Clutch/flywheel - what interchanges 79/80 & 81/85?

[Tony Smith]

Ok

I went for a ride this afternoon..

When i first started the bike there was a strange "rustling" or "whooshing' sound. Not loud but "odd" enough so that I stopped, did a quick check-over and even waved the timing light at it just in case I'd done something  ghastly on the weekend when I did a tune-up.


Didn't find anything amiss and in any event the noise stopped at some point when I was trying to diagnose it - so I set off.

Halfway up the range and the noise was back with a vengeance, much louder and changing pitch and tone - now it sounded for all the world like a ball bearing running dry.

Now it is a bit difficult to find a safe place to turn around on the range so I keep heading up thinking I'd stop at Kuranda, by now the noise was a positive howl. The only thing I could think of was that the crank outrigger bearing had gone bad, which surprised me because I fitted a brand new one and it is a Grade "C" bearing - lots of clearance and should just about last forever in an oil mist such as the inside of the timing chest.

There was a loud metallic "bang" and the noise stopped abruptly, no vibration, no mechanical distress sounds. Did a quick "boot check", no oil on boots, no alternator failure and no oil pressure warning.

Convinced as I was that it was probably the outrigger bearing I pressed on running at 70 ~ 75 mph to Mareeba, running smoothly, in fact the bike felt better than at any time since I got it running.

Reached Mareeba and as I slowed to turn left to Atherton, the howling started again, still no vibration, just a howl at (at that time) any engine speed.

I did a smart U turn and headed back to Cairns at greatly reduced speed - mostly no howling although it came and went, it was particularly loud going down the range  but on the premises that nothing had gone catastrophically "bang" so far I would just ignore the noise and press on for home.

Reached home, shut down, pushed the bike inside, got rid of riding gear and turned the ignition back on and hit the started button to be met by the most horrid grinding, graunching noise and absolutely no sign of the engine turning over.

I pulled the timing bung out and shone my little LED key fob light inside - yep the ring gear is completely free of the clutch carrier and the clutch carrier has neatly machined the ring gear all the way around.

Thank God I didn't stop the engine at Mareeba, I would have had to push start it.


So, now my questions start.

Clutch carrier failure does not seem to be a common occurrence, both the BMWOA forums and Snowbum are silent on the topic. I suspect that the ring gear is riveted to the clutch carrier and that corrosion has done for the rivets - Of course I will know for sure when I pull the trans out later this week.

I have in stock a 1979/1980 "heavy" flywheel and pressure plate. I also have in stock a new clutch plate for the later clutch carrier - I already know that these will not work together.

So a 1979/80 clutch plate is probably a whole lot cheaper than a 1981 -> clutch carrier, so my next question is will the 1979/80 flywheel bolt up to the > 1980 crank (I suspect that it must because I recall that the wife's R65/80 ended up with the 1979 R65 flywheel  when that job was done a couple of decades ago.

2nd last question _ Assuming the early flywheel will bolt up to my crank - is there any difference in the exposed input shaft length of the later gearbox? In other words, can I simply fit the older model flywheel and clutch and be back on the road? i am cautious on this because i remember that the older R65 flywheel was bolted onto the R80 engine, I cannot recall why but i wonder if it was to resolve a mismatch in input shaft length.

Final question.
given that the post 1982 clutch plate is the same for all airheads, that suggests that they all share the same clutch carrier - Do I have to buy an R65 specific clutch carrier or will any post 1981 clutch carrier do the job?

[Tony Smith]

Answer my ow question. I cannot use the early clutch because there is, as i half remembered, a difference in the length of the input shaft.

I could of course fit a post 81 clutch centre to a pre-81 clutch and all would be well, but that would be going just a bit too far.

Anyone got a clutch carrier they want to sell?

[Bob_Roller]

I took a look at a post 09/81 clutch carrier, there are 9 rivets holding the ring gear to the rest of the carrier .

If the ring gear / clutch carrier are in good shape, you may be able to replace the rivets and reuse the assembly .

You'll know for certain when you get this disassembled .

Just did a quick parts search on a BMW parts site and from what I found, the clutch carrier from 09/81, through the end of airhead production in '95, is the same part number for R65, R80 and R100 bikes .

BMW part number : 21211338722 .

[Tony Smith]

I took a look at a post 09/81 clutch carrier, there are 9 rivets holding the ring gear to the rest of the carrier .

If the ring gear / clutch carrier are in good shape, you may be able to replace the rivets and reuse the assembly .

Bob I only count 6 rivets.


I had a bit of a win - Motobins price for a brand new one is GBP123, Motoworks have a 2nd hand one for GBP75.

I was therefore very very happy to find a US seller with a 21-21-1-451-511  (the second last revision in 10/85 for the princely sum of $US50. Best of all the seller is in the eBay postal thingy so all up the new clutch carrier is going to cost me $AU107 delivered.

Going to start pulling the rear end of the R65 out either tonight or tomorrow night, right after I order new flywheel bolts, hub O ring, oil pump o ring and bolts, rear engine seal and gearbox front seal.

[goathands]

Tony,
I just discovered the same issue on my 1983 R65. I had assumed that that starter was the issue, and spent the morning trying to swap starters. Upon removing the old Bosch starter, I found that the ring gear had separated from the clutch carrier. I counted three points of connection between the carrier and the Gear ring (six rivet holes?). Are you planning on replacing the whole carrier or bolting the gear back to the carrier?

