Author Topic: Grimeca caliper piston (Read 7858 times)

Trevor from Warragul · « **on:** January 25, 2015, 05:20:43 PM »

Hi,

The grimeca front brake on my Morini 3 1/2 Sport began to bind the other day, so I stripped and cleaned the caliper. The caliper is in beautiful condition, but the pistons are a bit pitted. I searched everywhere for replacements, but it turns out they are rarer than rocking-horse poo. I managed to source one. So, I am wondering whether there is someone out there (preferably in Melbourne, Australia) who can use their lathe to make a pair for me out of stainless. I can send the piston for measuring purposes.

Cheers

Trevor

scottly · « **Reply #1 on:** January 25, 2015, 06:32:33 PM »

Based on the picture, that appears to be a usable part to me. It looks like the coating or anodizing is worn off in spots, but not much worse than the pistons in my Grimeca the last time I had it apart. A good, but gentle, cleaning of the bore and o-ring groove should cure the binding.

Trevor from Warragul · « **Reply #2 on:** January 25, 2015, 06:46:25 PM »

The photo is deceiving. The pitting on one of the pistons is quite bad. The other one I could probably get away with. Two new pistons in stainless would be the bomb

scottly · « **Reply #3 on:** January 25, 2015, 06:52:19 PM »

Are your pistons alloy?

Trevor from Warragul · « **Reply #4 on:** January 25, 2015, 08:36:11 PM »

Steel

754 · « **Reply #5 on:** January 25, 2015, 08:49:52 PM »

That is not anodized aluminum? Is it black oxide steel?

faux fiddy · « **Reply #6 on:** January 25, 2015, 08:54:18 PM »

Quote from: morini on January 25, 2015, 08:36:11 PM

Steel

Quote from: morini on January 25, 2015, 08:36:11 PM

Steel

Here on the other side of the world there's a lathe that mostly works and some disc shaped scraps of stuff around, bar stock that might be that big. Not all of it is stainless but some is.

It's seems like you would want your machinist to have both halves of the part. If things don't work out locally try to pm and I'll ask the machinist about it, but it would be kinda shooting in the dark without a few other measurements.

Is there a step on the end/ ball cutter size for the inside/ thicknesses/.

Trevor from Warragul · « **Reply #7 on:** January 25, 2015, 09:45:26 PM »

~~Steel~~

Bugger me. I just checked & they are aluminium. What the heck caused the pitting? It looks like rust damage...

faux fiddy · « **Reply #8 on:** January 25, 2015, 09:47:42 PM »

Brake fluid is nasty corrosive stuff.

faux fiddy · « **Reply #9 on:** January 25, 2015, 09:57:44 PM »

Is it like this one?

http://www.ebay.com/itm/NEW-GRIMECA-41MM-SMALL-BODY-LH-CALIPER-B256-DRAGBIKE-KZ-GS-KAWASAKI-SUZUKI-PMFR-/231459144430?pt=Motorcycles_Parts_Accessories&hash=item35e40a42ee&vxp=mtr

The guy has a bunch of Italian stuff.

Trevor from Warragul · « **Reply #10 on:** January 25, 2015, 10:33:17 PM »

Not really. But I wonder what the caliper pistons are like, and whether they can be ordered separately. Of course, Grimeca has just announced they are no longer making brake parts...

hondalav · « **Reply #11 on:** January 25, 2015, 11:19:40 PM »

Trevor,

Have you tried NLM in the U.K or Tritsch in Germany? They normally carry the full range of spares for the old Morinis. I recall that some German Mopeds out of the '70s used the same front brake setup (Kreidler?). Are you connected to the Morini folks in OZ? they have some good contacts.

simon#42 · « **Reply #12 on:** January 26, 2015, 12:38:34 PM »

have you had a look at brembo pistons , you can normally find one that will interchange with a grimeca piston
brembo also do pistons in alloy and are much easier to find
if not any good machinist will make you a couple , brake fluid does not damage alloy but to protect them from the elements it is worth getting them anodised

faux fiddy · « **Reply #13 on:** January 26, 2015, 01:57:37 PM »

