Supercharged111
Truly Awesome
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I was not aware of this TSB. That tosses any theories out the window.
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I want to switch to AMSOIL Severe Gear in both the front and rear diffs.
Mistake in logic. I didn't say that Amsoil was somehow special in it's incompatibility. I referenced Amsoil since the OP specifically mentioned it, and because I have experience with it.How? Most gear oils have posi additives so I don't see what would make Amsoil so exclusively incompatible here.
IF (big IF) there's a G80 involved, it's got clutches that will be contaminated by the "posi additive" and they won't work (grip) properly.And since there is no posi present, what is there to hurt? The while point of a posi additive is to have the right amount of friction present to allow it to do its job. No additive means the posi won't slip enough. What does additive present mean for a non-posi? Jack **** from where I'm typing, but I'm willing to learn if I'm wrong.
But it's the modifier ("posi additive") that makes it compatible.I have not seen any technical specs on various gear oils, but when I've read the backs of containers, it looked more like carefully worded marketing, that says it could be used with positrac differentials not that it actually included a modifier.
The governor engages the clutch packs, the clutch packs lock the differential. But the important thing is that there's clutches, and those clutches are allergic to "posi additive."I believe the G80 uses some sort of clutch mechanism to engage the lock.
Good catch. I was looking at the service specs for a 10.5 (full-float) axle when I stumbled on that tidbit about synthetic oil being incompatible prior to a certain build date."at the ends of the axles tubes".... I'm confused on the location. The only gasket I'm aware of, is not really on the tubes, but between the axle shafts and the hubs, in the case of a full floating axle.
You're right. The ends of the semi-float axle would not have a paper gasket or silicone sealer that would be exposed to gear lube.I'm not familiar with semi-floating axles. I can't picture where a gasket would go, assuming you're talking about a flat paper type gasket.
Mistake in logic. I didn't say that Amsoil was somehow special in it's incompatibility. I referenced Amsoil since the OP specifically mentioned it, and because I have experience with it.
ANY gear lube--synthetic or mineral--with "posi additive" will be unsuitable for a G80 rear axle. At this point, I don't think the thread-starter has ever confirmed that he has or does not have a G80.
IF (big IF) there's a G80 involved, it's got clutches that will be contaminated by the "posi additive" and they won't work (grip) properly.
Guys cry endlessly about how the G80 is a "Locker" and not a "Posi" or a "Limited Slip". Which is fine, except that each of them use some sort of clutch assembly--either multi disc or cone. There's differences in how the clutches are engaged, and there's apparently some difference in the clutch friction material. The friction material in the G80 clutches isn't compatible with "posi additive".
But it's the modifier ("posi additive") that makes it compatible.
The last bottles of gear lube that I bought--specifically because it did NOT seem to have
"posi additive" said that it was compatible with posi differentials but only if the fluid was being "topped off", not a full drain-and-refill.
The governor engages the clutch packs, the clutch packs lock the differential. But the important thing is that there's clutches, and those clutches are allergic to "posi additive."
Good catch. I was looking at the service specs for a 10.5 (full-float) axle when I stumbled on that tidbit about synthetic oil being incompatible prior to a certain build date.
'Course plenty of folks use RTV silicone on the differential cover. I've never heard of synthetic gear lube damaging the silicone sealer on the cover--so I don't really understand why they're so wild about silicone on the hub/axle. But they are, and I'm just passing that along.
Thank you! finally someone understands the operation of a G 80 locker.
I understand perfectly. I'm not sure why you have a problem. Maybe my wording isn't precisely to your liking?
So what happens when the clutch packs get old and worn out? Can you get replacement parts for the diff?
I looked back at some likely sources, but...no...I don't have a specific date.Do you happened to remember what that build date is? I always figured mine was filled with synthetic, but I've put regular in it.
Maybe. Like I said...it just doesn't make sense to me.Maybe it's longevity through the warranty period that GM is worried about.
I suspect that GM sells--or sold--replacement parts. I don't know if they're discontinued by now, or still available.So what happens when the clutch packs get old and worn out? Can you get replacement parts for the diff?