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Belt slipping off

3K views 28 replies 8 participants last post by  rodzghost 
#1 ·
I went to check my belt today and noticed that it's slipping off and rubbing against the plastic belt guard. I tried adjusting the tension tonight to see if it would improve things, but it didn't work. After tightening it up and pushing the belt back towards the wheel, it will work itself back towards the plastic guard and start rubbing again after just a few rotations. It sometimes make a squeeking noise as well. Also, the eccentric hub has a bit of side-to-side play to it. Is this a sign I need to replace the rubber cush drives inside?

On top of that, it seems the wheel itself has some side-to-side play. Does that mean my wheel bearings are going bad?

I was hoping to swap the belt myself, but I'm thinking I might just take it in to a dealer instead now.

Any advice on where to go from here?
 
#2 ·
Belt slipping off to me sounds like the rear pulley isn't aligned paralell to the front pulley, and you're saying there is sid-to-side play in the rear wheel too, so the axle - which holds the rear pully too - not being exactly perpendicular to the swingarm is probably causing the belt issue too is my guess.

No expert on the rear axle bearings, maybe look at getting a new S or ST eccentric & shaft assy from a wrecker?
 
#4 ·
call your BMW dealer & give him your VIN number.
I think 2006-2009? ST & S rear wheel bearings will be replaced no cost to you under a recall IF the bike hasn’t already been inspected under the recall.
If your bike rear wheel bearing has already been inspected by BMW under the recall & was found to be OK, I think you are now on your own, BMW has washed their hands of you.
LOTS of info on the forum, dig around.
And call your BMW dealer.
 
#5 ·
The belt tracking towards the outside on the rear pulley was one of the symptoms I saw when my rear hub bearings failed. (2013 F800GT) I also had saw that the tire was intermittently rubbing on the inside of the swingarm. Look for a polished spot in the road grim on the inside of swingarm. I tried to torque and wobble the wheel by hand but couldn't really feel or see much, but obviously it was flexing when under load and while riding. When I removed the rear pulley and took the eccentric hub out of the swingarm clamp, I saw a rusty color fluid stain all around on the inside surfaces. I believe my bearing seals failed and I got water into the bearings and diluted the grease. When i got the bearings out, I cut them apart to inspect and found the race and bearings were grooved and scared. Once I put new bearings in and reinstalled the hub, the belt track back towards the inside stop on the pulley and 5,000 miles since with no problems. I've don't pressure washed my bike, but have rode numerous long distances in the rain. Probably poor quality seals on the bearing and I unfortunately got them on my bike. Another thing, take the belt off and remove your brake caliper. On the center stand rotate the wheel back and forth slowly. I noticed more grinding and vibration doing this than just spinning the wheel. In the fine direction change is where I could feel the bearing slop. Good luck, just a couple things to try. Oh ya, my F800GT had 27,000 miles when I had this issue. Seems all good now.
 
#6 ·
Wow, thanks for the detailed post. The way you describe the wheel movement is almost exactly what I'm seeing. Mine barely moves, so I was thinking maybe it was all in my head. I did notice some small, circular grease spots on the inside of my rim, that might indicate the bearing seals have failed. Is the rear bearing hard to get to/replace? I'm hoping not as I've already put close to $300 worth of repairs/tools into the bike this past week alone. I swear everything seemed snug and tight last time I looked it over, and all of these issues are just coming up at the same time.

And now that I'm looking at the other threads on rear bearing failure, it's looking more and more similar to what I'm seeing. I also started hearing the squeaks and couldn't quite pinpoint their source. When I saw the belt rubbing against the guard, I figured maybe it was from that. They started about a week or 2 ago. I'll admit my sense of time has gotten really bad as I've gotten older, so it *could* have been longer....

If it is the bearings, I'm hoping the driveshaft is ok, as that would really hurt my pocket.
 
#10 ·
Yeah, my bad. It's the input shaft where the bearing is pressed into. Just waiting on my 46mm socket to get here so I can get to it.

Small consolation, but if it is destroyed, at least it's easy to replace. It will just cost me around $1000 US for the repair kit. Or I could try snag a used one for $350 and pray it had the recall done on it.
 
#11 ·
Rod. Buying used is risky. I know, I've been down that path. No guarantee that the bearing in it is good, or perhaps near the end of its life. Replacing the roller bearing (on the disc brake end of the axle), which is the one usually needing to be replaced (the other end uses a needle roller bearing and I've not heard/read of this one failing), is fairly easy if you have reasonable home work shop. There are a number of previous posts on the forum on how to do it. If not, any local car/bike shop should be able to remove it and press on a new one for you at little cost. The bearing itself costs about $30 and and is readily available. Much cheaper than going the other routes.
 
#12 ·
Thanks for the warning. I haven't taken apart the other side of mine yet, but here's some video and a pic of what I'm seeing on mine. The last pic is of a used one which has the green stuff covering the bearings.

Would mine be an example of a failed needle bearing?

Click link for video.

Little bit of rust here, it looks like.

Used part.

I'll try to see if I can find a shop that will replace the bearing(s) for me. I'm leaning towards just biting the bullet and getting a new one, but really want to avoid that if at all possible.

