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91 Cummins In a 71 Blazer issues

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rjkharry

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I just bought a 71 GMC Jimmy that sits on a cut down 91 Dodge 3/4 ton frame. The truck has a Cummins 6bt with a NV4500 5 speed Manual Trans. The guy who did the build seems to have gotten it running and looking decent and stopped there. There are ALOT of little issues :doah:. I plan on going through the truck and cleaning up alot, installing new rubbers, Roll Cage, Soft Top, and new interior. Other than that I jsut want to get the mechanicals that are there solid.
Issue 1:The transfer case isn't like the GM's and doesn't have a name plate. Does anyone know what it would be? Also when I try to put it in 4-wheel drive it is extremly difficult. Is there some thing I should check because I am assuming there is a linkage problem. It also is hard to take out of 4wd once it is in and I can here the front drive shaft turning even when it is off. One of the difficult things of buying a truck like this is I have no clue what is normal or what position is what on the 4wd gear shift. I assume all the way forward is 4 wheel Low, then one back is neutral, then one more back is 2wd, then all the way back is 4wheel high. I am not sure but that is what it seems like when I try each location. If anyone has any advice on this transfer case it would be greatly appreciated. Also I would like to eventually go to the NP241 Does anyone know if that is doable?
Issue 2: The steering is a death trap. I have read alot about the Dodge's having steering problems. Is there anything I can do Cheap to make it better now? Also I plan on changing the steering to something better. Is hydrolic steering worth the money or does someone have a better solution. I plan on doing some wheeling in this truck but don't want to F it up either so I won't go crazy.
Issue 3: I have changed the oil, batteries, and belt. I want to go through and change all the fluids in the Dana 60 front and Corp. 14 rear. Should I change out the fluid in the NV4500. I have been told it isn't necessary like it is in a auto trans. Is that true? Also what fluid would you put in the transfer case.

That is it for now. Thanks for the help.
 
Can we get a picture of the transfer case? The 91 Dodge would've had a 205 but the NV4500 has to be 94 or newer, so who knows what it has now.

Is the truck lifted?

Can we get pictures of the steering?
 
Well the t case is an Np205, if it's a dodge unit it should be a 29spline IIRC as I believe thats what came behind the Getrag trannies behind first gen cummins. *the small round cover with 3 bolts on the back is a dead giveaway on a 205.

I would think you should be able to convert the steering to a cross over set up, you have a Dodge d60, which is very similar to the GM d60. Chris (38377k5) should be able to help you out with that :D.

Not sure on putting a 241 behind a Dodge nv4500, the 205 you have is a male input as is the trans output (both should be 29 spline) there is a coupler sleeve that connects the two. I'm not an expert on 241's but I believe any passenger side drop would be either a 27 or 32 spline and female inputs :dunno: but that's just GM, I'm not sure if Dodge ever used one in 93 or back trucks that would adapt.....maybe.

I would change the fluid in the 4500, and yes it's is EXPENSIVE and IIRC it takes 5 quarts (generally recommend to "overfill" them). There are only a few companies that sell the correct fluid for the NV4500, do not use any old stuff as it will kill it.

The t case most likely has standard "gear oil" in it.
 
Forgot to mention, do a google search , or search over on Cumminsforum for "NV4500 5th gear nut" there is a common issue generally associated with Dodge 4500's having the 5th gear nut come loose and wreak havoc.


Also do you know if the KDP (killer dowel pin) has been addressed on the Cummins ? If not definitely something that can ruin your day and is cheap and reasonably easy to fix.
 
As mentioned, definitely a 205 and, assuming it's the diesel output shaft in the 4500, it's the big 29 spline connection (there's an outside chance it's a 23 spline connection). You do have the shift pattern correct.

The front driveshaft spinning a little even in 2WD (with the hubs unlocked) is normal, it's fluid friction and fluid being pumped around that cause it to spin. Shifting the 205 with a single shifter can be very difficult, gear driven transfer cases almost always have pressure on the gears and that makes them tough to shift. Shifting the case while going straight helps, as does shifting while just barely rolling or slipping the clutch just a little bit. Nothing makes as big a difference as a twin stick.

Why the eventual swap to a 241? Doing so with a passenger drop front axle is VERY difficult.

As far as steering goes, crossover is definitely the ticket on that truck.
 
The steering issues with the 1st gen Dodges, are mainly three things.
First it's got a really stupid way of mounting the steering box to the frame, with this plate in between.
It's even more prone to cracking than the Chevy frames.
And next thing is that they have a non-adjustable drag-link.
So if you lift it the steering box will most probably be off center,
and therefor have a lot of play when you drive straight.
And finally the lower joint on the steering shaft often breaks or gets worn out,
and the upper rag-joint isn't exactly the best either.

I've strengthened the frame some in mine:
http://www.1stgen.org/viewtopic.php?f=22&t=13461
And swapped in a slightly lengthened adjustable draglink from a Chevy.
http://www.1stgen.org/viewtopic.php?f=22&t=13462
And I've also swapped in a Borgeson steering shaft.

