2001 V70 XC Front Brakes

jlsmith · Post by **jlsmith** » 15 Nov 2011, 13:43

I have a 2001 V70 XC with 148k miles. The front brakes have given me problems surging since about 60k miles. Original rotors were turned twice, then new performance rotors intalled at about 120k miles and I just had the new rotors turned for the first time. This makes 4 new rotor surfaces since I purchased the car with 36k miles.

My service guy is very knowledgable and has loads of experience but not particularly with Volvo. He cannot figure out why the rotors are warping. We use brakes conservatively and shift down on hills whenever possible. Brake pad wear is very normal.

Can anyone give me some insight on why this is happening? I always give very specific instructions to hand torque the lug bolts to Volvo spec. which is 100 lb-ft. I'm at a loss.

Post by **asc325is** » 15 Nov 2011, 15:01

My rule is that if the rotor needs to be turned, its time to replace the rotor.

What brand pads/rotors are you using?

jlsmith · Post by **jlsmith** » 15 Nov 2011, 18:44

The performance rotors which replaced the original ones came from one of the online parts houses. Don't remember which.
If I replaced the rotors everytime they needed turning, I would have replaced them at least 4 times in 148k miles. Not good.
There has to be another problem. The pads were furnished by the shop that did the turning. All I know is that they are not ceramic.

Post by **jimmy57** » 15 Nov 2011, 22:21

THe caliper slide hardware needs to be cleaned and lubed or repaired to assure the caliper is free to move. The hubs need to be checked for lateral run-out to see that it isn't excessive. Then the rotors need to be mounted so the lateral runout of freshly turned rotors is at its lowest.
With the repeat history I suspect a hub with too much runout.
The hub lateral run-out spec is .02 mm /.0008 inch or less.
The rotor spec is .04mm/.0016 inch.

jlsmith · Post by **jlsmith** » 16 Nov 2011, 11:32

Thanks for the info. I've suspected something like this but wasn't sure how to check it. For sure, the problem is not caused by overheating rotors due to excessive brakeing.
I'll check the hub runout.

gilhuly · Post by **gilhuly** » 20 Nov 2011, 13:17

Replacing front rotors every 35-40k miles is not unreasonable. You should not be surprised if you turn a rotor and it subsequently re-warps as it has now had 3-5% more rotor material removed in addition to what came off as a result of use.

Are you properly bedding in new rotors/pads when they are first installed? This does help. I don't know what to tell you other than drive a lighter vehicle.

slc10844 · Post by **slc10844** » 25 Nov 2011, 05:57

I put aftermarket, premium, slotted rotors on the rear of my wife's 02 and after a couple of thousand miles it developed a noise and vibration when applying the brakes. Replaced the rear rotors with OEM and problem went away. Make sure the mating surface between the rotor and the hub are clean and free of any rust build-up. The rotor won't seat properly and will warp the rotors.

Post by **JRL** » 25 Nov 2011, 07:56

Stock VOLVO rotors
Stock VOLVO pads
=
No issues (except perhaps more brake dust)

NEVER turn (cut) modern rotors

BerniniCaCO3 · Post by **BerniniCaCO3** » 25 Nov 2011, 23:36

What does properly bedding/seating the pads mean?

Post by **JRL** » 26 Nov 2011, 06:41

Exactly what it says.
With new brakes there are two rules of thumb.
Either drive (brake) very easy for 100 miles to bed the pads to the rotors or do it in 15 minutes with 3 repeated hard stops from about 80 MPH to 20. If you go thst route DON'T let the ABS kick in
Both seem to work
Also bear in mind that for the first block or two you barely have any brakes... until they wear off the initial glaze on the pads and the rotors