TOPIC:

Hi all,

I am refurbishing my rear brake MC. After trying to re-assemble the old bits but found they are leaking, I had decided I need a new MC piston.

Part number for the rear brake MC piston is 43020-1009, but I seem to have read somewhere that the front brake MC piston is the same. That is part number 43020-1003.

The rear piston 1009 I cannot find anywhere, but there are several new 1003 front ones available,

Does anyone know whether these are interchangeable?

Cheers
Paul

The piston itself is different, and won't interchange with the front, or any in the rebuild kits.

Luckily, when the piston goes bad it's usually just the rubber seals that are bad, not the metal piston itself. Even better, the seals ARE identical, and will interchange no problem. The hardest part is getting the seals off the front plunger from the rebuild kit and on to the rear plunger from your MC without tearing them, but when I did it I ended up actually cutting the plunger in the kit to help get the seals off.

6 months and counting, just swapping the seals seems to be working.

It's the same 5/8 bore. Seals look the same but yes, the piston design is different. Just to confirm. But I saw at one place they were selling the direct replacement. Was it z1300.com or zparts? I don't remember. But they had it as new and that was the first time offered.

HI Stan,

It’s Z parts in UK.

www.zed-parts.com/product-page/43020-101...inder-piston-z1300b2

Thank you for the reminder. I have no experience with it, it does look a bit different than the stock, but I imagine it will work if the measurements are correct. It's all about the fabrication of the aluminum piston after all, and it's a simple straight forward shape.

Thanks all, My piston is fine, so I will order a new set of rubbers.

Paul