Final Drive Project, Help Needed

Ahvitved

Joined
Aug 8, 2010
Messages
11
Location
Cresco, IA
Bike
1993
Hey everyone, new to the site and have read through everything, but am in a time crunch to order parts so I thought I woul throw out this post while I search for answers. I was replacing the final drive gears on my 93 St when I ran into something not covered in the manual and just doesn't seem right. The pictures below show the back side of the old drive flange. The shiney spots are where the heads of the bolts holding the dampener plate wore into the flange. The mushroom heads of the bolts are worn to an angle and the plate has wear spots as well. The manual just shows a washer between the hub post and drive flange, but the new flange doesn't even make contact with the hub post since it doesnt have spots rubbed into it. Is this common and anyway to fix it?
Thanks

 
Hard to tell from the straight-on photo of the hub, but it looks like the bearing is sitting proud to the hub when it should be completely flush. This indicates that the hub around the bearing has been worn down, allowing the old flange to run closer to the damper plate assembly than it should. This worn down hub is the reason your new flange doesn't contact it.

Was the thrust washer missing when you disassembled it? I imagine it was ground into oblivion by all that apparent movement.

The dampers and inserts don't look too worn, is that how you found them or are those new?

Lots of final drive problems with the ST1100's are due to spline wear from lubrication and misalignment issues of the final drive assembly. What kind of shape are the splines on the old flange in?
 
Yeah, funny you should ask, cause lack of lubrication from previous owner is the reason we are digging into this project in the first place. Below is a picture of the old splines vs. the new ones. You'll notice that you can see where the flange started to wear down in the spline damage. The top of the splines don't show as much damage as the bottom. What I believe is the washer was there, it's so thin that it doesn't contact the hub and the flange at the same time. The new flange rests on top of the damper holder bolt heads, a good 1/8th of an inch above the hub. Is the flange supposed to set on the hub, or is there something behinde the rubber dampers that the five posts set on? We haven't touched the dampers so to the best of my knowledge there original.

 
Hey Hawkeye, what would be the harm with using more washers to shim the difference? Just not to spec or is there safety concerns?
 
hawkeyeST said:
Your wheel is shot. The bearing should not protrude like that. Seen this many times. You can try to make up the difference by adding more thrust washer(s) but I wouldn't recommend it.
Click to expand...


I'm going to go out and limb and ask, is it the wheel or simply the final driven flange and damper holder and bolts that are shot? Probably the rubber as well.

Is the flange supposed to sit against the damper holder or are the pins supposed to sit against the wheel and space it out slightly which would more than likely mean the wheel is shot?
 
Ahvitved said:
Yeah, funny you should ask, cause lack of lubrication from previous owner is the reason we are digging into this project in the first place. Below is a picture of the old splines vs. the new ones. You'll notice that you can see where the flange started to wear down in the spline damage. The top of the splines don't show as much damage as the bottom. What I believe is the washer was there, it's so thin that it doesn't contact the hub and the flange at the same time. The new flange rests on top of the damper holder bolt heads, a good 1/8th of an inch above the hub. Is the flange supposed to set on the hub, or is there something behinde the rubber dampers that the five posts set on? We haven't touched the dampers so to the best of my knowledge there original.

Click to expand...

This shot shows how the driven flange has been operating less than fully seated into the final drive splines. The flange has moved to the left (as mounted on the bike), away from the final drive and closer to the wheel. I'd be surprised if the final drive splines weren't trashed too.

The flange is supposed to rest on the thrust washer, which in turn rests on the wheel boss where the bearing is located.
 
Final Drive splines are shot, replaced both final drive gears and flange. From the sounds of things I may be on the line for a whole new rim as well. Any way to fix the wheel boss wear without replacing the entire wheel?
 
There was a thread here where someone welded on and then machined down that hub and saved a wheel. Unless you can find a shop willing to do this pretty cheap, you're probably better off with a used wheel from ebay or a dismantler.
 
I talked to my mechanic friend and we are going to try and machine our own thrust washer on his mill that will fit the worn hub boss. The only issue that I have is getting a measurement of what a the height of the hub boss should be. If too tall it could cause the splines to bind and if too short it could cause lash in the splines. Anyone know what the height under/over the hub boss should be from the bearing?
 

Here's a pic of the hub boss and bearing from the side to give you a view of what kind of wear has happened. The only issue is I don't know what it's supposed to look like.
 
I bet you could get most your money out of the splines you have if you got that wheel. I thought about it just to be able to have a tire ready to swap out to. Pretty good deal for a complete wheel with disk. I would buy the ABS ring from you.
 
I'm not opposed to getting the new tire except for the fact that my rims are silver and that one is gold. I don't see a major issue of using a shim on the hub since it would basically be a non moving part. My main concern is how it got that worn in the first place. The dampers appear to be in good shape.
 
Also, check if you have a distance collar on the inside of the hub, looking at how much the bearing sticks out, this is missing or you wouldnt have got the wheel in. its about 4 in long with a slight taper on the inside.

(the drive hub not the wheel hub)
 
You want to elaborate on that one a little Jonorow. I dont think the bearing is sticking out, I believe the hub boss is worn down around it. The distance from bearing to distance collar should be the same as normal, unless I'm not seeing it right, which is probly the case. I think the distance collar is there. Parts should be in tonight so I will be working on it in the shop after work. Any idea what caused the hub boss wear?
 
Just reassembled the final drive. Had to wait almost two weeks for new shims to get the correct backlash in the drive. Apparently the 1.91 was mailed from Japan. Aligned the rear tire as suggested by everyone. Unfortunately, it started raining so I couldn't test it out tonight.
 
Yeah, I considered going the ebay route, but I got a discounted rate on the gears w/ free labor so it wasn't bad. It wasn't $85 bucks, but it was a definite discount. Not sure how well it will work until I get a good ride in. When aligning the tire to the final drive by loosening the four shaft bolts, is that process necessary every time you remove the rear wheel? and totally skipped by the photos, wife put me under a time crunch.
 
So Rob, want to sell that final drive you scored?;)

My splines have been showing some wear for a long time, but I just pulled the wheel for a tire change and they are really looking bad now. I think the problem was I ran the bike for a long time without doing the alignment procedure (loosening the four forward case nuts then retightening with the wheel torqued down). Did it at about 50,000 miles and the splines started showing less evidence of heat than they did before that, but some of the damage was done. I'm at 76,000 miles now.

It looks like a major PITA to replace the driven gear in the case - special tools, gear alingment shims, bleah. What's the easiest and most cost effective way to get this done? I see I can get the whole unit new for about 1200 bucks:eek:

(Rob, will you be at FOF? I'm going for the first time since '02:D I'm gonna slather the splines with Moly 60 and hope for the best...)
 
I busted up my bad right shoulder - again - out in Moab back in April. It's healed OK (still sucks), but I gave up serious dirt/trail riding. Sold my KLX250S and KDX200 and bought a '09 Triumph Bonneville. Kept the KLR for easy gravel road stuff and of course the ST. Focusing on street riding more these days.

I saw a couple of drives on eBay but they are '91 and it's hard to confirm the condition. One guy has questionable feedback. Just have to keep looking.
 
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