R75 CDT rear caliper piston diameter

[COLVERT]

Originally Posted by QuestionMark

No, the caliper's seized, so I thought I'd replace the piston too. It's a matter of lazyness really, as I don't feel like taking out the piston only to check before I order But it seems like I have to, oh well.



They both allegedly fit:

Manufacturer catalogue

I came across this though:

Rimmerbros parts

Googling the part numbers indicates that SOB100020/30 are 36mm whereas SOB000040/50 are 40mm. So if you have a pre-252351 VIN, which I do, then presumably there's no way to tell which caliper is fitted without having a look at it - not to mention that the caliper fitted might not be the original type.

If the pistons have seized then you are going to find rust in the bores too as well as the piston surfaces.---

Bit of fine wet and dry should do the job though. Make sure the powder generated during cleaning is removed from the bore.

[QuestionMark]

Originally Posted by Lovel

Biggred list rear pistons as 36mm OD. I bought from them, they fit perfectly and are good quality. Stainless pistons woul be better in the long run but these conventional chrome plated version supplied by them are just as good if not better than original fit

I went out and measured one of them yesterday, it was indeed 36mm.

Originally Posted by Seanalf

I used one of these kits to refurb a set of front calipers on my last car. Quality was good, seals worked and they even provided the correct grease. Worked well imho

Thanks, glad to hear it!

Originally Posted by iandux

As far as I'm aware, the different diameters are used dependant on whether the rear discs are vented or solid.

Yep, I've got solid brake discs, so the diameter is in line with your theory.

Originally Posted by COLVERT

Bit of fine wet and dry should do the job though. Make sure the powder generated during cleaning is removed from the bore.

I was thinking steel wool, but perhaps that's not tough enough for the job. Thanks for the tip Should I just use brake fluid as lubricant/cleaning fluid (...)?