I have found the ones that I need including piston and seals for £17.25, but :-

 

Why would a seal kit be different for different size discs (280mm / 288mm) if both pistons are the same size (54mm).

 

I like to learn so if anyone can shed any light. Hopefully when you tell me I will not go Doh! and slap my forehead.

 

Cheers.

 

The only thing I can think of is that the bore is bigger and requires a fatter seal, but cannot understand why this would be the case.

Just a guess, but it could be that the factory sources the brake assemblies complete (disc, calliper, pads already assembled for bolt-on) from different subcontractors, so there could be minor differences due to the different makes.

Don't know about the front pistons but for the rear there are different piston sizes.

I brought a set of seals and a piston from Big Red in Worcester.

It wasn't until I removed the piston to fit the new seals that I discovered my piston was bigger than the seals I had.

Had another chat with them and there are 2 caliper options for the Vrs. TRW and another, if you look on the caliper you will see the name somewhere cast into the caliper.

From there you should be able to check if you have the right seals and piston.

Like I say, this is the rears I'm talking about, but it's worth looking into this for the fronts just in case you strip it down to find you have the wrong kit in hand.

Don't know about the front pistons but for the rear there are different piston sizes.

I brought a set of seals and a piston from Big Red in Worcester.

It wasn't until I removed the piston to fit the new seals that I discovered my piston was bigger than the seals I had.

Had another chat with them and there are 2 caliper options for the Vrs. TRW and another, if you look on the caliper you will see the name somewhere cast into the caliper.

From there you should be able to check if you have the right seals and piston.

Like I say, this is the rears I'm talking about, but it's worth looking into this for the fronts just in case you strip it down to find you have the wrong kit in hand.

But as my query stated, "both pistons are the same size, (54mm)".

It may be the outer diameter of the seal that is different for a different brand or design of caliper