Bolts Drive Shaft to Transmission

[brettironbutt]

Hello everyone! I know there was a thread on this earlier. To recap, R60/2. Just got my transmission back from Ulis, and have been struggling with the felt ring on the clutch release rod. I destroyed the new one I bought trying to get it over the rod, and just figured out you have to cut it diagonally first. In finding a new felt ring at 1800 on a Tuesday, I met an older gentleman that has a workshop, a dozen bikes, and a ton of parts. He sold me two new felt rings. I asked hime about the bolts for drive shaft to the clutch, and he said no lock washers any more. But... he said my replacement bolts were too long. (They are 14mm on the shaft of the bolt. He did not have 4 new shorter bolts. I bought 2, and considered trimming 2 of the new originals. When I bought a 75/5 a month ago (different bike, I know), it had a small box of extra parts. It looks like there are 4x 12.5mm (shaft length, not including the head), with red adhesive on the threads. They were in a baggie and look perfect for my needs. I have a few options:
1. Use the new 14mm bolts, with a new washer as I did in 2011.
2. Use the new 12.5mm bolts without a washer, although they are silver, not black.
3. Use the new 14mm bolts, but trim off 1.5mm with a grinder.
4. Use the new 14mm bolts without washers, and do not trim them. (Risk of hitting the seal?)

I am enclosing two photos. I am leaning toward option 2, but did want to see if there was something I was missing. Thanks for the help!

v-r
Brett

[schrader7032]

My two suggestions are. First do not use the longer bolts in any condition. Only use the shorter bolts with no washers. Second don't use red Loctite. That is for stuff that you never want to take a part again. Suggest you use blue Loctite. Probably don't even need the Loctite, as the stretch of the bolt probably takes care of retention. But for belt and suspenders approach use the blue Loctite and give the bolts a good grunt with your wrench. I believe the bolts are the same for / 2 and the AirHeads after that.

[brettironbutt]

Thanks Kurt. Appreciate the advice. Do you think these silver bolts are ok, even though the head of the bolt does not have the "indent"?

I spent 3 hours last night looking at parts on Salis, Ulis, Huggett, and BMW Max. All of them only had the longer bolts, with the disclaimer that they MUST be used in conjunction with the associated lock washers. I am disappointed I have not been able to source the shorter bolts easier.

Again, thanks for the advice.

v-r
Brett

[Seek]

Longer Bolts with the lockwashers are also fine. No need to get too scientific on this.

[schrader7032]

BMW stopped using the longer bolts when on occasion the washer would break and allow a bolt to back out. I suppose one could use a plan to check tightness routinely.

Don't know about your bolts. Kind of a critical joint...I'd get the right part. Surprised no one carries the shorter bolts.

MAX's site shows part 26 11 1 242 297. Looks like it's available.

[Seek]

From a modern point of view, the shorter bolts with some loctite are certainly better. The longer ones with the washer are plenty good enough. BMW used them well into the 80's (I don't know when they changed but the /7 still had the washers). An R60/2 is not going to snap them.

[Seek]

I was not quit correct. BMW changed in 1981 and changed it for all models, /5, /6, /7.
So, probably not a bad idea to change them on the /2 too. Not obligatory though.

[Flx48]

Brett-
Max sells both the original style (longer w/washer) and the new style. (shorter w/thread locker on the threads)
Both Salis and Uli offer the original longer w/washer.

I have one bike with original and one with new style, and agree with Kees; either one is fine on the Earles bikes.
There is nothing wrong with the original version, which was used on '55 through the /5/6/7 series bikes.

If I remember, there was/were an issue with washers breaking and bolts loosening upon some newer, bigger machines, hence the newer offering, but myself I've not had an issue, nor heard of one, on the Earles era bikes.

The sidecar bike has used the same bolts for the last five decades, after changing from the original Allen head bolts to the twelve point bolts, (12 pt. much easier to remove/replace) and they've been in and out for rebuilds, boot changes, seal changes, clutch...

Next time they need to come out of the solo bike I intend on going back to the longer w/washers.
This because I see now the newer style say they are a one use only bolt and then must be replaced; which sounds like a TTY bolt, (torque-to-yield) meaning they stretch and cannot be reused, and I'd rather have the option for reuse if caught out.
Best-
George

[schrader7032]

I'm not sure the shorter bolts stretch to yield. I'm sure they stretch, but likely remain in the elastic range of stretching. One can try feeding the used shorter bolts into the flange by hand and if they feed fine, probably OK. So something that could be done in the field.

I do see, however, that Service Bulletin 2078 says the bolts will be permanently stretched at 29 ft-lbs. Hmmm...I suppose so, but I don't know...would be fun to perform some tests. Note that users likely don't get close to 29 ft-lbs as it is difficult to accurately measure...there are adapters that can be used if done properly. When I've installed mine, I used blue Loctite and a good "grunt" with my tool kit wrench. Are they permanently stretched at say 26 ft-lbs???

That said, I seriously doubt any BMW repair shop would reuse either the long or short bolts if they were doing service...insurance issues and all.

As with all things on the bike, it's a personal call on reuse of any item.

[cwf]

Well, here's one for the chamber of horrors. I acquired a '65 50/2 with no previous history. It had been in some kind of accident : bent handlebars, bent forks and minor damage.

As I worked on it, I found the driveshaft bolts loose, with one missing. I assumed someone had had it apart but, when I hung up the swingarm to paint, the missing one fell out.

The evidence seems to show that the bolts came loose (wear under the bolt head), one came out and rattled around for a while (no threads and head rounded), finally getting trapped and badly distorted, locking the back wheel and tipping the rider off.

There must have been plenty of warning.