LSD Friction Modifier pooped out

[Vaughn MacKenzie]

I run Amsoil 75W90 which comes with friction modifier in my Dana 80, works good as-is without adding any extra modifier.



However after taking a fast, hard drive to southern California and back, my rearend was chattering and jerking like I'd just changed to standard gear lube with no modifier. It was pretty intense. Adding a tube (4 oz) of friction modifier smoothed it out but I thought that was a strange occurance.



Anyone else have this happen--have the friction modifier weaken or quit working?? I hope I didn't harm anything. The lube was still new looking and clean. It had 12,000 miles on it when I left and 15,000 when I got home.



Vaughn

 

[MikeR]

Hmmm. Been running the same Amsoil 75/90 as you and been to San Diego and back with no chattering.

 

[John]

Vaughn, I experienced the chattering while using Red Line synthetic gear oil and Red Line friction modifier. It seemed after I fine tuned the LSD characteristics (with Red Line friction modifier), I had to periodically add more friction modifier to JUST eliminate the chattering in low speed corners.



I had to add some Mopar friction modifier to my Amsoil Series 2000 75W-90 gear oil to eliminate the chattering in my LSD. I haven't had to add any additional friction modifier since I was through tuning the operation of the LSD though.

 

[lschultz]

My form a gasket was seeping so I took the cover off and redid it. Onyl had about 12000 on it. I drained the old out(still looked like new) and put it back in. No friction modifier. No problems yet. Son has around 60000(no fm) on his since we changed it and no problems. Seems like some need it and some don't.

 

[Archive]

Vaughn,

I've had the EXACT same thing happen to me with Mobile1 75w-90 synthetic. It operated perfectly for 8000 miles, and then I made a quick weekend trip from Memphis to Gainesville, Florida and it started to chatter. The chatter went away with a tube of friction modifier, but I went ahead and talked myself into replacing the Mobile1 with Red Line 80w-140. (I tow alot. )