Gearbox woes

[DamanC]

My transmission is acting up to the point that I'm nervous to ride it - downshifting is particularly rough especially going from 2nd to first.  I greased the input splines and still no success.  

I just got this '83 earlier this summer and found the gear oil milky and with metal shavings.  Since being cleaned a month ago more gritty metal shavings appeared on the drainplug.  What's the course of action? - another spline lube? deeper issue?

It seems that the problem is in the transmission not the actual gear lever shifting.  

- Any ideas?

[Bob_Roller]

Second to first gear downshift on an R65, is best done with the bike not moving, or moving at a slow speed, it's not real happy with it .

I would replace the gear oil in your transmission a few more times, before going for a transmission rebuild .

[tvrla]

I agree with what Bob says.

[Rob Valdez 79 R65]

If it is really REALLY bad, and you are consistently getting metal shavings on the magnet (not just fine fuzz), you might have a bearing or two going out, especially if the bike sat for a long time before you bought it.
The fact that you found milky oil on your first change indicates water in the oil.
When the bike is not running, most of the gears and bearings are above the oil level.  If there is moisture in there, they are very prone to rusting.
(photo courtesy of http://jhau.maliwi.de/mot/gearbox.html )

As the other guys said, do some frequent oil changes.
If this is your first airhead, you may not have the knack of changing gears down, yet.  These are not Japanese bikes.  And DON'T downshift into 1st until you are CREEPING to a stop, say 1 MPH or less.

And don't ride the bike any further than your best friend and his truck can come to get you.
Listen for squealing noises.

[montmil]

If you've got the splines cleaned and lubed, it's likely unnecessary to do it again.

Yes, it's a PITA, but stay with the gearbox lube "flushing" ritual a few more times. And do be at a slow walking pace, or less, before downshifting into low gear. Your box just may not like the 2nd>1st downshift.

Here's an idea for the forum's membership to respond to:

Considering the "gritty metal shaving"s attached to the mag plug, the difficult 2>1 shift, plus the original milky trans lube; might it be possible to overfill the transmission with a kerosene and light oil blend, pull the spark plugs and rotate the rear wheel while manually going up and down the gears?

Thoroughly drain the fluid, maybe repeat, then add fresh gear oil. If the transmission needs a good laxative, this might help. If the box is headed south, it may be worth the effort for confirmation.

Comments? Potential harm? To quote Tom Selleck in High Road to China, "Speak."

[tvrla]

A good flush couldn't hurt, but don't know if it would get everything. Normally, the first bearing to go is the front output shaft bearing, and it's facing into the housing. It's got its own little well and oil is delivered to it via a channel suspended from the roof - oil splashes into the channel and flows into that recess to lube the bearing. It's kind of walled off from the rest of the tranny, so I don't know if a flush would clean out that area - and that's where it's needed most.

[Barry]

Another good flush with something thin like Monte suggests won't do any harm and if water was in there I would want to do more than one oil change anyway. If you are going to ride the bike, like Rob said I wouldn't stray to far from home.

The problem is to know how bad is the gearbox.  Is it still producing new metal shavings or are you just flushing out what was there.  How does it feel if you rotate the rear wheel with the bike on the centre stand in neutral. It should be nice and smooth especially with warm oil after a run. If it's rough then you probably need to overhaul the box. A better but much more involved test is to disconnect the drive shaft and turn the gearbox output shaft by hand to feel for roughness. The risk of continuing to run the gearbox is that the you could be doing more damage which will push up the price of repair.

[nhmaf]

I'd also give the kero-flush a try - it might or might not help but at least it should get rid of any residual water and maybe some more bits of 'grit'.   At least, you'll only be out a few dollars for the kerosene and it *might* enable you to run the bike fow a bit longer (near home).   Is the only trouble spot the 2->1 downshift?   Maybe you can get some more time with it yet.  But, I suspect that the magic 8-ball will likely be telling you "Transmission Rebuild" in the future.

[Lucky_Lou]

Bit of Blue Sky thinking...........
Would removing the rear wheel then filling the gearbox with flush.Run the engine and go up and down the gears to properly flush do any harm ? there would be very little load on the gears ??
Lou

[Rob Valdez 79 R65]

Bit of Blue Sky thinking...........
Would removing the rear wheel then filling the gearbox with flush.Run the engine and go up and down the gears to properly flush do any harm ? there would be very little load on the gears ??
Lou

I certainly can't say.  But if I were to do a kero-flush, I would want to do a couple of SHORT-term gear-oil changes afterward to get all the kero out!

And if you want to put more than the usual amount of fluid in the gearbox, you are going to have to lean the bike over on the right side to do that.

But I wouldn't do a "power flush" with too much kero/light oil blend in there, as it might find it's way into the swing arm!

I'm not much of a chemist - would the kerosene have an adverse effect on the input/output seals?

[donbmw]

When I worked a the local Honda dealer. We would use engine flush for the locla auto parts house. It was basicly kerosen. We did this on ATV that owners went swimming with. Ran them till they were got and hot then drained and then did the same thing with oil two to three times. Never had any problems with seals. Knew alot of
ATV's being use for years after this. When Honda came out with the 400 compact engines this stopped as we found out that there were areas in this motor that held dirt and water that would not get flushed out and in a very short time the motor would start smokeing after a flush. We then started a tear down and cleaning when one of these motors had water in it.

Personally if this  was mine I would tear down and clean out and replace the seals and bearings. Not knowing the history of this bike.

[montmil]

...Personally if this  was mine I would tear down and clean out and replace the seals and bearings. Not knowing the history of this bike.

Unfortunately, the BMW transmission requires a substantial number of specialized tools for a proper rebuild, hence the number of riders shipping their gear boxes to Airhead gurus for the expensive $$$ rebuilds.

[DamanC]

To make things a little weirder I can shift down to first and all the way up to 5th but only with the engine on and the clutch midway released.  I cannot go through any gears clutch mid-released or closed when the engine is off...hmm.

[montmil]

To make things a little weirder I can shift down to first and all the way up to 5th but only with the engine on and the clutch midway released.  I cannot go through any gears clutch mid-released or closed when the engine is off...hmm.

Confirm your clutch cable is properly adjusted. For the Airhead, cable adjustment begins at the transmission's clutch push rod. The last adjustment is done at the handlebar.

With the engine shut down, you should not expect to be able to run up and down through the gears... not without rolling the bike back and forth a bit.

Please explain "clutch mid-released or closed". :-?

Monte

[Air4Life]

At first I thought, change the oil and ride it up at cruise speed for a good while -then again, maybe not.  Is there a particular speed or gear that would provide optimal circulation of the oil in the gearbox?