Rear Gear box rebuild-which needle bearing type?

[John Croucher]

Does the rear gearbox needle bearing use an inner race?  I found the correct size comes with and without the inner race.  The parts book does not show an inner race and Guzziology does not specify.  40mm 55 mm 17mm skf nao list both types with the same dimensions.

I am rebuilding the gearbox on the 2000 Quota.  After finding all the other bearings in poor condition from a life time in Florida sand and silt.  The input pinion taper bearing failed and I  replaced them.  Then big seal leaks, due to my own fault in installation.  I figure if I am going to do this repair over, I should do the whole gearbox.  Worst part is getting the cover off.  Guzziology say's to push it out from the inside the front opening with the pinion housing out.  Any other suggestions on popping the cover off?

[guzzisteve]

Yes, it has inner race goes on the hub, it has a couple slots to get off w/puller.  Have never used them, just chill hub & heat race w/torch or heat gun.

Oh yea, cover---   easiest what you say, otherwise thread 2 holes on cover only to use puller.

[Antietam Classic Cycle]

Does the rear gearbox needle bearing use an inner race?  I found the correct size comes with and without the inner race.  The parts book does not show an inner race and Guzziology does not specify.  40mm 55 mm 17mm skf nao list both types with the same dimensions.

I am rebuilding the gearbox on the 2000 Quota.  After finding all the other bearings in poor condition from a life time in Florida sand and silt.  The input pinion taper bearing failed and I  replaced them.  Then big seal leaks, due to my own fault in installation.  I figure if I am going to do this repair over, I should do the whole gearbox.  Worst part is getting the cover off.  Guzziology say's to push it out from the inside the front opening with the pinion housing out.  Any other suggestions on popping the cover off?

I just ordered this one for a Jackal I working on.
https://www.ebay.com/itm/165712097538
I've bought them on Amazon before as well.

To remove the cover I use my small three-legged puller with the legs reversed so that the tips point outward. I hook the tips under the splines, center arbor against the axle spacer. Fiddly but works every time.

[n3303j]

Been running moly additive in that final drive?

If so then its another data point of moly wiping out roller bearings, both conventional and taper.

BMW never ran additives in their final drives (airhead series) and they lasted forever.

[John Croucher]

I just ordered this one for a Jackal I working on.
https://www.ebay.com/itm/165712097538
I've bought them on Amazon before as well.

To remove the cover I use my small three-legged puller with the legs reversed so that the tips point outward. I hook the tips under the splines, center arbor against the axle spacer. Fiddly but works every time.

Found all the bearings and seals on Amazon.  $93.00 delivered.

Read somewhere to drop a socket into the hub for the puller screw to push against. 

[Antietam Classic Cycle]

Found all the bearings and seals on Amazon.  $93.00 delivered.

Read somewhere to drop a socket into the hub for the puller screw to push against.

Yes, a socket works too. I'd already removed the spacer on this Jackal rear drive, so used a deep-well 21 mm socket for the puller screw to push against. The bonus was that the socket helped hold the puller legs out as well.

[Willy59]

Sugestion ,in order to remove the end-gear-cover,
Maybe heating up a little (+/- 100 to 150 °C)this aluminium cover with an hot-air-föhn ?
Success willy59

[n3303j]

On my '77 T3 the final drive cover came off THE GASKET with little persuasion required. Re-use of the gasket allowed me to skip shimming the gears.

On my '98 V11EV the final drive cover was bonded and sealed with some (factory) green product that was hard as epoxy. It required using serious persuasion to break the cover loose. Then a lot of time in clean up. I used gaskets to re-establish the seal. This required re-shimming the gear set. Fun way to eat up a day.

[Antietam Classic Cycle]

The 2000 Jackal rear drive I'm resealing now has gaskets and so did the '98 EV rear drive I did a few months ago. Never found one that just had sealer.

[n3303j]

The 2000 Jackal rear drive I'm resealing now has gaskets and so did the '98 EV rear drive I did a few months ago. Never found one that just had sealer.

Not only sealer on the '98 V11 but the big metal shim in the picture set between layers of the sealer. Really nasty way to do things. I'd like to think mine was a "one off" and the production run was gasketed.

