85 wagon Limited Slip

[4hammond]

can anyone offer a little help. I would like to add a limited slip to my stock rear axel. Is this possible?

[IowaEagle]

Not offered as they would ruin the viscous coupling in the transfer case.   Maybe the only one that could have been use was behind the NP 128, and then AMC would have had to matched the front differential gearing to that of the rear.

[Whuntmore]

you could though if you changed out to a say, 242 T-case, matched gears and of course had the drive shaft altered.

[4hammond]

Sounds like it will take some work. I guess we will see how it handles in the snow this year and decide after that.

[carnuck]

Unless you are doing a ton of turning, it shouldn't affect the VC. Having a low range in mine (Tcase from an FSJ) allows me to do that. Trac Loc is pretty innocuous and should be fine. You have to apply the brake slightly with 1 rear tire spinning to get it to engage.

[AMC of Houston]

OK; someone please 'splain to me how a limited slip diff (with the same gears) could affect the VC.   I just can't see it.   I've had limited slip in mine (a genuine AMC 15 unit)  for the last 13 years and loads of miles, and no problems.   Anyone??

[eaglefreek]

OK; someone please 'splain to me how a limited slip diff (with the same gears) could affect the VC.   I just can't see it.   I've had limited slip in mine (a genuine AMC 15 unit)  for the last 13 years and loads of miles, and no problems.   Anyone??

I was going to ask the same question.

[carnuck]

If you have an '86 (or at least a NP128 case) it's a non-issue. It would only become an issue on really long excessive corners.... ie: Burnouts in a circle.

[Whuntmore]

Ok, but if you swap out the t-case to say, a 242, then it's also a non-issue, right?

[eaglefreek]

Yes, it's a non issue with a 242, but I still don't see how it matters with the 129. The viscous coupler is for front to rear bias, why would it matter if there was a LSD in the rear?

[IowaEagle]

I am not an engineer but there has to be a reason why AMC did not offer it.

[1985amceagle]

I'm not sure how the 119 is designed, but it might have to do with how it has to drag a wheel on turns

[eaglefreek]

I am not an engineer but there has to be a reason why AMC did not offer it.

I'm pretty sure LSD was an option on a NP229 equipped Grand Wagoneer with the tow package.

[IowaEagle]

I am not an engineer but there has to be a reason why AMC did not offer it.

I'm pretty sure LSD was an option on a NP229 equipped Grand Wagoneer with the tow package.

I found no mention of LSD being offered in the AMC Standard Catalog.

[eaglefreek]

I found no mention of LSD being offered in the AMC Standard Catalog.

I venture over to the FSJ forum quite often and have seen it talked about once and a while. Here's a quote from a thread over there.

"Both of my '90 's have caution stickers in the glove box stating that "this car is equipped with a locking type differential at the rear wheels ....""
http://www.ifsja.org/forums/vb/showthread.php?t=121725

[4hammond]

So is there an option for my 85 for Limited slip with just some rear axel work or would I have to change transfer case?

[The Dark Side of Will]

I am not an engineer but there has to be a reason why AMC did not offer it.

Because AMC was cheap and poor when they built the Eagles?

[Draekon]

Having LSD in the rear will not hurt the VC in the transfer case.  The VC is strained when the front and rear wheels are spinning at different speeds.  This will happen whether you have 1 rear wheel spinning (in the case of an open diff) or if you have both rear wheels spinning (in the case of LSD).  In fact, having LSD in the rear could help keep the VS in better shape, since it makes it harder to spin the rear wheels.  All of that is assuming loss of traction.  If you are driving in normal conditions, it will make absolutely no difference what type of differential you have in the rear.