V7 drive shaft spline alignment/wear issue: advice needed

[rocker59]

 
Some shaft drive motorcycles (second generation Suzuki GS shaft drive models starting with the GS650G, IIRC) had spring loaded ramps and cams incorporated into their driveshafts to cushion shock loads.

I suspect they were effective.

You are right.  Smaller pistons means smaller shock loads.

Shirley, it is no more difficult to incorporate cushions into the rear hub of a shaft drive bike that it is to do the same on a chain drive bike.

Do no shaft drive models do this?

Google "Guzzi Cush Drive".  Most Guzzis over the past few decades have had cush drive in the bevel box.  Rubber pie-shaped blocks that cushion the drive line.

https://www.thisoldtractor.com/guzzitech.dk/pdf/cush-drive-maintenance.pdf

https://www.mgcycle.com/index.php?main_page=product_info&products_id=4831&gQT=2

The only ones I'm aware of without cush drive, over the past 30 years, have been the Daytona 1000 and the Sport 1100 carb models.

[Moparnut72]

My 1970 R75/5 was just a few thousand miles short of 100K when I upgraded to an R90/6. Absolutely no driveshaft issues. The seal on the final drive seeped fluid into the shaft housing very early and fixed under warranty. To be fair it was one of the very first off the line so teething issues were to be expected. Granted the bike had a few short comings but were addressed in later versions but overall was an excellent bike especially compared to the rest of the market in 1970.
kk

[lewisham_phil]

My biggest issue here is not so much the rust and water ingress, but the poor alignment of the front of the splined sleeve. It really should be 5mm longer to avoid partial engagement on the shaft.
 The best I can do I think is move the sleeve forward as far as possible, and thanks to the wear evident currently, I can reasonably accurately determine how much I need to adjust the sleeve position: Currently the rear of the splined sleeve is showing 3.8mm clean metal before the output splines engage; On the input side to the sleeve, the drive splines on the drive shaft are currently engaging by 6.5mm only.
So I plan on inserting a 2mm spacer on the output side of the splined sleeve which will sit up against the back of the circlip: This will push the sleeve forward by 2mm, plus circlip thickness of 1.2mm, for a total of 3.2mm (I haven't got the pieces to hand, but I believe the rear splined collar is chamfered, and normally butts up against the backside of the metal disc rather than the circlip, hence my allowing for the extra 1.2mm for the circlip).
This should give much better engagement of the drive shaft (if not ideal), while still giving full engagement of the output splines.
 I need to double-check all this, but either way, I think I'll assemble everything, but before I put the wheel and suspension on, I'll move the swing arm to it's extreme positions and check nothing is binding or bottoming out.
The splines where worn have reduced by about 25% of their original thickness, so there is a reasonable slop evident. I'm aware also that by altering the depth of engagement using these same parts I'll then be putting the load through localised points which will cause high local wear... so I've decided to swap them all out - I have found some spares on Ebay, and from Gutsibits at a decent price (all in for under £100 for drive shaft with only 8,000 miles, sleeve and collar..), so I'll see how they fare.

[John A]

I thought there was a spring on that coupler but my only experience is on an early V65 last century….

[Dirk_S]

I thought there was a spring on that coupler but my only experience is on an early V65 last century….

There be. Final drive to coupler and spring plate to spring to driveshaft.

[lewisham_phil]

Just to say that everything went together fine; I'm glad I decided to replace the worn parts - seeing them back to back with the old parts, and feeling the difference in the fit (no slop at all..), it was clearly worthwhile.  GutsiBits here in the UK supplied the used  splined socket and sleeve, both in excellent condition. Adding the 2mm washer behind the circlip seems to run fine: There was certainly no discernible binding or resistance in the drive without wheel attached.

[Perazzimx14]

I don't think drive shaft life span is expressly referenced in any of the Owner's Manuals or Service Manuals.  I think it is like the clutch---you are supposed to know the clutch will eventually wear out, but who knows exactly when that will occur.

BWM does reference this change interval in a service bulletin watercooled 1200/1250 series bikes and offers free lifetime replacment (parts and labor) at 36,000 miles intervals.

BMW does reference this change interval on the 1300 series bikes, parts and labor are excluded.

Several years ago when BMW 1st offered the replacments on the 1200/1250 they reduced the price of the "prop shaft" from over $1,200 to $242. On the 1300's I believe th eprice of th edriveshaft is still over $1000. The price for oilcooled 1200's is $1,200.

For me if my 2024 GSA  ever reaches 36,000 miles I'll probably just spend the $242 and replace the DL myslef instead of wasting a day riding to and from the dealership and lingering around the shop for a couple hours while they do the swap. If its like other service notices BMW should reimburse me for parts??

[Kiwi_Roy]

A Newbie reading this thread would come away totally confused, the replies are all over the map.

Roy