75 C\Cab3\4 TON,44O gearing

[Andyp]

OK, I'm back to looking to buy the '75 full time 4by. Owner says rear diff is a 60 with 409grs,Frt=[he thinks] is a 44 with 393grs.
I read somewhere here that the difference between the two should only be like 5% ? This truck is stock as far as anyone knows...{ driven by a little old man for camping 88,000 miles}Will there be any issues with this setup ? is it stock ?
Learning lots here, you peeps r smart peeps
thanx
Andy

[712edf]

The vast majority of 3/4 ton Dodges with Dana 60 rears & Dana 44 fronts had a rear gear ratio of 4.10/1 and a front gear ratio of 4.09/1...

I'd probably assume the owner is just mistaken, it difinitely didn't come from the factory with such a difference between the two.

Is the vehicle driven regularly? Has it been tampered with.

Also you need to learn about greasing the front wheel bearings through the hidden grease fitting if you are not familar with this trucks set-up.

There are some certain characteristics unique to the NP203 full-time trucks. You are in the best place to learn about them.

[74w300uteline]

something ain't right, but I'm no expert

unless the old guy has been driving on ice for the last 88k miles, my limited understanding of running gear would have me thinking that the transfer case would be all wound/bound up from rotating at different rates. this would be a good time for one of the resident experts to describe the sequence of events which would result from mismatched gears. I been here for 5 years and I'm still learning.

[712edf]

my limited understanding of running gear would have me thinking that the transfer case would be all wound/bound up from rotating at different rates.

While I am no resident expert, you are correct, different ratios won't work together with equal circumference tires. 4X4 tractors that have much smaller front tires do utilize different ratios between the axles, but tractors are a different animal & are not operated on pavement continually.

Since this truck doesn't reportedly have any issues, I assume that the seller is mistaken about the front ratio. I have never heard of a 3.93 anyways. I have heard of 3.73 & 3.91.

I suppose that it's possible this truck has been changed to have 2 ratios, and I also suppose the differential action of the t-case could compensate for the difference. But it would have the same effect as driving a vehicle only in circles would have on a rear axle differential, stuff would wear out.
The big problem would arrise if someone ever shifted the t-case into either of the LOC positions. This locks the front & rear driveshifts together. Unless the trucks on ice,sand,mud where the front tires can lose traction/spin, something will bind/break within a short distance. The front tires would be spinning faster than the rear. It just won't work.

Take it for a test drive. Have the owner demonstrate how the 4x4 works. Let him prove its legit or tear it up.

Bucky

[74w300uteline]

3 lockers on a fulltime?

Good explanation. I never clearly understood which components were being engaged when shifting to LOC on a fulltime. Being more familiar with non fulltime, I thought that the LOC position somehow magically locked the rear axel (left and right as one) and simultaniously the front (left and right as one) I was applying the concept of cable OX lockers in my mind. Now I see that the LOC on a fulltime, locks the driveshafts together. Working off that assumption, are there 2 more differentials (front& rear) that could be defeated/ overridden? or am i getting ahead of myself on whole concept again? fulltime with a posi rear and a cable operated front locker?

Bucky thank you for the explanation, The light bulb went on over my head I havent fully understood the part time- fulltime thing.I knew that the m880 has never let me get stuck, try as I might.
Andy please forgive the hijack but this has been an eyeopener for me

[Andyp]

Thanx guys..very interesting,
I do also have from a '74 3\4 ton.. a 60 w\410s rear & a 44w\410 frt w\parttime hubs & a 203 all sitting under my work bench just in case I ever need them..sweet eh?
Andy

[712edf]

First I'll say that in my opinion 1974 is the year for Dodge 4x4's. Last year for mighty divorced 205 t-case, Dana 70 front, factory PTO & first year of clubcab 4x4.

Now about full-time 4x4. What that means is the t-case is sending power to both axles at all times, but power travels the path of least resistance. SO if one axle loses traction (or is off the ground), that axle will get ALL the power & spin aimlessly & the truck won't move. No power is sent to the axle that still has traction. HENCE the need to shift the t-case to one of the LOC positions (Hi Loc or Lo Loc). When not in LOC the t-case has a front/rear differential just like an axle has a side/side differential. Remove either driveshaft & the truck will only drive when in Loc. Also if neither axle has any sort of limited slip or locking differential, it is possible to get stuck just by one tire losing traction.

At least in LOC position a mininum of one wheel per axle is driving the vehicle.

Fulltime 4x4 got a bad reputation in the 70's for poor fuel mileage and excessive wear. Honestly the late 70's were the screwiest times in America. NP 203 fulltime 4x4's were I think some one of the greatest concepts out there. Incidently Dodge, Ford, GM all offered this set-up in the late 70's. You didn't have to get out and walk in the mud to engage it like the former part-time systems.

While the chains inside the t-case would stretch and the Dana 44 fronts were kinda kooky, all in all its a good system. I believe Adventuresport here on the forums owns several fulltime Dodges & swears by them IIRC.

I honestly think the truck you are discussing here has the same gear ratios in both axles.

Bucky

[Andyp]

that's about the best explaination of f\t I've ever heard
thanx
Andy

[Andyp]

'78 440,3\4 c,cabmin rust

here i go again now there is a 78 3\4 , c cabab ,440, all same, maybe more rust-all surface stuff but better int ..or the 75?, or the 84, i haven't told you about that yet..i will try to attach links Monday18[78 is dummy on price fyi]
thanx for any help
BUT , if i could get a great running good looking 4 door online some where i would like to ship it up to Alberta..where's the Ads ?
not sure how this site quite works with links yet , but will keep trying
thanx Andy

[USN78W150]

The NP 203 has a pto provision, also. I am another one who swears by the late '70's full time trucks. There is even a company that makes a 3:1 low range gear set for it. I forget the name, but it can probably be found on the internet.

[712edf]

here i go again now there is a 78 3\4 , c cabab ,440, all same, maybe more rust-all surface stuff but better int ..or the 75?, or the 84, i haven't told you about that yet..i will try to attach links Monday18[78 is dummy on price fyi]
thanx for any help
BUT , if i could get a great running good looking 4 door online some where i would like to ship it up to Alberta..where's the Ads ?
not sure how this site quite works with links yet , but will keep trying
thanx Andy

75 & 78 had some minor wiring changes & different grills/valance panels. Mechanically same.

I think the 78 grill is the best looking one!

Does any of these trucks have the Dana 60 front?

When you say c/cab, do you mean club or crew?

Bucky

[Andyp]

c-is 4 club

sorry about that,nobody speaks much of the Clubbys,but alot of the Crews, I will be more correct in the future.
I just missed out on an 84 crew-sold same day listed.
I'll have to e- them all again to see if the frt are 60.but I doubt it.
The 75 club[440 auto] said 44 but doesn't really sound like he knows jackpoop.he's come down to $3000
The 78 club[440 auto] will need the most body work but is the cheapest..$1500
Another 84[318 manual] is 1 ton non-dually reg cab but has been gone thru thoughly,sounds like a sound truck.$3000
My budget ain't much more than that either.
I really would like a Club or Crew.
I took the 1st offer{doh !} on my 4th {that I've owned} Ramcharger and now want something more practiable for hunting and daily driver{hauling dead moose up on that roof rack was killing me dude}lol
thanx
Andy