Gearbox differential swap - bearing preload w/o removing pinion?

[Christopher Schimke]

Okay, so here is the scenario: I have a brand new, 0 miles (new VW, never rebuilt) gearbox that I would like to put my Peloquin diff into. I need to swap the ring gear and bearings from the new gearbox's differential onto the Peloquin differential and set the bearing preload and gear backlash.

My questions is - is there a way to set the differential bearing preload with the pinion gear in place or does the gearbox need to be torn down to remove the pinion before setting the differential bearing preload? Obviously the differential bearings are brand new so the preload is supposed to be set at 27-31 in lb. Obviously there is some amount of "drag" from the pinion through the rest of the gearbox that must be accounted for somehow, but maybe it's not possible to do what I want to do without removing the pinion.
_________________
"Sometimes you have to build a box to think outside of." - Bruce (not Springsteen)

*Custom wheel hardware for Audi/VW, Porsche and Mercedes wheels - Urethane Suspension Bushings*
T3Technique.com or contact me at [email protected]

[jberger]

Why do you want to change the Pinion bearing preload? Just to verify what the factory did or you just like cans of worms? I would be more concerned with contact pattern and backlash.

J

[Christopher Schimke]

I definitely don't want to mess with the pinion at all if I don't have to. That's pretty much what I am asking. But I do have to set the bearing preload for the new differential and differential bearings. Since the differential bearing preload is determined by measuring the amount of "drag" on the bearings while rotating the differential, the differential bearing preload is normally measured before the pinion is in place to eliminate the additional drag/resistance from the pinion. So what I am asking is; is there a way to set the differential bearing preload with the pinion in place.
_________________
"Sometimes you have to build a box to think outside of." - Bruce (not Springsteen)

*Custom wheel hardware for Audi/VW, Porsche and Mercedes wheels - Urethane Suspension Bushings*
T3Technique.com or contact me at [email protected]

[Sodo]

You pretty much have to start by assembling it and verify the contact pattern. Which was set for the R&P you HAVE, right. If it's OK you're done, right?
_________________


'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb

[jberger]

Sorry, I misinterpreted, you could test it, pre tear down for the torque load needed to rotate the entire assembly, then shoot for that target with the peloquin installed. The wear pattern is the important part in my book.

[Christopher Schimke]

Thanks! Yes, getting the backlash and contact pattern correct are very important and I didn't mean to imply that they aren't. I have that covered and I'm not concerned about getting that part correct. I was simply concerned about setting the differential bearing bearing preload. Checking the total preload of the new assembly prior to tear down seems reasonable.
_________________
"Sometimes you have to build a box to think outside of." - Bruce (not Springsteen)

*Custom wheel hardware for Audi/VW, Porsche and Mercedes wheels - Urethane Suspension Bushings*
T3Technique.com or contact me at [email protected]

[Sodo]

[Christopher Schimke]

[Wildthings]

Gears posted how to do this maybe 1 1/2 - 2 weeks back. You set the bearings to zero preload and then turn the one ring in another predetermined number of degrees. You then turn both rings in the same direction the exact same amount to set the backlash.

[McRae]

Yes, you can do exactly what you are proposing. Record total bearing preload before taking it apart and then come back to the same with the new differential mounted. It's not "proper" procedure obviously but it works, done it plenty of times on highly stressed Porsche gearboxes with no issues.

Use a sweep dial torque wrench though, not a click type, those are too inconsistent for this kind of work.

[Wildthings]

Here is Gears instructions on setting the preload.

[MarkWard]

Christopher, set the bearing preload with the ring gear removed. Mark your rings, backoff so you can remove the carrier, install ring gear, and reinstall carrier. Turn rings back to where you marked them earlier. Backlash is the set turning the rings equal amounts. This maintains bearing preload.
_________________
☮️

[ZsZ]