72 3/4 ton 4x4 quirks

[Jvanloon]

Hey all I just picked up a 72 3/4 ton 4x4. The truck seems to be in good shape, but I'm just wondering if there are any quirks about this truck? Any special maintenance I should do? Anything I should keep my eye on? Any help is appreciated.
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[special-K]

Those are great trucks. The drivetrain is as updated as any truck built for nearly 20 year after...except better. Maintenance is change gear oil in rears,manual transmission,and transfer case every 30,000 miles and watch for leaks. If they seep just check keep the level up and see about replacing seal(s) when you can get around to it. With an automatic the service is the same as any. I'm not sure what the interval is,but a back flush and filter change are recommended. Honestly,I just keep the level up and never have a problem. The lock-out hubs I service once a year. I remove them,clean,and "oil" them,not grease. The front hubs/rotors should also get the 30,000mile service,which is cleaning and packing wheel bearings. Grease drive shaft & axle u-joints,tie rod & drag link ends every other oil change. If you have a manual transmission,grease the z-bar every 30,000. All these things are very forgiving,but those are just good guidelines to follow.

[mrein3]

An old timer once told me that in the middle of the summer I should put the t-case in 4Hi without locking the hubs and drive around a bit. He claims that you can get condensation in the transfer case which then sinks to the bottom of the case (oil floats) which can rust the internals down there. I've had my NP205 equipped truck since 1994 and haven't had an issue but I do get some 4wd work pulling broken docks out of the lake, etc.

Long story short you may want to use 4wd - at least engage the case in 4wd - every once in a while.

[special-K]

^^ Good point ^^

[Stocker]

Welcome to the best board on the 'net, bar none, from the opposite end of the state!

Congrats on your new truck! Having owned mine for 35 years, I'm hard pressed to think of any quirks. Other than a thirst for fuel....

Keep up on general maintenance items as suggested above, and fix whatever breaks -- which probably won't be much.
These things are solid old dinosaurs.

[One Chevy Scotty]

I have one and it is certainly easy to maintain....keep it lubed and the oil changed and you will be fine....I use the 4wd from time to time and have not had any problems with water in the transfer case....and yes, they are thirsty little monsters

[vectorit]

Welcome! I am just South of you in the Temecula area.

All of what everyone has said already is the best tips.

I have a K20 Suburban, and a K10 pick up.
Both weep gear oil from the trans/transfer case, so I just keep up on the lube to make sure all is right.
Running the 4x4 running gear from time to time on a dirt road is very good advice, I do it in both my old Chevy's and in my newer Toyota 4x4.

[Vintage Windmills]

Do you know the engine history? If its pretty old or original you'll want to run oil with a ZDDP additive since it probably has a flat tappet cam. Also maybe a lead substitute for the valve guides. ZDDP may cover that I'm not sure.

[Vintage Windmills]

Originally Posted by mrein3

An old timer once told me that in the middle of the summer I should put the t-case in 4Hi without locking the hubs and drive around a bit. He claims that you can get condensation in the transfer case which then sinks to the bottom of the case (oil floats) which can rust the internals down there. I've had my NP205 equipped truck since 1994 and haven't had an issue but I do get some 4wd work pulling broken docks out of the lake, etc.

Long story short you may want to use 4wd - at least engage the case in 4wd - every once in a while.

The old timer didn't know what he was talking about. The np205 has all the gears spinning all the time regardless of 2 or 4wd. All the shift rails do is lock the output shafts to the desired set of spinning gears. That said, It still probably wouldn't hurt to engage once in awhile to lube the shift rails and seals if nothing else.

[67swb72klb]

not realy any quirks just like most say very durable trucks not bad lookn also

[Jvanloon]

The engine is crate 350 put in about 12 years ago, and 4 years ago a hotter cam was put in and it was cleaned up a little. Not fully rebuilt, but inspected. Also, can you tell me what rear axle is in the truck? It's full floating. I know it's not a 14 bolt because I'm very familiar with those, and I'm pretty sure the 14 bolt wasn't made yet. And thanks for all the help guys! Reading your replies makes me even more excited about my new baby!
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[webfoot]

Probably an eaton HO 52, the diff cover will be round. Stouter than a dana 60 but harder to find parts for or upgrade. (parts are pretty expensive too, wheel bearing is $55 and it takes 4)

[Jvanloon]

Yea the diff cover is definitely round. Thanks.
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[Jvanloon]

Also just wondering, I haven't driven it much yet since it wasn't insured or registered until yesterday, but what kind of mileage should I be expecting? I'm used to a truck that gets 10, so when you guys say it's a thirsty truck, is it even thirstier than my previous truck?
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[webfoot]

That is right at what my 71 K20 gets.

