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Old July 12th, 2013, 04:09 PM   #1
KingCutlass
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Default Transfer Case rebuild?

Ok, so after searching the forum for specifics for my truck i've not really come to any detailed conclusions so I'll post up my questions.

I have a '77 K10 with a '76 NP203 TC with a 201 Ratio.
I also have two spare NP205 TC's, both with a Ratio of 196, one '77, one '78.

The problem:

I had new locking hubs put in the truck a couple years ago and for what little I drove it in the winter they performed great. I was able to free the hubs and drive the truck without issue until I parked it last winter to begin restoration/lifting it.

The issue is that I can lock the hubs in and it will drive in any gear in the transmission and any gear on the TC, however when i free the hubs and put the truck into gear, i will put it into any gear (R-1)and it just revs like it's in neutral. When I try to put it back in park it will make a grinding noise for about a few seconds and then quit.

I am going to flush it out and put new oil in it, but what would cause it to run in 4wd with the hubs locked, but not with them on free?

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I'm aware that this is an awd case, chain driven and that it usually is in HI when it's driving, but for whatever reason it's stuck now and I can't get the hubs to unlock and actually move under it's own power.

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Given that I have two spare 205's, are there any options to possibly change them out without having to buy a bunch of extra parts? I do have an adjustable driveshaft in the rear, however it's already extended out due to the lift, so I would most likely have to get a new rear driveshaft because of the shorter tail shaft of the 205. (I hope not to do this)

I've heard of people making "doublers" out of both cases, but I could not find an adequate explanation here on what exactly that is.

Keep in mind that I'm limited on funds and I still have to spend most of my money on other things for the truck that are more important, so I'm hoping to make repairs, not upgrade to a 208 or put in a fancy new kit unless it's absolutely necessary; in which case i'll drive it in 4x4 until I can afford to fix it. Gas already sucks anyway.

I'm not sure what exactly is wrong with it because I was able to unlock the hubs without issue a year ago and just one day it refused to free up. Also if it makes a difference, when I would step on the brakes and come to a stop quickly (shortly before I parked it) I would hear a clicking noise from the right front hub until stopped. Not sure if it's relevant, but being that they were new hubs, i'm wondering if something came loose or if something happened that could contribute to the issue. They move freely from lock to free without binding or noise, so i'm not sure if that makes a difference either.

Thanks
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Old July 12th, 2013, 04:45 PM   #2
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Not a big expert in this area, but recognize the grinding noise you are hearing is the t-case is in neutral when you are shifting the tranny to Park. Could your t-case shift linkage be off?

As for a doubler, that is a costly modification (about $1,500 in parts if you have the two t-cases) so if your funds are low, that is not a good option. If you need to replace the NP203, the least expensive thing to do is find another NP203.
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Old July 12th, 2013, 04:49 PM   #3
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Interesting, I thought it was the transmission grinding because it was trying to engage.

Being that the linkage on the transfer case consists of two rods connected by a plate and a single rod attached to the level by a cotter pin, I don't really see how it can be adjusted.

Some sites i've read said that they can't and some said that they can, however I've not been able to come to any definitive conclusion.

I can say that given the truck's condition that I purchased it in, It's probably not been serviced or adjusted since it was put in. The engine has had work, but I can hardly say the same for the drivetrain.

*I checked the oil in the case and it's pretty clean, so someone did change it not too long ago, and I don't see any shavings in the fluid, at least upon first inspection, so I'm not likely to think something internal has failed.

Last edited by KingCutlass; July 12th, 2013 at 04:54 PM. Reason: Edit to add
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Old July 12th, 2013, 04:49 PM   #4
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Probably the best out there for the doubler.


http://www.offroaddesign.com/catalog/doubler.htm
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Old July 12th, 2013, 05:04 PM   #5
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Very cool, thanks for the link!

I'll have to look into this for the future when I drop in an upgraded motor/trans combo.

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Old July 12th, 2013, 06:37 PM   #6
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If all you did was add hubs to the front axle and not a part time kit in the 203 itself, you need to run it in the LOCK position when the front hubs are unlocked. I think your linkage is out of adjustment, so you cant get the shifter all the way to the lock position.

Give this a try:

"The 203 full time 4-wheel drive transfer case is the only one on which linkage adjustment is possible.
Place the selector lever in the cab in the Neutral position.
Detach the adjustable rod ends from the transfer case levers.
Insert an 11 / 64 in. drill bit through the alignment holes in the shifter levers. This will lock the shifter in the neutral position with both levers vertical.
Place the range shift lever (the outer lever) on the transfer case in the Neutral position.
Place the lockout shift lever (the inner lever) on the transfer case in the unlocked position. Both levers should now be vertical.
Adjust the rods so that the linkage fits together. The indicator plate can be moved to align with the correct symbol.
Remove the drill bit."

I got this from http://www.justanswer.com/chevy/63fu...e-linkage.html

Some nice pics there, the shifter also is bad for getting mud and stuff stuck up inside it. Try and get it cleaned out and lubed, then adjust and see if that helps the situation.
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Old July 12th, 2013, 07:46 PM   #7
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I will give that a try this weekend and see what happens. Thank you!

I do have some mud around the TC that is left over from the last time it was mudded (I was lazy cleaning it) so that might cause problems given that it is field clay instead of regular mud. It's like a rock in clumps.

I'll see what I can do about the linkage and re-post.

Thanks again for the help.

:)
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