1971 R75/5 Tranny Output Flange

[DonTom]

I see the output flange is an easy thing to get. See here.

All those choices, do I want new or used and if used, what should I be looking for?

I assume the one that says Capital Cycle still in the wrappper up is new.

Do these things used ever give a problem? Is it safe to buy these used? Anyway, they look like they are easy to find on e-bay at any time.

BTW, what do they cost new from a BMW shop? I forgot to ask.

-Don- Reno, NV

 

[20774]

BTW, what do they cost new from a BMW shop? I forgot to ask.

You can go to RealOEM or MAXBMW and look at the fiche...that will be a good idea of the cost.

 

[happy wanderer]

I see the output flange is an easy thing to get. See here.

I assume the one that says Capital Cycle still in the wrappper up is new.

BTW, what do they cost new from a BMW shop? I forgot to ask.

-Don- Reno, NV

No need to assume. If you click on the Capital Cycle part you posted a link to the first thing it says below the item description is "Condition New" so yeah, it's a "new" part. Also, down below it says the seller actually is Capital Cycle and they are clearing out some inventory. All new parts...

As Kurt mentioned, if you want to compare to the cost of new OEM parts from BMW both MaxBMW motorcycles http://www.maxbmwmotorcycles.com/fiche/PartsFiche.aspx and RealOEM http://www.realoem.com/bmw/select.do host excellent and extremely easy to use BMW OEM parts fiches online complete with pricing.

 

[DonTom]

No need to assume. If you click on the Capital Cycle part you posted a link to the first thing it says below the item description is "Condition New" so yeah, it's a "new" part. Also, down below it says the seller actually is Capital Cycle and they are clearing out some inventory. All new parts...

As Kurt mentioned, if you want to compare to the cost of new OEM parts from BMW both MaxBMW motorcycles http://www.maxbmwmotorcycles.com/fiche/PartsFiche.aspx and RealOEM http://www.realoem.com/bmw/select.do host excellent and extremely easy to use BMW OEM parts fiches online complete with pricing.

Thanks, I see the price there for the tranny output flange is $184.96. The new one on e-bay is $120.83.

But is it fairly safe to use a used one? What can go wrong with these (other than the problem I had, which nobody even has a clue what caused it to be much like welded on).

BTW, I had no clue Capital Cycle was still in business. I did a lot of business with them around 30 years ago or so, when they used to send me their catalog which I have not seen in years. Except for here, when I just did a web search in the middle of this message.

-Don- Reno, NV

 

[DonTom]

I finally got back to SSF and picked up my old original gearbox from the BMW shop as well as started the install of the used gearbox I purchased in SF that I found on E-bay.

On my original gearbox, to remove the output flange, the shop cut off the four "ears" of the flange (I gave them permission to get it off any way they could). However, they left the threaded part still on the shaft and that will have to be cut off. They also mentioned they ruined a few sets of bolts on their tools trying to remove the flange the correct way, as happened to me.

I looked inside the gearbox and it all looked like new inside to me so I asked "What looks so bad in here?" and was told that since they had it open they felt that they should replace the seals and bearings (for a total of around a thousand bucks). Perhaps I should have just told them to put it back together, without doing anything inside. This (original) tranny might even be in better shape than the one I just installed. The original tranny has been rebuilt before, perhaps 20 years ago by a BMW shop, but the bike has NOT been ridden all that much since then. My other three bikes get a lot more use.

I have the E-Bay tranny installed, drive shaft back on, clutch and such seems fine from the best I can tell while the bike is on the centerstand. I did this yesterday afternoon. I still have to glue the rest of the bike back together (swing arm and such), which could be later today or tomorrow when I will be ready for a test ride. But so far, it went smoothly, and it was my very first clutch job I've done on anything.

But I wish I reread this thread yesterday as I forgot to put a dap of grease on the clutch rod tip. Too late now.

Anyway, I do have a question about gear oils in this old 71 BMW R75/5 (SWB). What should I use in the gearbox, shaft and rear drive? I think I heard synthetic gear oils are recommended these days, even in this old bike, so what brand and weight would be best?

