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Cookie Boy
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129 Posts
Discussion Starter #1
3 sets of disks and pads in 8000 miles.

I'm guessing this is not common.

Any clues as to why they keep warping?
 

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Faster than Zyrtec
Joined
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2,105 Posts
Heat, hard braking.

Sure they just don't need a disc machine ? Take it to another dealer for a second opinion.

Probably try getting them crossdrilled or slotted, it would help. Check there is plenty of airflow around the mags/hubcabs/whatever is on the wheel.
 

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Cookie Boy
Joined
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129 Posts
Discussion Starter #4
Thanks guys,

I've been a Land Rover owner for years and put the disks through hell and back with no problems.

Pick up the S40 to run round town, no heavy braking, disks and pads replaced by Dealer at time of sale and vibrations began.

They replaced the disks again, same story then replaced again.

They seem to be fine so can only guess part of a bad batch.

Cheers,

Neil
 

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Registered
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10,560 Posts
if vibration has occured from the moment that you had them replaced dealer I would check the following.

1. ABS activates under normal braking -- If you don't see the ABS warning light, I doubt that this is the problem.

2. Warped rotor, excessive run-out -- Since your had them replaced many times already, it's probably not the problem.

3. Swapping to a dissimilar pad -- The pads are designed to leave a VERY thin deposit on the rotor. If you change to a different pad, at some point the rotor will have deposits from both. If the coefficient of friction between the new pad is different with the two different pad deposits, you'll experience vibration until the old deposit is worn away (I've had this problem). Or worse yet, the different pad deposit can result in severe galling of the rotor, which I've also seen (but thankfully not on my car). Not sure the pads you have used.

4. Using a race only pad on the street -- Especially if the pad has not been properly bedded, you may have an uneven pad deposit on the rotor, which causes vibration as in #3 above. Can you determine exactly what pad compound your currently using, or confirm that it's a street pad?

5. Cracked rotor -- Especially if you now have drilled rotors, cracks can initiate at the holes, grow radially from hole to hole, and cause vibration especially when the rotor is very hot. The crack will tend to close when the rotor is cold, and the crack can occur on either side of the rotor. As a result, your rotors need to be removed from the car, and both sides must be carefully examined. Assuming that you have stock rotors I would doubt this to be the problem.

6. Rotor distorts under pressure -- I've never seen this, but others have reported this can occur if the wheel bolts are not properly torqued in the proper order when the wheel is mounted. I gather that you're not located in the U.S. by the Staffordshire UK tag under your name; but here, half of the mechanics I've seen either don't properly torque wheels or don't know how. If I didn't personally witness a mechanic torque my wheels, I'll redo it myself when I get home.

7. Bad wheel bearing -- This can cause vibration under braking loads. Since you've had a vibration problem with 3 sets of rotors now, perhaps this is the problem?

8. A SVT owner reported that his problem with vibration under braking was caused by worn tie rods. May be something to look into as well.


Just some thoughts and ideas as to why you are having the issues. Hope you can work it out. Let us know.
 

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Cookie Boy
Joined
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129 Posts
Discussion Starter #6
Guys,

Thanks for the replies.

The new set of front disks and pads have been on for about 5 days now and no vibration at all.

I was a little concerned that even with 20Kg N/S and 30Kg O/S (force) they could find a problem.

Bearings seem fine, hubs have no play or dead spots and only normal wheel vibration when driving (smallest of shimmy on rough roads).

If it were my 90 or Disco I'd just take a hammer to it until something stopped wobbling or fell off, guess you can't take this approach with a Volvo. :insane:
 
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