I noticed that you can access the rivets through the starter pretty easily. Would it be possible to bolt the ring gear back on to the carrier without having to open the engine rear.

This sounds like a bad Idea right?

Please let me know what you discover.

Thanks,
James

[Tony Smith]

Tony,
I just discovered the same issue on my 1983 R65. I had assumed that that starter was the issue, and spent the morning trying to swap starters. Upon removing the old Bosch starter, I found that the ring gear had separated from the clutch carrier. I counted three points of connection between the carrier and the Gear ring (six rivet holes?). Are you planning on replacing the whole carrier or bolting the gear back to the carrier?

I noticed that you can access the rivets through the starter pretty easily. Would it be possible to bolt the ring gear back on to the carrier without having to open the engine rear.

This sounds like a bad Idea right?  

James

I'll start at the end....


Firstly, my sympathies.

Yes it is a bad idea to even think about using bolts inserted by simply lining up the now vacant holes in the starter cavity  :-)

I would seriously consider re-riveting the ring gear to the carrier if:-

1/. I had it all out of the bike so i could look at it and line it up the same way the factory did for balance reasons.

2/. The holes had not been wallowed out, as it is a no- brainer that at least the last couple to let go will be well wallowed out, figure on re-drilling all holes and then reaming them to a precise size.

3/. I had the time to turn up and harden a dolly and press to form the rivets (you can't buy them, I tried a few years back when i wanted to rivet rather than weld something and nobody has riveting tools anymore.

4/. I could buy the rivets, or buy suitable stock steel (which would then mean having to either make yet more tools to form the initial rivet shape or (more likely) turn rivet blanks from round stock (I should mention at this stage that I have no idea of what properties rivet steel needs to have, but i guess an engineers guide at the Uni library could tell me, and at some point the decision as to whether this would be a cold or hot rivet process would need to be made.

My further reason for not trying to re-rivet is that if the manufacturer thought bolts were appropriate they would have used bolts. Now having said that there are plenty of cases of rivets being successfully replaced by bolts - on my own bikes I have brake discs bolted to carriers and rear wheel drive cups bolted not riveted. But in both cases there was ample "prior art" to verify that bolts in place of rivets would work. Replacing rivets with bolts on the clutch carrier would make you a pioneer - I am generally no in favour of being a pioneer around things that might fly to pieces and hurt me.

And my last reason for neither bolting or riveting a failed carrier - why did it fail in the first place?


Ringwood motorcycles have a 1984 R100 with a complete carrier and clutch. the BM shop in Brisbane has one for $130 + post (and Christoph is a good bloke). After that there is Motobins for a new one or Motorworks.


There is a long (and expensive) list of things you need to do this job properly:-

Essential
5 New flywheel bolts.
6 new Clutch bolts (and star washers)
4 new drive shaft bolts
Molly paste for spline and clutch diaphragm lube

Probably need and a good idea anyway.

Rear Engine oil seal
O ring for intermediate carrier
O ring for oil pump
4 new bolts for oil pump
New clutch plate
Front gearbox seal
Neutral switch (if your existing one is leaking, now is the time to fix it)
Driveshaft boot - the chances of getting a 30 year old boot back on without tearing it are very low.

Tool wise you will need to buy a clutch centering tool (there is a procedure to use the gearbox itself on the web, but I reckon it is a bit rinky-dink. You are also going to have to shorten up the working arm of an 8mm allen key to get at the RHS lower gearbox mounting bolt. Buy a cheapie and cut 3/4" off the other end and weld a washer to the end of it - instant crank blocking tool which you are also going to need.

The reason you need all new bolts is that the originals driveshaft, flywheel and clutch bolts are of the "torque to yield" type and should NEVER be re-used. The oil pump bolts are ordinary hi-tensile bolts, but they are torques well into the upper range for a bolt of that size, replacement is sensible as digging a broken one out from that location would be a bugger.

No matter how good it looks i could not bring myself to re-use a 30 year old clutch plate.


I will put up photos when I do mine, which may be of some assistance to you. My cltuch carrier is about to leave the USA and I ordered everything (except the clutch plate which I already had) yesterday from motobins (with a few service items chucked in, just past $170).

[goathands]

Tony,
Thanks for the Run down. It's very helpful to know what I would be up against.

James

[Tony Smith]

Tony,
Thanks for the Run down. It's very helpful to know what I would be up against.
 

James

I missed the fact that you are in the USA. Monte's favourite eBay seller Lamonsfurd (or something similar) is wrecking his personal R65LS and when I asked last week, he still had the clutch carrier.

[montmil]

Tony,
Thanks for the Run down. It's very helpful to know what I would be up against.

James

I missed the fact that you are in the USA. Monte's favourite eBay seller Lamonsfurd (or something similar) is wrecking his personal R65LS and when I asked last week, he still had the clutch carrier.

<http://stores.ebay.com/lamontsanfurd?_trksid=p2047675.l2563>

Larry Chabira is one cool Austin, Texas character. Bought my '83 R65 from him pretty much sight unseen. Periodically check his site for Airhead treasures. Highly recommended fella. Ask Larry if he's been "meat drunk" lately.  

[goathands]

Thanks Tony,
I'll take a look. at the Clutch assemblies available on Ebay.

James