And what about for the engine? I heard that has changed too, from the 30/40 weight straight recommended in the owner's manual (which I still have).

-Don- SSF, CA

 

[20774]

Don -

I think gear oils is something that is a personal choice, but a good quality brand 80w90 is the way to go. I think they're either semi synthetic or pure synthetic. I don't think either matters or is that much better.

As for engine oil, I'm surprise that the /5 manual still suggests straight weight oil. I know the /2 models did...maybe the early /5s did, too. You could still use straight weight but likely will need to pay attention to temps and maybe change the oil twice a year. Personally, I'd suggest using a good quality 20w50 that has an API rating of SG/SH and call it a day. Check the March 2013 ON for my article on oils and levels of ZDDP.

 

[DonTom]

Don -

I think gear oils is something that is a personal choice, but a good quality brand 80w90 is the way to go. I think they're either semi synthetic or pure synthetic. I don't think either matters or is that much better.

Seems they still sell non-synthetic gear oils in 80W90 as well as much more expensive synthetic in 75W90 at O'Reilly's Auto Parts. I ended up buying the Lucas Synthetic 75W90 and already put it in the tranny and shaft drive housing. I will drain the rear drive tomorrow and put this stuff in there as well. If it's the same company, I hope Lucas oil is better than some of their electronic stuff!

As for engine oil, I'm surprise that the /5 manual still suggests straight weight oil. I know the /2 models did...maybe the early /5s did, too. You could still use straight weight but likely will need to pay attention to temps and maybe change the oil twice a year. Personally, I'd suggest using a good quality 20w50 that has an API rating of SG/SH and call it a day. Check the March 2013 ON for my article on oils and levels of ZDDP.

I found a couple of quarts of Chevron 20W50 in my garage, and changed the oil and filter and put this Chevron 20W50 in.

Anyway, I went for a test ride and after about a mile, it SEEMED like my clutch cable broke. So I stopped the bike and looked under the bike and noticed the clutch cable was still moving the clutch throwout lever. Then I almost panicked, wondering what went wrong, thinking it had to be something serious inside the tranny. But then I noticed the real problem, I forgot to tighten the lock nut for the adjuster screw. What a relief to discover that was all it was! But I was surprised how fast that adjuster screw can unscrew itself. The clutch felt normal just seconds before. Anyway, I tightened the nut and rode for about 25 miles and it all ran perfectly, no more problems of any type.

It looks like I will ride the bike back to Reno in a few days, to leave it there permanently. The weather looks good over the mountains for this 225 mile ride.

-Don- SSF, CA

 

[DonTom]

Well, it took a few thousand miles, but I discovered I screwed up when I did my clutch job.

Yesterday, I was riding down a hill and felt a big jerk. Several more, along with a bang from the rear wheel. I was very close to home when this happened, less than a mile, the rest was up hill and no more problems getting back home.

When I got back home, I could hear a lot of noise when I moved the rear wheel by hand when on the centerstand. So I removed the rear wheel and then discovered the noise was from the shaft drive. So then I removed the swing arm and found two loose bolts inside the drive shaft, from the output flange. The other two were still mounted, but so loose I could remove them by hand without any tools.

Then I looked these up in my BMW parts book. The lock washers were missing--all four of them!

But are these bolts only for one-time use? I mean was I supposed to replace them after they were removed? Also, what about the clutch bolts? I reused them all, I was wondering if I was suppose to replace those too, but I didn't. I was kinda in a hurry to get the bike from SSF to Reno, which I did accomplish fine. I didn't have the time to wait for parts and such at the time.

Anyway, it seems there was very little damage caused by these two loose bolts. I can tell where they hit the outside of the U-joint, just some scrathes on the outside of the U-Joint. The U-joint itself and the drive shaft case is fine, so I was very lucky. I purchased some new bolts, but I have to wait for the lock washers to come in. I guess I didn't notice these lock washers when I put the bike back together. But was I supposed to replace the bolts too? And what about the small bolts on the clutch? Should I now worry about those coming loose too?

