Rear Drive Bearing Cup-Grease Cup Purpose?

[Orange Guzzi]

I was replacing the bearings in the rear drive in my 2003 spoke wheel California.  The parts list, list all 4 wheel bearing as the same part number.  The bearing in the rear drive side has a larger o.d. inner bearing race, same i.d. and o.d. as the other 3 bearings.  It is a 2rs/double rubber sealed bearing. Has a SKF 6204/2rs on the markings.  But different type inner race???  The parts list a "grease seal cup/retainer" pn17633550, that goes  on the inside of the gear drive housing spacer prior to inserting the bearing,  pn 92204220. 

Other than keeping the bearing from fully seating and setting the proper stack height of the bearings and inner spacer tube, why is there a grease cup?  The bearings are double sealed.  I was thinking about leaving the grease cup out and putting a shim in it's place to get the correct stack height.  The cup is very thin sheet metal stamping. The grease cup/retainer does not work properly on the pn92294229 bearing with the smaller o.d. inner race.  It presses the inner flange into the grease seal. 

Another delay in sending the hubs off to be laced up to new aluminum wheels.   

[Kiwi_Roy]

I am having trouble visualizing the bearing seal.
The bearing in the rear drive side has a larger o.d. inner bearing race, same i.d. and o.d. as the other 3 bearings.
Is it possible it's different because it's been replaced before?

Can you post a link to the drawing.

I do know the 2RS bearings are not very well sealed, I had a policy of changing them with a new set of tires, especially on the front wheel where I had one spit out the balls.
If the seal is on the outside exposed to the weather I would keep it even if you have to use the old one.
But if it's protected from the elements and you think its interfering with the bearing then its your call.

Is it possible the seal is from an earlier design with just 1 RS?

[guzzisteve]

I have a cush drive hub that has had 4 bearing swaps and is .007" bigger than stock and needs swapping out. I'm not going to try matching it to a bearing. Never seen a grease cup in the wheel, could be your spacer and rings that go on it.

[Orange Guzzi]

The bearing has never been removed/changed.  I was reassembling another rear hub I am going to have rebuilt with new spokes and aluminum rims.  When I installed the new bearing and attached the brake rotor carrier with the left hand bearing installed, the spacer tube interfered with the brake rotor hub seating against the spoke hub.  I did not look closely at the parts assembly list and see the "retainer/grease cup and put the bearing  in the right side without the "retainer/grease cup".   I looked at the assembled rear wheel assembly and the parts drawing, #28 page F11California.  Realized that I left the "retainer/grease cup" out.  The drawing calls out all 4 wheel bearings as the same part number and p/n 24 "retainer"/grease cup installed on the right rear.  I took the wheel assembly I am replacing apart and found that the bearing is labeled 6204 2 rs SKF, but different from the other three wheel bearings. 

M.G list two bearings for the same application?  Suggesting that one grease seal should be removed if the the "retainer" is used.
http://www.mgcycle.com/index.php?main_page=product_info&cPath=218&products_id=2442
http://www.mgcycle.com/index.php?main_page=product_info&cPath=218&products_id=1428

The rear drive side has a part number 24  17633550 "Retainer"
http://www.mgcycle.com/index.php?main_page=product_info&cPath=218&products_id=2912

The  "retainer/grease seal does not work on a 6204 2rs bearing because the inner race o.d. is too small.  causing the "retainer/grease seal to sit on top of the grease seal.  This makes me think three things.  One, remove one grease seal if using the retainer. Or two, do not use the retainer and replace it with a shim washer and leave the grease seal on both sides of the 6204 2rs bearing.  Three, use the alternative bearing as listed on MG site with the "retainer/grease cup".   

I know I am not the first to replace rear wheel bearings.  Whats the best approach option 1,2 or 3?

[Kiwi_Roy]

I wouldn't expect the cup seal to work with a bearing, I don't think there are dimension specs for that part of the bearings, more likely to work with a machined spacer.

