V11 bevelbox, (Again!)

[pete roper]

I'll try & post some pics here.

 

Ok heres another (I hope)

 

Now that I've gotten the thing out on the table, does anyone have some advice on how to get the pinion nut off? It has an indentation in it to hold it tight I suppose. I've tried to pry it loose with a very small screwdriver, but no luck. I'm not going to try & force it either. Although since I'm wanting to have a new gear made, I doubt that damaging the old one will matter much.

 

Sacrifice trhe nut and grind it off.

 

Incidentally that is the sort of damage that occurs if the driveshaft isn't aligned. WAs yours prior to the failure?

 

Pete

[richard100t]

Yeah it was aligned. I revved the bike up, dumped the clutch & presto! No wheelie, no black stripe just a snapped very expensive & hard to replace gear. Needless to say I dont even pretend to try & burn rubber or pull wheelies anymore.

[pasotibbs]

Yeah it was aligned. I revved the bike up, dumped the clutch & presto! No wheelie, no black stripe just a snapped very expensive & hard to replace gear. Needless to say I dont even pretend to try & burn rubber or pull wheelies anymore.

I'm at the same point as you are now, as Pete says grinding the nut off would seem to be the only way to go,

I've reassembled my drive and put it back on the bike to try and loosen the nut but the torque is too much for the rear brake and it just laughs at my airgun

Good luck

[richard100t]

Ok I've grinded the nut off as per Pete Ropers instructions. Unfortunately the seal underneath the nut got sacrificed in the doing. Also I nicked the large bearing under that pretty good too. But all in all its off. The end of the gear seems to have all the dimensions printed on it anyway so I probably didnt need to take the whole assembly apart except to salvage the bearings maybe?

[Paul Minnaert]

They are made in couple, not sold seperate. That has a reason. I think some italian matches couples that fit best toghther. Hard to do in a one off.

[richard100t]

They are made in couple, not sold seperate. That has a reason. I think some italian matches couples that fit best toghther. Hard to do in a one off.

I remember well you telling me this when the problem first happened & you are right about what you say. The dollar amount that the couple cost was too high so I bought an entire used rear drive instead. What I am doing right now is just stripping the gear down to bare so that I can take it & its mating gear to a local shop to see what it would cost to have a duplicate made. If it can be made at a low enough cost I'll have it done & sell the other rear drive to someone here who may need one. If the cost is too high, well then I'm not out any extra money just for checking.

[mike wilson]

If you can find someone who will do that for a reasonable price, I want their name and address.

[richard100t]

If you can find someone who will do that for a reasonable price, I want their name and address.

Well I'm pretty sure that if I can get 5 to 10 people to team up maybe I could get a discount. I havent checked into it yet but if anyone would be interested pm me or post it here.

[big J]

I remember well you telling me this when the problem first happened & you are right about what you say. The dollar amount that the couple cost was too high so I bought an entire used rear drive instead. What I am doing right now is just stripping the gear down to bare so that I can take it & its mating gear to a local shop to see what it would cost to have a duplicate made. If it can be made at a low enough cost I'll have it done & sell the other rear drive to someone here who may need one. If the cost is too high, well then I'm not out any extra money just for checking.

 

Usually when gears are made in the hobbing machine,the ring gear and pinion are machined at the same time to ensure that the tooth profile matches across the face of the tooth.I'd imagine that you'd have a fair degree of difficulty trying to match a tooth profile on a single gear. I'm not saying it would be impossible,just bloody difficult.

 

Saying that,how accurate would the Guzzi machining be?

 

Good luck

[rossoandy]

Usually when gears are made in the hobbing machine,the ring gear and pinion are machined at the same time to ensure that the tooth profile matches across the face of the tooth.I'd imagine that you'd have a fair degree of difficulty trying to match a tooth profile on a single gear. I'm not saying it would be impossible,just bloody difficult.

 

Saying that,how accurate would the Guzzi machining be?

 

Good luck

hmmmmmm. I thought a hobbing machine made biscuits!!

 

Hobnobs!!!

 

Seriously though these parts are indeed a matched pair and I would be surprised if a replacment pinion could be made to a satisfactory std and cost.

[chaterlea25]

HI All,

I have undertaken to replace the seals in the 2003 V11 final drive box that is talked about in the thread by Gino.

The vent cap was blocked and a fast run from Cork in Ireland to Scotland forced oil past the inner seal!!

