Steering wheel shudder when braking at high speeds

nick91111, Dec 3, 2:31am
2003 BL5 Legacy GT. Have already replaced the front rotors and pads thinking this was the case, but the fault still occurs.

Some reading online says common faults are torn lower control arm bushings (have had a quick check can't see anything obvious). Or even a wheel bearing? Any ideas? The car is fine braking harder at 50kph speeds, and is only noticeable at motorway type speeds with harder braking.
budgel, Dec 3, 2:43am
I had that problem in my BMW. replacing the control arms fixed it.
I replaced the whole control arm as the balljoint was worn as well as the bushings.
franc123, Dec 3, 4:26am
I'd say you've got suspension play where it shouldn't be, if the balljoints check out OK, get a socket that fits the wheel nuts and with a decent size half inch bar, place it on the nut and rock the front wheels one at a time back and forth quite hard with the bar, obviously not hard enough to loosen the nut but enough to load up the suspension bushes, you may be able to see and feel excessive fore and aft movement of the wheel. Get expert assistance if in doubt. Also bear in mind that when replacing rotors the hub surface must be totally clean with no rust or dirt causing high spots and causing the rotor to not run perfectly true, its possible to replace genuinely worn rotors and still have a similar issue afterwards if not enough attention is given to this.
pandai, Dec 3, 2:39pm
As just mentioned above - check that rotors are true to hub. If they are not then you could do with a light skim using an on-car lathe.
321mat, Dec 3, 7:53pm
Make sure the wheel nuts are tightened properly.

I know this sounds like an oddball solution, but trust me, you will have the same symptoms you've mentioned if the nuts are not tight enough.

The other possible fault could be worn steering rack bushes.
plasticboys, Dec 3, 10:19pm
i would of said brakes disks need machineing
lookoutas, Dec 3, 10:31pm
It's not a stupid suggestion - make sure all nuts are evenly torqued.
lookoutas, Dec 3, 11:34pm
And that means torqueing them up systematically.
Don't just tighten one right up and move to the next one.
nick91111, Dec 4, 1:50am
Thanks I'm thinking so too. Rotors were done at a workshop, so I'd like to assume they did a proper job! The vibration was there before the new rotors and pads were fitted, and it's still there now, so i'm leaning towards suspension play. Will have a closer look over the weekend.
nick91111, Dec 4, 1:51am
Yep wheels are all torqued up correctly in the star pattern.
nick91111, Dec 4, 1:52am
The vibration was there before the new rotors were fitted, and it's still there now. I've barely driven the car, and haven't braked hard at all, so it's unlikely I've warped the new rotors already (given it did it before they were fitted).
nick91111, Dec 4, 1:53am
Thanks, yeah I think if this proves to be the case it'll be the easier way to go to save pressing out the bushes etc too.
ntalke, Dec 4, 2:23am
Would be helpful if you could find out if the workshop did a runout test with a dial gauge after replacement
Important to have the surface of the hub completely clean before installing the new Rotors
nick91111, Jul 30, 1:33pm
Just an update. I couldn't find any obvious movement of the wheel/suspension joints, so took to another workshop. They confirmed they were not bedded in correct and have hot spots. On each rotor you can see the contact point is very small and incorrect also. Also noted that they've used the wrong type of grease, and put the retaining clips inside out, so the wear indicators facing the outside of the pads. Wow, I'm very disappointed.