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welp, that sucks. gear swap problems

ashman

ashman

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I'm doing a gear swap and locker install on a 2003 Tahoe with an 8.5 rear end and I've had nothing but problems. All related to the wrong gears being in the right box.

The owner ordered this first:
20240210_172233.jpg

Got it out of the box, and...
20240210_172412.jpg

yeah, that ring gear looks a little small... turns out it was like 7.25", so he returned that and decided to go with Yukon gears.

20240218_193931.jpg

Ring gear measured out right, but was a bitch to get on the carrier. Unfortunately, again, not the right gears in the box.
20240218_185511.jpg

I don't know what those markings are, but it's not Yukon markings. When I tried to install them in the diff, the ring is impacting the pinion, even with all of the shims pulled out of the left side.

20240218_193716.jpg

Looks like its a thick gear set, but I can't make anything from the numbers on it, so it might not even be for a GM 8.5.

3rd set of gears is on the way. /sigh
 
Can a 4.56 gearset for the 2.56-down (car) carrier exist? Assuming the G80 differential shown has 3.42 gears, that thickness change to a 4.56 seems fairly normal. The ratio change is from 3 fewer teeth on the pinion, which is why it is smaller in diameter.

1708447859471.png

Stupid question - could you have the (assumed) 3.42 pinion installed instead of the 4.56?

Did you measure the locker compared to the G80 to be sure that's not the problem? As a sanity check you could install the old gears on the new differential (or vice versa), but that does add a lot of work.
 
Blue85 said:
Can a 4.56 gearset for the 2.56-down (car) carrier exist? Assuming the G80 differential shown has 3.42 gears, that thickness change to a 4.56 seems fairly normal. The ratio change is from 3 fewer teeth on the pinion, which is why it is smaller in diameter.
Click to expand...
[/QUOTE]
I just checked the original gears and it's stamped 41x11 so 3.73.
Blue85 said:
Stupid question - could you have the (assumed) 3.42 pinion installed instead of the 4.56?

Did you measure the locker compared to the G80 to be sure that's not the problem? As a sanity check you could install the old gears on the new differential (or vice versa), but that does add a lot of work.
Click to expand...
Worth asking, but no, I had the right pinion installed.

I did consider installing the old gears on the locker just to be sure, but after looking the new gears over closely, along with the locker, I'm pretty sure the locker is correct and the gears are wrong.

I'll know for sure Thursday when the new ones show up.
 
ashman said:
View attachment 468183
Click to expand...
Are there any other markings on the ring gear (like between the bolts) or on the pinion gear? It seems weird to grind down a presumably balanced item to add markings, especially for a new, name-brand gearset. Is DP the Diametral Pitch (i.e. 41 teeth on 7.26" circle)? Could it be a DePth measurement like .0565 shim used?
 
Wes Harden said:
which locker is that you are installing ?
Click to expand...
It's the yukon grizzly locker. Basically a Detroit.

@Blue85 there were some other markings, but if they were yukon gears there would have been a part number, and that wasn't there.
The etched markings could be anything really. Nothing stood out to me though.
 
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