New guy here with a 78 gmc jimmy !

[Phil513]

Yup...when not "in" 4 wheel, it IS front wheel drive....funny how many folks didn't know that.

Not entirely correct. It's not that it defaults to front wheel drive. If you don't have the transfer case locked, and take the rear driveshaft out, it won't go anywhere either. The transfer case acts like an open diff.

 

[Lito]

As it is, you can pull that REAR drive line, and drive all over the place. I had one just like that one. Was quite the surprise to find out it was front wheel drive.

Man I keep making mistakes!!
Got to check my "mind" at times...

 

[Lito]

A friend told me it was, and I didn't quite believe him, till I put hubs on it....

 

[Phil513]

If you put hubs on the back axle, and unlock them, you still wont go anywhere.

Nevermind. I'm out.

 

[Lito]

'Course, this was back in the late '80's....I ain't so young no more! But I was a farm kid with a 4-wheel drive rig!

 

[blazer74]

Look at it this way, just like an open diff in a car or 2 wheel drive truck.

Jack one wheel off the ground and the wheel in the air spins. Swap to the other side and that wheel spins but they both can drive when on the ground depending on road and driving conditions.

Path of least resistance.
Front, rear , left , right, both or all.

 

[nvrenuf]

Yup...when not "in" 4 wheel, it IS front wheel drive....funny how many folks didn't know that.

Not quite. A full time truck with an unmodified np203 basically has a differential it. When it's NOT in "LOC" it acts like an open diff directs power to the axle with the least amount of traction, front or rear. The reason it won't move with locking hubs in the free position is because the rear axle has traction so it sends all the power to the front driveshaft which spins the unlocked internals. If you just removed the rear driveshaft it still would not move.

 

[UpnAdam]

Well I'm thoroughly confused "but I was told its a 4x4?" lol

 

[Bent77]

Back on track here everyone...


@chevy4x4power , how goes the battle?

 

[chevy4x4power]

If your lucky you can get the bulb free by twisting the glass part,or the remains of the brass "shell" of it,in the socket..use gloves if you try twisting the glass--or needle nosed pliers on the brass shell part..you'll probably have to dig out the rest of the glass from the bulb's base first..

The "bowtie" filter is an FB-59 AC ,but any parts store will have one in whatever brand they carry,they can cross the AC number to theirs..View attachment 209744

As for the factory CB/stereo,I practically gave the one I had away,because it needs repair,but did work...I have seen them listed on craigslist and e-bay for 100+ bucks in "unknown" working condition...

I will look into that part and see if my local napa has it ! I think the cb still works in the jimmy !

Don't forget that to remove the bulbs you need to push the bulb inwards a little while twisting it...

Thanks for the tips !!

Back on track here everyone...


@chevy4x4power , how goes the battle?

Going to go home today or tomorrow and try and fix the bulbs (or atlas tget them out !) and if i can pick up one of those filters I'm gonna give that a try too !!

Dad got the carb spacer on and he said it clears the carb just fine !


As to the whole hi and hi loc, is it worth it to convert it to part time 4WD? can it be done with just hubs or does the transfer case need to be taken out?

 

[Bent77]

I will look into that part and see if my local napa has it ! I think the cb still works in the jimmy !

Thanks for the tips !!

Going to go home today or tomorrow and try and fix the bulbs (or atlas tget them out !) and if i can pick up one of those filters I'm gonna give that a try too !!

Dad got the carb spacer on and he said it clears the carb just fine !


As to the whole hi and hi loc, is it worth it to convert it to part time 4WD? can it be done with just hubs or does the transfer case need to be taken out?

Just change the hubs. If you do junkyard hunts, the ford and dodges also use the same lock out hubs you need

 

[campfire]

Just change the hubs. If you do junkyard hunts, the ford and dodges also use the same lock out hubs you need

While this is true (I'm running hubs that I pulled off of an F150), it's only true for certain series of Ford/Dodge/GM/IH/Jeep trucks. Check the application chart if you're in doubt. A lockout from any axle that fits part number 20990 will fit your truck (whether or not the hub is Warn brand).

https://www.warn.com/truck/hubs/premium_application_chart.jsp

 

[82355]

If you just install hubs on the front axle, without installing a part time kit in the NP203, you will have to drive the truck in "Hi Loc", as it will just unload the differential in the NP203 otherwise.