[special-K]

I get 12.5 in my GMC with automatic. I also got that in one with a 400 SBC/4spd/4.10s/12.50x35 tires.
The idea of putting in 4wd occasionally goes beyond the transfer case. You want to turn your driveshaft and work the u-joint so it doesn't wear in one position. The same goes for the axle shafts,differential,bearings,and axle u-joints.
The rear axle is the Corporate rear,known as the HO52. It's very stout,yet lighter than a 14-bolt,with far better ground clearance. Parts are available. I wouldn't waste my time with the big box clowns or Johnny Come Lately Internet suppliers.Go somewhere like Napa or just get the numbers off your bearings and seals and match them up that way from anyone who deals with bearing & seal companies.

[Jvanloon]

Well I took her on the maiden voyage today, and boy does she drive nice. On the freeway, she cruises along at 65 nice and smooth, but the transfer case shifter does rattle above 60mph. Steering is a bit loose, but I'm going to jack it up and inspect everything and lube everything tomorow. All three gas tanks are filled, and work. The helper springs on the rear will definitely have to go, since every bump breaks my back lol.
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[mrein3]

Originally Posted by Jvanloon

Well I took her on the maiden voyage today, and boy does she drive nice. On the freeway, she cruises along at 65 nice and smooth, but the transfer case shifter does rattle above 60mph. Steering is a bit loose, but I'm going to jack it up and inspect everything and lube everything tomorow. All three gas tanks are filled, and work. The helper springs on the rear will definitely have to go, since every bump breaks my back lol.
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Being in California I don't suppose you know what a chopper is. Eh?
A chopper is a leather mitten with an attached liner for warmth. If you had one, simply sliding it over the transfer case shifter takes all the noise out of it while screaming down the slab at 60+ miles per hour.
A standard work glove or similar works too.

When I swapped my manual out for a th350 automatic, I replaced the transfer case adapter from the doner with a new one off the shelf from the local Chevy dealer. I'll have to roll under there and verify where it is exactly but the newer parts had a grease zerk that allowed me to squirt grease into the shifter bolt area which took a lot of noise out of the shifter. However it still rattles and still gets a chopper installed when I have to take it out on the road so don't go spending a ton of money on the newer parts - that stuff is WAY to heavy for that little of a better system.

[Vintage Windmills]

I wonder if a spring could be installed around the mechanism to hold the shifter from rattling. Just something to keep it held lightly against one side of the bolt instead of rattling from side to side?

[Jvanloon]

I've been working on it all day long. All fluids are changed, joints are lubed, camper shell is gone, helper springs are adjusted, plugs and wires are good and I checked compression, but I found one big problem. The frame bracket for the cab mount, is broken. The bracket is riveted to the frame, and I need a new one. I can drill out the rivets and then bolt in a new one with grade 8s if this bracket is available. Does anyone know of a reproduction bracket on the market? I can just weld it up and patch it since a big chunk is missing, but a new one would be easier.
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[landsurvey1]

How about some photos?

[kevmcrae]

Originally Posted by mrein3

Being in California I don't suppose you know what a chopper is. Eh?
A chopper is a leather mitten with an attached liner for warmth. If you had one, simply sliding it over the transfer case shifter takes all the noise out of it while screaming down the slab at 60+ miles per hour.
A standard work glove or similar works too.

When I swapped my manual out for a th350 automatic, I replaced the transfer case adapter from the doner with a new one off the shelf from the local Chevy dealer. I'll have to roll under there and verify where it is exactly but the newer parts had a grease zerk that allowed me to squirt grease into the shifter bolt area which took a lot of noise out of the shifter. However it still rattles and still gets a chopper installed when I have to take it out on the road so don't go spending a ton of money on the newer parts - that stuff is WAY to heavy for that little of a better system.

I had the same rattling issue with my 71 t-case. I ended up looking closer at the linkage and noticed it was loose due to regular wear. I replaced the washers and also added some rubber washers. No more rattle! Just make sure you don't get it TOO tight. still needs to move freely.

[Vintage Windmills]

Originally Posted by Jvanloon

I can drill out the rivets and then bolt in a new one with grade 8s if this bracket is available. Does anyone know of a reproduction bracket on the market? I can just weld it up and patch it since a big chunk is missing, but a new one would be easier.
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You should be able to find a good original takeoff on the parts board here. PM tkorinek as I recall he was parting out a 69K20 awhile back. If its the same as a 2wd I'll send you one.

[67swb72klb]

Originally Posted by kevmcrae

I had the same rattling issue with my 71 t-case. I ended up looking closer at the linkage and noticed it was loose due to regular wear. I replaced the washers and also added some rubber washers. No more rattle! Just make sure you don't get it TOO tight. still needs to move freely.

i did this same thing on my other 72 years ago it solved the problem keep a little lube on it also it will work smooth

[1972RedNeck]

Supposedly the side bracket from the frame to t-case should be removed. It is supposed to crack/break the transmission to t-case adapter.