[Terran]

Had the front brakes replaced on my 02 about 3-4000miles ago. Recently noticed a slight grabbing / vibrating when slowing down. I can feel it in both the pedal and steering wheel. I thought I could originally always feel it, but I'm not so sure about that. It seems most pronounced when braking.

 

[stan_t]

Could be warped rotors. Wheels over-torqued?

Stan

 

[The Black Box]

Try rebedding them.

 

[Terran]

Try rebeddding them.

Try re-whating them?
I should mention the car has 104k on it. Seems like, of course, it went away right after I made that post, but it still doesn't seem quite right. It seems to be more noticeable when slowing from higher speed. Aka speed dependent

 

[The Black Box]

If it happens only when braking then try doing a few hard stops from 50 down to 15MPH or so and then let the brakes cool by driving around a bit. Be sure to not come to a complete stop with your foot on the pedal until the brakes cool.

You're just heating the pads and rotors up and redistributing and wiping the old layer of pad material off the rotor.

 

[abacall]

Try rebeddding them.

+1. Common problem. Pad material unevenly distributed on the disk surface.

 

[AJ711]

It would take a lot of hard heavy braking in order to warp the stock rotors, and the stock pads would deteriorate long before that would occur. You need to "re-bed" the pads. Old rotors need to be turned before doing this to create a clean surface. If you change the pads or rotors, you need to bed the pads in. Basically, heat them up so they mate with the rotors as best as possible. This is done as described by The Black Box, 5-6 heavy hard brake runs from 60MPH to 5MPH and then let the brakes cool via driving around and not using the brakes. This puts an even layer of brake pad material on the rotor and provides the optimal braking surface.

What you are experiencing is pad deposits in the rotor. This causes uneven braking surfaces along the rotor, making it feel like the rotor is warped. I liken it to what a record would look like, or a wavy washer. Stoptech has a good write-up on "warped rotors" and also on bedding the pads in. The only time you should ever have to replace the rotors is when they are too thin per your local safety standards. I replaced mine at 120k miles as they were too thin to turn.

 

[Terran]

It would take a lot of hard heavy braking in order to warp the stock rotors, and the stock pads would deteriorate long before that would occur. You need to "re-bed" the pads. Old rotors need to be turned before doing this to create a clean surface. If you change the pads or rotors, you need to bed the pads in. Basically, heat them up so they mate with the rotors as best as possible. This is done as described by The Black Box, 5-6 heavy hard brake runs from 60MPH to 5MPH and then let the brakes cool via driving around and not using the brakes. This puts an even layer of brake pad material on the rotor and provides the optimal braking surface.

What you are experiencing is pad deposits in the rotor. This causes uneven braking surfaces along the rotor, making it feel like the rotor is warped. I liken it to what a record would look like, or a wavy washer. Stoptech has a good write-up on "warped rotors" and also on bedding the pads in. The only time you should ever have to replace the rotors is when they are too thin per your local safety standards. I replaced mine at 120k miles as they were too thin to turn.

I'm going to believe this is the situation, as I too had my rotors replaced when they were too thin also. I do feel some wobble at speed, but that's probably something else (i.e. out of balance rim). I will find a place to try rebedding them, any suggestions where i won't cause an accident?

 

[neoshi]

Industrial side of town.

 

[abacall]

I never had to resurface my rotors to rebed them. I just take brake cleaner and steel wool with some heavy-duty rubber gloves and clean the rotor face as best I can, then follow bedding procedure.
Remember not to let them cool between braking, only after the 5 repeated stops.
It's important not to keep your foot on the pedal after those stops because you can actually warp the rotors if you do.
I usually follow bedding procedure twice in order to ensure even deposit.
It's amazing how much better your car will brake after that.

 

[Terran]

This is good to know for when I do my rear disk swap as well.

 

[The Black Box]

Another thing to know with hubcentric wheels is you should hand tighten (using just the socket and extension) the lugs before you apply any torque. I use my toe to press the wheel against the hub as I turn the nuts. It centers the wheel on the hub.

 

[funkymonkey1002]

Another thing to know with hubcentric wheels is you should hand tighten (using just the socket and extension) the lugs before you apply any torque. I use my toe to press the wheel against the hub as I turn the nuts. It centers the wheel on the hub.

Same. Then torque in a star pattern and make sure you get the same torque at each lug. If the lugs are overtorqued it can also sometimes make it feel like the rotors are warped (usually when a tire shop uses their impact wrench to tighten them down). Also if theres rust on that hub lip I like to take my dremel with a wire wheel and clean that whole area up.

 

[FLfrstr]

Aren't most passenger cars lug-centric? I don't recall ever seeing a tapered hub on the forester that would be responsible for centering the wheel. The lugs are tapered though, aren't they used to center the wheel?

I have seen hub-centric rims and they do not have tapered lug holes or tapered lug nuts. At least the semi ones don't.