Rear Axle: Dana 44 Pinion Depth Adjustment

[c locke]

Hi there Gang. Work on changing out the 4.89 in my 2R5 to a TT 3.73 is progressing well. Slow, but well. I finally got all my shims and adjustments made and put the carrier into the case. Due to the .008" extra shim to provide bearing preload, that increased my backlash from .0035 to .010. I'll need to bring that down below .006". Not a major concern, but i made a tooth pattern while I was in there. The pinion rides pretty high on the ring teeth, top half of the ring teeth show clean from the prussian blue. SO, i need to get the pinion out closer to the carrier to get the pinion tooth contact a little deeper on the ring teeth. Here is my question to all you BTDT's on the list...

Is there a relationship between how much shim i remove from the pinion bearing cup to how much the tooth contact area changes on the ring? i.e. add .003" shim to the pinion and the contact area will move 1/16" deeper on the ring... Is there such a relationship? I'll do it if i have to... but i'm not looking forward to pushing out the pinion .003", completely reassembling the entire rear end just to get a wear pattern, to find out i need to do more. I imagine I could come up with a mathematical relationship from the first adjustment, and calculate the new shims the second time around, but since the tooth isn't flat (the contact surface is beveled) the relationship wouldn't be linear, and one measurement wouldn't be enough. Just looking for a little time saver... thanks all in advance for your help, experience, and wisdom!

My dad told me years ago good judgement comes from experience. Experience comes from bad judgement...

chris

[bezhawk]

If the contact pattern is centered in the ring gear and only the depth needs adjusting, then adjust the shims on the side of the carrier bearings.
Since the gear teeth are tapered , deeper will also decrease backlash as it meshes with a wider section of the gear.

[grobb284]

I have found that the GM shop manuals are a good source for setting up Dana 44's. They have some very good pictures of patterns and recommended adjustment.

It runs in my mind that the pinion depth is 2.625, +/- the specified marking on the end of the pinion gear itself. This saves the time of loading and reloading the ring gear carrier assembly, and then having to remove it to reset pinion depth.

The Dana brand gear sets now ship with excellent drawing of the pattern setups for both hobbed gears and milled gears respectively. They actually set up slightly different for pattern depending how the gears were manufactured.

I don't have the specs in front of me now, but .006 backlash sounds tight, for a max. specification. I have seen .003 variation on a properly assembled ring gear. It is better to error on the side of the larger backlash, than be too tight. I'm thinking that GM specs are .008 max. This also has a relationship to whether using new or used bearings.

The mating pattern does not always shift from toe to heel, or crest to root of the tooth profile, but somewhat a 3 dimension diagonal by moving the x-y coordinate shims on the carrier and pinion. That is the reason I suggest reviewing the mating patterns and suggested changes by Dana.