Changing discs - pad change as well?

[Homer]

I feel stupid asking this, but if I change my rear discs should I change the pads at the same time? The obvious answer is yes, but is it really such an issue?

 

The reason I ask (and maybe this is poor understanding) - When changing pads they very quickly bed themselves to a used disc, but will a used pad bed itself into a new disc, or cause the disc to wear itself into the pad and cause eneven wear in the disc surface and compromise future pad changes (discs wear far slower than pads IME, especially on the rear)

 

Hope you understand what I mean...!

[Scott]

I asked this very question a year or so ago.

 

A lot of people seemed to think it was a good idea to change them. However, in my opinion I don't think it is necessary. As long as the pads are in half decent nick, and you give them an adequate time to bed in properly, there should be no difference between new and old pads. If the pads you have are badly and unevenly worn then I would change them. If they look OK, give them a rub down with some course emery paper to even them off perfectly, to make the bedding in easier.

[hodge]

Personally I'd change them Darryl for the simple fact that it's already stripped and you won't have to strip it down again. If it's an issue of funds and the discs are wazzed then I'd say it was fine refitting the pads if they've got plenty of meat on them.

[Homer]

Thanks for the replies gents So essentially, there's no real issue provided the pads have good life on them? I've not checked them since the car went on the road, but they were at a rough guess 50% worn.

 

The reason for wanting to change is the brakes are very noisy under braking and don't seem to give good braking power - it's very hard to describe the noise, but think it's down to the discs being seriously pitted.

[mrgee2jz]

Thanks for the replies gents So essentially, there's no real issue provided the pads have good life on them? I've not checked them since the car went on the road, but they were at a rough guess 50% worn.

 

The reason for wanting to change is the brakes are very noisy under braking and don't seem to give good braking power - it's very hard to describe the noise, but think it's down to the discs being seriously pitted.

 

There are a few issues using old pads:

 

1. If your using your old pads which have shaped around your old worn disk, especially if its very out of straight will then, firstly take a lot longer to bed in, (not a biggy)

 

2. My main reason that i dont like using old pads is that the pad will wear the disk unevenly if its not straight, now a rear disk on a supra normally fouls on the inside edge, (the disk face that you cant see) so that normally ruins your pad, which in turn, ruins your new disk, now why would you want to do that to a new disk?

 

If you sand down your pads surface and make them 100% flat, then in theory they are pritty much as good as new. So if you have a good amount of life on them (over 3/4) then its worth doing, if not, just bin them

 

Or if you are using grooved disks, they will do the sanding for you too but i would still sand them staight anyway.

 

Good luck, I have some worn pads if you want them, LOL

[Digsy]

If the old disc has started to lose its inner and outer edges, these will have worn the pad away in the corresponding areas. These areas of worn pad will not then wipe the new disc clean on its inner and outer edges and they will corrode very quicky and you'll end up right back where you started much quckier.

[Dnk]

Just flat them down using 80 - 120 grit paper on a flat surface or if you have access to a milling machine mill them down till the pad material is nice and flat

[Homer]

Thanks again guys, good info

 

Unfortunately having had a closer look at the pads, one of the inside ones is much more worn that the other, so looks like there is a sticking slider or piston and the pads will not be resuable.

 

So, new pads and discs it is then!