Archived Help, Binding Or Lurching In Rear End

[Henry]

Getting on here is becoming a habit. I just replaced my rear driveline u-joints because one was screaming at me and turned out to be near failure. I just replaced my rear diff gear oil with Amsoil last week. I noticed that intermittently, and only when I am making a tight turn from a stop, something in the rear-end seems to be binding slightly. When this occurs, it feels like the truck lurches mildly. This disappears when I straighten the truck out. There is no discernable noise when this binding or lurching occurs. I have looked at the front drive line u-joints and they all appear to be fine. It really feels like it is coming from the rear end. The new u-joints are thoroughly greased with synthetic grease and the rear diff is full of oil. Is the Amsoil arguing with the limited slip rear end? Do I need an additive in the rear diff with the Amsoil to make the limited slip work properly? I can't imagine that it is the Amsoil because that is what I used before and never had an issue. I am truly at a loss. I'd sure appreciate some input if you think you know what the cause may be. Thanks in advance!#@$%!

 

[jmadden]

guessing you have a dana 70 rear and as I understand it... the side gears are loaded when you turn... in the 70 the thrust washers have been known to wear and fail [was a write up at some point in the past in the tdr mag]... guessing as they wear and fail there could be some binding. Seem to recall the issue being attributed to truks w/ more than 130k on them... and it's unique to the 70 rear.

 

[Henry]

That is an interesting thought. If that was the problem, wouldn't the truck act similarly every time I started from a stop in a turn? It only acts this way intermittently on accelerating from a stop in a turn.

 

[jmadden]

If I figure out what box the old mags are in I'll see if I can find the article and see if symptoms are listed... if only I had unpacked from the move last year. It'll be a couple days, unless someone else can shed some light on it.



any noise? chatter in the turns? low speed knock? when you changed the fluid did you drive in figure 8's [10-12 of them] to lubricate the clutch packs? Don't see anything on diff binding in the '04 service manual... if/when I get my y2k manual back I can look in it too.

 

[Henry]

I sure appreciate the response. I searched the old threads and it looks like I may need to just add a little friction modifier to the rear diff. I shouldn't need it with the Amsoil 75W-90 oil, but it shouldn't hurt anything to try it. I was going to track down the Mopar stuff unless someone knows of a better product. Thanks again!

 

[Larry Willard]

I have changed mine multiple times with Amsoil, and only once did I have that problem, adding the Mopar limited slip "stuff" did the trick. Don't forget to do so,me figure 8's in a parking lot to get it mixed into clutches.

Larry

 

[ROADWARRIOR]

Sounds like you need some friction modifier.



Dan

 

[ELaslo]

You can get friction modifier also from the Ford or Dodge dealer.

 

[Extreme1]

Add 1 ounce of the friction modifier! Then go do some figure 8's and drive it a few days before adding more. I got a deal on my LSD carrier from a member because his new truck came with too much modifier in it and he got stuck in a field (farm truck). He put in a locker to solve the problem.



I disassembled and cleaned up the carrier and installed it with no additive and it didn't start to bind until 3,500 miles later. I added 1 oz of modifier (with a MagHytek cover which holds 2 gallons of lube) and that was all it took.



Edit: The mopar stuff seems to be the best. It's a little more $ but you don't need as much.

 

[Henry]

Added the modifier and it seems to have solved the problem. It's interesting that I have never had an issue using Amsoil before and now it wants to act out. Regardless, thanks for all the input folks!

 

[KevinSmith]

The friction modifier for the limited slip would be my suspect of choice.