-Don- Reno, NV

 

[20774]

RE: the output flange bolts. One thing is you don't really want the older style longer bolts with lock washers. What has happened, and likely happened in your case, is the washer fractures leaving slack in the bolt and the it backs out. BMW replaced these bolts with shorter bolts, no lock washers. The service bulletin said that sufficient long term testing had been done to indicate their use was fine. These bolts are installed to 29 ft-lbs...I also use blue Loctite. They stretch a bit which is what gives them their holding power and resistance to backing out. I've read on Snowbum's site that if they thread into the output flange by finger OK, they were not stretched enough to warrant replacement. That's the thing with metals...as long as it remains within the elastic range, it should be fine. That said, it might be best to replace them if there's any doubt. The other thing is that it is somewhat easy to check on them once in a while, so maybe reuse is OK.

As for clutch bolts...we'll they are hidden and you can't easily check them. Personally I would replace them...and use blue Loctite on installation. But reuse is probably OK for short term. But it would make me wonder over time. Again, it's not easy to check them. Internal stuff, I try to use something quality because I may never see it again. Outside stuff, maybe I can consider alternatives because it's right there for checking.

 

[DonTom]

RE: the output flange bolts. One thing is you don't really want the older style longer bolts with lock washers.

I didn't know this has changed. I ordered my bolts by part number this time, so it might be wrong. If I am supposed to use a bolt that does NOT have a lockwasher, where can I find the part number? The four new bolts I have are 26-11-1-230-414. When did they change? The old four bolts in there could have been changed as I had a clutch job done in a BMW shop many years ago (20?). Let me compare my new bolts to my old right now, --I will be right back!

My new bolts look exactly like the old. All eight of them are just over 3/4" (20 mm) long.

I now think what happened is my bolts never had any lock washers when I did the clutch job. So now what probably happened, IYO?

If these bolts are over-torqued, could that damage them? I only could find a 10 MM box end wrench to fit in there, IIRC. Or is there a special 12 point small socket that I can use that will fit the heads of these weird bolts with a torque wrench? I doubt if I left them too loose, but I suppose that is possible too.

I guess I don't have to wait for the washers to put my bike back together. This time, I will use the lock-tite for sure. Is that blue the medium strength stuff?

-Don- Reno, NV

 

[20774]

Same part number...the old ones are supposed to have been eliminated from the system. You really can't use the long bolts without the washers...they will likely run past the flange and create an interference. The new short bolts are really the right way to go. Just use the wrench from the tool kit with rag in your hand...step on the rear brake and give it a good grunt... blue Loctite is a good idea...not red. There are special adapters for torque wrenches...they've been discussed before. Not really needed, though.

 

[DonTom]

Same part number...the old ones are supposed to have been eliminated from the system. You really can't use the long bolts without the washers...they will likely run past the flange and create an interference. The new short bolts are really the right way to go.

What year did they change to the short bolts? Anyway, this makes me wonder why they fell off. But this time, I will use new bolts with the blue locktite.

Just use the wrench from the tool kit with rag in your hand...step on the rear brake and give it a good grunt... blue Loctite is a good idea...not red. There are special adapters for torque wrenches...they've been discussed before. Not really needed, though.

Other than the locktite, and reusing the same four bolts, that's what I did last time. If anything, I over- torqued them, that's why I was wondering if that could mess up the bolts and make them get looser faster. But I take it there is nothing special about these bolts, and I normally should be able to reuse them (but I won't from now on!).

BTW, I wonder why the local BMW shop let me order those washers, if they have been discontinued. I didn't know BMW would change a part but keep the old part number. I take it these washers won't even fit the short bolts.

I have never even seen the longer bolts. They were probably changed with my first clutch job that I let the BMW shop in SF do back in the 1980's.

BTW, have you heard of these bolts coming loose before? If so, is there sometimes a lot more damage? Seems everything is okay with my bike, just a couple of scratches on the outside surface of the U-joint.

