Caliper question

[AndyB57]

Yet another question - should there be a brass ferrule in both bores? It looks as though there should be, have searched this site and more widely but can't find an answer.

Caliper.jpg (57.65 KiB) Viewed 9853 times

[EVguru]

There should be a ball bearing under the bleed nipple, so that the ball provides the seal, rather than the nipple. This is to avoid galling of the seat.

The nipple should have a flat end with a slight indent for the ball.

[AndyB57]

Thank you EVguru. There is no ball bearing and the end of the bleed nipple is flat with no openings. Strange. Do you know where I can find detailed schematics for the caliper? My Google searches are not delivering

[mbmm350s]

Hi Andy,

I have never seen any dimensioned drawings or assembly drawings of the Grimeca calipers.
The homologation drawings only show basic dimensions.
The calipers were procured as assembled items including all bolts by MotoMorini.
What do you need to know? They are pretty basic, they are a 1976 design.
There is a rectangular section rubber ring between the two caliper halves.
The piston seals can usually be re-used if undamaged as mentioned before
Pistons can be re-manufactured if necessary.

Mark

[AndyB57]

Thanks Mark. I'm trying to work out if anything is missing, there's a seat in the bore without the brass insert which looks as though something should sit in there. Such as the same type of insert! If not I can get on and refit it.

[Ming]

I don't recall seeing any seats in calipers on mine. Tapered drilling, ball bearing and flattened bleed nipple is the best I can describe the layout on mine.

[EVguru]

On which sides were the bleed nipple and hose?

[AndyB57]

I'll have to look at photos....

[AndyB57]

The bleed nipple was on the outside of the caliper. A ball bearing has been mentioned but there's no sign of one. Hmmm

[3potjohn]

I must admit back in 2007 ish when I first delved into the brakes I was unaware that there was a ball bearing under the bleed nipple, it looked a bit rough so I replaced them. Goodness knows what size they are, my note taking was not up to scratch.
John

[EVguru]

Someone has presumably then substituted the ball with whatever that brass piece is. I don't have a note of the size either, but it's not too critical.

[AndyB57]

Someone has presumably then substituted the ball with whatever that brass piece is. I don't have a note of the size either, but it's not too critical.

Thanks for the replies. I'll put it back together with fresh pads and fluid, disc will be ground sometime when things get going again....

[Daddy Dom]

I was sent a new bleed nipple with ball bearing from NLM a while ago that I've never used. I'll look it up for you and see if I can tell what size it is.
DD

[themoudie]

Aye Andy, stripped out my Grimeca rear brake caliper on a 1986 K2 350 today. It was grim Untouched since assembled in 1986.

However, when looking at this rear caliper, the outer half has the word 'GRIMECA' cast into it and the inner is plain. The bleed nipple, located in the inner caliper half has a flat base, with a small indent in it to locate a ball bearing and the ball bearing is 5mm in diameter. The hose is connected to the outer caliper half.

The seal between the two caliper halves is square in section, 2mm deep and with an O.D. of 11mm.

Pistons are the 'thick walled' type, O.D. 32mm and a depth/height/length of 16mm. Piston seals are rectangular section 4mm deep x 32mm I.D. x 38mm O.D. Rebuild kit appears to be available from: brake-caliper-repair-kit-32mm-x-16mm-for-grimeca-brake-caliper

However, "Caveat Emptor" I have yet to order my kit and have no idea of quality or fit Will post update on the saga.

Good health, Bill

[AndyB57]

Thanks Bill, let me know how the service goes.....Good luck!

That's a bigger ball than I though it would be. I've still not come across any mention of a brass ferrule/ring like the one I found in mine.