Brake overhaul

[Jimod]

I'm doing an overhaul of my brakes. Cleaning and fitting new seals and pads etc. I split the two halves of the calipers to get into the cylinders and clean them out. So far so good...............then I dropped one of the square "O" rings that seal the fluid tranfer holes from one side to the other and now I can't find it.

 

Yamaha don't even have a part number for these "O" rings and I can't get a replacement part from any auto brake parts supplier here in Australia either.

 

I'd like to replace the lot as mine are probably originals and the bike is an '83 model and they have hardened and have lost their elasticity.

 

Does anyone know where I can get 6 of these ?

 

Thanks in anticipation

 

Jim O'D...............................................

[Condor]

I'm doing an overhaul of my brakes. Cleaning and fitting new seals and pads etc. I split the two halves of the calipers to get into the cylinders and clean them out. So far so good...............then I dropped one of the square "O" rings that seal the fluid tranfer holes from one side to the other and now I can't find it.

 

Yamaha don't even have a part number for these "O" rings and I can't get a replacement part from any auto brake parts supplier here in Australia either.

 

I'd like to replace the lot as mine are probably originals and the bike is an '83 model and they have hardened and have lost their elasticity.

 

Does anyone know where I can get 6 of these ?

 

Thanks in anticipation

 

Jim O'D...............................................

 

Yamaha suggests to not split the calipers, but being as that's what you done I'd suggest picking up another set off Ebay. You can split them to get your seals or use them as-is. It's going to be very hard locating one of those seals. Which reminds me... I have a set of calipers off my '83. The left side was rebuilt about 2 years/5km ago. Shipping might be an issue, but if you intereested and can't find a set locally.... $50US bucks plus shipping and you own them. LMK....

[Sling]

First I've never split the calipers so I don't know what the Oring looks like,is it square because it has been in place so long, or is it made that way.

I know from working in the aviation field. that if you use an O-ring in an oblong hole it will take the shape of the grove it is in. If you can find an O-ring to fit and take some grease and coat it you should be able to put the two halves together

before the O-ring moves out of place.

Hope this helps.

[dingy]

Jim,

 

I have a spare O-ring out of a caliper I can send you if you can't find a suitable replacement.

 

Came out of an 83 rear caliper.

 

Size is 14 MM O.D. x 9 mm I.D. x 2 mm thick. I.D. could vary smaller, it would still work O.K.

 

Gary

[Jimod]

G'day Condor, I read in the manual that you shouldn't split the caliper, but how are you supposed to clean out the grooves properly without splitting the halves ! Just my luck to lose one of the "O" rings. Surely there must be a replacement part available somewhere.........

 

Jim O'D.......

[Condor]

G'day Condor, I read in the manual that you shouldn't split the caliper, but how are you supposed to clean out the grooves properly without splitting the halves ! Just my luck to lose one of the "O" rings. Surely there must be a replacement part available somewhere.........

 

Jim O'D.......

 

I've never noticed before, but maybe as suggested a regular o-ring will form to fit?? Or ask Dingy send you what he has??? I've never seen the inside of a caliper so I'm not sure what grooves you're refering to?? When rebuilding a caliper in the past all I've ever done is replace the piston seals, and if they don't leak they're good to go. Anytime a piston and the caliper wall are badly rusted I toss the caliper. BTW any crud inside the caliper should get washed out with regular fluid changes

[Jimod]

The grooves I refer to are the groves the seals fit into. If I can't get the same seals I'll try a round "O" ring and see if it works.

 

Jim O'D.......

[Snaggletooth]

Spitting the caliper halves is not fatal by any means. I had to split both of my front ones as I could not blow out the pistons with air pressure. One side would come out and the other would stick. PITA!

 

There is no seal like an o-ring or a gasket between the halves. Just a machined surface. I suppose that is the reason the manual warns not to split. The fluid ports run though both halves so the surface MUST be clean, undamaged and retighten properly. There is some wiggle room there in the bolt holes but it does not seem to affect alignment of the halves by very much and does not seem to affect the axis as far as the pistons being tighter on either the front or rear edges. My pads are wearing evenly and no leaks at the joining surfaces.

 

The grooves he mentioned are the ones for the piston seals, the square (or flat sided) o-rings. And yep, they are made that way. I got to say cleaning the grooves is much easier with the halves apart. There was a lot of crud in my after being stored for nine years.

 

Now the question would be is it the wider of the two or the narrower one? There are two o-rings and they are different.

[bongobobny]

I've ran across a lot of calipers that had o rings instead of the flat rings, and they seal up quite fine! I've rebuilt about 5 pair of them using both and no problems...

 

PS Snaggletooth, there is indeed a rubber seal between the two halves, the ones I am talking about...

[Jimod]

Thanks bongobobny & snaggletooth

 

Fount it !!!!

 

I almost pulled the workshop apart before I fount it .......... now I'll just lightly smear it with a gasket goo called 3Bond. It's used to join metal to metal machined surfaces.

 

I was going to resort to round "O" rings if I didn't find it.

 

Thanks for all your help fellas.

 

Jim O'D........................................