Rear Sprocket Carrier Bearing Failure

[glitch_oz]

Slowly getting a complete set of BMW GS wheels together for the Strada (where'd I be without Ebay and PayPal??), I wanted to make things as easy as possible for a quick and clean swap without unbolting bits off one wheel-set to use on the other.

The last bit missing was a rear sprocket carrier and we've all heard the stories and seen the pics of shredded bearings, ground to mush on a Sunday ride.


The carrier is from an '06 GS Dakar with under 20.000km on the clock.
The part shows a different manufacturer (TOMOS is a Slovenian mob making parts for BMW amongst other things), but the same part number as the Husky unit.

Inside surfaces showing friction-wear, indicating worn cush-rubbers helped along by a sloppy outer bearing, allowing too much free-play and "sprocket-skewing" during acceleration.

SKF-Explorers made in France aren't too bad....but there's a reason BMW stipulates new bearings+cush rubbers to be installed as a set on the F+G singles!!

Standard BMW F/G-series stack of 30x40x7mm seal----6204 bearing----spacer+ C-clip-----6204 bearing

You guessed it...the outer bearing after the seal's removed...yuck!!

One out...one to go. No surprise this thing was on the way out....

Let's start with some fresh stuff then...off to the bearing-shop on Monday for some
better stuff.
Anyone got a decent source for the 3 cush drive rubbers?

 

[drzcharlie]

Glitch et al,

I've got a question. Admittedly, I have never removed bearings good or bad from moto wheels. Since these are held in place by cir-clips is it still necessary to drive them out afthe cir-clip is removed. Additionally, I am wondering what exact bearings you would use on the stock wheels.

Our interchange list shows (rear wheel): 2-SKD 6203 & 2-SKD #6204 presumably inside and outside bearings? Also, 2-30 X 40 X 7 MM bearing seals. First is this accurate? I have replaced other bearings but not sure about removal and replacement on these wheels.

Thanks all, for helping out old geezer.

 

[Baddrapp]

One question for the bearing experts. What is the best or easiest bearing puller to use?

 

[duibhceK]

Our interchange list shows (rear wheel): 2-SKD 6203 & 2-SKD #6204 presumably inside and outside bearings?

2x 6203 for the wheel 2x 6204 for the sprocket carrier

One question for the bearing experts. What is the best or easiest bearing puller to use?

Whichever one you choose, you'll be cursing
I used a set like this:

But this type will work just as well:

 

[glitch_oz]

Glitch et al,

I've got a question. Admittedly, I have never removed bearings good or bad from moto wheels. Since these are held in place by cir-clips is it still necessary to drive them out afthe cir-clip is removed. Additionally, I am wondering what exact bearings you would use on the stock wheels.

Our interchange list shows (rear wheel): 2-SKD 6203 & 2-SKD #6204 presumably inside and outside bearings? Also, 2-30 X 40 X 7 MM bearing seals. First is this accurate? I have replaced other bearings but not sure about removal and replacement on these wheels.

Thanks all, for helping out old geezer.

Hi Charlie

In the sprocket carrier, the inner (towards the hub) bearing is just a straight tap-out job. Initially I used a small tire-iron with a bent tip to gain purchase on the edge of the inner bearing race.
A couple of good, solid taps, turn 180deg, another few taps, swap tyre-iron for an old, sharp-bladed screwdriver...keep tapping and turning until the bearing drops out.
That exposes an alum spacer ring and the C-clip. The spacer is loose, the C-slip needs to be removed in order to knock out the swingarm-side bearing. And yes, it also has to be tapped out through the double-depth seat after removal of the first bearing.


Both front and rear wheels of ALL TR's (and suitable F+G series BMW wheels) use a pair of 6203 each....the sprocket carrier uses a pair of 6204 (same for any suitable F+G series BMW parts).
ALL TR's (and suitable F+G series BMW wheels) use a single 25x40x7mm seal at the front....and a 30x40x7mm seal at the rear wheel, as well as another one of the same dimensions in the sprocket carrier.

A complete shopping list for wheelbearings and seals incl. the sprocket carrier for ANY TR looks like this:

4x 6203
2x 6204
1x seal 25x40x7
2x seal 30x40x7


And thankfully none of it is proprietary stuff, all are bog-standard generic parts used in millions of applications from washing machines to golf-carts and available from any bearing-shop on the planet.

 

[glitch_oz]

One question for the bearing experts. What is the best or easiest bearing puller to use?

Whichever one you choose, you'll be cursing

 

[MotocycleWriter]

I just picked up a set of real nice Strada wheels. I bet I should put in some decent bearings before I mount them...

 

[engineerk9]

Hi Charlie

In the sprocket carrier, the inner (towards the hub) bearing is just a straight tap-out job. Initially I used a small tire-iron with a bent tip to gain purchase on the edge of the inner bearing race.
A couple of good, solid taps, turn 180deg, another few taps, swap tyre-iron for an old, sharp-bladed screwdriver...keep tapping and turning until the bearing drops out.
That exposes an alum spacer ring and the C-clip. The spacer is loose, the C-slip needs to be removed in order to knock out the swingarm-side bearing. And yes, it also has to be tapped out through the double-depth seat after removal of the first bearing.


Both front and rear wheels of ALL TR's (and suitable F+G series BMW wheels) use a pair of 6203 each....the sprocket carrier uses a pair of 6204 (same for any suitable F+G series BMW parts).
ALL TR's (and suitable F+G series BMW wheels) use a single 25x40x7mm seal at the front....and a 30x40x7mm seal at the rear wheel, as well as another one of the same dimensions in the sprocket carrier.

A complete shopping list for wheelbearings and seals incl. the sprocket carrier for ANY TR looks like this:

4x 6203
2x 6204
1x seal 25x40x7
2x seal 30x40x7


And thankfully none of it is proprietary stuff, all are bog-standard generic parts used in millions of applications from washing machines to golf-carts and available from any bearing-shop on the planet.

When I renewed my bearings I used better quality Niachi, I removed the inner seal from each then filled the void space between the bearings with grease, the intention being to extend bearing life

 

[drzcharlie]

Thanks guys. When I got the wheels off I was pleased to find that the bearings are in great shape. I just packed them as best I could and put new seals back in. But, I now have the bearings I need to replace them if necessary.