Ford 8.8 swap, pattern too deep but no shims left to remove

[ylidk]

Title about says it all. Swapping a 28 spline 8.8 axle from a 2000 ranger onto my 91 ranger, in the process of regearing with used 3,55 gears. Using the old pinion bearing as a setup bearing, dremeled it out to a slip fit, and am installing the pinion with the old crush sleeve, outer bearing, and oil slinger. Started off with the stock shims on the pinion and carrier, and the gears were bound up. Re-shimmed the carrier so it had the right backlash and the contact pattern was too deep toward the root, indicating the pinion shim was too thick. Re-shimmed the pinion multiple times and the contact pattern was raising up, but I ran out of shims to remove and it still looks like it needs to come up. Each time after re-shimming the pinion I made sure it was rotating at ~12 in-lbs of torque (spec for used bearings that I found said between 8-14), and re-shimmed the carrier to get ~0.010" backlash before testing the contact pattern. Not entirely sure where to go from here, aside from just sending it and keeping the current setup. Anyone run into this before, am I just missing something or doing something wrong? This is my first time rebuilding a diff so I wouldn't be surprised if I missed something that caused this.

I do have a set of 4.10 gears that this 8.8 came with that has a small chip in the pinion gear, though out of the contact patch. I wanted to increase the gearing for highway driving anyway so I picked up the 3.55's, if the 3.55s just won't work out I guess I can always go with the 4.10s.

Let me know if there's any info I left out that I can add to help. Any help is appreciated, thanks in advance!

 

[sgtsandman]

Have you played with the carrier shims any? I'm thinking the carrier needs to be shifted left to make room for the pinion shim that is needed but I'm also not an expert when it comes to differentials.

 

[ylidk]

Have you played with the carrier shims any? I'm thinking the carrier needs to be shifted left to make room for the pinion shim that is needed but I'm also not an expert when it comes to differentials.

Yeah, so I started off with the stock shims to get the overall shim thickness I need to match, but have been using the shims that came with the the rebuild kit. It actually has been shifting the carrier to the right though, usually by 0.003" or 0.006" shims being taken from the right and moved to the left each time after decreasing the pinion shim thickness to maintain the 0.010" backlash.

 

[ylidk]

Yeah, so I started off with the stock shims to get the overall shim thickness I need to match, but have been using the shims that came with the the rebuild kit. It actually has been shifting the carrier to the right though, usually by 0.003" or 0.006" shims being taken from the right and moved to the left each time after decreasing the pinion shim thickness to maintain the 0.010" backlash.

I should make sure to emphasize that the pattern has been creeping upward as I removed pinion shims, just not enough to make a good contact patch before running out of shims to remove from the pinion

 

[ylidk]

I will also add that I am using a Koyo bearing on the pinion, and testing the thickness it comes to about 1.036" under pressure. I bought a Timken bearing that I ended up not using since I'd have to buy a second to make into a slip fit setup bearing and press in a new race as the profiles are slightly different, but it measures around 1.029" under pressure. I don't think 7 thou would be enough to fix the contact pattern since I was dropping shims by 10 thou at a time and only inching my way upward, but that is another possible way to shave a little more depth