Rearend Ratio

[dirtlord420]

I'm trying to find out what ratio my dana 35 has. my jeep is a 88 4.0 auto lwb 2x4. is there an axle code in the vin? there was no tag on the rearend.

[HOrnbrod]

No axle code in the VIN. 99% of MJs with the AW4 have a 3.55 ratio. Only sure way to tell is pull the cover and divide the # of pinion teeth into the # of ring gear teeth. Should be 39T ring gear & 11T pinion.

[Pete M]

a quick (and decidedly less dirty) method is to put the trans in neutral, jack up one rear tire, and rotate it around exactly twice while counting the number of times the driveshaft rotates.  if it goes around a bit over 3 and a half times, it's a 3.55.  If it has a limited slip in the rear axle, then you'll need to jack up both tires and rotate them around once.

 

 

If you've got no idea when the last time the gear oil was changed, then it's a great time to pull the cover and kill 2 birds with one stone. :thumbsup:

[onlyinajeep726]

:agree:

 

If you're going to replace the diff. oil, full synthetic is the way to go IMO.  75W-90 is the appropriate weight for normal everyday driving.  If you do a lot of heavy pulling/towing/wheeling, put in 75W-140.  Mobil 1 makes some good synthetic for around $12 a quart.  Also, if you have a limited slip, don't forget you need the oil additive or buy some diff. oil with the additive already mixed in.

 

Going back to the original question though, like Don said, you likely have 3.55 ratio with that given setup unless for some reason the PO changed it.