Shuddering while braking and rear driver side dips at low speed

Bob_the_dog

Afternoon All,

The wife's 08 Mini has developed a shuddering under braking and at very low speed in a car park earlier the rear driver side corner seems to be dipping down like a stuck brake on every rotation.

Going to do a quick check after the match. Any obvious I should be looking out for?

Tks Bob

Veloce

Bob_the_dog wrote: »

Afternoon All,

The wife's 08 Mini has developed a shuddering under braking and at very low speed in a car park earlier the rear driver side corner seems to be dipping down like a stuck brake on every rotation.

Going to do a quick check after the match. Any obvious I should be looking out for?

Tks Bob

Is the car driving straight on a flat surface? Jack up the affected side and rotate the wheel 360 degrees.

Bob_the_dog

Veloce wrote: »

Is the car driving straight on a flat surface? Jack up the affected side and rotate the wheel 360 degrees.

Car running straight on flat surface, when jacked the rear wheel will only rotate freely for 270 degrees ish then sticks.

Warped disc? far bit of wear on the disk so will need to be replaced anyhow

Veloce

Bob_the_dog wrote: »

Car running straight on flat surface, when jacked the rear wheel will only rotate freely for 270 degrees ish then sticks.

Warped disc? far bit of wear on the disk so will need to be replaced anyhow

How much does it stick by? Like would you need a lot of force to rotate it through the 90 degrees it's sticking?

Usually when there's a bit of runout ("warped") you'd feel a vibration through the foot pedal at motorway speeds (if front discs) and through the seat (if rear discs) and not that much at slow speeds unless the warping was very bad. I can't say for sure what's causing the car to sink or pull down, but it sounds like a suspension issue.

Bob_the_dog

Veloce wrote: »

How much does it stick by? Like would you need a lot of force to rotate it through the 90 degrees it's sticking?

Usually when there's a bit of runout ("warped") you'd feel a vibration through the foot pedal at motorway speeds (if front discs) and through the seat (if rear discs) and not that much at slow speeds unless the warping was very bad. I can't say for sure what's causing the car to sink or pull down, but it sounds like a suspension issue.

Needs a fair bit of force to shift it thru the 90 degrees, I marked the wheel where it stuck and got herself to drive slow around the house, every time the mark and brake pads lined up I could see the rear corner dip a little.

Veloce

Sounds like a bad disc. If they're that bad I'd nearly replace the discs as opposed to skimming them. Check for pad wear too - they're likely to be shot.

Any play in the wheel hub?

mickdw

Well the dropping down is due to this partial sticking of the brakes at that particular position so that will go away once sticking is fixed.
If you imagine that the caliper is mounted rigidly behind the rotating parts, any of the rotating items could be at fault.
You are therefore looking at warped discs, damaged, warped hub where the disc is mounted or faulty bearing.
I would be inclined to check for play at bearing / hub and if no real movement is found, check runout at disc and hub.