1981 R65 with Dual Discs

[ShutterPilot]

Hi,
I've got a 1981 R65 with dual ATE calipers. Bike is bone stock, so it came this way. I see this mentioned in Noemi's FAQ, and parts referenced by Mike V in his doc "ATE Front Brake Caliper Housing O-Rings", but I'm having difficulty with parts/verification via both fiche and repair manual, other than an entry "optional dual front calipers" in the Clymer manual.
The owners manual that came with the bike documents the original purchase and maintenance history thru 1986, so the manual's original, but is generic enough to only picture a single rotor throughout. But its 1981 specific enough to record the lower compression ratio of 8.2:1, rather than the prior 9.2.
Can anyone point me in the direction of documentation covering these brakes, and proper parts etc for rebuild?
Or is the Mike V doc still the primary resource for a How-to on these?
(Thanks, Mike V for that doc, BTW)

[Barry]

I didn't look at the online fiche but I believe the caliper pistons are no longer available. Not the end of the world as stainless ones can be made easily enough.

Motobins stock everything else that might be needed like seals and brake pad pins. Possible exception is the O ring between the two halves of the caliper. You will have seen that Mike V covers that.

As for documentation they are covered very poorly in the original BMW work shop manual with the only useful information being the 36mm piston dia. That is probably why the aftermarket manuals are also poor on the subject.

There is nothing especially difficult about a caliper overhaul. Can't remember if Mike mentions this but you won't find a torque value for assembling the caliper halves. You will finds threads here where we have discussed this in the past and I posted the value that I used which has been no problem.

[ShutterPilot]

Hmmm, you bring up an interesting point Barry...
Are the ATE calipers and parts on the dual setup different specs than on the single disc setups? I was thinking/hoping I'd just order 2-sets of ATE rebuild kits from MB...

So far, pre-1981, I only find single ATE's referenced, and after 1981 I see Brembos listed for the dual equipped /LS

Sorry for sounding much the noob, but I've tried "search" on this forum, and only get 3-4 returns on "caliper", "torque", "brake" etc. But manually scrolling thru I see many more posts than this...

I hope soon to learn enough that I can contribute, rather than just always coming to just drink from the well, so to speak.

Thanks to everyone who have helped me with this project so far.

[Barry]

I'm sure the spec for dual calipers will be the same. Only thing different will be the master cylinder diameter.

Yes the early models had ATE and later had the very similar Brembo. I recall Julio did a very good post that compared the two.

Some previous threads.

http://www.bmwr65.org/cgi-bin/yabb2/YaBB.pl?num=1311933847

http://www.bmwr65.org/cgi-bin/yabb2/YaBB.pl?num=1270141341/0#0

http://www.bmwr65.org/cgi-bin/yabb2/YaBB.pl?num=1286640929/4#4

http://www.bmwr65.org/cgi-bin/yabb2/YaBB.pl?num=1296075723/1#1

[georgesgiralt]

Hello !
My '82 R65 came with dual ATE. (I bought it new...in 84).
Frankly, they are the same as the Brembo. Main exception being that parts are less/no more available and brake pads being more expensive because of the lesser volume.
I had one calliper rusted and difficult to mend. So I switched to new Brembo instead of buying only one ATE (which was available from BMW at that time).
BMW sold a few R65 with single brakes. They did not sold well. So they offered the dual set-up very soon. I can't remember having seen a single disc R65 (the R45 is a different matter). The right hand calliper has a different hole diameter for affixing it to the fork because they used an existing model and thought they could benefit from this because the reducing bush also serve to centre the calliper versus the disc rotor.
If I were you, I'll will maintain the ATE until I find a couple Brembo in good shape and, then, switch to the Brembo. Keep in mind that the pads are different...
P.S. If I'm not mistaken Motobins used to sell new ATE piston but at a price...

[NC Steve]

A suggestion, if you haven't already checked there, is Bombar's Beemers, in your own fair city of Durham, NC. They specialize in restoration of older Airheads, and I know their master technician, George Ratterman, who is currently rebuilding my R65 transmission at his home shop. George has been working on BMWs all his life, and should know exactly the job you're trying to complete. The other staff have many many years of combined service work as well. If anyone local might have the parts you're missing, it could very well be them.
Good luck!

http://www.bombarsbeemers.com/Pages/default.aspx

[Luca]

My 82LS has dual ATE's and I rebuilt them with Motobins kits.  The internals are the same as the single disc setup and two kits will have all you need...  except the o-ring that seals the the two caliper halves.  I found the pistons were much easier to install with the calipers separated, and the internals were easy to clean.


Also, when you use the forum search, the default time window is pretty short.  Turn it up to "all posts" and you should find a lot more.

[Mike V]

Does this link help?  I can't remember the torque values I used but I have them somewhere in my notebook.  Should I research for you?

http://s428.photobucket.com/user/gruntyman66/library/81%20R650%20Restoration/Front%20Brakes%205-09

The dual ATE's are quite good on my R65.  I have also re-fitted the MC with a 15mm variety.  A little wooden but incredible stopping power with adequate feel and modulation.

ATE' Brake Caliper Rebuild Kit: 34 11 1 454 809.

-Mike V.

[tvrla]

I also had an 81 R65 with dual discs. From what I'd heard, the 81 was the only year that came with duals stock, besides the LS. And mine had the ATEs as well - I believe that was the stock configuration.

I had always thought the calipers were unique to the R65, but I've been told recently that they're Brembo F08s and no different than other F08s.

And, yes, it's true - the calipers are all the same except for being handed - all have the same diameter pistons. But I think the ATEs are prettier than the Brembos.

[ShutterPilot]

Thanks all for the great info -very helpful.
NC Steve - I have the 34 11 1 454 809 kit on order from Bombars Beemers. Peter was very knowledgable and helpful.
Thanks Luca for the Search hint, I'll try that.
Mike V - do you still have a supply of the little o-rings if I open the caliper? I could send you a SASE and some cash if you do.
I'm hoping the pistons are in good enough shape to clean up with some emory and pop back in - I haven't popped them out yet to see, till I have the seals in hand.

I'm hoping to now have Bombar's do head/valve seat work after I get the brakes sorted.

[Mike V]

Shutter,

I believe I have a few left.  You're welome to them.  No need for reimbursement of any kind.  Send your mailing address to my personal email at mvtv@cox.net.

I'm leaving town this weekend and will return next week.  If you still need them just let me know and I'll get them moving in your direction early next week.

-Mike V.

[ShutterPilot]

Thanks Mike - just sent you a PM about the o-rings.

And NC Steve - stopped by Peter Bombar's saturday to pick up the brake seal kit, and checked out the ongoing restorations on an R90, an R69 (i think) and Norton Commando head. While I do most of my own wrenching, I still don't know a lot about BMW's, so I just nodded my head, with a couple of MmmHmm's thrown in while he went on about this and that. Very fun and informative, but hoo-boy did I feel ignorant.

[Mike V]

Shutter,

O-rings are in the mail.  Keep us informed on the project.

-Mike V. / San Diego

[ShutterPilot]

Thanks Mike V!

NC Steve is in the know - For anyone looking for headwork on their airhead, Peter Bombar really looked like, well, the Bomb. He showed me the head work he's been doing, the Serdi machine and I saw some 5-angle valve grinding - all impressive:
http://www.bombarsbeemers.com