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final drive ?


JamesW

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My '04RT has 40K miles and my question is: Do you think it a good idea to remove the rear wheel then pry out the large seal on the FD and inspect the large bearing for signs of wear? Seems like it would be easy to do kind of like a routine maintenance check. I may be getting a bit paranoid from reading all these threads about FD failures when in reality in 8 years and 40K miles about the only thing to really go bad, not counting battery and tires, has been a left side throttle cable. I don't count all the tinkering to compensate for the lean burn of these beasts. In fact that part (tinkering) has been kind of fun and certainly interesting. Oops, hijacked my own thread. :dopeslap:

 

Thanks

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Danny caddyshack Noonan

To inspect the bearings, you'd have to disassemble the bearing and measure the balls.

IMHO, I think just looking at the drain plug and doing a hearing and tactile wiggle check on the FD is about as good as you can get.

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Afternoon James

 

A good thought but probably not very productive. That bearing is recessed quite a ways into the bore under the seal area. You won't be able to see much but the balls themselves. What you really need to view is the bottom of the ball grooves in the inner & outer race & that won't be possible just looking in through the seal area.

 

If the bearing is degraded enough to see any signs of destruction from the seal area you would have a lot of debris in the drained oil & lots of sharp pieces on the magnet.

 

At 40,000 miles on the original bearing personally I would ride it until you get some wheel movement, or something showing on the magnet, or in the strained gear oil. (OR) just pull the side cover then replace the bearing & re-shim as well as inspect the other spool bearing.

 

What I used to do on the 1100/1150 was to change the final drive gear oil at every motor oil change then strain the dropped gear oil through a coffee filter. Then take that coffee filter out in the sun & look for sparkles or flecks of bearing or bearing ball separator.

 

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As usual DR has it right, I would also advise carefully inspecting the drain plug magnet and fluid carefully at each drain interval for any signs of metal flakes (fuzz is OK.) If (or rather when, if you keep the bike long enough) you begin to see them you can then separate the crown bearing and ring gear from the housing (black part and the silver part) and inspect the bearing. This is possible if you completely de-grease the bearing (any oil on the surface will make it impossible to see light damage) and shine a bright light in there and carefully inspect the inner races. You may well see the beginning of some spalling and if so time to replace the bearing. And of course even if not I would still be be very suspect if there were flakes in the drained oil or on the magnet.

 

This is just one of many good reasons to do your own service. A shop will never take the time or care to inspect your bike as well as you will, and as in this example catching a failing bearing early will help insure that you can maintain the final drive on your own schedule vs. having a trip interrupted.

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Thanks guys. I do change the FD oil with every motor oil change but will pay more close attention and strain the FD oil. So far the only thing that has ever shown up on the magnet is just a gray paste which I think is normal gear lapping.

 

I always use 80-90 wt valvoline durablend which is only part synthetic. I really think any name brand GL-5 rated dino oil is fine and only reason to change often is just to look for signs of metal chips.

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What is considered to much play in the rear wheel? Any? On two bikes I have some play. If these are bad I will have now had 5 failures on 6 late model bikes. Eightyfour percent failure rate.

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Check out RealShelby's FD minder. You can easily check your FD status after every ride :) !

 

Phil,

 

Where do we find info on this?

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What is considered to much play in the rear wheel? Any? On two bikes I have some play. If these are bad I will have now had 5 failures on 6 late model bikes. Eightyfour percent failure rate.

 

Morning KDeline

 

 

No BMW posted (max wear limit) spec that I have found. The bearings that control wheel play are set to a PRELOAD as assembled so using that as the spec means any wheel play (in the bearings) is too much.

 

But bearings & races do wear a bit as they get miles on them so if the starting preload was set at the minimum of just under .002" then conceivably they could wear to a "0" preload or even a slight amount of play & still be good.

 

The spool bearings in the 1100/1150 are a tapered roller on the right & that deep groove large diameter ball bearing on the left. The R/H being a tapered roller can run a bit loose without any issues. The deep groove (crown) bearing being a large diameter & deep groove can also run a bit on the loose side without damage as long as the roads are smooth & the bearing doesn't see any sharp force radial or axial inputs that could cause bearing damage.

 

The 1200 hexhead with a similar (but not lubed from the final drive oil) L/H bearing & non tapered needle R/H bearing does allow for a bit of wheel movement (1mm at wheel rim @ under 95°f). In fact the real tight ones as new seem to be the ones that fail.

 

Too much wheel movement on the 1100/1150 is a bad thing but if just a little & no sharp fragments coming out at gear oil change or clinging to the magnet then I wouldn't consider that a failed final drive. But it would be a drive I kept a closer eye on with maybe gear oil changes at every oil change interval.

 

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Be sure that the play is in the hub. It is very common for the two taper bearings between the FD and the shaft tube to wear causing movement of the wheel.

 

Andy

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  • 4 weeks later...

Mine always had just enough play that you could feel a slight movement. If it does the same amount when you rock it side to side when holding it at 6 and 12 oclock positions as it does when you do it at 3 and 9, then it is more final drive play. If it is mostly at 3 and 9 then it is the pivot bearings.

 

I have had my pivot bearings replaced and then started noticing a slight increase many miles later of movement at both 3-9 and 6-12. At the last tire change this was discussed with my mechanic. Peter acknowledged that the time was drawing close to replacing it but not critical. Still it was near enough to make plans for it. He felt it could last another 6-10k but could also fail in another 3. If he had a used one on hand he would use some slow time to rebuild it and then I would merely have mine changed for that one, and give him mine as a future rebuild for another person. Alas he didn't have one to fit the K-RS. I think it is a 33/12. I also would need a new rear rotor at some point soon so figured now was a good a time as any for that change as well. The initial plan was to rebuild my FD and put a new rotor on. In looking around I found a used low mileage unit, with rotor and swing arm. This was for only a bit more than a new rotor will cost. So the plan is to change the FD and rotor out between the originals and these 'previously owned" ones, We will strike up some casual gentlemens understanding about how he might could use/need the old FD and swingarm. He may store them or I may keep them here and he call for them as needed. Anyway, it actually seems to be one of the easier repairs over the last year (bike is being freshened up as it gets near 100k. (last spring, new suspension frt/rr, annual service found needed new distribution rail (crankcase vacuum system), fall alternator fail (only rear absolute failure on the bike) so did clutch, rear main, slave cylinder, starter refurbish). At the moment, the FD/rotor is being changed and new brake lines put on.

So like I said, the FD getting weak at near 100,000 miles is about the same as having to change out front wheel bearings on my car at 100,000. Not cheap but not a horrid expense any.

 

So, get it checked to verify yes it is or isn't the FD bearing starting to fail. Change the fluid to check for any unusual metal bits. If they say it probably is the FD bearing wearing out,And then, if you are worried about it, change it. You don't need to worry that if you take off for a 400 mile ride, 200 miles from any support or dealer that it will fail.

 

You have time to develop viable options.

 

NCS

 

 

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I understand that there is a difference of opinion on this, but if you are getting metal bits on the FD drain plug, then it's time to replace the big bearing in the final drive. Just doing an R&R of the bearing is not that big a job and can be done in your garage. Paul Glaves' opinion is that if you are just replacing the bearing, then the shim preload does not have to be remeasured. Some will disagree on this.

 

I got 90,000 on my FD so I figure the shim was reasonably set; so I just did the bearing R&R with the housing still on the bike. This meant I didn't have to disturb the swing arm pivots which were solid. For me, about $130 in parts and I ended up paying for some dealer shop labor so they could install the new bearing on the crownwheel. I then reinstalled the crownwheel with new bearing back on the bike.

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