I stripped the bevel box without much bother, and found it was neccessary to remove the inner needle roller bearing to change the inner seal, so I heated the housing with a hot air gun (out of gas again) for about 5 or more min, I would have rather got it a bit hotter as a test spit was only simmering not bouncing!!!!!!!!!!!!

I used a soclet that would just fit into the axle needle roller bearing (inner race removed) and a gentle tap pushed washer seal and bearing out without damage.

I find pullers will normally pinch the outer ends of a needle rollerbearing rendering it useless

 

I was then checking out the condition of the parts when I noticed the pinion shaft had play???????

The housing was still hot to the touch, as it cooled the play decreased, but there is still some there when cold

I then joined this forum to try and find out what the **%% is going on!!!!

No REAL answers though, only blaming Luigi

My experiences in setting up automotive pinion bearings is that the normal taper roller bearings are pre loaded by either shimming or a crushable sleeve and measuring the torque required to turn the pinion

Split race bearings used in car wheel bearings are usually torqued to a very high setting (up to 350lbft)

There is no way that the thread in the Guzzy final drive housing will take a high torque value like that!!!!!

 

So here is my theorie of whats happening!!!

As the alloy casing heat cycles during use the alloy relaxes and the factory preload is lost

OR the alloy expands and allows the bearing to move further in to the housing as others have suggested (doubtful)

Looking at the photos here it appears that this bearing has a split inner and outer races?????

The high torque applied at the factory on the pinion shaft nut is evident, Hence the reason that people are resorting to

cutting off the nut??????

So how tight should the outer sleeve nut be??????????????

 

I have two thoughts!!! (for what their worth)

 

1, Heat up the housing to around 40-50 degrees C, then tighten the sleeve until there is no play, let it cool and check how tight it is.

the alloy contracting should not damage the steel bearing.

 

2, preload the sleeve cold, measure the pitch of the sleeve thread, divide by 360, this will give a value of distance by degree turned

select a preload value???? For example 0.10 mm

Screw in the sleeve nut until just tight and then the calculated number of degrees to apply the preload

and again check how tight it is!

 

What do you all think?

The Manual is useless in this respect and not a patch on the Guzzi Factory Manual I have for the old T3's etc

 

Best Regards

John O R

[Gino Rondelli]

John, hope its fixed now, hopfully see Kevin in May back over in Scotland for the Guzzi Rally.

[andy york]

I'm at the same point as you are now, as Pete says grinding the nut off would seem to be the only way to go,

I've reassembled my drive and put it back on the bike to try and loosen the nut but the torque is too much for the rear brake and it just laughs at my airgun

Good luck

 

Anyone needing to remove the pinion nut would be wise to do so before the box is disassembled.

ie...remove the rear wheel and the bevel box and the driveshaft.....then reassemble the rear wheel

and bevel box.

This way you can have a large human sit on the bike and use the rear brake ...while someone else with

a breaker bar and a really long (just long will do) cheater bar...or a piece of wood through the wheel spoke.

If you use an air gun a- it wont work and b- you end up hammering the ring and pinion teeth against each

other.

good luck to all

andy

[docc]

Oh, I'd grind a nut of for you guys, sure I would . . .

[mike wilson]

So here is my theorie of whats happening!!!

As the alloy casing heat cycles during use the alloy relaxes and the factory preload is lost

OR the alloy expands and allows the bearing to move further in to the housing as others have suggested (doubtful)

Looking at the photos here it appears that this bearing has a split inner and outer races?????

The high torque applied at the factory on the pinion shaft nut is evident, Hence the reason that people are resorting to

cutting off the nut??????

So how tight should the outer sleeve nut be??????????????

 

I have two thoughts!!! (for what their worth)

 

1, Heat up the housing to around 40-50 degrees C, then tighten the sleeve until there is no play, let it cool and check how tight it is.

the alloy contracting should not damage the steel bearing.

 

2, preload the sleeve cold, measure the pitch of the sleeve thread, divide by 360, this will give a value of distance by degree turned

select a preload value???? For example 0.10 mm

Screw in the sleeve nut until just tight and then the calculated number of degrees to apply the preload

and again check how tight it is!

 

What do you all think?

 

similar to the Velocette idea of preloaded main bearings. Which makes sense for a crankcase that heats up relatively quickly. I'm not so sure about the idea for a part that will take some considerable mileage to attain working temperature, which may be not so much hotter than ambient.