Drive shaft noise ??

[40427]

Bad news

Took the drive line loose and the problem is not there, it is inside the transmission:

Rotating the output shaft flange reproduces the catch/bump , so it is at least the rear bearing. There was more swarf on the drain plug than the last time I changed the fluid.

We pulled the transmission out of the bike and fought the lock nut on the output shaft until it came loose. The flange that mounts on the tapered shaft won't come free with the puller we have so I will try and get to the dealer in Greensboro tomorrow and see if I can convince them to take it off for me. They should have a special BMW tool for the job.

After that , we will inspect the whole works and decide if we can just replace the output shaft bearing or if it needs major attention by a specialist.

Stand by

 

[ISAMEMON]

tranny circlip time.


if thsi tranny has not been apart before adn the circlip done, then u really should consider it.
when you unbolted the trans, did it push itself away from the engine at all, if so , then the lacking circlip has done lots of damage already forcing the gears etc forward

If the bearing is floating on the shaft thats because the circlip is not there and allowing everything to move and eat bearings etc but has not moved forward enough to do the above listed push

well at least thats been my experience but im not a bmw tranny man, only have had two rebuilt both missing circlip trannys

 

[helmut_head]

Sorry about your trans. It's worth it to fix it if everything else is in order.

Oh, yeah. So you can't get your FD off of your driveshaft? Get a heat gun, a rubber mallet and a buddy. Heat the FD in that flange area and hit it judiciously with the mallet. Give your buddy a beer, but have him set it down while he catches the FD as it falls off.

 

[40427]

It's not on the drive shaft, it's the flange on the back of the transmission that the drive shaft bolts up to that is giving trouble. It's a tapered fit , i think Fritz the hammer mechanic put it together originally.

The puller we have is a Harbor Freight special

We went at it again today and managed to bugger up a bolt so gave in and called the dealer.
They have a BMW special puller and have agreed to do it for a half hour labor charge ( it will take all of 5 minutes in reality, but they feel the need to hose me for the half hour)

I did loosen up the bolts that hold the back cover on just to see, it jumped up and gave a pretty good gap from the transmission body. This tells me that either it was assembled from the factory with too many shims on the rear carrier bearing, or due to no cir clip the bearing has walked a bit. Won't know until I get it apart completely.

Also when those bolts were loose i turned the flange and there is no klunk or resistance. Tightened the cover bolts back up and the klunk/resistance returns.

Since i have gone this far i will do the job correctly and get the groove cut for the cir clip if it is not there, replace bearings as needed and hope there is no gear /shaft damage.

Should be good to go after that. In the mean time i am doing a bit of house cleaning of the usual sort on parts you don't normally access. I am constantly surprised at how clean and original this bike is.

I will probably sell it shortly as i don't enjoy all this tinkering as much as I thought I would when I bought and old bike.
Doug

 

[donbmw]

We went at it again today and managed to bugger up a bolt so gave in and called the dealer.
They have a BMW special puller and have agreed to do it for a half hour labor charge ( it will take all of 5 minutes in reality, but they feel the need to hose me for the half hour)

I work in the service industry. There is no such thing as a 5 minute job. Yea it may on take 5 minutes to pop off the flange. Look at the steps you are making the dealer go through for a 5 minuter job. Open a shop work order, give part to the mechanic, mechanic has to go where the special tools are keep, installed tools and remove flange. Put tools back. Mechanic fills out work order and turns to dealer to close and get with you on payment. A 30 minute charger is not unreasonable.

Don

 

[40427]

donbmw; point well taken.
I was just grousing a bit and the dealer was the closest target as usual.
( he is actually a pretty good guy and a friend most of the time)

So they removed the flange, I ordered a gasket /seal kit , went to my buddies shop and took the transmission apart. A little heat from my heat gun did the trick.

We found the large bearing 6403 to be the culprit. The rest of the pieces & parts are sweet, clean and run smoothly.
Called around to a couple of bearing places locally and ordered the 6403 and a 6304 on the same shaft just to be assured of a nice straight assembly.

Local drag race engine builder with all the correct tools ,lathes, bridgeport mills and more stuff that you can imagine is in line to cut the groove for the cir clip. Still looking for a cir clip 17 x 1.

If all goes well I should have all the parts and be ready to reassemble the box by next week.

 

[helmut_head]

Yer doing better than I'd be doing at this point. My process was remove it, ship it, tinker while waiting (clutch, rear main, oil pump seal), wait a little longer, tinker a bit more, then re-install after it comes back. Good thing for you not to have to wait, then pay!

Odd how our vintage of bikes have similar issues. Wonder what that German engineer was thinking?

Sorry about my confusion on what you were having problems with.

 

[40427]

I would be doing better if i was out riding with my friends.

Still in a quandry about whether to keep the old thing or let it go to someone else who has the patience and fortitude to keep it on the road.
The bike itself is so clean runs great and has been well kept over the years it deserves to live on and give someone enjoyment.

