Grimeca hydraulics

[Seagreen]

Morini rear master cylinder_IMG_2220.jpg (182.04 KiB) Viewed 11354 times

Grimeca rear master cylinder for 500 Morini

Morini rear master cylinder_IMG_2219.jpg (161.4 KiB) Viewed 11354 times

Hi,
I am in the process of renewing the seals, boots etc on my 1984 Morini 500 Sport and would appreciate some advice.
1. In the mouth of the mastercylinder there appears to be a dust seal/boot at the entry to the main bore that is perhaps retained or just sited behind a "washer" - see photos. How do I remove this so that I can replace the seal/boot that seems to be torn and which I suspect will make the insertion of the piston subassy difficult?
2. In order to remove the caliper pistons and their seals, is it best to split the calipers into their respective halves? If so, are there 2 'O' rings that seal the 2 halves? Is there a torque setting for the 2 cap head screws when reassembling the halves?
3. I realise that I should probably have pushed the pistons out with the mastercylinder still connected to the caliper - does anyone have a good method for extracting them by other means?
4. Finally, where is the best place to buy these parts from - Mdina seem to have a very limited set of items on their website. I would have thought that it would be possible to buy a refub kit for both the mastercylinder and the caliper with all seals, boots, 'O' rings, copper washers and springs. Am I living in a dreamworld or have I just not found the right site?
Thanks,
Charles

[MickeyMoto]

Charles,

Talk to DucrapiPaddy, he did my Grimeca calipers. You can have a conversation about Chinese parts with him!

MM

[Seagreen]

Hi Mike,
Thanks for replying; I had contacted Paddy before my posting on this forum. He referred me to Mdina Italia. As for Chinese copies, never heard of such things
Adios,
Charles

[MickeyMoto]

Maybe Paddy was warned off after doing my calipers!

[AntietamClassicCycle]

4. Finally, where is the best place to buy these parts from - Mdina seem to have a very limited set of items on their website. I would have thought that it would be possible to buy a refub kit for both the mastercylinder and the caliper with all seals, boots, 'O' rings, copper washers and springs. Am I living in a dreamworld or have I just not found the right site?

I bought seal kits from this ebay seller for my K2:
https://www.ebay.com/sch/m.html?_ssn=va ... a&_sacat=0

[Ming]

Ariete products are fairly easily available this side of the Atlantic, try a search using the reference from above.

[Seagreen]

Hi Mike, Ming and Antietam,
Sorry to be a bit slow in responding but have had trouble logging in to the web site via my phone over the last couple of days whilst I have been away (some sort of SQL error whatever that means) but thanks for your comments - Mike I think that you must have administered the kiss of death to Paddy, he did not seem to want to know!! I have checked the Antietam site but as it is in US, the costs of shipping to UK will be very high but I have found an Ariete site in Italy, again cost of shipping will add significantly to the cost so I will try to find somewhere in UK. What about the spring for the m/cylinder?
About removing the pistons and cleaning everything, would I be correct in thinking that the calipers will have to be split and if so the 'O' ring seal (2 off I presume) will need replacing. What about the torque required to tighten the 2 halves together?
Adios,
Charles

[huub]

i did rebuild the calipers on my morini using plain o-rings ,
you need EPDM o-rings for use with brake fluid.
i did not have to rebuild the master cylinder , cant help you there.

[Seagreen]

Thanks Huub, can I ask where did you get your piston seals and dust covers from?
Adios,
Charles

[huub]

Thanks Huub, can I ask where did you get your piston seals and dust covers from?

Hi charles,

My 1976 morini did not have dust covers fitted not sure if they were fitted originally.
i just changed the seals with EPDM O-rings from my local bearing/industrial supply shop,
total cost was less than a euro..
the pistons were damaged too , i ended up making a set of stainless ones

[Seagreen]

Hi Huub,
Thanks for the info. I have bought some seals + O ring from Mdina Italia. They are similar but not identical so am wondering whether the old seals were incorrect - could they have been Brembo parts?
As for the dust seals, well those that I bought are significantly different to those that I took off so I am a bit confused.
Adios,
Charles

[norbert]

One thing are the dust covers that are not that imortant another thing are the seals for the pistons (plus the O-ring between the two parts ofthe caliper)!

For Grimeca, Brembo, Lockheed ... stuff contact Jörg Bohnenstiel "Bomoto" bomoto@t-online.de I guess he can help you
https://www.bomoto.de/joomla/

norbert

[EVguru]

Using O-rings as caliper piston seals is likely to result in brake drag.

The shape of the ring groove, along with the rectangular section seal, retract the piston a small amount.

[norbert]

That´s absolutely right. The seals for the pistons have a rectangular shape. The little one between the two halfs (missing on the foto) maybe have a round shape, I don´t remember it well. Anyhow they have to be of a brake fluid resistant mterial.

[EVguru]

Seal kits for 41mm Grimeca calipers are available from several sources. There is a version used to replace the AP Lockheed caliper on Triumphs and Nortons and the seals are the same as the 1010 and 1025s.