Rear master cylinder replacement

[boompse]

Hi there,
My rear master cylinder keeps seizing. I've pulled it apart. The piston and bore look good but the spring looks mangled. Mdina Italia offers the seal kit (M12868) but that doesn't include the spring. I would prefer to replace the whole master cylinder - does anyone have suggestions as to where I could get a new master cylinder or a new piston with seals and spring?

[morini_tom]

I have no clue if this would be a direct replacement or if they are any good. But I did read somewhere that classic karts used grimeca master cylinders similar to ours, and found this copy of one online.

Worth investigating possibly?

https://www.ebay.co.uk/itm/Motorcycle- ... 2196571847

Alternatively, previous owner of my triple disc 350 fitted a new brembo master cylinder on the rear. It works well and doesn’t look out of place, although he did have to cut and weld the actuating arm to get the angles right, which is not ideal on a brake component. Part number 10.29(or maybe 28).34.02

['It must be a .....']

Hi, the rear master cylinder from the 501 Camel (small tank pre electric start) is a direct fit on the road 500

It also makes the brake much more progressive than the original (different piston diameter?)

[boompse]

Thanks for the reply. The 500 Camel does indeed have the same rear master cylinder but my problem is, where do I get one? Mdina Italia have been not helpful - partly I think because whatever parts book they have is not the same as the parts book I have. I was sent a 'rebuild kit' which is hilariously useless. There appears to be no 'Grimeca.com' and whatever Grimeca bits I can find are all for Piaggio and Malaguti scooters, etc. I'd get a Brembo master cylinder - some of those look similar - but I don't want to pay a fortune, wait two months to have it delivered and then find it doesn't work. Surely someone has a 500 with an aftermarket rear master cylinder and if so, what is it?

[MickeyMoto]

Thanks for the reply. The 500 Camel does indeed have the same rear master cylinder but my problem is, where do I get one? Mdina Italia have been not helpful - partly I think because whatever parts book they have is not the same as the parts book I have. I was sent a 'rebuild kit' which is hilariously useless. There appears to be no 'Grimeca.com' and whatever Grimeca bits I can find are all for Piaggio and Malaguti scooters, etc. I'd get a Brembo master cylinder - some of those look similar - but I don't want to pay a fortune, wait two months to have it delivered and then find it doesn't work. Surely someone has a 500 with an aftermarket rear master cylinder and if so, what is it?

Or maybe nobody who reads the forum has an aftermarket rear master cylinder on a 500. In which case when you find one that fits you can share it with us.

Have a chat with Ducati Paddy. He is very helpful, but as he does Brembo may not be able to help.

[Daddy Dom]

Storz Perfomance list this Grimeca one (1118) although it's pretty different from the one on my 1983 triple-disc 3½.
Also I'm not sure how current their catalogue is.

https://www.storzperf.com/catalog/page34.html

[morini_tom]

Read my post from 10th September above!! I’ve given the details of the brembo on my bike which can be modified quite easily to fit.

Late 350 with a disc (k1 and k2) have the same master cylinder as the 500

[huub]

you might have a look on aliexpress ,
they list pretty similar master cylinders for a couple of euro...
could be worth checking the dimensions
(ex, look for zx7 brake cylinder)
i have good experiences with these chinese brake cylinders
https://nl.aliexpress.com/item/32826060 ... 0035%22%7D

[3potjohn]

https://www.stein-dinse.biz/index.php?c ... 914_19_109

Anything here?