Hi,
I have a 1993 Cummins D-250 with an auto and I believe a D70 Rear axle. 218,000 miles. Pulled about 20,000 miles with a 19,000lb 5th wheel RV. It is making some real funny noises going around corners. Here is the situation:

I hit the brakes, stop, accelerate left out of a stop sign and I get this chatter. Once I straighten up, it goes away. The same problem occurs when I turn right out of corners, but not quite as bad. It does not chatter if I roll around the corner (with out accelerating)

I have pulled the hubs, brakes look good. Re-torque the wheel bearings properly. Drums aren’t dragging when I jack the rear up and spin the tire.

It does have a posi, just not sure if that is the problem. Driveshaft u-joints are tight. I have done lots of rear end work (gears and lockers and such) but don’t know a lick about limited slip diffs.

Do you think it is:

-Improper gear lube or friction additive
-worn posi
-pinion gear nut (by the driveshaft) loose

Has anyone else had this type of problem before?


Thanks,

Brock

 

I don't know much about them either but if I had to guess I'd say it's your limited slip. You could jack it up and take off the cover, spin everything at different speeds and see what you find.

 

pinion nut will click all the time, my f150 does it, its your posi unit, with that many miles it would surprise me if it wasnt, pull the pan on the rear and take a look.

 

i was just driving today and it did not chatter untill it warmed up.

So, i am thinking it is worn clutches in the posi.

I will have pop the cover and see whats in there.


Will it hurt if i drive like this for a couple of weeks or shoud i be concerned and fix it right away?


Also are there any options for upgraded limited slip differentals, or can i just get a rebuild kit?

Thanks a ton.

brock

 

Before you spend a lot of time and effort, go to the parts-house and get TWO tubes of whatever brand of LIMITED SLIP ADDITIVE.

Squirt both tubes in the differential, through the filler-plug.

Then, drive around and around in figure "8s", for quite a few laps.

My truck started doing the same thing, a long way from home, with a trailer-load of cattle.

I expected the worst; but, merely adding two tubes of additive cured the problem.

 

well if its worn clutch pads it will get so bad that when you start going uphill or any bit of a load the clutch pack will just start spinning and you wont go anywhere. so try the additive and if that doesnt help, youll have to replace the clutch pack. im not sure if the dana 70 is the same set up as what ive worked on in the past but i think it probably is. most my work has been on a Furd 9"

 

I was under the assumption that power would still be supplied to the spider-side-gears, and that it would just perform in the manner of an "open" differential.

If the clutches can give out, such that the truck won't pull itself, then my next differential is going to be "open".

 

I would try puttingin the friction modifiers and see if this clears it up...

If it was not put in there the clutches could just be grabbing causing the clatter...

I had a chevy and put an Eaton Posi in it... The springs were so tight I clattered and skipped a tire all the time.. I had to change to a softer spring and put in a couple of bottles of the Friction modifer.. cleared it all up..

Gerry

 

Thanks for the input.

I picked up some friction addtitive from the parts store. I'll see if that clears it up.

 

Actually what happens is the spiders and the side gears get further and further apart. Hopefully you notice the extra "slack" in the driveline before they get too far out of mesh and you strip off teeth.

Try Bearkiller's fix first, but with that kind of mileage you ought to think about replacing the clutches. It's about 2-3 hours worth of driveway mechanicking.

 

Does anyone know where i can get a rebuild kit for the clutches in the differental?

Thanks

Brock

 

I got mine from Reider Racing.

http://www.reiderracing.com

 

well lets just say i had a 81' Bronco , that i changed the spider gears on and where it had been driven with a axle stripped in 4wd. the clutches were gone. and when i pulled out i went up a hill and it rolled back down. and i think if the clutches are bad enough out then when one axle slips it begins to spin the spider gears, which in turn spin the clutches even faster.

 

Different style posi. Ours will continue to move the truck even after the clutches are gone - it just acts like an open diff and there is a lot of slack.

 

Yea, I just rebuilt mine. I found several sets of Dana 70 clutches on Flea-bay. Dana OEM stuff pretty cheap. Clutch set is about $80 shipped.