12 bolt LSD axle clunk?

[[JP]]

I guys, need a little help to put my mind at ease and check if this is normal or not.

Seeing as I’ve never driven any other truck other than mine I don’t know if what’s happening is normal or I should be worried.

So basically I had a 12 bolt open diff, that kind of went wrong and I managed to get another diff, 12 bolt was well, which I had a bit of a result with it as my axle rebuilder guy found...

the differential in it was actually an early clutch-type limited slip diff which I believe was made by Eaton for GM, the part no. is ED 30060.
It 'feels' like an open diff when turning by hand, and only grips when one wheel tries to turn without the other under load.

Does anyone know much about these?

I used Kendall Limited-Slip Gear Lubricant SAE 80W-90
I then added a bottle of friction modifier to the diff as been told it would quieten the diff down, but it has not made much difference.
When driving around town is kind of ok on the tight turns setting of road junctions, but after a long drive, I guess once the oil is warm, then the clunking is quite noticeable, anything with the wheels not dead straight and it will clunk.
It feels like the back end is skipping along, it happens when setting of junctions when turning, even if only a slight turn on the wheels.…I think the only time it won’t clonk is if I’m not accelerating, like going downhill and let it roll…

Is there a way to adjust an axle so it doesn’t clunk this much? Or is it normal and no problem?

Thanks
JP

[jayoldschool]

Was the "friction modifier" the GM stuff? Is the Kendall synthetic?

[[JP]]

Hi, the friction modifier was this one:

Torco Limited Slip Additive
TYPE (for General Motors)

http://www.ebay.co.uk/itm/1719631494...%3AMEBIDX%3AIT

the Kendall was this one




thanks!
JP

[jayoldschool]

If it were mine, I would drain it, refill with regular gear oil (no "special ltd slip additive), and add real GM posi additive.



However... are you SURE the posi is a clutch type? It sure sounds like a Gov-Lock the way you are describing the way it works...

[andyh1956]

Every Eaton pre-loaded clutch type diff I have ever owned was "Clunky" on the turns. Makes me feel good knowing there is something back there that will work when I need it to...

[[JP]]

Originally Posted by jayoldschool

If it were mine, I would drain it, refill with regular gear oil (no "special ltd slip additive), and add real GM posi additive.



However... are you SURE the posi is a clutch type? It sure sounds like a Gov-Lock the way you are describing the way it works...

errmm.... the axle builder dude said was an early posi, but I dont know anything, he knows his stuff though, he builds drag cars etc...
How can I find out what you are asking? guess its a case of looking inside right?

Originally Posted by andyh1956

Every Eaton pre-loaded clutch type diff I have ever owned was "Clunky" on the turns. Makes me feel good knowing there is something back there that will work when I need it to...

well.. that's good to know you had the same experience.
the damn thing is so clunky that I dont even accelarate hard when doing turns..... Now I'd love to do some doughnuts, after all, having a 350 V8 and skinny tyres that's what its all about, but currently I only dare to spin the wheels when on a straight line as the clunk noise makes me too afraid to break something...

[jayoldschool]

For sure, take others' experienced advice. I don't even know if there is a Gov-Lock available for the 12 bolt. You could still try the GM additive, though.

If it were mine, I'd sure want to see what was in there...

[lumpy63]

the gm posi additive is the best i have found , back in the day I had a hot 69 camaro ss 396 375 hp with a moroso clutch type posi unit. on extended straight line driving i found that the lubricant would work its way out of the clutch packs. try going into a large parking lot and making a series of figure 8s this will work the lubricant back into the clutch packs. personally a little clunking and tire chirping around corners is typical of a nice tight posi.

[[JP]]

Originally Posted by jayoldschool

For sure, take others' experienced advice. I don't even know if there is a Gov-Lock available for the 12 bolt. You could still try the GM additive, though.

If it were mine, I'd sure want to see what was in there...

damn.. I should have taken some photos of it when it was all apart and put back together!
Basically my axle builder took all the bits off the axle I sourced and put it inside my axle casing (because the axle I had sourced they had cut the mounts off)

How would I know if its a posi or gov-lock?

[jayoldschool]

Google pics of them. They look completely different. Like I said though, I don't even know if they make one for a 12 bolt. If it is a clutch posi, GM additive will probably help.

Just pop the cover off to ease your mind.

[61K10]

If the posi clutch pack was taken apart or rebuilt, you need to do the figure 8 thing. as lumpy said, you need to get oil back in between the clutch plates.

[[JP]]

oh right!! I thought he was joking! hahaha

ok, I will do that on Friday as have the day off work

[andyh1956]

One other thing, be sure you use GL5 gear lube. GL4 is for trannys (not THAT type of tranny) & GL5 is for diffs.