arb locker and 4.88 ring and pinion-m simi floating rear axle

[feather]

I'm working through installing an ARB locker and 4.88 Sierra ring and pinion set in my 87 60 series rear dif. The ARB folks have a tech. bullitin out which outlines there recommendation to grind back the ring teeth:

"RING GEAR CROSS SHAFT RELIEF​

In the case of C-clip differentials, the long cross shaft of the Air Locker must be removed to install the C-clips which retain the axles. Using aftermarket ring & pinion sets that are numerically higher than the original ratio (e.g., changing from 3.56:1 to 4.88:1) can sometimes mean that one of the ring gear teeth will block the path of the cross shaft. NEVER MODIFY THE CROSS SHAFT TO CORRECT THIS PROBLEM. Simply grind a small relief into the ring gear tooth directly across from the cross shaft hole as shown below. A small relief of this type will not affect the strength of the ring gear."

Seems to me with only one or perhaps two adjacent teeth ground back that things will be quite a bit out of balance and I would expect a lot of vibration. does anyone have any experience or references i could use to help me chart my path forward.

feather

 

[rchalmers3]

feather,
I do not have direct experience with making clearance for the cross shaft. But that won't stop me from giving my opinion! I recently took ownership of a truck with 4:88 gears and ARB lockers. There is no discernable vibration from the diffs. The rough ride of the agressive 33's are so prevalent, there's no worries, 'mate!
Given the ring gear mass is very low, and the effective ring gear diameter is small. a small amount of material removal will not affect the balance to a noticable degree.
I would recommend removing only enough material for assembly and allow a large radius on the inside corners to eliminate stress areas.

 

[pismojim]

Don't worry, it's common practice.

I have ARBs w/ 4.56s and the a "gear tooth or two" adjacent to the cross ping have been ground down slightly. It doesn't need much and no reason to take off more than you need.

Recently, I also ground down a couple teeth adjacent to the center block opening. When originally installed teeth were not ground and the center block would not come all the way out. It would come out enough to drop the C-clips and remove/install the semi-floating axles. However, it was a HUGE PITA. I did it 2 or 3 times, very difficult to put the C-clips in while the center block was blocking the access hole. Last time I spent 30 seconds with a dremel on the ring gear and installation was easy. I felt like an idiot for not doing it before.


Anyway, no vibrations, not problems.

Good luck

 

[pismojim]

Oh Yeah, "feather" WELCOME to 'Mud!

Everybody likes pictures..

My center block - before clearancing with the dremel. (Sorry no "after" pics, or at least I can't find them.)

 

[Mace]

it will be fine..

 

[Cruiserdrew]

Oh Yeah, "feather" WELCOME to 'Mud!

Everybody likes pictures..

My center block - before clearancing with the dremel. (Sorry no "after" pics, or at least I can't find them.)

Jim-I think you can turn that portion of the center block around and the bevel gives enough relief to get it past the gears? I think that's how mine is set up (also with 4.56)

For the cross pin, a slight grind is all it takes and makes an impossible job, easy.

 

[Letsgomoreplaces]

grinding

Grinding for the crosspin is unavoidable on the LC semi float diffs. I have done this on 100s of diffs and have yet to see one fail as a result. This is quite common in the setup of low ratio gears in the differential world. Here's a pic

 

[pismojim]

Jim-I think you can turn that portion of the center block around and the bevel gives enough relief to get it past the gears? I think that's how mine is set up (also with 4.56)

Dude, I know, I know, but trust me I spent HOURS fiddling with that thing. It would not come out. It took VERY little grinding to let it come out, but it also takes very little rigid steel to prevent it from coming out. Mudrak, assembled it originally and admitted to using a "custom" tool for installing the C-clips. I've actually installed them in 20 seconds - first try - using my own custom tool (a piece of baling wire). However, most times it took way longer than I care to admit.

EDIT: I know what you mean about the bevel being on the gear side. BUT... if you can't get it out, how can you turn it around??? (I cussed at Mudrak, but he just laughed at me.)

 

[Tapage]

I cut a half of the cross pin to make it fit .. and leave un touched the ring theeth.