Ride feels bumpy during braking

[theholycow]

Well, I didn't get to look at it much until I had to drive it again. It got worse, but the good news is that now I'm definitely feeling it in the brake pedal. That narrows it down; it could conceivably be a wheel bearing or a brake rotor.

I'm pretty sure it's one or both front brake rotors. I took off the wheel and spun the assembly by hand. It gets difficult during part of the rotation and I think I can see the tiny gaps between the pads and rotor disappearing during that difficult part.

I wasn't able to measure the thickness or runout because I don't think I have any appropriate tool. Actually, I just realized I could probably have used a feeler gauge between the pad and rotor. I planned to use my digital caliper but I forgot that the edge of the rotor would have a lip.

Questions:
1. Does my assessment sound realistic, that the difficulty turning means I'm probably looking at a rotor issue?
2. Is a feeler gauge between the pad and rotor a reasonable way to measure thickness variation and runout?
3. Can I get the rotors turned and stick them back on without replacing my pads, which are still meaty?
4. If I ignore it and keep driving on it, will it damage anything else?

[GasSavers_RoadWarrior]

In my experience, bearings quieten down under brake application because the clamping of the disk reduces the side/side movement, although I guess a really bad one could transmit that through the pedal.

Does your digital caliper not have a depth gauge on it, long rod connected to the bottom arm that sticks out the end of the ruler part? You can use those when you secure the caliper to the brake caliper assembly.

[theholycow]

It does have a depth gauge. I don't understand how I would use that for this, though.

My digital caliper is a standard cheap Chinese one like this:


My drivers side front brake:



Rust sucks.

[GasSavers_RoadWarrior]

Well you can use it just like a dial gauge, meaning you clamp the caliper to a non-moving part (brake caliper) somehow, and use the depth gauge to measure runout.

Buuut, I'm not liking the look of the rust on that rotor, if you can gouge a fin out with a screwdriver it's definitely done even if the surface is in spec. I know anywhere damp they get to look a bit like that in a year, but it is looking like you've lost more than half of the fin thickness at least now.

[theholycow]

Well, I really have to get out there with the caliper to try to see if they're warped.

Do I really need to replace the pads at the same time? My pads are barely worn.

[Jay2TheRescue]

Pads are so cheap, why not? I'd be afraid I'd screw up the new rotors.

[GasSavers_JoeBob]

Originally Posted by theholycow

What kind of carnage results from ignoring a failing bolt-in hub bearing? Wheel falls off, or bearing noise just gets worse? Edit: Or it destroys the axle...

The one time I had that happen (with the Cad), the car just stopped moving forward. Nor would it move backward. Eventually, I got it to roll again, and got the car home (fortunately, I was just a block or two from home). Put on a new bearing, and everything was happy again.

Looking at those rusty rotors makes me just that more glad to be living in California...for all our problems, cars rusting out is very low on the list.