-Don- Reno, NV

 

[20774]

The service bulletin is dated June 1983. It's not unusual for BMW to change the part but not the part number. I suspect that the supplier of the older bolts (14.5mm) just has them on hand and continues to sell them. The shorter bolts (13mm) is the proper part. In this situation, the owner has to know what the part should look like...unfortunately, that's the situation for us unless you have a good parts guy like the people at Max BMW.

The bulletin says the bolts are permanently stretched when torqued to their value. So, my suggestion they can be used needs to be reconsidered. If they can be turned into the output shaft flange easily by hand, that would suggest they were not permanently stretched (ie, the torque was less than the required) and could be reused.

These bolts coming loose has been discussed on various lists before. Oak Okleshen was one of the ones who was discussing it...Snowbum as well. His page covers the issue:

http://bmwmotorcycletech.info/drvshftboltstoolstorque.htm

I don't think you've done any real damage. The fact that two bolts were still in place, although loose, prevented more damage. The noise you heard was just the loose bolts moving around. You should probably check that all threads in the output flange are still good.

 

[AntonLargiader]

The short bolts have a different part number.

BMW might occasionally change a part while keeping a part number, usually in some ill-conceived supersession, but it's far more common for them to change a part number while not changing the part.

 

[20774]

Anton's of course right...I reread things and see that the part numbers are different. Long was 26-11-1-230-414 and short is 26-11-1-242-297. RealOEM shows the old number for use up to 9/1980 but the new number after that...I checked for my /7. Max BMW fiche says "These short bolts 26111242297 fit 1981-1995 Airheads; do not use washers. Some people like to use the short bolts on pre-1981 models also (without washers.)" In reality, you shouldn't use the old longer bolt with lock washers. When I was working on my R69S, I specified the short bolts.

I remember it happening where the part changes but the number doesn't...since I don't deal in daily parts ordering, I wouldn't know how much that is/was.

Thanks for the correction, Anton...

 

[DonTom]

Anton's of course right...I reread things and see that the part numbers are different. Long was 26-11-1-230-414 and short is 26-11-1-242-297.

When I measure the total length of by bolts, I get 21.36 MM. If I only measure the thread, I get around 14.8 MM.

Anyway, it looks like my first post in this tread was correct. I had the long bolts with no lock washers. And this might explain why my driveshaft gear oil lever went UP since then. Perhaps the seal in the flange now has a leak because of the longer bolts. I hate to think I need to take the tranny out again. I just put the bike back together last night, save for those four bolts (was awaiting more info. which I now have).

I wonder how much damage was done to the seal.

Anyway, it looks like I should get the new shorter bolts.

I guess what I will do is put in the short bolts and keep a close eye on the drive shaft level as well as the tranny level. I hope not too much damage to the seal in the last 2 or three thousand miles. However, if my drive shaft level has been going up, I assume some damage has already been done.

Thanks for the very helpful info!

-Don- Reno, NV

 

[barryg]

Tranny safe cracker


I had some strange stuff going on in my transmission. Found out that '74 models had issues. Got the tranny out and it looked like a bank vault. Got my caipers and scale out did a little measureing and fabbed up this tool. Worked like a champ. Wasn't to happy to find out that the cluster gear was toast. Ouch! Exspensive! Thought those German engineers were better than that. Opening up that gearbox made me feel like a safecracker.

 

[DonTom]

What has happened, and likely happened in your case, is the washer fractures leaving slack in the bolt and the it backs out.

But if that's the case, how come I didn't see any evidence of washers in the shaft? Not even on the two bolts that were left on the flange. I am just curious what could have happened to the washers, assuming they were installed.

-Don- Cold Springs Valley, NV

 

[20774]

Don -

You kinda suggested that maybe you installed the longer bolts without the washers. The lock washers were designed to keep the bolt from backing out. I suspect that the metallurgy changed with the shorter bolt...they designed it to be stretched, thus creating the clamping force. I would think that the older bolt didn't have the same characteristics so it relied totally on the lock washer for the support.

So, I forget in this discussion...when did these bolts go in? And what did you remove....short bolts or bolts with lock washers? Originally it would have been with the lock washers. Unless it was a Friday installation or someone else has been in there since the factory.

 

[omega man]

Nice job on that tool Barry
OM