Anybody have an idea of what the breakaway torque for a stock Auburn unit is? Mine was measuring roughly 30 ft-lbs and that is obviously low - its pretty easy to get the inside tire to go up in smoke when I power out of a turn in second or third gear.

A buddy of mine was setting up the differential in his Datsun (2200 lb car with driver) with 75 ft-lbs breakway torque.

Which brings me to my next question - has anyone shimmed the springs on Auburn units to increase preload? I haven't ever had this type of differential disassembled so I'm not sure that it would do any good to shim the springs if the cones are worn into the casing.

I have GM limited slip additive in there right now, can't recall what weight gear oil I put in off the top of my head - probably the standard 85W-90.

 

I can't say what the breakaway torque is, but I can usually torque my lugs to 100 ft-lbs with both tires off the ground.

 

There are no springs. It uses a cone clutch system where the cones are forced into the side of the case by the load on the spider gears. Its a non-rebuildable system. You might try changing the fluid to a Mobil 1 or Castrol Syntech and leave out the friction modifier. This might increase wear but increase static friction as well.

 

I was under the impression that the little yellow coils I saw inside were springs:

http://www.auburngear.com/aftermarke...f-exploded.jpg

Will change oil and leave out friction modifier next time to see what that increases capacity to. I have heard it's good for about 15% increase in torque capacity (but that was with clutch units). Auburn's website says to use friction modifier.

Thoughts?

 

Whoops, you're absolutely right. I was thinking about the cone clutch itself and misspoke. If you take off the cover and play with it you'll see that the springs aren't under much tension, unlike an Eaton with clutch plates that rely more on the base tension.

I should shut up because I'm an Eaton fan, they have more clutch area.

No doubt changing the fluid will have an effect, but it will wear the clutch material quicker.

 

I'm old school back to the 60s' and 70s'. Never added friction modifiers to Auburns back then. Friction modifiers were added to Eatons to prevent the EP additives of rear end lube from attacking the bronze particles imbedded in the clutch material. In the GM service manuals back then, GM advised the use of 'positraction additive' only in clutch pak posi units.
Torque specs generally ran 75-110 ft.lbs. for breakaway torque.
Springs can be shimmed to compensate for cone wear. As cones wear,they go further apart,thereby decreasing the spring load.
Once the cones are 'wore out'. the 'cones' are no longer functioning as 'tapered' clutches and their ends are bottoming out in the differentiial case.
As Auburn cones wear out, the 'worn out' material (iron/steel particles) are in suspension in the fluid and act like abrasive/grinding material to cause further wear. Changing/freshening up the fluid will prevent that abrasive mixture from also causing wear on bearings,seals,ring and pinion,and spider gears.

 

4th Gen OEM 10-bolts use the Auburn Clutch-Cone posi. When the cones wear-out they they are "done" and there is no rebuilding the Auburn posi unit. Auburn does offer their Pro-Series replacement posi unit with a three year free rebuild/replacement.

WD

 

Here's what Auburn has posted on their FAQ page.

http://www.auburngear.com/aftermarket/faq/#q8

 

So it seems that although low, my torque values aren't THAT far off what Auburn says. Thanks for that link. Still weak though.

Last time I broke the spider gears I just got a whole rear end out of another car with 4.10's instead of going through the effort of setting up a carrier in the 10 bolt. I guess if it gets too bad I'll be dropping in a Torsen T2R.

 

I'm glad that was of some help.

When my Auburn wore out in my 95, I replaced it with a Zexel Torsen from a 2000 Z28. Keeping the same gears made for a simple repair.

 

did you check out randys ring and pinion. i had ordered some parts to increase the torque capacity with their special springs and clutches. it will chatter on turns but stick tight

 

That's for Eaton's.