[John Croucher]

In the process of reassembly of the gear box, I checked the stack height of the ring shaft spacing between the needle bearing race face when seated in the housing and the roller bearing.  The .050" thick spacer and two gaskets will allow the pinion gear to float end to end .050.   Which means the ring gear can be pushed away from the pinion gear when the shaft floats.  I could see on the ring gear shaft that it had been moving on the shaft and the inner race was turning.

Are there thinner shim's?  Two paper gaskets are .007 think. Which should be enough clearance with out the shim.

Any thoughts. 

[John A]

https://www.thisoldtractor.com/guzzitech.dk/gb_en_complex-technical_bevel-box.htm
This may help

[John Croucher]

https://www.thisoldtractor.com/guzzitech.dk/gb_en_complex-technical_bevel-box.htm
This may help

Had this part figured out.  But, the shim allows clearance on the sides of the big bearing and floating of the rotating shaft. 

If the big bearing is seated fully in the cover, the inner race does not seat against the shaft flange on the opposite side. It has .050 inch clearance. Allowing the shaft with the crown gear to push away from the pinion gear as it is pushed through the inner bearing race toward the cover side. Increasing clearance.   

Assembly with out the .050 inch shim worked with no binding. 

Using shims in the cover to get a good fit does not sound right.  The rotating shaft has a brass/bronze bushing on one end and nothing to stop the shaft from moving toward the cover Except the inner race seated against the shaft shoulder and outer race seated in the cover.  The this can create side loading problem on the big bearing if not enough shim is used and flight if two thick a shim is used.

I think the cover, big bearing clearance and no end play should be done first.  Then shim the pinion in or out. 

[n3303j]

The final drive gears have to be shimmed to get the proper contact pattern between the teeth on the ring gear and pinion.
The ring gear is pushed into the large bearing in the housing cover by its interaction with the tooth form of the pinion. That large ball bearing is carrying both a radial and a thrust load.

It is not unusual to set the ring gear position by adding multiple cover gaskets or by adding a shim behind the outer race of the big bearing. As far as clearance between the outboard end of the ring gear support bearing is concerned it is important that there is some so the big bearing is not preloaded by lack of clearance. In use the ring gear will always be thrust against the big bearing. So that is where clearance is set for the ring gear.

Properly setting up a final drive is a somewhat long, trial and error process.



png pictures

Put Prussian Blue on a section of ring gear and spin pinion through it a couple of ring gear rotations in each direction under a slight load. Then inspect the transfer pattern. Adjust gears until the pattern is correct. Then ride 100,000 trouble free miles (no moly).

[Wayne Orwig]

If the big bearing is seated fully in the cover, the inner race does not seat against the shaft flange on the opposite side. It has .050 inch clearance. Allowing the shaft with the crown gear to push away from the pinion gear as it is pushed through the inner bearing race toward the cover side. Increasing clearance.   

I'm not sure what you mean. The crown wheel assembly floats in the big bearing. You need to 'load' it away from the pinion gear when you check the clearance and alignment.

[n3303j]

You are correct that you should load the crown wheel away from the pinion when checking contact patch. But you don't want to introduce a preload on the big bearing when it is in service.

I'm also used to finding the big bearing being an intimate fit on the ring gear and in the housing cover. None of the assembly is floating.

[John Croucher]

You are correct that you should load the crown wheel away from the pinion when checking contact patch. But you don't want to introduce a preload on the big bearing when it is in service.

I'm also used to finding the big bearing being an intimate fit on the ring gear and in the housing cover. None of the assembly is floating.

Remove the pinion gear, drop the crown gear mounted to the shaft into the needle bearing.  It comes to rest on the brass thrust bearing. 

If the crown gear mounted to the shaft is installed with the roller bearing seated on the shaft shoulder face and fully seated in the cover, the opposite end will not be touching the brass thrust bearing (on my gear box) .o52 inch. With the two paper gaskets and .050 shim. 