You might be better to leave it out since the bearing is already sealed.
Perhaps remove the centre out of it so it still acts as the packing spacer for the bearing outer race.

I'm not a mechanic though so don't take my word for it LOL

[Wayne Orwig]

 


I can't visualize what you are saying. The two rear bearings are the same,

Here is a photo of mine from where a bearing failed during a long trip. Both bearings are 6204 2RS.

[Orange Guzzi]

Wayne, the pieces you are referring to tha go around the spacer tube are not installed on my assembly. I have seen these on spacer tubes in other motorcycle wheels though.

  The "grease cup" I am referring too is available on the MGCycle website. http://www.mgcycle.com/index.php?main_page=product_info&cPath=218&products_id=2912  It sits inside of the steel tube with the snap ring that is installed into the aluminum hub.  It drops in before the bearing is installed.

Without this grease cup, the spacer tube would have to be shortened and the bearing would move to the left side because it is seated deeper into the hub,  causing the gearbox not to seat properly against the bearing because the bearing has been moved further to the left/deeper. 

http://www.skf.com/us/products/bearings-units-housings/ball-bearings/deep-groove-ball-bearings/deep-groove-ball-bearings/index.html?designation=W%206204-2RS1

Dimension "Da" and "D1" is the referenced dimension that is larger on the installed 6204-2rs1 bearing.    This allows for the "grease cup" to seat around the inner race rather than on top of the grease seal on the smaller inner race bearings.   

I looked at various 6204 bearings, the "Da" dimension varies based on the second set of numbers.  From 41.4mm to 42 mm.  And the D1 dimension varies from 26.3 mm to 29.5 mm. 

 

[Orange Guzzi]

Fixed it.  Dropped two 2mm thick x 45 mm shim washers under the bearing before insert.  Exact stack height/fitment.    Obviously I have a parts bin bike in more ways than one.  Makes me wonder how many people have changed out the bearing and did not put the grease cup in causing the bearing to be side loaded and failing.  Or thought it was the washer that went around the spacer tube and put it in the wrong place. 

[Tom H]

Interesting.

Here is Harpers page for the rear wheel you may have if I picked the correct Stone.

http://www.harpermoto.com/parts-by-motorcycle/2000-up-moto-guzzi-motorcycles/california-stone-1100-2001-2002/rear-wheel-en-california-stone-1100-2001-2002.html

Tom

[Kiwi_Roy]

It looks as though the cup 24 rides on the spacer 4

it's hard to see why it's needed though.

[Orange Guzzi]

It looks as though the cup 24 rides on the spacer 4

it's hard to see why it's needed though.

No.  It sits inside the the steel tube mounted in the aluminum hub and with the open side facing the bearing.  The I.D. is to large to do any good if it was placed around the spacer tube also.    Raising the bearing 4 mm from the bottom of the steel tube in the aluminum center  hub.  Giving the correct stack dimension when the brake carrier with the bearing is attached to the left side of the center aluminum hub, spacer tube installed between the left and right bearing.  With out the cup, the space tube is 4 mm to long and the brake carrier will not seat against the center hub without pushing the bearing back out on the right side and causing a side load.

 I took my wheel apart and that is how it was assembled at the factory.  It did not have the ring/rings around the spacer tube. The parts drawing for my model does not show the rings around the spacer tube.   It did have the grease cup and bearing on the right side with double grease sealed bearings.  The bearing on the right side has a different part number electro engraved on it with a different inner race than the other three bearings. 

It is odd that the "factory" would use the grease cup seal as a shim.  I found two 2 mm x 45 mm shim washers in my box of stuff and it worked out perfect.   McMaster Carr sells a pack of 10 for cheap also.   The grease cup is thin and could easily cause the bearing to be improperly installed and cause a side load. 

There is no mention of this in Guzziology. 

http://www.mgcycle.com/index.php?main_page=product_info&cPath=218&products_id=2912