ATE caliper O-rings - UK/USA source

[Ian_N]

Hi

After a year of ignoring the pile of bits in the corner of the garage, I'm working on the R65 again.

The calipers are apart and need a new everything. Most of the bits are available, but the unavailability of the little square faced O-ring between the caliper halves is giving me a headache.

(calipers from 82 LS)

I remember a forum member in the US found a supply - but has anyone sourced suitable O-rings in the UK?
I'm not sure what materials will be suitable, but it seems synthetic brake fluid does not react with much (except paint!)

Thanks for any info

Ian

[montmil]

Ian, have you checked with Motobins?

http://www.motobins.co.uk/bmw-parts.php?model=R%20Series%202%20valve%20Twin

Are the O-rings actually a square cross-section or are they simply deformed by the install; as the O-ring in the oil filter?

Monte

[Mike V]

Ian,

You'll need to source locally an EPDM (Ethylene-Propylene-Diene-Monomer) material o-ring for it’s resistance to high heat along with its properties to resist glycol based fluid exposures.  

Size: 0.41"OD x 0.21"ID x 0.10"W.

-Mike V.

[Ian_N]

Thanks for getting back to me.

motobins and motorworks do not list them. The local BMW dealer says they are unavailable

I have one reasonably intact one that appears to have been 'square' section when it started life. Looking through some Nissin repair bits with the man from my local powdercoaters ('Griffs reality motorworks') they are square.

Mike V - I found your original post. It looks like you have used a circular section O-ring (could be the picture). 2.5mm (0.1") is quite a bit fatter than the one i have (<2mm thick). I suppose squashing an oversize round section o ring will create sufficient contact surface area to seal relaibly under pressure

I can find metric (round section) O-ring kits in EPDM - and 10mm outside dia x 2.5mm section appears to be a standard metric size.
Well, i said i can  - now I've lost the link

Ian

[Mike V]

Ian,

Here it is in PDF form attached.  A bit of an "over-kill" of information now that I look at it again.  I believe Monte to be right (again) about the original shape of the OEM o-ring being round regardless of what I mention in the attachment of it being square.  I assumed it being square based on it's shape when removed.  The round o-rings I mention and installed on my dual ATE' claipers are working perfect with no loss of pressure or fluid.  I have a pile of these I'm happy to send you but not sure if you want to wait that long to receive them with such distance between us.  Let me know, or search some local avenues.

[wilcom]

Great pdf attachment Mike !  

 I know one of these days I will be rebuilding my calipers and will not have to redo all the searching for this part. I would achive that in the R65 FAQ
Thanks

Joe

[Lucky_Lou]

Motorworks do them ive had some....Part No BRA54809 but if they are ATE the caliper must be pre 81 .
Lou

[Ian_N]

I learn something new every day!

Because the engine is 82 - and it came with black fork legs - I had assumed the dual calipers came off the donor bike for the engine.

Mixed parentage, this bike.

[Ian_N]

To conclude this thread...

Mike V has very kindly sent me a dozen O-rings. If anyone in the UK needs one or two, please PM me

Ian

[Rob Valdez 79 R65]

I am going to move this thread to the FAQ section so we will remember it is Mike V in the US and Ian_N in the UK to contact for these o-rings.

Thanks guys!