Steering wheel shaking, but only when braking in a straight line

Anzezaf · Post by **Anzezaf** » Sat Feb 15, 2020 10:05 pm

Welp, not much else I can add..
Driveshafts are in good condition (recently replaced) and the car doesn't shake when accelerating so we can rule those out anyways.
Must be something to do with the brakes I guess, but the rotors themselves look fine to my amateur eye.

The steering wheel shakes more to the touch than the body / dash / interior and the shaking only happens when braking in a straight line.
Braking easy or braking hard, doesn't matter.. the shake is there in both cases.
If I brake in a turn, there is no shake.

Any ideas?

YouTube · Post by **Sailor** » Sat Feb 15, 2020 10:13 pm

Make sure you look at the entire surface of the rotors (both sides). Any discolouration could be the result of fine surface rust that's not being cleaned by the pads - ie: a slight warping of the disc.

km666 · Post by **km666** » Thu Feb 20, 2020 2:32 pm

I had a BMW that did that, turned out the caliper was sticky.

Anzezaf · Post by **Anzezaf** » Sun Feb 23, 2020 8:50 pm

Yeah, might be a sticky caliper. Noticed the left brake rotor being awfully hot, while the right one was only warm to the touch

toadster · Post by **toadster** » Sun Feb 23, 2020 11:32 pm

Lo

I have replaced 3 of the four calipers on My Lude with refurbished ones.
Cheers

Toadster

ATR84 · Post by **ATR84** » Mon Feb 24, 2020 8:58 am

Your symptoms are certainly pointing to a sticky caliper, you can get refurbed ones on an exchange basis (you send your old one back after fitting the refurbed one), which helps keep costs down.

Scott560 · Post by **Scott560** » Mon Feb 24, 2020 8:02 pm

any caliper getting sticky, its worth checking the guide pins. Common sense might say they only get stuck 'off', but they can get stuck 'on' just as easily as i found out the other week. Easy enough to check, wheel bolts loosen, jack up, wheel off, 2 caliper bolts, check both pins slide in and out and turn round (be careful not to pop off the seals). If its not smooth to move by light hand pressure, then they need removing, cleaning up, and regreasing with some silicon based lube.

If they are fine, then the caliper is getting stuck either because the piston is binding up due to rust (inside the bore) , or there is a problem with pressure being relieved in the brake line or at the master cylinder. Rare but not unheard of for rubber brake lines to collapse internally creating a bit of a one way valve. Possibly a reason why you only gt it in a straight line (when steering the line is manipulated and the blockage releases?) Hard to test for that. If you've faffed with the brake pedal mech recently, check you have enough slack on the mastercylinder, i've read that no free play can cause pressure to not release also...

If the car was jacked up actually, you could check if the caliper is binding by pumping the brakes, confirm unable to turn roadwheel , then turn the steering wheel, if its not the guide pins, then that could well point to the rubber brake line (pressure released when rubber brake pipe is moved).

Let us know what you find

Anzezaf · Post by **Anzezaf** » Tue Mar 03, 2020 10:29 pm

Turns out it was a combination of a sticky caliper guide pin, sticky brake pad and a bent rotor

Ordered some rebuild kits for the calipers and gave them a refresh. Also straightened the rotors on a lathe and everything is back to normal.

Thanks for the help guys!

Scott560 · Post by **Scott560** » Wed Mar 04, 2020 9:32 pm

its quite easy to overlook them, i was quite shocked the otherweek to find a seized guide pin, even though it was overhauled not that long back.

Bent/warped rotor is pretty unusual though, was it not true on the hub or was it actually warped?