Rebuilding final drive on ST1300

Has anyone rebuilt a final drive? Does it take special tools like the manual says? Can one make do?

I have two or three posts describing the clunk in my bike. Short story, it began with a clunk as I let out the clutch when shifting from 4th to 5th, then whenever shifting up from any gear. Now I can get the clank after slowing to enter a curve when I increase the throttle to exit the curve (even with no braking beyond engine brake). This progression has unfolded over about 4 to 5,000 miles (the bike has less than 30K on the clock)*. As I said in other posts, my mechanic heard the clunk with his stethoscope at the final drive and suggested it might be the splined drive shaft or U-joint. I pulled the pumpkin, checked everything visually, and re moly-ed the splines. U-j felt fine. No difference in noise after reassembling the bike.

Kevin - the mechanic - pulled the final drive and says there is excessive play between the pinion and drive gear but they show no excessive wear patterns. Splines look fine, U-J shows no excessive play. He does not have the special tools to rebuild the unit, and a dealership has quoted in the 5 to $600. So, I found a final drive on e-bay and will see if this gamble will pay off. I don't want extended down time on the bike now, but I might rebuild my final drive if possible in the next year or so.


*And yes, I know this part never goes bad this young - but then, the maladies I suffered on two Econolines "never happen to Fords" either.

It may only be a u-joint.. which several here, including myself, have had to replace.

Here's a video on what mine sounded like:
[video=youtube;otnNHbI-EiM]http://www.youtube.com/watch?v=otnNHbI-EiM[/video]

Definitity check the u joint before changing out the pumpkin, eBay has them or pick one up new.
The only reason I would think there would be problems with the final drive was it ran low on gear oil.

How does the gear oil look. When I bought my used ST1300, I had to do a few flushes though-out the years to get the silvery metal floating around in the gear oil out. Nice and clean after the flushes.

E bay is your friend you can buy them sometimes for less than 50 bucks.

before you condemn the final drive, is there any thing out of specs like backlash. That measurement should be done. In my experience with auto differentials excessive backlash (that was not there before) would be caused by something worn. Now that pinion depth has changed there would also be a whine from the drive unit either on acceleration of deceleration. My concern is that if it was the drive unit why does it not clunk in 1st or 2nd gears?? If it had excessive play it should have a clunk all the time. Have you checked the swing arm bearings? That could possibly explain the noise on turns ?? I'm not really sure but to me it does not sound like a drive unit.

I bet your bike is and has been normal in all respects.

Can you arrange to swap bikes with another ST owner?

dduelin said:

I bet your bike is and has been normal in all respects.

Can you arrange to swap bikes with another ST owner?

Click to expand...

Well, the cheapest option seems to be to just swap the final drive with a cheap one from ebay. I know that's a gamble, but pulling the swingarm to change the UJ would be almost as much in sturm un drang as swapping final drives. I'll update this after I do that. And at that point I'll definitely know a whole lot more.

Mellow said:

It may only be a u-joint.. which several here, including myself, have had to replace.

Here's a video on what mine sounded like:
[video=youtube;otnNHbI-EiM]http://www.youtube.com/watch?v=otnNHbI-EiM[/video]

Click to expand...

My final drive/UJ sounds dead silent when the rear wheel is rotated by hand. The clunk appears only under these circumstances: shifting up and letting out the clutch or braking (either engine or brakes) for a curve followed by accelerating. And, while it is most noticeable on curves, it also happens on straightaways if I use engine braking and then accelerate.