Spec'ing limited slip differential...

[Unique 289_FIA]

I would like to add a limited slip to the Jag rear end. I am considering the Auburn, but I have questions on the proper spec. I know it's a Dana 44, but is it w/ or w/o C-clips? What does that refer to? 30-spline is correct? Why does the gear ratio matter (3.92-up or 3.71-down)?

Would this be a correct model: http://www.jegs.com/webapp/wcs/store...0002_744538_-1

Model: 109-5420109

I have no experience working on rear ends, but have built a few motors and rebuilt the 3550 tranny and generally know my way around a car. Is this something I can install myself or should I leave it to someone with more experience? I understand that the lash has to be set just right (?).

Thanks, guys!

Robert

[JeepSnake]

Robert, I can't tell you much about the Jag rearend, but on any differential, the gearset ratio matters because of the carrier size. I can't remember which direction it goes in relation to numerical ratios, but you have to get the right gear mesh between the pinion & ring gears. As you change gear ratios, that spacing changes, and the manufacturers cover it with usually two different carrier sizes.

In the aftermarket, you'll see thicker ring gears and ring gear to carrier shims to allow you to put gears onto a carrier the factory never meant for them to be on. There are a lot of opinions on these practices: thicker gears run too hot, longer ring gear bolts let the gear wiggle around, longer bolts are apt to shear, etc. etc.

The carrier ratio "breaks" for a couple I remember from Jeeping...
AMC 20: had one carrier for 3.07 and higher (numerically) gears, another carrier for 2.73 gears only
Dana 30: had one carrier for 2.73 - 3.54, and one for 3.73 and higher

Want to smoke your Cobra tires worse than you already can? Stick some 5.38's in there! (A standard Jeep Dana 44 ratio for years & years.)

As for C-clips, you'll see them in live, semi-floating axle applications. Some live axles are designed such that the outer bearing retainer (behind the brake drum) holds the axle shaft in the housing. A Ford 9-inch is a good example of this. Other live axles let the bearing carry just the load, and they have a little groove on the end of the axle that fits into the differential carrier. Once the axle is inserted into the house, you put a C-clip into this groove to hold the axle in. Generally, the groove portion of the axle is much smaller diameter than the main shaft, so they are considered a weak point in severe duty. Good examples of this type are the Ford 8.8 and the Chevy 10-bolt.

All the axles in the C-clip discussion are semi-floating. This means that the outer end of the axle shaft is supported by the bearing at the end of the housing; the inner end is supported by the carrier bearings. The axle shaft transfers power AND supports the weight of the vehicle. In a "full-floating" arrangement, a set of wheel bearings in the hub carries the weight of the vehicle, and the axleshaft does nothing but transfer power. Full floaters are usually found in heavier trucks, etc.

Now, this post won't help you much, but I needed a break!

[ralphscott]

One suggestion and a very easy one is to call Butch Capps at 865-524-4800 EST. He will give you the straight scoop.

Ralph

[JeepSnake]

For posting Butch's phone number! I need to give him a ring about some other parts, and was just about to call Mom & Dad to see if they had it.

[ralphscott]

You are welcome Zack hope your family has a wonderful Easter. Give you parents a hug from Gayle and I. We all have so much to be thankful for. Even the tough times

Ralph