After that it actually handles pretty good.
A set of Bilstein shocks didn't hurt performance either:waytogo:

There's a lot of more good info on that forum when it comes to 89-93 dodge trucks with cummins diesels.

I think your drag-link angle could be overcompensated with that lift block for the steering arm.
Ours seams to have about the same amount of lift, and I've tried a steering block, and it was too much for me.
Overcompensating the drag-link angle is much worse than undercompensating it.

But if you plan of doing any offroading I'd do crossover instead.
Then you ditch the steeringbox-plate and move the steering box slightly back,
so you can mount it the same way it is in a 2wd dodge truck,
But go ahead and strengthen the frame anyway.

And yes, the shifting pattern you mentioned is correct for your NP205

Good luck! and please post some more pics :popcorn:
You've really got the best from two worlds with that one :waytogo:
 
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I would change the fluid in the 4500, and yes it's is EXPENSIVE and IIRC it takes 5 quarts (generally recommend to "overfill" them). There are only a few companies that sell the correct fluid for the NV4500, do not use any old stuff as it will kill it.
Click to expand...
What is the Correct Fluid? I have searched this and came back with a few different answers. Also there is no drain plug on anything. I am assuming the best way to change the fluids is Remove the diff covers, Remove the trans pan, and not sure on the NP205? When I have the diff covers off how can I tell what the gearing is?

I am leaning toward the crossover steering. No one said anything about Hydrolic steering. Is that not necessary. I am also going to replace the shocks but I want to make sure I am happy with the lift first. I am going to shoot some pictures of it and post them as well. I would love to get some opinions there as well. I would like to add dual resevoir shocks on the front.
 
I would confirm the fact that it is a nv4500 first. That's a first gen dodge Cummins chassis. Could be the getrag tranny. Completely different. The steering horror stories your reading about are probably about the second gens. They had strength issues around the box. The push/pull steering you have isn't that bad if you're doing a lot of street driving with no lift. Appears yours has some lift to it, go crossover for sure. If any thing with hydraulic, go assist. It does help with death wobble when you have it. Typically used with larger tires to assist steering in off road conditions. If your tires aren't that large and you don't plan on serious off roading, A couple of stabilizers would be much cheaper.
 
Here are the pics of the Trans. Can you tell by them if it is an NV4500 or a Getrag?

Also the only reason I was going to try to switch to the 241 is that is what was reccommended to me in a previous thread when I asked which Tcase to go with. Can you get a slip yoke eliminator for a 205

2013-01-10_07-54-41_53.jpg

2013-01-10_07-54-53_313.jpg

2013-01-10_07-55-36_699.jpg
 
looks like a 4500 to me . but i have never seen a gertrag in person i can recall.

why slip yoke eliminator ? that 205 you have is already fixed yoke AKA no slip yoke / slip yoke eliminator.

check to see if you can use a jeep steering shaft to swap in place and no spend crazy money on borgesen shaft.

swap to a 2wd steering box and do crossover. and if i recall on those dodge's 2wd dont use the adaptor plate to frame ? ? but i might be wrong as i dont play with dodge much to be sure.

and dodge dealer seems to be cheepest for the nv4500 fluid. and get 1 extra qrt of it to over fill it 1/2 qt to help lube the input bearing . lots of talk on this over the years. and to over fill dump it in the shifter hole.
 
sweetk30 said:
swap to a 2wd steering box and do crossover. and if i recall on those dodge's 2wd dont use the adaptor plate to frame ? ? but i might be wrong as i dont play with dodge much to be sure.
Click to expand...

Yes, as I said before the box can be mounted further back and without the plate, like it is on a 2wd frame.
But only if you go crossover, otherwise the drag link would be too short.
And there's no need to swap out the steering box,
on a dodge you can just move the pitman arm 90 degrees.
 
A couple other things.

1. Is it intercooled?
2. is it a 12 valve or 24 valve?

Non-intercooled 12 valves are '89 and '90, intercooled 12 valves are from '91-'98, intercooled 24 valves are '98.5 to '02 in '03 they got the common rail, 24 valve.
 
rjkharry said:
What is the Correct Fluid? I have searched this and came back with a few different answers. Also there is no drain plug on anything. I am assuming the best way to change the fluids is Remove the diff covers, Remove the trans pan, and not sure on the NP205? When I have the diff covers off how can I tell what the gearing is?
Click to expand...

Ok, a few questions that got missed.

The correct fluid has been covered :D
Drain plugs- the t case has a drain and a fill, in the pics you can see the 2 square plugs on the back of it, lower one is the drain, higher one is the fill.

Diffs- remove the covers to drain, depending upon what axles it has there will be a fill hole with plug in either the cover or housing- gear ratios- there should be numbers stamped on the ring gear or you could always count teeth and divide.

Trans- remove one of the PTO covers to drain, and like mentioned fill though the shifter hole and overfill 1/2 quart. There is a fill plug on the side but using it you won't be able to over fill.


Back to the steering, you said it's terrible/ scary etc. What exactly does it do or not do? Is it just super sloppy, does it have a horrible shake at a certain speed, does it wander, or does it change lanes when hitting a bump ? More info will help us help you :D
 
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