Locker for a K3500 Dually

[DmaxMaverick]

John's correct. Do not use ANY additive. That stuff was for older limited slip diffs, which you shouldn't have (and don't, according to your test). For the older trucks (~1995), GM 85w-90 GL-5 was the recommended lube. Problems with some later on found the use of synthetic 90 GL-5 cured the issues.

The Gov-Loc is open (and should spin freely) until locked, exactly like an open diff, until it locks. With both tires off the ground, you should be able to spin one side by hand (or foot) fast enough to engage the lock. The wheel should lock and jerk at this point. The 100 RPM differential wheel speed may sound like a lot, but it isn't, and with both wheels up, it only takes 50 RPM's on one side to get it to lock (50 RPM's forward on one side + 50 RPM's reverse on the other side = 100 RPM differential). I can't tell anything by looking at the pic you posted, and I couldn't get the larger images to load at your picture album site (tiny thumbnails only??), so I can't tell what you have. Try posting the larger images in this thread, like you did the first one.

[JohnC]

I jacked up the back wheels and spun the tires. The tires on the other side turned in the opposite direction.

This is normal operation.

I have used power lock and true-trac lockers in previous trucks, and those lockers always engaged so that the wheels spun in the same direction.

Right, but the gov-loc is unlocked normally.

I had a friend hold the tires on one side while I tried spinning the other side, and they definitely held firm.

I assume you had it in park or in gear if it is a standard. Again, this is normal. If one wheel can't turn and the driveshaft can't turn then the other wheel won't turn either.

Have Steve spin his wheel backwards while you spin yours forwards. When it grabs you'll feel a jerk as both wheels try to turn the same way. (They can't if the driveshaft can't turn, but they'll try.)

Do you have the RPO codes in the glove box? Does it list G80?

[JetBoater]

It was in park... thanks, makes sense. I will give it another spin after work today in neutral. The glove box did not list G80 code that could see, just cargo weight capacity.

I won't use additive. Sounds like I have the right gear oil, GM 85w-90 GL-5. Here are a few more pics.





I found this diagram on the web also, and assume it depicts my carrier?


Sorry if the pics weren't the greatest.

[JetBoater]

pics are not showing up properly, I downsized to 800 x 600 but they are huge... sorry, will try to fix.

[JetBoater]

Smaller pics:

[JetBoater]

Ok, good and bad news.

Good news: I found the G80 number on another decal under the glovebox junk. This would indicate I have a gov-loc.

Bad news: I spun the tires and had my neighbor jam the opposite wheel when it got up to speed, and no clunk. We did this 3 times and felt the wheels slow down, but that was it.

What now? Rebuild or replace? Cheaper to rebuild it I guess....
JohnC / DmaxMaverick, I do appreciate you workin with me on this

[JohnC]

Just spin them in opposite directions as fast as you can. If nothing happens, then it isn't working. If it grabs, one wheel will try to switch directions.

Maybe time for new clutch packs.

[crashz]

Well, at least you have an easy axle to work on. The 14 bolt is real easy to set up, especially when ou don't need to touch the pinion gear.