Regear 8.8 Pinion Depth Help

[JerZDevil81]

Hey guys -

So I got my Richmond 4.56 and I am trying to figure out the pinion depth. Hopefully this makes sense to someone.

Etched on the gear, it says Centerline Distance should be 2.626. If I'm correct in my math here this means:

4.415 (MHD) - 2.626 (CD) = 1.789 pinion depth.

When I mic my pinion where the bearing rides, I get a reading of 1.786. This should mean that I need a .003 shim to get my pinion depth right or close correct?

Or am I totally off the wall, need meds, and to go according to the shims on my old pinion? And has anyone confirmed that MHD is 4.415 or the dubious 4.4199?

 

[RangerSVT]

Usually about 90% of the time reusing the shims off the old gear the pattern comes out good. Start with the old shims. You can do the math and figure out pinion depth, but that isn't 100% accurate with every axle, as each housing is different. It will get you close, but not dead on every time. Calculating pinion depth is good when you get a housing that has no gears, but if your swapping gears, I usually start with the original shims...

SVT

 

[JerZDevil81]

Jesus, am I confused.

Got the bearing off the old pinion, and when I mic face to where the bearing rides I get a measurement of 1.878 and the NEW pinion is measuring at 1.786. Thats a difference of .102, are my eyes deceiving me or does that seem like way too much of a difference?

Is this MHD thrown out the window for gears other than Ford Racing?

 

[RangerSVT]

That is a lot, I'd double check that, IF I was setting up from scratch and didnt have a set of stock gears to work from. I've done dozens of gear swaps, new bearings, reused bearings, etc. I always try reusing the original shims first. Ive found it saves me time most of the time...

SVT

 

[4x4junkie]

Agreed, if you have the original shims from the old gears, just start there (don't worry about the markings on the pinion). Way more often than not, it'll be within a few thou of where it needs to be and will give you a good readable pattern.

When i did the Yukon 5.13s in my BII's (Explorer) 8.8", the factory shim was dead-on, and for my D35 I think I had to add .003" or something like that, I forget exactly.