Auburn cone-type limited slip differential -- Is Auburn friction modifier required?

[mbres2000]

I have an old Auburn limited slip differential that uses cones instead of clutches. Auburn's additive is expensive and I can't find it locally. Is there anything special about theirs vs. Ford XL-13 and others? Gear lube is GL-5.

 

[MolaKule]

Most GL-5 differential fluids these days contain an LS modifier chemistry but the only way to tell if it is sufficient for the specific LSD is to fill the diffy with the GL-5 fluid and do tight figure 8's in a parking lot with your windows rolled down. If you hear and feel chattering noises then add an extra FM in increments of an ounce at a time, and then repeat the figure 8 routine.

The chemistry of most OTS LS FM additives is pretty much the same.

O'Reiley's has the K&W TransX 402508 additive for around $10.00

or Advance Auto has the ILI LubeGard stuff for about $7.50.

 

[mbres2000]

Thanks for the info. My local AutoZone has the K&W in stock. The Lucas gear lube I'm using does have an LS modifier, but their tech support guy said he'd still add 2-4 oz. I think I'll go the figure 8 test route. Don't remember any chattering in the past, but did occasionally get a little chirp-chirp-chirp of a tire on tight corners.

 

[MolaKule]

Most people overtreat their LSD's and then wonder why they get stuck in the mud.

I would add only enough LS additive to get rid of any chirp or chatter.

 

[Rand]

not a fan of lucas gear oil it has had issues in the past.

 

[mbres2000]

BTW, the truck is a 69 Chevy C10 that now leads a docile life. It used to have a semi-hot 383 with an open diff, and would spin one tire like crazy, even when I didn't mean to. But it won't being seeing any of that, or any off-roading!

 

[mbres2000]

Brought the diff lube to within a 1/4" of spilling out the fill hole. Drove the truck 5 miles to a parking lot and did several figure 8s with the windows down. Didn't hear any noises at all. Also did a burnout that left two 15-20ft rubber tracks. Then did some more figure 8s at varying radii and speeds. So, the diff appears to be working fine with just the additive in the gear lube. Just need to top it off.

Thanks to MolaKule for the advice.

 

[2EHA]

Most people overtreat their LSD's and then wonder why they get stuck in the mud.

I would add only enough LS additive to get rid of any chirp or chatter.

some lsd vendors including auburn specifically recommend to use “non-synthetic” gear oil

any particular reasoning behind this?

 

[MolaKule]

Brought the diff lube to within a 1/4" of spilling out the fill hole. Drove the truck 5 miles to a parking lot and did several figure 8s with the windows down. Didn't hear any noises at all. Also did a burnout that left two 15-20ft rubber tracks. Then did some more figure 8s at varying radii and speeds. So, the diff appears to be working fine with just the additive in the gear lube. Just need to top it off.

Thanks to MolaKule for the advice.

Glad it worked out.

 

[MolaKule]

some lsd vendors including auburn specifically recommend to use “non-synthetic” gear oil

any particular reasoning behind this?

I have yet to see a technical, tribological reason for this statement.

 

[Greasymechtech]

some lsd vendors including auburn specifically recommend to use “non-synthetic” gear oil

any particular reasoning behind this?

Because they are stuck in the 1980's thinking that synthetic oil is bad.... bunch of fools!

 

[mbres2000]

some lsd vendors including auburn specifically recommend to use “non-synthetic” gear oil

any particular reasoning behind this?

Would be nice to speak with an Auburn engineer about it. And I mean engineer, not salesperson! Redline's website shows at least some of their synthetic gear oils are suitable for use with clutch-type diffs, but they don't mention cone-type.