'80 R65 ATE twin piston o-ring

I think ATE is not the only one. Brembo is similar. In a nutshell, if the pistons can be removed and seals replaced without splitting the caliper, they don't give you bolts or an O-ring in the rebuild kit and they definitely will not go off the track by giving you instructions for that unapproved operation. These are major corporations making brake components... you're not going to find cowboys there giving out unapproved advice.

Because of my job, I have fairly deep resources to find things like bolts. Apparently, at least in sunny Australia, no one makes 10.9 grade SHCS in zinc plated steel. All bolts like this are now 12.9 grade.

So that part of the story seems to be true: the original bolts are no longer available.

& because I have no life, I came across this little gem on bolt torques: https://www.youtube.com/watch?v=FjBaWo0QMYU

Which once again begs the question: if, the bolt stretch is not being measured, how can you be sure the bolt is being torqued to yield as is required?

Anyway, I punted. I put Loctite on the threads & antisieze on the shaft & under the head & torqued the cap screws. I adopted a torque method from some of the turbine aircraft engines I worked on: I started at 25 lb-ft, waited 15 min, then 35 lb-ft, waited 15 min, then 45 lb-ft, waited 15 min & final torque was 50 lb-ft with 5 min between 3 torque applications.

So far everything seems happy.

For completeness, I'll ride this thing for 500km & then post back if it worked or not.

......so...since I am rebuilding calipers today - and missing the o-ring and found this great gem of the thread and about to order EPDM-107 o-rings to replace the old squared "unavailable" o-rings ... I beg to ask... did you survive your ride? I'd like to know since..you know.. I want to finish my calipers and make sure I can safely.

All R65s have opposed piston calipers, first from ATE, then from Brembo.

Those Ate calipers must be made of good quality alloy to stand that. Isn't that more than the usual torque spec for a lubed 10.9 bolt. Many years ago I used a fraction of that value on my Ate calipers and have had no problems with leaks. Perhaps I need to tighten them up some more though.

Brembo F08 calipers completely new with new pads at only $108.00 US
http://www.mgcycle.com/index.php?main_page=product_info&products_id=1034
The ATE,s are barely worth fooling with especially for the 78 thru 85 R65

Are you suggesting the Brembo's will just swap out with the ATE's?

I sure am
And on the 79 -85 R65 you get better brake force because the pistons are bigger in the standard F08

I did the swap about 2 years and 26000 miles ago

You guys rock!

What money you spend converting the calipers will be saved in brake pads. The last time I worked on an ATE-equipped R65, the only source I could find for pads was BMW, with predictable pricing.

Very true In the long run you are better off just getting the F08

A rebiuld kit and pads for the ATE caliper is over $80.00 US

Same stuff for a F08 is about $45.00 US