1980 GM Corporate 14 Bolt 10.5in Full Float I’m guessing….some help

[roguewave]

I get one heck of a clang when shifting from reverse to drive, I was under it tonight and checking the driveshaft, u joints and spline. Sure seems like the slop is coming from the differential (or axels maybe but I doubt it).

My question is; what is the fix? I found no metal or shavings in the diff after pulling off the cover. Can shims fix it or am I going to need a whole new differential $$ ?

thanks for any input.


1980 3/4 ton round eye 4X4, auto/350 (400 was the original power)

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[bucket]

Notice the round "holes" that are formed where the two carrier halves are joined together? If there is four of them, you either have an open diff or possibly a Detroit locker. If it's open, it's just some wear in the spider gears that are likely causing the slop. Not a big deal really. If there's a Detroit in there, the slop is perfectly normal.

If there's three of those "holes", it's a Gov-Loc. Again, probably just a little bit of wear, but it's possible it could be hanging up too and locking up when it's not supposed to. Possibly a clang as the driveshaft changed directions and it happened to unlock.

 

[shiftpro]

Lower your idle speed.

 

[roguewave]

Thanks for the education and input, is there a fix to take the play out? and thus the noise? It’s kind of embarrassing because the truck is kind of a looker and when you put it in gear or back up the clang echoing up the driveshaft is rather loud and concerning.
The idle is a low as it can go.

You must be registered for see images attach

Notice the round "holes" that are formed where the two carrier halves are joined together? If there is four of them, you either have an open diff or possibly a Detroit locker. If it's open, it's just some wear in the spider gears that are likely causing the slop. Not a big deal really. If there's a Detroit in there, the slop is perfectly normal.

If there's three of those "holes", it's a Gov-Loc. Again, probably just a little bit of wear, but it's possible it could be hanging up too and locking up when it's not supposed to. Possibly a clang as the driveshaft changed directions and it happened to unlock.

 

[roguewave]

I’m wondering it the number on the passenger side axel housing tells me the axel ration ?

K G0252

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[DoubleDingo]

TH400? Normal. Just wave when the sound happens.

 

[roguewave]

TH400? Normal. Just wave when the sound happens.

yes 400

 

[Bextreme04]

yes 400

Mines a 1980 K25 350/TH400 and I get a pretty good clunk when putting it into reverse but not when going from reverse to drive. I highly doubt it is the rear end. Mine had what I thought was excessive slop that might have been making the noise, but I just put a Yukon grizzly in it and fully rebuilt the rear with new bearings all the way through including wheel hubs and I have about the same amount of slop in the driveline as before. This is with a measured gear backlash supposedly right in the sweet spot and a great wear pattern.

I'd honestly be looking at motor mounts, cab mounts, and transmission/transfer mounts. Get under the truck and see if you can see a spot where the T-case or transmission might be making contact with the cab.

Video might help us(and you) in troubleshooting it as well.

 

[Bextreme04]

I’m wondering it the number on the passenger side axel housing tells me the axel ration ?

K G0252

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The numbers don't tell you anything. The three letters before the number will give you year, gear ratio, and whether it is an open or locking diff though.

You can look up the codes here: https://www.gmsquarebody.com/threads/squarebody-rear-axle-codes.4185/

My 1980 K25 had "RHJ" which is 1980 4.10 non-locking