Quote from: simon#42 on January 26, 2015, 12:38:34 PM

protect them from the elements it is worth getting them anodised

There are any number of different coatings which have different thicknesses that if you used them you would want to consider a couple ten thousandths difference in making the part.

simon#42 · « **Reply #14 on:** January 26, 2015, 02:26:39 PM »

Quote from: faux fiddy on January 26, 2015, 01:57:37 PM

Quote from: simon#42 on January 26, 2015, 12:38:34 PM
protect them from the elements it is worth getting them anodised

There are any number of different coatings which have different thicknesses that if you used them you would want to consider a couple ten thousandths difference in making the part

anodising isn't so bad its only a few microns thick and you dont have to allow for it on something like a caliper that isn't made to very fine tolerance
other coatings as you say could be different

faux fiddy · « **Reply #15 on:** January 26, 2015, 02:31:37 PM »

Quote from: simon#42 on January 26, 2015, 02:26:39 PM

Quote from: faux fiddy on January 26, 2015, 01:57:37 PM
Quote from: simon#42 on January 26, 2015, 12:38:34 PM
protect them from the elements it is worth getting them anodised

There are any number of different coatings which have different thicknesses that if you used them you would want to consider a couple ten thousandths difference in making the part

I hear of using some coatings to make up for a cylinder bore that is too big for the only piston available.

anodising isn't so bad its only a few microns thick and you dont have to allow for it on something like a caliper that isn't made to very fine tolerance
other coatings as you say could be different.

faux fiddy · « **Reply #16 on:** January 26, 2015, 04:26:44 PM »

I mentioned to the lathe operator that "that guy that sent me an oil valve from around the world out of the blue" was asking about this.

754 · « **Reply #17 on:** January 26, 2015, 09:15:27 PM »

Easier to make out of Aluminum than Stainless...if..you can get anodized. Reasonably.
Try Columbia Car and Cycle in Nakusp bc......search laverda Nakusp.
He got me to cut the diameter down on some pistons, then we anodized them, and we made some fuel caps for. Some SFC,s. He has good sources in Italy..

Trevor from Warragul · « **Reply #18 on:** January 26, 2015, 10:21:53 PM »

Boy, I'm now an expert in Grimeca calipers! Mine is a 1010, this was superseded by the 1025. The 1025 pistons (pucks) are also 41mm, and should fit the 1010. I've found a source for a 1025 caliper rebuild kit, and one is on order...

Quote

"that guy that sent me an oil valve from around the world out of the blue"

I believe in paying it forward. The replies to my post show that my belief pays dividends. The encouragement & suggestions inspired me to keep investigating!

Cheers fellas!

Trevor

hondalav · « **Reply #19 on:** January 26, 2015, 10:50:44 PM »

@754

You seem to know Wolfgang and his Laverda business

754 · « **Reply #20 on:** January 26, 2015, 11:14:14 PM »

Yes, he lives about 3hrs from here, I met him first at a vintage motorcycle race and show..
I made a few parts for him once in a while...

01Thomas · « **Reply #21 on:** January 27, 2015, 01:17:21 PM »

Hi Morini
I live a couple of kilometres away from a shop (Grant at Natal Resleeving) that has converted all my brake pistons to Stainless. Hondas, Moto Guzzis, 4-piston Brembos, the lot. Give me a shout if you don't come right elsewhere and we'll work out something.

Regards
Thomas

Trevor from Warragul · « **Reply #22 on:** January 27, 2015, 10:08:30 PM »

Thanks Thomas,

Nice collection of bikes you have there...

Trevor from Warragul · « **Reply #23 on:** January 31, 2015, 08:02:15 PM »

The 1025 rebuild kit arrived (on a Sunday) & the pistons (pucks) & seals are a perfect fit.

faux fiddy · « **Reply #24 on:** January 31, 2015, 08:28:14 PM »

The new one looks like a little bit more mass to it. That set is aluminum also?

News:

Author Topic: Grimeca caliper piston (Read 7858 times)