How to check if LSD is working properly?

basinite

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This link is for a 2015 JK Willy's with a Dana 44 Trac-Loc. You will see both tires spinning in the same direction. I will try to find a video of a JL and post, but I'm sure Dana Trac-Loc didn't change from the JK and JL.




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Well the one thing I found interesting is there is no preload spring between the clutch packs. That is normally what you would find and would keep the axles "locked" under light load, like having both wheels in the air. But with no preload spring, it might be normal to be able to rotate the wheels in opposite direction with no load.

If you want to test it old school, turn off the traction control, drive off the pavement with one wheel in dirt or grass and one still on pavement and floor it in 2H. If you leave a black strip on the pavement, it's working!
Apparently no one reads the posts. Here's a picture I TOOK to prove it:

no spring.jpg
 

Bikemobile

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The load on the driveshaft is the factor here. The clutch packs are under a slight preload and activate under a difference of speed or fiction so they are reactive vs Some of the more aggressive limited slip differential’s which are proactive in that the clutch packs are always engaged in must slip or disengage to turn.

No springs equals no pressure. So with the transmission in park the wheels will turn opposite directions with it in neutral theoretically they would turn the same direction unless the friction in the transmission overcomes the friction in the clutch plates at rest.
 

basinite

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The load on the driveshaft is the factor here. The clutch packs are under a slight preload and activate under a difference of speed or fiction so they are reactive vs Some of the more aggressive limited slip differential’s which are proactive in that the clutch packs are always engaged in must slip or disengage to turn.

No springs equals no pressure. So with the transmission in park the wheels will turn opposite directions with it in neutral theoretically they would turn the same direction unless the friction in the transmission overcomes the friction in the clutch plates at rest.
This makes perfect sense and helps explain some of the discrepancies.
 
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This link is for a 2015 JK Willy's with a Dana 44 Trac-Loc. You will see both tires spinning in the same direction. I will try to find a video of a JL and post, but I'm sure Dana Trac-Loc didn't change from the JK and JL.

So I take it with the findings here it did change from the JK and JL.
Presuming that the JKs had the preload spring in them.
 

basinite

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So I take it with the findings here it did change from the JK and JL.
Presuming that the JKs had the preload spring in them.
Probably not, but I'm not certain. The technology is probably very similar from JK to JL, but that being said I couldn't find any useful info when I searched. Bikemobile brings up a good point about if your transmission is in park vs neutral and etc. However, I stand by what I said earlier; if you have a LSD your tires should spin in the same direction. Every limited slip I have ever owned (including Jeeps and Trucks) have done this. Not only mine, but family and friends (as well as countless YouTube videos demonstrating this).

If your tires DO NOT spin in the same direction, your clutch plates are probably worn, or some other issue. I purchased a new 2020 JL Willys that I'm hoping will ship in the very near future. It comes with a LSD. I will test it first thing when I get home and post my findings here on this thread, so we can settle this once and for all. Even if I am wrong, I will still post it. I am 99% confident when I jack it up and spin my rear tires they will both spin in the same direction. Could be wrong, but we will have to wait and see.

When I do my test I will try the tranny in park, as well as neutral (the normal way). We will conduct an experiment and see what happens. Should be fun.
 
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The load on the driveshaft is the factor here. The clutch packs are under a slight preload and activate under a difference of speed or fiction so they are reactive vs Some of the more aggressive limited slip differential’s which are proactive in that the clutch packs are always engaged in must slip or disengage to turn.

No springs equals no pressure. So with the transmission in park the wheels will turn opposite directions with it in neutral theoretically they would turn the same direction unless the friction in the transmission overcomes the friction in the clutch plates at rest.
My opening video was done with the transmission in neutral.
I have yet to see a JL with LSD lifted with tires spinning in the same direction yet.
 

basinite

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My opening video was done with the transmission in neutral.
I have yet to see a JL with LSD lifted with tires spinning in the same direction yet.
Just thought of something; I don't think the tires would spin at all if the tranny is in park??? Regardless of if you have an Open, LSD or locker differential. Am I overthinking this....LOL.
 

basinite

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I just received my new Willy's, which comes equipped from the factory with the LSD as a default option. I jacked up the rear end and gave it the old fashioned "spin the tire test", as I said I would do. To my surprise........they spun in opposite directions like an open differential!!! I am not happy with Dana doing this, Grrr.

Now we have no way to test our LSD's to make sure the clutch plates and etc are still in good working order. As to the OP's questions "How to know if LSD is working"? The only way I know how is to do what I did about an hour ago. I went down to a lake near my house, turned off Traction Control, kept the Jeep in 2H and had my wife climb a hill in the snow, while I stood behind watching. The LSD worked perfect and both tires stayed locked in the entire time while she was trying to climb the hill. Surprisingly, she actually made it up the hill in 2H!!! I guess I trained her well. LOL.

Needless to say, this may be a funner way to do it, but it is time consuming compared to the "old" way of just having to jack up your rear end and give the tires a spin.
 

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The only way both tires COULD turn forward together is with the transmission in neutral.

In park, the driveshaft will be locked solid. If you jacked it up snd turned the passenger side wheel forward the spider gears in the differential would spin the drivers side wheel the opposite DIFFERENTIAL direction.

As I said before, some LS diffs have spring pressure holding the clutch plates together. These are “tight” versions that are always on but allow slip for turning.

The dana LS is a “loose” LS that allows the spider gears and clutches to slip until a certain amount of slippage “activates” the friction surface on the clutches and locks the diff which gives you equal wheel speed left to right.
 

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I find this post very interesting and need to ask a simple question.... I looked up in manual and this is what it says about how to tow 4 wheels on the ground. So does that mean the LSD is having all wheels going in the forward direction.

4 wheel towing instructions. Page 375 of -2018-All_New_Wrangler-OM-3rd_R2 .png
 

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just lift one wheel up and try and spin. shouldnt spin freely if i remember right. if i get a couple mins ill lift my jeep and test. i Do have LSD and i know it works used it a lot on the trails
 

basinite

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just lift one wheel up and try and spin. shouldnt spin freely if i remember right. if i get a couple mins ill lift my jeep and test. i Do have LSD and i know it works used it a lot on the trails
You need to lift both tires and make sure your tranny is in neutral. Let us know what yours does.
 

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You need to lift both tires and make sure your tranny is in neutral. Let us know what yours does.
just did this on my 76 pick up to figure out if it was an open dif... it was LOL. ill report back this evening
 

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How to check if LSD is working properly?

Typically, wait at least one hour. Sit in a comfy chair. By then a sailor will come through your wall and tap you on the shoulder,
 








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