When the change Brake Discs?

[philrocks]

Hey guys,

Anyone know how to tell if your disc needs replacing?

I did notice the outer pad has worn more than the inner, so it might be a piston or something is sticking, will check that. But I have no idea how to tell if a disc needs changing.

Cheers,
Phil

[T5R92011]

If you have any kind of vibration when braking, you almost certainly need new discs.

A car that is riding on brand new discs and pads all round rolls very smoothly. You can just feel it.

If there is a significant lipped edge on the disc then I have found that you get some low frequency groaning from the pads as the edge rubs against the lip when moving and steering at low speed.

also If you're the sort of people who sits with your foot on the brake at traffic lights, you should change your discs every time you change the pads!

[Thassos]

Discs have an acceptable range of thickness, the min thickness should be fairly easy to find, then you need somethung like a micrometer or digial vernier for accurate results, but its generally something like 2mm less in thickness from brand new to worn out discs on front ventilated discs, its also possible you could have warped discs if they are poor quality or have had a hard life with regular overheating.., you usually notice vibration on braking from something like 70 mph less, i recently swapped front discs and pads on a car that was showing vibration at the described speed, result (after they had bedded in) was super smooth and much more effective braking with no vibration.. so its worth it..

I tend to stick with oem braking parts, although pagid make some good quality discs in my opinion.

And good point T5r.. probably something 90% of drivers are unaware of,

[keefbeef]

Should always bear in mind that if you leave a disc/pad change too long - you can end up having to replace the calipers as well. The piston's come out too far and water gets in pass the seal.

Just replace my front discs/pads for £80 - well worth the money - but unfortunately I don't take my own medicine and had to get a caliper as well. At £65 - not too pad - I've had to pay more!