If the roller bearing is installed in the cover first, crown gear and shaft dropped into the needle bearing and resting on the thrust bearing, Cover with bearing installed on crown gear shaft, there is .052 clearance between the inner roller bearing race and the shaft shoulder face on the crown wheel shaft when the cover is installed. With the two paper gaskets and .050 shim 

The crown gear shaft has to be sandwiched between the brass washer and the inner race of the roller bearing seated on the crown wheel shaft shoulder face with some amount of clearance and no side loading.  .052 seems a little excessive with the shim installed. 

The procedure of installing the pinion and then raising or lowering the crown wheel with shims (and adjusting the pinion) raises or lowers the crown wheel shaft off or onto the thrust washer.  Allowing the shaft to float if the clearance is excessive.  To me, it looks like it is a combination of adding or removing brass thrust washers on the needle bearing end and shims in the cover to get proper positioning on the crown wheel and pinion and to make up for the end play of the crown gear shaft.

If there is clearance between the end of the crown wheel shaft and the brass bushing, the crown gear will be using the pinion gear as a stop instead of the brass bushing at the end. 

 Installing the big bearing in the cover fully seated, the big bearing on the crown wheel shaft fully seated.  When the cover with the crown wheel is installed  using 2 paper gaskets to get .0025 end clearance between the thrust washer and the crown wheel shaft end.  Recheck the pinion to crown wheel fit.  A paper gasket is .0075 thick.  If I only use two, I get .0025 clearance between the end of the shaft and bushing. Since the crown wheel is pushed toward the big roller bearing under load, this small amount clearance should no allow excessive pressure on the pinion and crown gear if the shaft moves toward the thrust washer when not under a load. 

The brass thrust bearing is there to stop the crown gear and the pinion gears from being too tight or loose. The two gears are not suppose to be the side thrust stop when meshed. The inner race on the big gear and the thrust ring are.

[Antietam Classic Cycle]

The "brass thrust bearing" is only there for the roller needle cage, nothing else. If you add more than the original one, the outer race will be protruding from the housing.

I'm puzzled as to what you're trying to fix. Assembled the way they come from the factory, a properly shimmed and maintained rear drive will last 200k miles or more.

[n3303j]

John changed all the bearings so I'm sure alignment has changed too.

[John Croucher]

The "brass thrust bearing" is only there for the roller needle cage, nothing else. If you add more than the original one, the outer race will be protruding from the housing.

I'm puzzled as to what you're trying to fix. Assembled the way they come from the factory, a properly shimmed and maintained rear drive will last 200k miles or more.

The stack height between the thrust washer and the seat of the flange cover.  With out the gasket and .050 inch shim the height is .025 inch to tight.  The cover will not seat against the housing.
 Adding the two caskets and shim is .027 clearance. 

This allows the crown gear move .027 inch away from the pinion gear. Creating slack or clearance between the pinion and crown gear.   Using 4 gaskets is .030 or .005 inch clearance. 

If the big bearing is installed fully seated in the cover and the crown gear fully seated in the big bearing inner race, the shaft sits .025 inch off the brass washer.  Then if the pinion gear is adjusted, the pinion an crown mesh too tight if the shaft moves toward the brass washer. I checked to see if this happens by changing the shims in the pinion bearing housing.  Moving the pinion gear in and out moved the crown gear and shaft . 025in. Toward or away from the washer or outer cover with two gaskets and .050 shim.

The Stock. 050 shim is not always the correct thickness, in my assembly.

[n3303j]

The important part of this procedure is that the tooth contact pattern is correct, backlash is correct and bearing preload is correct. (All at the same time!)

That's what makes it so much fun

I have done Urals, BMWs and Moto Guzzis. It's the reason I have a 6" X 12" pack of shim stock from .002" to .050". I've gotten reasonably adept at cutting (and finishing) shims for each possible position.

This is not the job for someone who doesn't understand the total relationship of that type of gear tooth form. It is not the task for someone without a fair amount of patience. Your personal safety is dependent upon the unit being correctly set.

[Wayne Orwig]

The brass thrust bearing is there to stop the crown gear and the pinion gears from being too tight or loose. The two gears are not suppose to be the side thrust stop when meshed. The inner race on the big gear and the thrust ring are.

Yes, the gears are the side thrust, loading the crown out into the big bearing. The brass washer doesn't do anything for alignment. Ignore it.

Got the tooth contact right with it against the big bearing, and you are done.