CARC O-ring

[Peter from Sch'dy]

Hello,
Trying to find the size of the o-ring found between the pinion shaft seal runner and the inner race of the outboard tapered roller bearing. Actual measurement or Parker number would probably be good. I don't believe there is a Guzzi part number but if I'm mistaken please let me know what it is.

TIA,
Peter

[Vasco DG]

No, there's no part number as it isn't supposed to be serviceable

From memory I used one the same size as the ones used for the same purpose on the five speed gearbox output shaft but it really isn't that critical. It's purpose is to prevent oil running up the pinion inside the seal runner. Whatever the shaft OD is will be the o-ring ID and 2 mm or so will suffice.

Pete

[Peter from Sch'dy]

Thanks Pete.
 A friend has suggested an interesting way to determine the torque needed for the pinion retaining nut. He thinks it could be tightened until there is a specified load measured by torque wrench of the rotational force required to turn the pinion, some number of inch/pounds or newton/meters etc., say 20 in/lbs. The last time I had it apart I tightened it one tab beyond hand tight and it was loose on disassembly today after 5000 miles. disassembled due to a small leak. Any comment on this suggested method and/or pinion assembly rotational load?
thanks again,
Peter

[Vasco DG]

Thanks Pete.
 A friend has suggested an interesting way to determine the torque needed for the pinion retaining nut. He thinks it could be tightened until there is a specified load measured by torque wrench of the rotational force required to turn the pinion, some number of inch/pounds or newton/meters etc., say 20 in/lbs. The last time I had it apart I tightened it one tab beyond hand tight and it was loose on disassembly today after 5000 miles. disassembled due to a small leak. Any comment on this suggested method and/or pinion assembly rotational load?
thanks again,
Peter

Use a new tab washer, (It's the same as the crank sprocket lock washer as used on early Tonti framed bikes.) make sure the threads are clean, (Use a new nut as well if you think yours may be the worse for wear, it too is the crank nut off the same period bikes.) use some Loctite 243 on the threads and tighten the nut to slightly more than before, (Try 25 in/lbs.) and then stick a couple of drops of super-wick-in onto the top of the threads for good measure.

Because the bearings use no solid spacer between the inner races the preload is effectively governed by the collapsible spacer between the outer races. Unfortunately this part is not available separately so after its first use any subsequent use requires a slightly higher torque to maintain the preload.

No, it's not ideal, but it worked for me!

Pete

[Peter from Sch'dy]

Use a new tab washer, (It's the same as the crank sprocket lock washer as used on early Tonti framed bikes.) make sure the threads are clean, (Use a new nut as well if you think yours may be the worse for wear, it too is the crank nut off the same period bikes.) use some Loctite 243 on the threads and tighten the nut to slightly more than before, (Try 25 in/lbs.) and then stick a couple of drops of super-wick-in onto the top of the threads for good measure.

Because the bearings use no solid spacer between the inner races the preload is effectively governed by the collapsible spacer between the outer races. Unfortunately this part is not available separately so after its first use any subsequent use requires a slightly higher torque to maintain the preload.

No, it's not ideal, but it worked for me!

Pete

Thanks Pete

[Wayne Orwig]

When there is a solid spacer, you actually want a very small amount of play.
Is there a chance that putting a preload on the bearing, might let them bind, when the assembly warms up?

[Peter from Sch'dy]

Hello Wayne,
It might. But I think a small pre-load must be important to keep the seal runner from slipping on the pinion. There does not appear to be any other positive anti-slip device incorporated in the design of the runner like perhaps a key. Maybe the collapsible spacer effectively regulates the pre-load as Pete described if I understand his explanation correctly.  Since I have 65000 miles on it and am chasing a very small leak it'll probably be fine if it doesn't overheat or spit the nut. Interesting though.  (shrug)

Peter

[Vasco DG]

When there is a solid spacer, you actually want a very small amount of play.
Is there a chance that putting a preload on the bearing, might let them bind, when the assembly warms up?

This is the reason the preload is so low. The collapsible spacer is actually between the two outer races of the pinion bearings. The bearing races are a tight fit in the reactive bridge when the unit is cold but can float when warmed slightly. The way I do it is warm the bridge with a butane torch and then apply the preload. The collapsible spacer is in the form of a wavy-washer between the outer races. Preloading the inner races will compress this a it applies pressure to the bearings but it's only light.

The depth of pinion engagement is governed by shims under the outer race of the bearing between it and a register in the bridge. The whole lot is kept in place and correctly loaded by the seal holding collar which is in turn locked with a G clip that indexes in the castellated surround of the reactive bridge.

It's a bit hard to explain but when you see it it all makes sense.

It actually works well and is absurdly strong but why they don't Loctite the pinion nut at the factory is beyond me? It's asking for trouble when you have only a light preload and are relying on a crappy tab washer to prevent the nut coming loose!

Pete

[Peter from Sch'dy]

I've got O-rings coming from McMaster Carr and hope to reassemble and test in time for vacation to NC area. Love the bike, '07 Norge.

Peter