All time 4x4 / NP203 Truck Questions, hard to make tight turns

[TCulpepper]

Hey guys, so I purchased an all original 1977 Chevy K20 with the all time 4 wheel drive, I just got it back on the road for the first time since 2004. Apon driving it, anytime I make a turn, most noticeably to the right, the front tires start to bind/hop and makes it very difficult to turn, even on what I would consider a pretty wide turn. Keep in mind, I am not doing U-turns, nor do I expect it to turn like a 2wd truck. This is my first experience with driving one of these full time 4x4 old trucks, so I am looking to see what I should expect, if this is normal, or what parts I should be looking at to replace. Thank you for any help or advice on this topic.

 

[Goldie Driver]

My 1st instinct would be to see if it is in Loc as that will cause it to fight on turns. Both ways, however, not just right. Just get the transfer case lever in Neutral and pull it back 1 notch - that will be regular 4 Hi, not 4 Loc.

Got pics of the 77 ?

 

[H2OnSnow]

My 1st instinct would be to see if it is in Loc as that will cause it to fight on turns. Both ways, however, not just right. Just get the transfer case lever in Neutral and pull it back 1 notch - that will be regular 4 Hi, not 4 Loc.

Got pics of the 77 ?

And know that even with the t-case in the normal position and not Loc, you can still get some lopey, hoppy feel if you do a full lock turn with some giddyup on the pedal. This has always been one of the reasons to do a part time conversion on a 203.

 

[TCulpepper]

My 1st instinct would be to see if it is in Loc as that will cause it to fight on turns. Both ways, however, not just right. Just get the transfer case lever in Neutral and pull it back 1 notch - that will be regular 4 Hi, not 4 Loc.

Got pics of the 77 ?

I didn't drive the truck much, and now that I think about it, I may have only been making sharper right hand turns on the route I took, LOL. I did mess with the transfer case lever and it feels extremely loose, possibly disconnected. When messing with the lever, the light for 4 Loc would come on, but like I said it didn't feel like it was actually changing anything, extremely sloppy. When I get back home from out of town, I am going to investigate further. Also attached a couple pics of the truck!

 

[TCulpepper]

And know that even with the t-case in the normal position and not Loc, you can still get some lopey, hoppy feel if you do a full lock turn with some giddyup on the pedal. This has always been one of the reasons to do a part time conversion on a 203.

What all goes in to doing the part time conversion and how difficult of a job is it?

 

[H2OnSnow]

What all goes in to doing the part time conversion and how difficult of a job is it?

In my mind there is the right way, and there is the other way. You can get a kit to convert the case from a full time to a part time case. It means pulling the case (you don't HAVE TO pull it) and replacing some internals. There are a couple of versions of the conversion. Then you would add selectable hubs. Another way that has been done many times is to just install the hubs and leave the case alone. If you leave the case and just do hubs then you are still spinning the case internals, the front driveshaft, the axles, the u-joints int the axles. All of that means part wear and mass movement that wouldn't need to happen with the case conversion.

 

[Smtty58]

What shape are the axle joints in? Rusted, seized joints will cause this also.

 

[TCulpepper]

What shape are the axle joints in? Rusted, seized joints will cause this also.

I will have to check, these are the things I'm curious about so I know what to look for. Thank you!

 

[Jawzjeep]

My 78 k5 did the same thing. Eventually the case will slip as long as it's not in loc, its a 203 thing. Best conversion kit is one that includes a 205. A 208 will work too.

I swapped selectable hubs on and went that route as opposed to getting into the transfer case since I'll be swapping it at some point. One of the transfer case conversion kits I looked into said it needed to be put into 4x4 every hundred miles IIRC.

 

[Grit dog]

What shape are the axle joints in? Rusted, seized joints will cause this also.

Good call. In my experience a binding u joint will not cause the pronounced hopping like 4wd on dry pavement but but more of a minor see saw motion in the steering wheel. But I’ve only experienced this with one u joint binding and it was not from rust and non use but the first sign of the u joint wearing out after it goes dry.
So 2 rusted up u joints could increase that effect like you’re describing.
The former is a good warning indicator that you need to do a u joint in the semi near future. Once the steering wheel motion goes away again that means it is now worn to the point it’s sloppy and not binding up.

 

[midnightblue]

I did the 203 conversion and lock out hubs in my 78. It worked. You just have to remember to put it in 4x4 mode once in a while to oil the internals. the 203 requires the chain that powers the front axle to sling oil for lubrication.
I would also check the front axle u-joints first

 

[legend57]

Before doing any major swaps, I'd encourage you to go through the shifter mechanism. I believe the NP203 gets a bad rap (at least partially) because of the shifter. When set up well, it works well. But if it is dirty or was reassembled incorrectly, it is terrible. I went through mine and it was night and day. Here is a link to the thread that walks through the process:

https://www.gmsquarebody.com/threads/np203-shifter-w-rebuild-how-to.43883/

Before I did this, I was considering twin-stick or even a t-case swap to something else. I did ultimately convert my 203 to part time, but I am happy with how it shifts now.

 

[75gmck25]

Ref post #4, you have a light that shows it is in Loc? I have never seen any documentation of a truck that has a sensor/switch and “Loc” light. It would be great to have on my ‘75.

 

[legend57]

Ref post #4, you have a light that shows it is in Loc? I have never seen any documentation of a truck that has a sensor/switch and “Loc” light. It would be great to have on my ‘75.

Interestingly, my shifter has a provision for a switch, but nothing was installed. Maybe an option(?). I can't say for sure my shifter is original to my truck, as many things had been changed, but it does look like the NP203 shifter, at some point, had a switch as an option.

 

[TCulpepper]

Ref post #4, you have a light that shows it is in Loc? I have never seen any documentation of a truck that has a sensor/switch and “Loc” light. It would be great to have on my ‘75.

Yes, the light indicator appears on the dash, I believe that was introduced in 1976.