4.88 Yukon - Second Opinion On Pinion Depth

[Landin patton]

I’m setting up a 2017 Ford F-350 with Yukon 4.88 gears in a Dana M275, and I’m looking for a second opinion on pinion depth and backlash.

Currently I’m running a .047 shim behind the inner pinion race and I’ve got about .012” backlash. I’m within spec but on the high side, and I’m debating whether to drop the pinion shim to .046 or .045 to help center the pattern.

From what I understand, Yukon gears typically like to run slightly shallower, and I’m thinking pulling .001–.002” may clean up the pattern and allow me to bring backlash closer to .009–.010”. Before I tear it back down again, I’d appreciate any input on it.
• Whether .047 seems deep for a Dana M275
• If .046 is the better next step versus jumping straight to .045
•Where you’d personally set backlash on a Yukon 4.88 in this axle
Thanks in advance for any insight.

 

[ihpartsjeff]

Well I don't think you will find much experience here on M275 rear axles as IH never ran those. Not sure what the specs of a M275 are supposed to be at. I will say try adding some gear oil to your marking compound as it will help with reading the pattern. But looking at what you have I would say you are too deep and to remove around .003 from the pinion and then reset the backlash.

Also, Facebook has a few real good pages on setting up gears where you might find better help. Here is one that I am a member of and find the information helpful - https://www.facebook.com/groups/732975063811349