unLIMITED SLIP DIFFERENTIAL?!?!

[Texas Diesel]

Had a chance to test my unLSD pulling up the boat ramp yesterday. One wheel in the grass, dug a pretty trench, the other wheel on the ramp didnt seem to notice that I was trying to get the boat out of the water. I put a MagHytec and Mobil 1, had the friction stuff ready but didnt have a chatter in turns so I didnt add any, figured the synthetic was slippery enough. Opinions? Comments?

 

[jwdeeming]

I don't have one, but my buddy with a Phord says this does happen with an LSD. He says there is a torque limit - if the torque imbalance between the two wheels gets too great, it will slip and only spin one wheel. He says if he puts one wheel on the pavement, one on the gravel shoulder and stomps the go pedal, only one wheel will spin and this is normal behavior.



I just had this conversation with him because I was bemoaning the fact that I allowed myself to bring home a new truck without the LSD. He said don't bother - for trucks this size, a locker is the only way to go.



Hope this helps.

JimD

 

[Texas Diesel]

Thanks Jim for your input. This sucks, my 95 Dakota, V-8 & "trac-loc" will burn rubber with the wheel on the pavement. That is what I call "LSD". This one does not even TRY to transfer torque to the wheel on the pavement. You are better off w/o a LSD, it is easier to install a locker in an open diff.

 

[BV]

LSD's

Gee mine must be broke cuz I can dump the clutch and hit the go pedal which leaves 2 black strips on the street or 2 trenches on the gravel driveway.



Sounds like there is to much modifier in the fluid or the clutch packs are to loose.

 

[thepitts]

9989

Mine must be broke also, it will leave two black marks. I also did a test by jacking up one side at a time and trying to move the truck. Boths sides would move the truck with the tire off the ground.

 

[jwdeeming]

BV,

The point was that TexasDiesel had one tire on pavement and one on dirt, with a load on the truck. That creates the potential for a pretty large torque difference between each of the rear wheels. Cutting two patches on asphalt, or two trenches in dirt would be expected behavior because of similar traction.

Just my guess - not an expert.

JimD

 

[Vaughn MacKenzie]

jwdeeming is correct. . . I recently mastered the 3rd gear launch and can lay major rubber under both tires for several yards. But in the winter if one wheel is on ice and the other wheel has traction, I will go absolutely nowhere. Remember maximum torque is in 1st gear, which makes it much easier to slip the rearend.





Vaughn

 

[klenger]

I ordered mine without the LSD because of all of the comments of poor LSD performance. I was thinking that I might install a better system sometime in the future, but really haven't noticed the need yet. The only time I have noticed where the LSD might help is on wet pavement, where the traction would be equal, but the tires can brake loose because of the torque. In snow, 4x4 works fine.

 

[jwdeeming]

I've been trying to learn a bit about this before I chunk some money on a rear end. There are some old threads on this subject that I read today that are really enlightening - you guys might want to search on "limited slip" and check them out.



Hilights for me were:

- several reports that not all LSDs are the same. Might be differences between Dana 70s and 80s

- may be differences in "assembly" that cause varying torque settings.

- DC manual says if you jack up one rear wheel and try to turn it with a torque wrench, it should turn at between 25 and 100 foot pounds.

- One member reported getting a reading of 235 foot pounds!



There seem to be several variables here so everyone with an LSD may not see the same behavior, but it does seem to hold true that limited slip differentials do slip - eventually.



I have a recent 4x4 magazine article comparing different setups, LSDs versus lockers, etc. It seems to support the above findings on LSDs and does not recommend them for "serious" fourwheeling.



I just don't know yet if I want to put up with Detroit Lockers on a daily driver that I have to park 3 or four times a day.



JimD

 

[ET]

mine works too good i can't keep tread on the tires, if i turn a corner with any power. all i get is chirp chirp chirp untill i'm around the corner.

 

[DarrellB]

I have the same problem and with almost 800ftlbs of toque driving in the rain or on wet roads is really fun. You sould see the looks on people faces when they see a truck this size brodsliding in their direction.

 

[MCummings]

Originally posted by DarrellB

I have the same problem and with almost 800ftlbs of toque driving in the rain or on wet roads is really fun. You sould see the looks on people faces when they see a truck this size brodsliding in their direction.

WHOOHOO, THAT'S WHAT I'M TALKIN' ABOUT!!



Has to be the coolest thing. Nicest thing is compared to my "old" gasser, was, when my big Duallie goes sideways under acceleration, the Wheel speed isn't excessive Which Translates to a very controlled slide,, haha, you SHOULD see other peoples faces,, It looks like they have seen the world come to an end as they know it, and you are the Devil with the intent to kill EVERYBODY in the world.

Well, that's what the faces of Econo box drivers look like.

Mustang and Camaro owners usually just have dropped jaws.





MerrickNJr

 

[Big P]

I'm currently on my 2nd Dodge ram with a posi and they both suck! I should be ordering the Cummins in a couple of weeks and I will get the posi again, but my question is will taking some of the friction modifier out help the situation or just burn up the clutches?

 

[Gizmo 007]

Mine will leave FOUR big black streaks on any surface, and with one tire on pavement and the other on gravel. The rearend wil chatter and lock in, squalling all four. Guess I got lucky.

 

[Okie-Go]

Wish I had been lucky. I have a locker installed after I bought the truck and love it. I would only get stuck with a load and to me that is no good. For serious traction with a load I would get a locker. (My 2 cents. )

 

[BV]

LSD

Tried it again with one tire on the hard top on one in the soft. Result was you could see the tire track in the gravel but it didn't spit it everywhere. Traction was very acceptible.

 

[Diesel Freak]

Originally posted by MCummings





WHOOHOO, THAT'S WHAT I'M TALKIN' ABOUT!!



Has to be the coolest thing. Nicest thing is compared to my "old" gasser, was, when my big Duallie goes sideways under acceleration, the Wheel speed isn't excessive Which Translates to a very controlled slide,, haha, you SHOULD see other peoples faces,, It looks like they have seen the world come to an end as they know it, and you are the Devil with the intent to kill EVERYBODY in the world.

Well, that's what the faces of Econo box drivers look like.

Mustang and Camaro owners usually just have dropped jaws.





MerrickNJr

hehe, yep, I know the feeling

 

[Ramafid]

I see you have an ETH. That means you have a dana 80 which means you have a Trac-loc LSD. These units stink!!! I have owned two in the past and they were both crap. I have the dana 70 which has the Power-loc LSD. Works like a dream. I have been on snow and ice with one tire and pavement with the other and can take off ( full throttle) with no wheel spin. The Power-loc is just a lot more HD.

 

[KWIKKURT]

My Hybrid Dana 80 Limited Slip worked as it was designed for about 25,000 miles which was about 5,000 miles past the Real Bombing. No it is worthless. I read months ago that some of the 80's had improperly machined housings that would cause early clutch failure.



I also read you can boost the clutch performance by changing the clutch pack "Packing Order". I know years ago "Back on the Farm" we used to do this to John Deer Tractors PTO's Drive because we had a Bailer we had bombed and it would spit hay out like you would not believe. But it would slip the Ptos or shear drive pins. So we would add one clutch pack, shim up the springs or just change the order of the packing.



When I have a little time I will yank mine out and see what we can do to improve the stock setup. I want but cannot afford the REAL THiNG" YET