trailshredder
New Member
Is there a way to tell what rear end is in a truck other than the VIN? I know the rear end has been swapped out but don't know what to.
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If you're just looking for gear ratio, jack up the back tires, turn one by hand one full rotation and count the driveline revolutions. If you only jack one tire you have to double, or half, your counting....can't remember which way now, but with one tire on the ground you are working the spider gears which changes how fast the driveline turns.
Just thought of something. The gear ratio better be the original unless they also changed the front diff as well.
If you have not noticed any drive-line binding, then your probably OK! If they changed out the read end, then they probably used the same gear ratio that was in the OEM differential. If not, then you would definitely notice within a few miles. Front end and rear end turning at different ratios.
The pump rub issues are with the transfer case, not the Allison! If it is a GM rear end, count the number of bolts. GM uses 10 bolt, 14 bolt, etc. I would venture to guess that the same type of rear end was put back into the Suburban. That would have been the easiest fix.
you can never assume anything. There are really stupid people out there.
Yes, with both back tires off the ground, tranny in neutral, turn one tire one full rotation, the driveline will turn 4 times plus a little more. That equals 4.10 gearing. Not quite 4 times is 3.73
The only time you would notice the binding would be in 4wd. If the only time 4wd was used was on ice or slippery mud it might not be noticeable to someone who doesn't pay attention to those things. It would feel really squirrelly though.
I suppose you could jack all 4 tires off the ground, put it in 4hi, tranny in neutral, make a mark on the front tires, rotate one of the back tires one rotation and see if the marks on the front tires stop at the same place. There's going to be a little slop with drivelines and tcase gears but it should come out pretty close.
If the guts of the differentials have been messed with you probably can't rely on any stamps on the outside saying what ratio it is.