As usual I get the one of a kind

Just got that 8.8 I had asked about a couple of days ago. (thanks for the responses, The info was helpful).

Just striped it down to find it has a 3.27 ratio and no trac-loc even though it was in the XLT model witch should have guaranteed trac loc and at least a 3.73. I guess it is not that big of a deal because I was going to regear my D30 to match the lower ratio, now I will just regear the 8.8 to match the 30.

Ok, here is the question in this. does anybody know what part of the vin is the gear ratio. I am 99% sure it is a 3.55 but would like to be 100% before I order up gears for the 8.8. Before you say to check the tag, they are both gone, the tags went the way of my rocker pannels and fenders. From rust to rust as the saying goes.. The Jeep is an 89 XJ pioneer, 4.0, AW4 auto, no tow package.

Pull the ring and pinion, count the teeth on each, divide.

I apreciate the thought mat, I was hoping not to strip the 30 if it is a lower ratio than the 8.8. it has no problems as it sits, I am trying for the simplest soution and the 8.8 is on stands in the garage. the 30 is mounted and in tact.

Spin the tire one revolution and count the number of times the pinion rotates. 3 1/2 turns = 3.55s

Most likely ratio given the engine/trans combo.

There should be a tag bolted to the diff cover on the 30. In one corner it will be stamped with the ratio. If not you will have to pull the cover and count the teeth to be 100%. The turning tire and counting the driveline turns isnt very acurate. Most likely you have a 3.55 ratio.

IllianaXJ said:

Spin the tire one revolution and count the number of times the pinion rotates. 3 1/2 turns = 3.55s

Most likely ratio given the engine/trans combo.

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Actually I think it is 2 tire revolutions.

Matt98XJ said:

Actually I think it is 2 tire revolutions.

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my point exactly

How is that inaccurate? The pinion gear turns 3.55 times for each ring gear revolution (assuming 3.55 gears), hence the 3.55:1 ratio. The ring gear turns the carrier, which turns the shaft/hub/wheel.

I agree the counting teeth method is better, but for a quick and easy verification, the rotation method works just fine.

If you turn one wheel and the other turns the opposite way, you will get a skewed number, as the spider gears are working their magic. I tried this method when I had my rear jacked up, and new I didn't have a 2 point something ratio in the rear. Engaged the locker and got the 4.56 rotations.

Did you clean the dirt and grime off the diff cover and look for the ratio? i have owned 3 xj's and everyone of them had the ratio on the diffs!

Not only the spider gears, but its also hard to tell the difference between 3.55 and 3.73 just by looking at the pinion. Whateves.... to each there own but better safe then sorry imo.

what I should do is just reset them both to 4.88s but to do that I need to start collecting donations,... Who will be my first sponsor?

Take the cover off of the diff, count the teeth. Only way to be sure.

I just got off the phone with jeep and they cant come up with a build sheet for my vin so I guess I will have to do it the hard way. after my december trip to RC I will pull what is left of my 35 apart and get a tooth count, then order up the parts for the 8.8.

I just pulled one axle on the 8.8 and it is a 31 spline and everything looks to be in good shape, just needs a difrent ratio. I am on a budget (actually over budget by a lot but it is expected with a jeep. just cancled my alaska cruise for this summer because of other ... im rambling,, back to topic) and I have a winch and tow strap. Is it a realy bad idea to just put it back together open and go for a locker next year? Or is it a big enough job to install the locker that I should just do it all at once?

I just got off the phone with jeep and they cant come up with a build sheet for my vin so I guess I will have to do it the hard way.
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Unless you got the Jeep new and/or know it's not been regeared the build sheet may not have been right anyway.
A non OEM axle may be the reason your 8.8 was not what you were expecting.
Also watch some boneyards will pull a switch. You never know what you getting if they pull it and you don't get to watch. If it's a you find it and they pull it place. Take a can of spray paint and mark the part to insure you get what you wanted.
Pulling your cover will give you a good chance to inspect as well as count. Maybe saving you a trail repair.
If you inspect often, paint a line down you shaft. When the painted line shows a axle twist of 90 deg or more replace axle.
When I use to pound hard on my ride. This trick saved me more then one trail repair. Clipless axles make this job a snap (pun intended).
Some axles can also be converted to use no clip.

Kevinma255 said:

Is it a realy bad idea to just put it back together open and go for a locker next year? Or is it a big enough job to install the locker that I should just do it all at once?

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in my opinion, running the axle open is totally fine, and down the road when you want and have the money for the locker, you can always get a lunchbox locker for it, which takes an afternoon in the driveway to install. Just take out your spiders and replace with locker. Unless you wanted a locker that is a full case replacement, in which case you may be better off saving up and doing it all at once, because if you don't then you'll end up setting the gear set twice....