Engine/Transmission (1998.5 - 2002) Limited slip giving me the slip!

[EdK]

Since changing the rear differential lube to full synthetic and adding two bottles of MoPar limited slip additive (dealer said to ALWAYS add it) my limited slip acts more like an open differential. I figure the lube is too slippery thanks to the MoPar additive.



Do you think changing out the gear lube, but NOT putting the MoPar additive in will return the limited slip function, or did I ruin it ? #@$%!



Ed

 

[EBung]

I would put ONE bottle in.

 

[rkressg]

Two bottles is too much. About 1/2 is more than enough.

I gave up adding the additative to my rear because it did nothing. I am going to disassemble the rear this spring and re-stack the clutches (they have about 10 clutches and 10 disks, but they are all stacked together, not disk/clutch/disk).

 

[EdK]

A thought

I thought about changing out the existing gear lube and refilling with regular dino, but not adding the MoPar stuff. I'd drive it that way for a few hundred miles, watching for chattering when turning, then dump it and refill with synthetic ONLY.



Thoughts?

 

[aircop]

I would dump whats in there, put in new synthetic and drive it. If it chatters add a bottle of the limited slip addditive. Use only as much as you need to keeep it from chattering.

 

[AFoulk]

Most of the synthetic gear oils have additive in them already.

 

[FTwardoch]

When I had my PowerLok installed (they rock!) the shop put in Royal Purple with NO additive.

 

[2-ND TIME]

Limited slips

Does your synthetic have the additive in it ? If so you have added double what is required. Find that out Q1. After you filled it up did you do a bunch of figure 8's to mix the oils up? At a parking lot and night works well less people wonder what you are doing? I take it that when you need the limited slip it isn't working? Might the clutches be warn? I have used the Mobil 1 75W/90 since new and it works wonderful. I add more modifier then nessecary and it still works the way it should! You may have (alot of modifier on the clutches and have to work it off and to mix it?)

 

[EdK]

Another idea

I'm sure the dealer's advice to add TWO bottles of additive did me in. I'm trying to think of how to get rid of the excess additive, thus the original idea of changing to regular diff oil for a few hundred miles... trying to work the additive out of the clutch plates.



Another idea would be to remove the cover instead of sucking the old oil out. Then I could spray the clutches down with brake cleaner, dry with compressed air, and refill with new synthetic lube. Anyone know if the brake cleaner wil damage the clutch plates?



Ed

 

[AFoulk]

That would be the perfrect time to restack you clutches too and inspect them for wear.

 

[2-ND TIME]

If anything I would only replace the diff oil with known oil that doesn't have the friction modifier in it. Yes inspect the clutches but maybe hold off on adding the modifier for a week or two till you figure that the modifier is out of the clutches. Myself I wouldn't spray it with brake clean. But that is just me. I am toooo cautious.

 

[DFerverda]

I would drain the new oil out and save it. Then refill with new oil and if you need modifier, add some what you took out in the first place that you nuked with modifier. I use royal purple but add 1/2 bottle of modifier after a while cause it started to
"growl" a bit.
Dirk

 

[BDaugherty]

My experience has been that with a new clutch type limited slip, you'll need friction modifier to prevent chatter. With a worn out one, you don't need it at all. Remember that you can always add straight oil and if it chatters, THEN add the modifier. I recently rebuilt the trac-lock in my D80 using new clutches and discs. I staggered them instead of using the factory arrangement and I really like it. To be honest, it's a lot like driving a spool when unloaded, but when I have some weight in the back it does slip. With the long wheelbase, there are no driveability issues. What I really like is to be able to stop with one tire on dry pavement and on in the dirt and when I nail the throttle, it will spin them both.

Also, brake cleaner should NOT hurt the clutches. However, what I would do in your shoes is just to drain/fill using new oil of your choice and not add any more additive.

 

[AFoulk]

Bdaugherty, where did you get your kit to rebuild yours? I wanna restack my clutches, but I was thinking of just getting a rebuild kit incase I take mine out and they are shot. It doesn't do anything but slip right now.

 

[BDaugherty]

I bought my rebuild kit from Randy's Ring and Pinion. It was pretty expensive... around $200. Before I rebuilt mine, I could put the rear axle on jack stands and with the transmission in gear grab one tire and turn it, making the other tire spin the other direction. That's how loose and worthless mine was. I'm very happy with it now.

One thing to mention is that there are apparently two different possible styles of limited slips available in Dodge D80's. According to the salesman at Randy's, you have to pull the cover and look at the shape of the cross pins. It's either diamond or oval if I remember correctly.

 

[AFoulk]

Well, thats good to know. I guess mine isn't that bad yet. I can jack mine up and turn one wheel, and the other one still turns the same direction.

 

[Gary - K7GLD]

Just too much modifier - don't sweat it, no harm to the clutches - lots of guys limited slips aren't working right, and they don't even know it... :-laf:-laf



Swap in some new stuff, add NO additive, do the figure 8's, and if chatter is too heavy, start with a half bottle of additive, drive for a while to check results, and keep adding more if needed - but slowly, and after putting on a few miles to verify.



There's LOTS more effort to re-stacking clutches than the casual advice seen here - give it lots of thought before diving in...



It always SEEMS easier a few months AFTER doing the job than at the time... :-laf

 

[EdK]

Thank you

Thanks to everyone for the suggestions. I've decided to drain it and refill and watch for chatter.



Ed

 

[AFoulk]

I changed my rearend lube to the Royal Purple stuff a few weeks after i bought the truck. It already has the additive in it. Could the RP stuff have to much additive in it for my application? I didn't really pay much attention to the LSD when I bought the truck and it had the factory stuff in it. I don't know if it worked better than it does now before I changed the oil.

 

[Gary - K7GLD]

I changed my rearend lube to the Royal Purple stuff a few weeks after i bought the truck. It already has the additive in it. Could the RP stuff have to much additive in it for my application? I didn't really pay much attention to the LSD when I bought the truck and it had the factory stuff in it. I don't know if it worked better than it does now before I changed the oil.

YUP - that's why I mentioned further above, that MANY guys don't really KNOW if their LSD is working properly - or at all!



The 2nd generation LSD is just THAT, a "LIMITED Slip Differential", not a gear type or locker, so a significant percentage of slippage is designed in, and NEEDED for proper operation (and decent lifespan!), It has been posted on this board that about 90-100 ft. lbs is the threshold at which the differential should normally start slipping - that's with one wheel in the air as it is measured for slippage point.