New Cush Drive - Ohhh What a Feeling!

[robkc]

Wow what a difference a new cush drive makes on a 21 year old bike. So much smoother and a more solid feeling. What I originally thought was kind of a clunky clutch feeling is totally gone. Glad I took the time to pull the plate and check the rubbers out while I was putting a new tire on.

BTW, appeared that PO's or their maintenance tech had never realized there was a o-ring between driven flange and hub or that this area needed grease occasionally. :censored Area is Pic #2 on Mike Martins maintenance info Elusive 3rd O-ring. That #2 o-ring was worn flush with the hub material and melted into the old grease in the groove for it. It took a lot of scraping to clean out all the gunk. Fortunately the hub face did not appear worn or scored where the thrust washer mates to it.

What a relief to have such great resources here and on ST-riders.net to get me through these headaches.


Next up on my list of ToDo's for this neglected girl will be flushing the fork oil and replace with 10wt. Maybe new springs and a rear shock this winter if that doesn't firm it up enough. Also need to source a cheap 40 amp alternator and GL1500 wheel.

That'll have to wait till another rainy day though because I need to get out there and ride.

 

[robkc]

I just put a new final drive on my 93. I too was impressed at the changes. No one should "know the feeling" of a failing final drive. But it looks like both of us now know that feeling.

I hope you changed the entire FD assembly and not just the cush drive.

You have a red 91? Custom paint job?

Whoops I goofed up. She is younger Karen, it's a Candy Glory Red '92. :

Why entire final drive? My only has 52,000 miles and I think I caught the lack of grease issue early enough between hub and final drive surface. It looked like the splined areas of the final drive had been greased with each tire change although probably not Moly 60. I could not detect any wear on the splines. There was very minimal wear on the pins that go into cush drive.

 

[robkc]

Agreed yours definitely needed replacing. My splines in the final drive and driven flange both looked virtually new as the PO was having grease applied to them at each tire change. However, the back side of the driven flange with the posts that go into cush drive is where grease was lacking. Nothing other than original factory grease where the thrust washer meets the wheel hub and dry as a bone. :-(

 

[Mark]

Karen,
With only 50k on the drive there might be very little wear on both sides of drive (flange and spline).
I'd suggest staying on top of those o-rings with the moly 60 from now on though!

 

[robkc]

They wear together. I have never heard of one wearing and not the other. I hope someone else will chime in here to back me up.

I suspect you are just not seeing the wear on the FD side and that you will need to replace both it and the cush drive again very soon. As the cush drive will have so much room inside the FD, it to wear them both out quickly. Not sure how much riding you do, but I doubt that new cush drive will last 10K miles unless you replace the FD.

Karen,

I believe you are misunderstanding the difference between cush drive, final drive, and final drive flange.

The final drive is the female splined part in your picture #1.
The final driven flange is the male splined part in your picture #2.
You are correct in that these final drive parts must be replaced as a pair.

The cush drive is under the plate that the pins on the back side of final driven flange (pic #2) go into towards the wheel hub. There are five pieces of rubber with aluminum inserts for those pins that cushion the shock of gear changes from final drive to the wheel so that the aluminum wheel hub is not torn up. Two of my five 20 year old rubbers fell out when I pulled the plate. All of the holes in the aluminum inserts were oval and loose in the rubbers.

If you have never pulled that plate and inspected them then the worn rubber inserts might be the cause of the accelerated wear on the last final drive you installed.

HTH,
Rob