Front caliper piston sizes.

[Veemax]

Could someone please answer a question that I have about front caliper piston sizes. I own a ZXR400 L3- I’m rebuilding the front Tokico caliper with new pistons and seals. The size of these pistons is 27mm in diameter but I’ve also seen an alternative size of 34mm for the same model. Was this an upgrade for the SP- was it a completely different caliper, or is the 34mm size a mistake? Thanks.

[cargo]

There seem to be different part numbers for H and L which would suggest a differnce in size ?

[Veemax]

It looks like the H models are all 30mm. Still seems strange to me that some suppliers list 34mm!

[jaiendea]

I had the same problem. I believe 34mm is the outside diameter of the seal for the 30mm pistons.

[Ewetea]

I have experienced a problem with the front brake calipers on my L1 recently, and this was the only post that I could find on the subject. I wanted to replace the seals and found a company on the internet that advertised sets of seals for ZXR400 L1-L9 for a reasonable price, so ordered some. In the meantime I removed the pistons and seals from the calipers ready for re-assembling. When the seals arrived I found that they were too large. I had pistons 27mm diameter, and the seals were for pistons of 34mm diameter. I contacted the company who expressed surprise as they had apparently sold a number of the packs with no complaints. They told me to return them, and they will sort out something suitable. I investigated further as I have a number of spares. It would seem that H models have 30mm diameter pistons, and L have 27mm dia. The two can be distinguished by the TOKICO letters on the outside. If they are close together (30mm long) they are 30mm pistons. If they are spread out (60mm) then they are 27mm dia.
I am slightly bemused, as I would expect the increase in size to apply to later models, to increase area pressing on the pad, but the opposite has happened, with a down-sizing. Also, the increase in area from 27 to 30 is about 12%, for which additional brake fluid will be required. My master cylinder seal diameter is 16mm, and a 12% increase takes it to almost 18mm, and I'm sure that there is a master cylinder of that size. Has anyone replaced seals in their calipers with 34mm diameter seals, and if so, what was the model? Any other comments would be appreciated.

[stuart42]

Funny seeing this as I ordered some brake pads from M&P the other day.

Listed as fitting an L1, but they were too big.

I asked why this was and was told that I had an R version? The strange thing is I've ordered L ones before and they've fitted.

This leads me to ask, are L model ones bigger?

Cheers
Stuart

[banner001]

H uses a 300mm disk, L is 310mm, you would think this would lead to a larger pad too...