Hi everyone, im refurbishing my calipers and i want to buy the pistons so that i can change them with the seals, anyone knows the diameters of the pistons, mk1 gto tt awd aws.
Hi I am doing the same on my 92TT and just got the entire kit which includes pistons and seals from BIGG RED ltd based in UK
Can you send me pics and diameter of the rear pistons please, if it is possible for you.
Hi sorry if I missed understood did you say rear pistons? the rear only has disc brakes and the front has 4 caliper pistons on each side, but there is a size difference in piston size on each caliper that one needs to pay attention to if doing this for the first time. Please go to show n shine category for pics and more info regarding my 92TT on going project nick name ‘THE GREAT WHITE’ 
I shall send you all the measurements of the pistons tomorrow have to get a battery for my digital caliper dont have one around the house.
Thanks alot mate really appreciate it
Hi so here are the measurements. FYI as i mentioned earlier, the pistons and caliper housing are NOT the same size, and three dots seen on the piston head perhaps represent size difference so when you get a new complete kit also make sure that the seals which have color coding on them go in the correct size housing or you will have serious issues with brake fluid leaks and perhaps brake failure.
These calipers are the front? The rear caliper has 2 pistons or 4? Thanks
I have not done the rear yet but it has only one piston.
I see, many thanks mate. I ask my mechanic to check.
Sorry about that dont know where my mind was, yes the rear has only one piston but I have yet to work on the rear to take them apart for a good cleaning, so i am not sure what the diameter of the single piston is and not sure of the factory manual has any info about it but have to check.
Im trying to buy from bigg red, james told me to send him pics of the calipers. You have part number that he sent you?
I bought the kit on ebay listed by BIGG RED
Sorry forgot to mention the kit only for the front and not the rear yet. The rear shall be done in a few months, I am just doing everything only for the front as in engine and entire suspension.
Its ok, i ordered a whole set so that i can change everything. 