Also, is the pic of the used one above an example of the latest revision? (Not sure if it's even possible to tell just from that one angle.)

Thanks for all the help and suggestions everyone. It really helps take the sting out of this whole process.
 
#13 ·
Cool, you got it out. Since my closest BMW dealer is 4 hours away and the shop I bought my bike from is 5 hours away, here's what I did. I bought the 3 bearings(parts) from the dealer and they agreed to ship them and the BMW replacement procedure to me and i did the work myself with a good engine mechanic looking over my shoulder. I think the parts cost me $220, which I know was premium, but I wanted to be certain they were BMW correct and not a cross matched version from NAPA. I think they quoted me $200 labor if I had them do it, but the distance away was a problem. I was a little nervous trying it, but having a good work space, the correct cool tools and the drawings / procedure helped a bunch. I don't feel bad for paying up on the parts, this bike hasn't cost me anything but tires, gas and oil for a ton of fun. GOOD LUCK
 
#16 ·
Would you happen to still have the part numbers for those bearings? Max BMW only shows the full "repair kit" which is over $1000 after taxes for me. I'd like to try bringing these to a shop (MotoGuild) to do something similar and have a mechanic watch me do the repair myself.
 
#14 ·
The rear hub assembly is the same for the ST/S & the GT, no?
Was this revised at some point?
BMW must have started sourcing different bearings or an installation procedure (hence the recall of early ST & S) but for me it’s kinda murky here.
Thanks Rod & XR1000 for the pics & info.
BTW 46 socket is same size as 1-13/16 socket if this helps.
I might be inclined to buy a used hub Assembly off of a wrecked bike & take a chance if it was me.
I have replaced failed parts with used parts in the past, so far (knock wood) they’ve all worked fine.
Of course YMMV
 
#17 ·
Folks. BMW changed the specs on the ST/S axle/bearing assembly from about 2007. The tolerances on those earlier ones were too lax and in some cases allowed the roller bearing to spin on the axle shaft. They also had some rather suspect bearings. Hence the recall on those models. BMW has made it easy to determine which axle is which. See the attached photo. Font Circle Auto part Illustration Drawing
 
#18 ·
I found the packing slip, pretty sure these are the actual BMW part numbers. Bearings-33177658575,33117660003,33358526136, Shaft seal-33358526137. I replaced all 3 bearings just to safe. Riding home from northern Alberta with failing hub bearings is not a trip I care to experience again.
Good Luck.
 
#19 ·
XR1000, thanks for the part numbers.

Redned (or anyone else), not sure if my part is the "repairable" version or not from the pic in the recall notice. I'm leaning towards no, but can't be 100% sure. Here's a pic of mine:



I'm curious if the recall only addressed the bearings, or if they also changed out the whole input shaft and axle assembly as well? Anyone got pics of a 2008+ or repaired version?
 
#22 ·
Just got a call from my dealer asking for video of the play in the axle. I'm hoping I get some good news today. Either way, I'll be replacing parts since in the course of taking it all apart, I found other things that needed replacing.

I knew this hobby would be expensive, just wasn't expecting it to be quite this bad.
 
#23 ·
Rod. Looking at the pic you posted, it appears a little different to the ones I have (and the pics I posted). I have both the later ST version and the latest GT one. Neither have the splines on the axle at the wheel mount end. I'm guessing this must be a very early one. Someone may correct me on this.
 
#25 ·
Well, bad news from the dealer. They're saying since it was inspected 4 years ago, combined with the high mileage on the bike, that they won't be covering it. Plus side is I've found a few potential used ones from F8GT's that are the "updated" versions. And, in case anyone is wondering, the above pics are the older style.

Here's a pic of the updated one:

Rim Automotive tire Nickel Bicycle part Jewellery


Kinda hard to see, but it has those 3 "rings" from the sketch. That example is from another bike with a failed bearing.
 
#26 ·
Rod. Yep, your last pic of the old style ones is the same as the older ST one I have. Also, just because it is the updated version with the three "rings" is no guarantee that the bearing won't fail. I know because I've had one do so. The roller bearing is a commonly available one ( fitted to many vehicle air con units), and many bearing manufacturers make them. BMW source their bearing from various companies (probably whoever gives the lowest price). This can lead to a bad batch of bearings being fitted. Not blaming BMW, most manufacturers of anything do the same.
 
#27 ·
Oh, no doubt about that. But the shaft was updated along with the bearings. So my plan was to get the updated shaft and also put new bearings on it. I'd also check that the axle is straight. My dealer doesn't seem to want to sell me the bearings alone, so I'll be looking for replacements elsewhere. Would you happen to know the part number for them by any chance?
 
#28 ·
Rod. I usually replace the roller bearing with an NSK 6559469. However, Timkin, Nachi, SKF and others have equivalents. Steer clear of cheap Chinese copies. I have never needed to change the needle roller bearing as they were always in good condition. I have never heard or read of one failing although it's possible. If you do change it (the needle bearing), be aware that it is different for ST axles and GT axles (although the eccentric/axle as a complete assembly is interchangeable). The English site Motorworks has the info on their site as well as selling individual bearings and sleeves. As you are in America this may prove a bit more expensive than sourcing the bearings locally. Hope all this helps.
 
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