Brakes. Skorpion & Baghira

[GordonH]

Skorpion: Pistons on front caliper are not releasing quickly. Very iffy on the track. Removed some fluid from the master and seemed to help somewhat. I'm thinking that either the caliper is heating up causing the fluid to swell not letting the lever come back, or adding to that problem, the pads are worn too far.
Baghira: Lever coming back close to the handlebar and not what I think, a lot of braking going on. I'll check the pads on this also, and change the fluid to see if that helps. Any opinions?

While I'm here, a huge thank you to Bill Jurgenson for all his help on this forum. If we ever meet, I owe you a nice dinner.

Gordon Hamilton
AHRMA #58r

[radiograf]

Sounds like its time for a complete overhaul of your braking system on both bikes. I would definatly change your pads, and fluid , the skorpion sound like it needs a caliper overhaul as well.
If you haven't already fit the stainless armoured brake pipes, they are a vast improvement, and don't chafe through. (Been there, done that, got the underwear cleaning bill to prove it.)
Incedently, brake fluid is hygroscopic, whch means it absorbs moisture from the air, this has the effect of lowering the boiling point, hence you have problems as the fluid heats up, so should be changed every couple of years.
Another thing to watch is the grade of brake fliud you use, as some are not compatable with the seals in the caliper or resevoir, always follow the manufacturers recommendation.

[hb7]

The fix is to clean the piston area carefully and apply some silicone grease ( dielectric grease ) aka brake caliper assembly lube
on the piston with a qtip. Just work it in and the pistons will stop sticking. This has worked for me...without disassembling the caliper.
There are no spare rubber parts for Grimeca calipers, so I would not dissemble them unless I could renew the rubber parts.

Henri
http://moto-science.com/

[jimc]

+1 on the silicone assy. lube /Q-tip maintenance, worked for me.
However (if you'd searched) there is a source for front Skorpion / Grimeca caliper rebuild kit consisting of
pistons, inner and outer seal rings :
Mike Morse at Vintage Brake stocks them .
http://www.vintagebrake.com/index.html

[hb7]

Is it Grimeca or Brembo rubber in the kit ? Do you have any part #'s ?

[jimc]

Mike claims to be a Grimeca supplier. The website shows bothe Grimeca and Brembo logos, so who knows?
The Kit I got has the pistons & seals in a package:
tag inside the sealed bag reads 70781/82 , don't know if that's a Grimeca number or a V.Brake number
Vintage Brake 15069 Lupine Lane Sonora CA 93570 USA (209) Morse 533-4346 Mike
I ended up not using the kit since I was able to free up/lube as detailed above, so I cannot state 100% that
it all fits, the piston diameters appear to be correct though. try calling , he was pretty helpful on the phone.
Jim

[droy]

Guys - the pistons size on the Brembo and Grimeca 40 mm bolt distance calipers are different. I've had both apart at the same time. For the stock front Skorpion the only seal option is the Grimeca (or a copy).

Doug in NJ

BTW - Jim, how are you?