You wouldn't believe how often that stupid "NP203's are front wheel drive" use to come up on Facebook.......

Martin

 

[chevy4x4power]

Just change the hubs. If you do junkyard hunts, the ford and dodges also use the same lock out hubs you need

10-4 ! i want to !

While this is true (I'm running hubs that I pulled off of an F150), it's only true for certain series of Ford/Dodge/GM/IH/Jeep trucks. Check the application chart if you're in doubt. A lockout from any axle that fits part number 20990 will fit your truck (whether or not the hub is Warn brand).

https://www.warn.com/truck/hubs/premium_application_chart.jsp

Thanks for the link and insight !

If you just install hubs on the front axle, without installing a part time kit in the NP203, you will have to drive the truck in "Hi Loc", as it will just unload the differential in the NP203 otherwise.

You wouldn't believe how often that stupid "NP203's are front wheel drive" use to come up on Facebook.......

Martin

So will driving in hi loc while having just the hubs up front mess anything up? Will this allow me to make it a true part time 4x4?

What advantage does having the transfer case part time kit give me over just doing the hubs?


https://www.amazon.com/gp/product/B009774GCA/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=ATVPDKIKX0DER


Does this look like a good fit for the crank case tube?


Also, the crank tube on page one is really loose feeling and i stuck my finger inside it a little bit and it was kinda oily ? is this normal?

 

[chevy4x4power]

Anyone?

 

[Bent77]

Yeah that tube be oily. I stuck a breather cap in mine.

I dont know much about that part time kit so Ill abstain from voting

 

[USSkoval]

With the part time kit and locking hubs, you can save wear on the front driveshaft, differential, shafts, and tires.

With just the locking hubs and running in "loc" you will save some of the wear on some things like tires and shafts, mostly due to less stress. But everything will still be moving.

 

[RubberFloorMat]

I dont mean to hijack but I just picked up a 78 K5 myself. I know a ton more about the 87-91's than these but im learning too. The NP203 is a weird duck, its strong but apparently not very sought after.

 

[chevy4x4power]

With the part time kit and locking hubs, you can save wear on the front driveshaft, differential, shafts, and tires.

With just the locking hubs and running in "loc" you will save some of the wear on some things like tires and shafts, mostly due to less stress. But everything will still be moving.

So will adding just the locking hubs make it a 2wd truck? Sorry if I'm not following

I dont mean to hijack but I just picked up a 78 K5 myself. I know a ton more about the 87-91's than these but im learning too. The NP203 is a weird duck, its strong but apparently not very sought after.

pics of your blazer? I wish i had one without the 203 lol just couldn't pass it up for the price !

 

[campfire]

So will adding just the locking hubs make it a 2wd truck? Sorry if I'm not following

pics of your blazer? I wish i had one without the 203 lol just couldn't pass it up for the price !

It's not a hard thing to swap out if you have a strong disliking for it. If you hafta take it down and tear it apart for a part-time conversion, it's probably less work to just throw a functioning 205 in there. Assuming this truck is too old to have the newer 6-bolt transfer case pattern (which would give more options yet).

To answer the first question, you'll only have power to the back wheels when the hubs are unlocked, but you will always be spinning the front drivetrain (driveshaft, gears, axle shafts, etc). It will function like 2WD, but you will burn extra fuel and put extra wear on the gears. Whereas a part-time system will disengage the front drivetrain entirely.

You also will not be able to go anywhere when the front hubs are unlocked unless the 203 is locked. Otherwise, it acts like an open differential and will just spin the front shafts (which aren't hooked up to anything).

So hubs are a step in the right direction, but they only get you half-way there.