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Rear Wheel Bearing Check


Lockguy

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2004, R1150RT, 50K miles

In doing my maintenance, with bike on centerstand and rear wheel off ground, I give the rear wheel a twist top to bottom and front to back. I get a very, very small movement. I can't see it move but I can feel it. What is too much? If someone could direct me to a thread discussing this, I would appreciate it. My searches haven't revealed anything for me. Thanks

 

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Morning Lockguy

 

First, be darn sure your movement isn’t in the swing arm or final drive pivot bearings (just a little movement here can feel like it’s in the crown bearing). Maybe see if you can feel any movement between the rear brake rotor & the caliper mounting bracket.

 

On the rear movement you can feel?

 

There is a spec on the rear crown bearing but it is all preload (no movement) that preload is (0.0020”...0.0039”). Now that doesn’t mean if you have a little movement it will soon fail. I have seen quite a few live a long life with just a little movement. If you have a bike that was originally set to the min spec of .002”, with some miles it can easily get to the point of a bit of bearing movement. My BMW manual doesn’t give a max play spec just the set-up spec.

 

With a bit of movement in the crown bearing it might be a good idea to keep a close eye on it. Maybe do more frequent final drive oil gear changes looking closely at the magnet to see if any SHARP metallic residue shows up on that. Also strain the removed gear oil through a coffee filter or clean paper towel then take the filter out in the sun to look for shinny particles in the filter.

 

A good rule to use is change the final drive fluid at every engine oil change.

 

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I have a little movement in mine at 6 and 12 "O" Clock positions. It is more noticeable when cold and tightens up after the drive is warm. Since I take the bike on the road trips the rear drive gets an oil change at every 6k miles and also just before a trip of 1k+ miles just to check the magnet. I wash the magnet carefully using a light brush and gasoline. The silver bearing race flakes you are watching for can be below the the "black mush" attached to the magnet. I speak from the unfortunate experience of being stranded 200 miles from home.

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Thanks guys for the info. I have checked more closely and determined that the movement I am detecting is in the swing arm. Now to investigate the effects of this. I too change all fluids at every engine oil change. As I drain the FD this time, I will do the straining and inspect for the chrome particles. Thanks again for your help.

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Peter Parts

Worth a few dollars to buy a dial test indicator and magnetic base (using a giant allen key) to separate FD bearing from Paralever bearing movement. Movement shows up a lot faster that way and you can keep track of it numerically. Esp. after a snug-up of new or old bearings.

 

I find sticking my thumb into gaps tells me a whole lot more about movement and locus than grossly grabbing the wheel at 3 and 9.

 

Yes, I change FD and transm. oil from time to time but can't think of a good reason why. Just wears out the delicate plug threads that are never loose enough to avoid stripping or tight enough to hold reliably... yup, that's what I think after 45 years with these boxers. Always use new crushable washers.

 

Ben

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OK, me again. I was glad to come to the conclusion that the slight movement I was feeling was in the swing arm pivot bearing. Then I drained the final drive. I found what seems to be very small chrome chips on the perimiter of the drain plug. Is there a way to tell if this came from the crown bearing? Is there a way to be sure it is chrome chips? Do I remove the final drive and have it rebuilt? I have a 2.000+ mile trip planned the 3rd week of August and want no problems on the road. Of course I could just take my Suzuki WeeStrom and bag the RT for this trip. Any consultation would be appreciated.

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Grab a partner to help you check. As stated, wedge your fingers into the gaps all around between the wheel and the final drive and have your second grab the tire and try to move it both ways. There should be (virtually) no perceptible movement there. If that checks out, then I wouldn't hesitate to take the bike on an extended trip despite what you describe seeing on the drain plug. :thumbsup:

 

 

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Morning Lockguy

 

That is one big advantage to changing your final drive oil often, it allows you to find problems while they are still small & before they strand you out on the road in BFE somewhere.

 

I hope you still have that gunk from the drain plug. If so just rub it between your index finger & thumb. If it is sharp (or draws blood) then you probably have something terminal going on inside your final drive (probably crown bearing ball separator starting to fail or bearing races pitting)

 

If the gunk is just soft & smooth feeling that is pretty normal & as a rule nothing at all to worry about.

 

Did you strain the removed gear oil through a filter of some sort? If so what showed up?

 

A very good rule of thumb when it comes to that final drive & possible bearing problems is to take it apart for inspection (or have it done).

 

For just a crown bearing-- personally I never even remove the final drive from the bike. Just remove the final drive cover bolts, then remove the cover (ring gear + carrier & all) , then heat & remove the bearing off the spool.

 

At this time just clean the bearing of oil then use a lighted magnifying glass for a thorough bearing inspection.

 

You can also look around in the final drive housing for more chunks of bearing flakes or other debris that have settled to the bottom or into the crevices of the housing.

 

If the original bearing is still good then no shimming required so it’s just a simple reassembly. If the bearing is starting to go out then it will require a precision measurement & re-shimming. Not at all difficult to do yourself but it does take some experience & some measuring tools.

 

If you at all suspect your crown bearing it might be best to replace it (or have it replaced) otherwise your trip will not be as pleasant as it could be as you continually worry about that bearing as your ride along.

 

Just a simple crown bearing replacement is no big deal at all, it’s when the bearing completely fails & you ride for a while contaminating the pinion bearings that it becomes a big (and expensive) deal.

 

 

 

If you at all suspect that your crown bearing is starting to flake & choose to take your trip anyway at least purchase a new bearing & seal to take with you (or have at someone’s house to overnight it to you). About any auto repair or motorcycle shop can install a new bearing (if you have one to install). They might not be able to shim it correctly but the factory shim will be close enough to complete your trip without issue then shim it correctly when you get home.

 

 

 

 

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OK the final, for now, saga of my rear wheel movement situation.

 

I checked out the chrome looking chips on the drain plug and got no cuts or sharp feeling. I also strained the drained fluid through a coffee filter and found no additional chrome looking material.

 

I had my son help be with checking for any wheel to swing arm movement with the "fingers in cracks" method and found none.

 

I rigged a measuring divice by C clamping a flat piece of metal to the final drive to swing arm mounting bolt and past centerline of the wheel with a finger over to just clear the FD housing. I found that I do have a .1 to .13mm movement. I am assuming that this is in the pivot bearing.

 

With all this, I am comfortable with buttoning it up and going for a long ride. Obviously, I will keep a close eye on the situation.

 

You guys are extremely helpful to me as you always have been. I got my bike in the fall of 2007 and after reading a LOT on this forum, got up the nerve to take a 7K mile trip around the US. What a blast for an Old Fart!! Thanks again.

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