembo rotors and all good again.

Any cupping on front tires?? Ball joints at 270,000 K is definetly not parts cannon! ;)

Front rotors.common.

I had exactly the same problem on mine. Brake shudder at high speed but smooth at mid-low speed.

It went away after I replaced 31122180422 and had a four wheel alignment. Unfortunately I did them both at the same time so couldn't tell you which one fixed the shudder! :D I'd assume the arms.

at 200K every suspension part is worn out beyond its service life. Replace them all.

X2 on rotors. After a complete front rebuild, mine still had shudder under hard load. Did a complete front and rear rotor/pad replacement. Stops like a Porsche.

No cupping on tyres.

Have ordered new Brembo rotors - will start there then progress to front control arm ball joints then lower control arms...

Boom..

Have you ever replaced the tension strut bushings? just because they look ok doesn't mean they are ok.

The front ones? Yes - have Meyle HD bushes up front. Replaced those about 70,000kms ago.

They are easy to diagnose - clunking when you dab the brake at very slow speeds.

Brembo goodness.... let's see if this sorts it. :D

https://i.ibb.co/x1Vq5LX/20230121-101712.jpg