1965 7-1/4 Refurb - Sure Grip Upgrade

[PocketAces]

On Monday I started again with another shim. Sanded it down to .085. This time I was sure to torque down the pinion nut get the correct amount of drag on the bearings.
View attachment 20140915_140642.jpg
Pinion Depth Shim: .085"
Carrier Shim - Ring Gear Side: .269"
Carrier Shim - Differential Side: .262"
Backlash: .005"

Too deep

 

[PocketAces]

Sanded another .003 off the shim for a thickness of .082
View attachment 20140915_145108.jpg
Pinion Depth Shim: .082"
Carrier Shim - Ring Gear Side: .269"
Carrier Shim - Differential Side: .262"
Backlash: .007"

Drive side has moved off the toe, but now coast side is hanging off the toe. I guess I went too much.

 

[PocketAces]

Sanded more material off the thinner shim and added a .012 for a total thickness of .084.
View attachment 20140915_162739.jpg
Pinion Depth Shim: .084"
Carrier Shim - Ring Gear Side: .269"
Carrier Shim - Differential Side: .262"
Backlash: .006"

I think I can live with that.

 

[PocketAces]

I sanded down a pinion preload shim and torqued the pinion nut. I ended up with 28-30 in-lbs of drag on the pinion. Spec is 15-25. I hope that's not a problem.
View attachment 20140915_183050.jpg
Spread the case with my homemade spreader and added a total of .012 to the carrier shims. I did it in such a way as to purposely increase the backlash in hopes of moving both patterns away from the toe.
View attachment 20140915_184438.jpg
Pinion Depth Shim: .084"
Carrier Shim - Ring Gear Side: .271"
Carrier Shim - Differential Side: .270"
Backlash: .008"

I ended up with .008 of backlash which is what I was shooting for. Not sure it made enough difference to be worth being out of spec on the backlash. Spec is .004 to .007. I'm at .008.

 

[PocketAces]

I decided to decrease the backlash to get it into spec. So I changed the carrier shims
View attachment 20140915_222849.jpg
Pinion Depth Shim: .084"
Carrier Shim - Ring Gear Side: .275"
Carrier Shim - Differential Side: .268"
Backlash: .006"

You could argue that my pattern looks too deep on the drive side, but I'm also close to the toe on the coast side. I've found that removing pinion shim moves the coast side even closer to the toe. So I'm thinking this is the best compromise.

I think I'm done unless those with more experience convince me that I can do better. I would hate to add up the number of hours I have into this thing.

 

[AJ/FormS]

Yeah, that looks like a good compromise. I used to hate those crossed patterns. Always best to bias for best drive side. Your pattern looks very streetable.Congrats.

 

[PocketAces]

I'm starting to get this nagging feeling that I've got the pinion bearings too tight. The 1965 Factory Service Manual spec is 15-25 in-lbs. But my Google search turned up many different pages calling for 12-14 in-lbs on new bearings and only one page calling for 15-30 in-lbs.

Mine measured 28-30 in-lbs. Do I need to go back into this thing?

Later designs used a crush sleeve, while the 1965 design used preload shims. I think it would be very difficult to get preload accurate to +-2 in lbs using shims which might explain the different specs. But they are the same bearings so shouldn't they have the same preload, regardless of how that preload is achieved?