It does "some" of that for me still, and if I were younger I'd keep it for sure.
I am blessed with friends who have access to serious machine tools and work shops.

One thing is certain, if I sell it the new owner is getting something well fettled.
I do not sell junk and always give a complete and honest disclosure of all the records I have on any bike I pass along. They can rest assure that it will have been repaired/upgraded to the absolute best of my ability, I am a bit anal about maintenance. Never sold one that came back ,or heard any complaints from buyers.

 

[ISAMEMON]

you will get the tranny fixed, spring summer will be here, you will ride around for a bit and fall in love with it again
wont see that bike on craigslist

 

[40427]

Shush , quiet !!

I am already campaigning for another bike with SWMBO

 

[helmut_head]

I would be doing better if i was out riding with my friends.
.

You could always hope for alot of rain while your fixing it.

Also, the transmission is about the worst thing you'll need to deal with in my opinion. You'll get it all fixed up, sell it to someone, and they'll never have problems with it. Always happens that way.

 

[40427]

I would never wish rain upon a fellow rider.
Well maybe a hord of locusts, or a mess of black fly's

Picked up my gasket/seal kit from the dealer yesterday, and the two bearings this morning from a local supplier. Funny the bearings were made by SKF in Argentina according to the boxes they came in.

I lived in Schweinfurt , Germany for almost 13 years that's the home of SKF. Guess they outsourced the work to the families of the thousand year reich who escaped.

Another friend had a transmission apart from an air head.
His has a shaft with the groove already in it, so we will measure the end play and if all goes well should start putting it back together tomorrow or Monday at the latest.

Thought about just putting the transmission back together without the groove/cir clip. It lasted 27 years that way already , but if the other shaft is good I'll put it in so who ever ends up with the bike, should I put it on the market ,will have no worries.

I did speak with two other air head riders locally who both told me they had transmission problems ,and both of theirs had the cir clip in place.
So i really wonder if it is all that great a fix. BMW stopped installing it from the factory for a reason. But we will never know the truth at this point.

 

[wecm31]

I'll throw out a comment from my personal experience and 'Heads I ride with..

"The gear box is the weakest link in the engine-trans-FD chain"

For the mono shocks atleast, the engine and final drive will never need a rebuild.
New valves and head work maybe, perhaps a driveshaft. But before either of those, you'll be getting the gear box serviced, clip or no clip.

 

[20774]

BMW stopped installing it from the factory for a reason.

By that reasoning, they began installing it again near the end of production! Soooo, that means what?

 

[40427]

I suppose it is one of those things that there is no clear and absolute answer to.

I do not remember how many different makes of motorcycles and cars I have owned over the years, but it's a bunch.
Never ,and i mean absolutely never , have I had to repair a transmission in one.

When i road raced cars and motorcycles i probably rebuilt everything else on all of them , but not once did I need to rebuild a gear box. On my TZ 250 Yamaha's I did occasionally change the gear ratio inside the box for different tracks. But never a rebuild or a bearing failure.

If as you say the transmission in the mono shock bikes is the weakest link in the drive line , my best guess would be sloppy tolerances at assembly from new , having to do with end play on the shaft inside the box.
We know that ball bearings do not like side load, and too much or too little end play would cause this type of failure.
I will be measuring shim sizes very carefully

 

[20774]

I suppose it is one of those things that there is no clear and absolute answer to.

True...but one thing I've heard many people say is that some pricing guy came up with the idea that if they eliminated the circlip and the time to put the groove in the shaft, they could save $X per bike. The CEO liked that...make it so! Pure conjecture, but there might be some slice of truth to that.

 

[40427]

Hmm, might make sense considering the time.

Late 1983/84 every manufacturer world wide had their eye on what was happening to/ in the auto industry.

Bean counters in control, crappy products developed by the consumer after the sale, instead of by the manufacturer's .

Government intervention rampant, no one taking responsibility. It's always the other guy who caused the problem.
Quality suffers world wide in everything

 

[ISAMEMON]

too bad yours did not have the groove

mine was a odd one, the shaft had the grove, but no circlip
must have been right at that turning point in production

too bad the person putting it togehter on assembly line did not say,

hey boss its got the groove, sure we dont have any of those 10cent clips around

nine, is not cost effective, back to work you swine

 

[krpntr]

Interesting. Verrry interesting

I just bought a '92. With 56K Does this mean I should run down the transmission shop and get the groove cut and the circlip installed before the damage starts, or should I wait for the inevitable clunk ?

 

[20774]

I just bought a '92. With 56K Does this mean I should run down the transmission shop and get the groove cut and the circlip installed before the damage starts, or should I wait for the inevitable clunk ?

Yes! Whatever you do, don't let it get so bad that the price for repair skyrockets. The easiest thing to do is watch the drain plug for more build up than normal. 'Course, you only just got this bike, but I'm sure you know what to look for.