Dana 30 Powr-lok Fluid & Amount Of Friction Modifier Issue

Roughly 12 years ago, I installed my 1982 Dana 30 into my 1971 RII with a complete refresh of all bearings, seals, ball joints and a used Powr-Lok with new clutches. I had a pro shop install the LSD, replace the clutches and set up the R&P. I installed the axle, filled the differential with fluid and added the friction modifier.

Being so amazed with the tighter turning radius, I just figured the LSD clunking in tight turns was a break-in issue.

The clunking never quit after years of reliable service. I did change the Lucas 80W-90 fluid and added friction modifier about 5 years ago. I used Delco Limited Slip Lubricant Additive 88900330. Both MOPAR and Motorcraft have their own variety of LSD additive, but not sure if they’re any different.

Nickmil said there should be no noise from a Powr-Lok but didn’t really have a solution. He theorized that something was damaged internally.

The clunk bothered me, but to have others on trail runs ask me, “What’s that NOISE?”, got irritating.

I finally bought a VEVOR differential bearing puller, an Eaton True-Trac and all the stuff needed to swap a differential in my garage thinking I might have to change out this LSD.

I spent a few hours of research on this site and the web. There are plenty of related threads here but nothing addressing amount or type of friction modifier required. I did find a couple of web sites that indicated TOO MUCH friction modifier could cause LSD noise or other strange handling. HMMM! I will say that a Dana 25 / 27 may never exhibit such an issue because they don’t turn as sharp as a Dana 30 (just speculation).

I’ve been using Lucas Performance 80W-90 in both differentials for 12+ years. My rear D44 Powr-Lok never makes a clunk and works great. It also has aggressive clutches. I also add the little bottle of friction modifier to it.

The Lucas label says its suitable for LSDs, so my last effort was to drain and refill the Dana 30 but NOT add any extra friction modifier.

The first drive yielded no difference. However, I know that all the clutch surfaces have to be ‘worked’ to get new fluid to them. I drove in hard sharp circles both left and right. I did figure eights, also. The noise was decreasing!

I took it out for a drive the next day and absolutely NO NOISE in tight corners, either accelerating, or decelerating. Maybe the issue is resolved…time will tell.

I made some hard circles on pavement. I can always feel the rear end grabbing on tight corners and some rubber skid occurs. To have the same thing on the front end was really amazing as that LSD works great so long as all tires are in contact with the ground.

While it’s still hard to believe that too much friction modifier can cause those clutches to lock up so hard and clunk when they release, that’s what I think was happening. I am still a strong proponent for the Powr-Lok!

For now, my True-Trac and bearing puller are on the shelf. I won’t make any final decision until after this years’ trail runs.

 

I suppose this would be a testament that you really can have too much of a good thing ?
Never have experienced what you have.
Early QTracs 1973 came with Chevron Aviation oil in them (similar to ATF).
When they soon had complaints about stick/slip with the differential inside the unit they had yet to develop
Qtrac fluid as it later became known.
But figure 8s with a Qtrac filled with ATF was the procedure for cleaning/flushing a really noisy/chaterring unit later on.
Then a fresh refill with Qtrac fluid quieted the unit up.
Glad you can become happy with your unit now.