8 3/4" Pinion depth-where to measure?

rod440 · Dec 31, 2019

I have a new US Gear 3.55 R&P set. The pinion depth (2.763") is written on the back of the pinion. There is a small step on the back of the pinion that extends .035" past the rear edge of the tooth. My question is do I measure pinion depth from the rear edge of the tooth or from the actual rear face of the pinion?
Thanks!
Rod in Wi.

Cranky · Dec 31, 2019

I've always measured from the machined face of the teeth. Are you using a slip fit 'dummy' bearing? If so, it'll be real easy to set it up that way and then check the pattern. In fact, I recommend using a slip fit trial bearing.

vance.dykes · Dec 31, 2019

Cranky said:
I've always measured from the machined face of the teeth. Are you using a slip fit 'dummy' bearing? If so, it'll be real easy to set it up that way and then check the pattern. In fact, I recommend using a slip fit trial bearing.

i too have a test barring for my #2 case . cut the old barring off the old pinion use on new, use test barring to set last adjustments

rod440 · Dec 31, 2019

I don't have a setup bearing,if I don't get it right on the first try I'll hone
the old bearing & go that route.

Cranky · Dec 31, 2019

rod440 said:
I don't have a setup bearing,if I don't get it right on the first try I'll hone
the old bearing & go that route.

You've already installed the new bearing on the 3.55 pinion?

65-440 · Dec 31, 2019

Cranky said:
I've always measured from the machined face of the teeth. Are you using a slip fit 'dummy' bearing? If so, it'll be real easy to set it up that way and then check the pattern. In fact, I recommend using a slip fit trial bearing.

Bingo ! And don't forget to check the pattern, numbers might look good but pattern tells everything ...

rod440 · Dec 31, 2019

I installed the old bearing on the new pinion with the original .030 shim to check initial PD. It looks like I need to add another .050" of shim to get to the recommended PD,using the edge of the gear tooth as a reference.

Cranky · Dec 31, 2019

65-440 said:
Bingo ! And don't forget to check the pattern, numbers might look good but pattern tells everything ...

The first several times setting up using a setup tool/dial indicator, the pattern didn't look right. Plugged the thing into my car and it ran quiet. Did that with several of them and all were the same but ran quiet and got where I didn't pay much attention to the pattern.....

65-440 · Dec 31, 2019

Cranky said:
The first several times setting up using a setup tool/dial indicator, the pattern didn't look right. Plugged the thing into my car and it ran quiet. Did that with several of them and all were the same but ran quiet and got where I didn't pay much attention to the pattern.....

Did it give you the same too deep/too shallow pattern each time or was it always different ? I used a setup tool once and the pattern was off, can't remember which way though. I just used that as a starting point then adjusted depth by pattern. Was too chicken to throw it in the car and chance how it ran !

Cranky · Dec 31, 2019

When the tool told me it was on the money I would check the pattern and it just never looked like what the pictures were showing....

5.7 hemi · Dec 31, 2019

I like using both, pattern and math. Most of the time I screw up somehow on the math side (forget to write something down). The pattern is what I go by 90% of the time.

451Mopar · Jan 1, 2020

rod440 said:
I have a new US Gear 3.55 R&P set. The pinion depth (2.763") is written on the back of the pinion. There is a small step on the back of the pinion that extends .035" past the rear edge of the tooth. My question is do I measure pinion depth from the rear edge of the tooth or from the actual rear face of the pinion?
Thanks!
Rod in Wi.

2.763" from axle centerline is 1.13050" below the lowest part of the bearing bores. 1/2 of 3.2650" bearing bore diameter = 1.6325" from axle centerline to lower part of bearing bore. 2.763" - 1.6325 = 1.13050".
I haven't had a gear set with the step you mentioned, so I don't know where they are taking the measurement from?
From this install instruction, #4, measurement is from the face of the gear?
https://www.usgear.com/usg-admin/resources/literature/us-gearmanual-instructions-2017-1.pdf

I just use a 1-2-3 block on top of the gear face, and add the extra 0.130" of shims on top of the 1-2-3 block, and run a straight edge between the lowest points of the bearing bores. Any difference between the shims and straight edge needs to be added (or subtracted) to the pinion bearing shim.
Next, shim the front pinion bearing. 489 case uses crush sleeve, but I like the crush sleeve eliminator (spacer.)
Pinion pre-load needs to be correct with the yoke correctly torqued. Start with more shims (looser pre-load), and remove shims to add pre-load. If the pre-load is exceeded before correct pinion nut torque, add shims.

Put the differential/ring gear in, and use the carrier bearing adjusters to set the back lash. Check gear pattern with drag on ring gear.

Daves69 · Jan 1, 2020

rod440 said:
... There is a small step on the back of the pinion that extends .035" past the rear edge of the tooth. My question is do I measure pinion depth from the rear edge of the tooth or from the actual rear face of the pinion?....…..

Curious, Is that small surface rough or ground? You don't need that clipping the carrier if it gets too close. A call to US Gear for support might help.

rod440 said:
.............It looks like I need to add another .050" of shim to get to the recommended PD,using the edge of the gear tooth as a reference.

Do you have .050" you can place behind the race to verify?

BTW, If it helps, my setup standard is 3.262" diameter.

rod440 · Jan 2, 2020

Per the US Gear tech rep the measurement is from the edge of the gear tooth like you guys recommended.Thanks for all your input!
Rod

8 3/4" Pinion depth-where to measure?

rod440

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