Brake Caliper Seals

[Drect]

Good day,

I'm new on here, but not new to bikes and have worked a fair bit on Honda CBs. I have an 82 CB900F in the garage at the moment. Pretty much a rebuild as it hasn't ran since 08. I took the calipers apart and cleaned them and bought new seals from the Honda dealer. The kits were from All Balls. the front seals fit fine but the rear seals are 2mm too small. Ordered another set, and the same thing. Ordered OEM and the same thing. The pistons are 30mm on all calipers.
So my questions are:
- Is the rear caliper different than the right front, and supposed to have smaller diameter pistons? (I just have not seen this before.)
- Has anyone ran into this before?

I know I can use a front seal kit but the guys at the Honda dealer can't explain it. Thank you in advance.

Cheers

Dan

 

[SenseAmidMadness]

I couldn't tell you the specifics of your bike or the model, but it is pretty typical for rear calipers to have smaller pistons than front calipers.

Did someone swap your rear caliper? Or maybe the production got changed mid-year?

If the pistons and seal grooves (inside the caliper bore) are the same sizes between your rear caliper and your front right, then you can definitely use the front seal kit and there should be no issue.