I changed the rear differential fluid today and the limited slip seems like it is limiting too much. Around slow corners the truck will shudder sometimes with noise. I used Redline lightweight shock proof. I've heard of others using this. The sales person were I bought the oil said the friction modifier was in the oil already. I'm not sure he was correct. Do I need to buy the additive separately? What would cause the rear end to do this? Does friction modifier make the "binding" less or more severe? Is there too much additive the the oil I used?

I hope the differential is OK. What else could be the problem?

 

I updated mi sig. so we all know what truck I'm talkinig about.

John

 

There is no set amount of friction modifier to use, it all depends on clutch wear and the brand of lube. Just because a brand says it contains modifiers doesn't mean it will work on every rear end. I prefer a brand that doesn't have any, too much modifier and the lsd won't work, the clutches slip.
The sound you are hearing in turns is the clutches grabbing due to not enough modifier. I add half a bottle at a time, do some figure 8s, if it still makes noise add another half bottle.
Take care not to overfill the differential, the spec is 1/2" below the bottom of the fill hole. Any more can result in seal leaks and oil contaminated brake shoes.

 

You can get posi additive at autozone. It comes in a tube.

 

I went out and bought some additive right after I posted. Going to put some in now and see if it resolves the issues. Can any damage occur driving without the friction modifier?

 

I added 4 oz of Sta-Lube Equa Torque friction modifier that I bought at Kragen. The chatter seems to be getting worse. Did I use the wrong oil or wrong modifier? Do I need more modifier? I drove without problems for about 5 mi. before any signs of chatter, now it chatters around every corner. I hope nothing is damaged. If I have to I will buy the additive from a dodge dealer and use non synthetic oil; I'll just be out the $50 I spent on what I thought was the best oil for my truck. I'm going to call the dealer Mon. to get their recomendation.

 

Well I used the bottle from the Dealer. It wasnt very expensive and I only used 1 bottle.

 

I've used several brands of modifier and have found the Dodge dealer's to be the best.
The others are cheaper but take more.

 

i ve had problems using the non - factor y stuff in the blue tube from advanced auto. my posi always used to worked properly. then, i changed out the fluid and added the off brand and my limited wouldnt work at all in mud the next day. i changed it out again and added the factory stuff from dodge ( their book says to add 10oz on a 4x4 dana 80) and it was ok again. now, i wont take chances - i run the oem

 

I used the redline shockproof heavy in my diff. I dont think redline adds the additive in the shockproof line. I had to use 10 oz. of additive before mine started to act normal again. I just used the cheap stuff from autozone.
good luck

 

Thanks Wilson. The fact you had good luck with Redline makes me a little more comfortable. I will buy at least 6 more oz. of the additive.

John

 

I got it. I can just feel the clutches in tight figure 8s. It took 11 oz of the Sta-Lube stuff. Thanks for the help. This is my first LSD.