R65 blown clutch??

[Rob Frankham]

I'm sorry to say this but I am fairly sure simple clutch slip would not cause the symptoms you experienced. My first though was gearbox input shaft splines but I see that these are fine so I am left with the conviction that it must be something internal to the gearbox. The fact that it ocurs in all gears suggests that the issue isn't with the gear change mechanism or the mainshaft and countershaft clusters so I would guess at a failure in the input shaft to countershaft gearing or the input shaft shock absorber mechanism. I hope I'm wrong but I've experienced enough slipping clutches for various reasons and on various vehicles to know that it normally doesn't come with an audible accompaniment such as you describe.

By all means put the gearbox back in to check if the symptoms have gone away but don't be surprised if they haven't...

The next move, to my mind, will be to drain the gearbox and see if there is any debris attached to the magnetic drain plug (always assuming there is one fitted) or in the oil that comes out. If there is, game over... the box needs to be stripped down and repaired.

Of course, this assumes you are sure that the noise comes from the gearbox in the first place. While you have the bike apart, it is well worth checking the splines and shock absorber at the final drive end of the drive shaft as well as that the final drive itself is working smoothly.

Sorry for the Jonah mode post but I do think it's a bit unrealistic to see the symptoms you report as simple clutch slippage.

Rob

[gspd]

I hope I'm wrong but I've experienced enough slipping clutches for various reasons and on various vehicles to know that it normally doesn't come with an audible accompaniment such as you describe.

+1
Typically a slipping clutch caused by wear or oil contamination won't be 'noisy'.

i've never personally heard what a slipping clutch caused by loose bolts sounds like.
Maybe the bolts holding the flywheel to the crank are also loose?
That combination could possibly explain both the slipping AND the noise.

Just wondering....Is this bike's 14K original miles a certified fact, or is it simply based on the odometer reading?
Could it be 114K? or 214K? or more?
MANY airheads have been lovingly and repeatedly ridden around the (speedo) clock with very little apparent wear (or no evidence at all) to prove it.

[Rob Frankham]

I would suggest that a clutch where the attachment bolts were so loose as to cause the sort of noise mentioned would have no drive at all...

Rob

[enigmaT120]

It was easy when my clutch went out at maybe 25,000 miles... when I got the bike home and opened up, the clutch friction disks had turned into a rat's nest. They don't last forever even sitting. Especially in western Oregon. I had that happen to a car of mine too, an '89 CRX, and had no warning. I was driving and it went pffttt..... Sucks.

[jjkklm1010]

Well after meticulously tearing the old r65 down I have rulled out everything but the transmission. My best "not a transmission expert" guess is a failure with the input shaft spring.

Still runs great, but I can't throttle down at all without losing all power to wheels. Shifts much smoother after lubing the splines and adjusting the cable. Still can shift easily through all gears. Transmission oil was clear of any debris, zero metal noted after draining.

Not sure if a transmission teardown is worth it or just looking for a used transmission is the better option? Am I missing anything?

[gspd]

Well after meticulously tearing the old r65 down I have rulled out everything but the transmission. My best "not a transmission expert" guess is a failure with the input shaft spring.

Still runs great, but I can't throttle down at all without losing all power to wheels. Shifts much smoother after lubing the splines and adjusting the cable. Still can shift easily through all gears. Transmission oil was clear of any debris, zero metal noted after draining.

Not sure if a transmission teardown is worth it or just looking for a used transmission is the better option? Am I missing anything?

Sounds like that could be your problem.
I've never personally experienced the effects of a input shaft spring failure.(very, very rare)
Some adjacent parts are no longer available from BMW but the spring is (for under $20).
If you're lucky all you need is a spring and a gasket and a few hours labour.
A relatively easy fix.
Where are you located?

I have a used input shaft, unfortunately it's not for a r65.

[Rob Frankham]

Post in error...

[Rob Frankham]

I have a used input shaft, unfortunately it's not for a r65.

The gearbox on a R65 is the same as that fitted to all contemporary models. Unfortunately, not all transmissions fitted to R65s are the same. If that shaft comes from a comtemporary transmission, it will work. Dofferences are in the pitch of the primary drive gear and the length of the clutch spline on the nose of the shaft. If the gearbox is fitted with a kickstart, there will also be a matchiong gear on this shaft..

Rob

[gspd]

I have a used input shaft, unfortunately it's not for a r65.

The gearbox on a R65 is the same as that fitted to all contemporary models. Unfortunately, not all transmissions fitted to R65s are the same. If that shaft comes from a comtemporary transmission, it will work. Dofferences are in the pitch of the primary drive gear and the length of the clutch spline on the nose of the shaft. If the gearbox is fitted with a kickstart, there will also be a matchiong gear on this shaft..

I stand corrected.
I should have said "unfortunately it won't work in jjkklm1010's 1979 r65"
Thank you.

BTW - I think in Europe 'gearbox' means just the outer casing and 'transmission' means its internal parts.
In America, the two terms are pretty much synonymous and interchangeable.

[Rob Frankham]

In the UK at least, the whole assembly is commonly referred to as the gearbox. The casing is (unsurprisingly) the gearbox casing. Transmission is traditionally used to refer to the whole system of transferring power from the engine to the rear wheel, including the clutch, the gearbox, the driveshaft and the rear drive (in relation to airheads... would include the chain and sprockets on other machines) although this is gradually changing under the influence of language drift caused by exposure to US usage.

Rob