Dodge TerraVan 4x4 drivetrain modification

[Brooksbank]

hey all,
ive had this van for 20+ years.

1975 Dodge Sportsman 1 ton 4x4(done by TerraVan)
360 with 2 barrel holly carburetor
3 speed automatic transmission
203 transfer case; 201 ratio
33 inch tires
last time i checked on the highway 14mpg on flat with tail wind

from what ive been told:
Dana 60 rear end(tag says 4.10)
Dana 40 front end(tag says 4.09)

havent driven it for 8+ years(long story). but anyhow got it goin again. i finally have the space and funds to continue restoring it and possibly put a 4 cylinder cummins diesel. i dont need too much power(just better mileage). maybe a 6 cylinder if need be. mostly highway driving. also id like to put a tranny with an overdrive(or a gear splitter kit?). any suggestions? i cant find much on TerraVan 4x4 conversions on the net. just pathfinder conversions.
mainly asking where a good place to look for a donor, what transmissions will bolt up to a cummins/my transfer case(it is married), if i should look into changing differentials, torque problems maybe. im kinda just starting to get back into this van and im not that much of a gear head to know the specifics. ive read that the dodge 1992 tranny may work for my situation. id actually not mind putting in a manual tranny. i know all this stuff will take much time but i have plenty now.
i can take better pix of the underside if anyone wants.
but any input at all will be greatly appreciated.
thanx,
scotty

 

[dsw4x4]

Any transmission that came behind a 6bt will fit a 4bt. If you go with a manual I would use a nv4500. I am doing the same thing to one of my vans it is getting a 4bt with a 5speed manual. Your axles will work for the drivetrain swap if you do not plan on wheeling it. If you start to find that you like to be adventuresome the front end will not hold up and it will be time to swap it out for a 60 front axle. Not to sure on what will bolt up to your t-case but I would just use whatever t-case came behind the nv 4500 anyway. Yes it will not be as strong but chances are it will be lighter and package easier and drive quiter on the road.

 

[Brooksbank]

what do you mean it wont hold up(front dana44)? with the new engine or like it is now? will the gears break or the tubes snap? i have taken it on lots of gnarly off road situations in the past and seems fine. im not gonna ever do anything like the rubicon trail out here in tahoe or anything. clarify please.

 

[Deleted member 9101]

Its not that the axle is weak.. its that you will be making 3 x the torque at a much lower RPM.

 

[dsw4x4]

Oops I should of said wheeling it "hard" a 44 is fine for light wheeling (fire roads and mountain passes) jnich77 is right you will be creating some torque with the 4bt add to it the extra weight and bind it up in the rocks you will be breaking parts. Anything from knuckles tubes axles lock outs r&p you name it. I went through the whole beefing up a 44 process it expensive and in the end it still is not a 60.

 

[dwh]

4:10s are good depending on what tires you are going to run.

I wouldn't bother with a manual trans - too much hassle to hang the clutch pedal (especially in a van body). Auto trans with a B&M cable shifter is pretty bulletproof and easy to install.

The 203 t-case uses a chain belt to drive the front shaft. That belt stretches over time and is not adjustable. You need to check it and replace it if it's stretched, or just replace it as part of a regular overhaul of the t-case. Personally, if I was changing out the engine/trans anyway, I'd dump the belt-drive 203 and go with an all gear t-case.

The 44 is a good axle. Most likely to break is either a locking hub, or an axle shaft - neither one is really all that likely under normal off-road use. Extreme use and/or rock crawling with good traction and a lot of torque...well, then you can surely break it.

There are various over/under drive units. Most install between the trans and transfer case. They are all expensive. Personally, if I just had to have overdrive, I'd look for a tranny with overdrive and leave it at that.


I'm not all that knowledgeable about diesel swaps, so I don't know what trans would bolt up to whatever engine you are looking at, but your best bet is probably a complete engine/trans/t-case setup from a donor truck.


If you are looking to do the engine swap just because you want to save money on fuel - you have to do the math on that. If you spend say $3000 (and good luck doing it that cheap) to make it a diesel, how many miles will it take before the extra mileage saves enough on fuel to cover the cost of the conversion? How long will it take you to rack up that mileage - 5 years? 25 years?

Once you do the math, you might well find that it would be cheaper in the long run to keep the 360 and spend 2 grand extra on fuel instead of 3 grand extra on a diesel swap.

But what if the swap costs more than 3 grand? Then you might find the math shows you are better off just buying a Gear Vendors overdrive for 3 grand instead of doing a diesel swap:

http://www.gearvendors.com/4x4d3s.html



It looks like you've got a good truck there. Those forward front spring hangers look like someone was doing what worked rather than what looked pretty. That's always a good sign.

If it's not going to do any extreme off-road, I'd probably just go through and clean it all up, do a B&M shift kit and torque converter on the 727, swap the 203 for a 205 and run it like it is.

I'd probably also have the drive shafts rebuilt and balanced, and while I was at it, replace the yokes to run 1350 u-joints instead of the 1310s or 1330s that are probably on it now.

 

[Brooksbank]

thank all of you for your awesome input. im gonna be trying to figure this out for a while. most likely go with a donor. i actually had a frito lay delivery van i bought just for this conversion. but i was leaving the country for 4 months and no one would let me park it so i got in a pinch and had to sell it. had a 4bt and a 4 speed manual tranny. oh well. automatic will be my best bet. just finding a donor takes forever and a ton of searching every day. ill put the word out at the semi-local junk yards.
and ive never heard of a "B&M shift kit". i searched it but still not too clear on what it actually does. anyone?
thanx again everyone.

 

[dwh]

B&M Racing builds (and has for as long as I can remember) ultimate beef-a-zoid automatic transmissions. They also sell kits to "improve" stock transmissions.

Stock trans are setup to give a nice smooth shift. That causes several issues. The most important issue is heat. Since the clutch plates spend more time slipping and less time grabbing, more heat is generated.

Heat is the enemy. IIRC (and I might not...it's been a while), when the trans fluid reaches something like 320 degrees F, it has the same viscosity as water. (Oh, and it's also ruined, so you better change it right away.) At something like 420 the fluid starts to smoke and mutate into a varnish or something. Most auto trans don't die from age and wear - they mostly die from having the hydraulic fluid destroyed by heat (which results in increased wear).

A shift kit will adjust the setup so that the shifts happen quicker (less time spent slipping), and usually also increase the line pressure a bit to make the clutches grab tighter.

A shift kit will help any auto trans work *much* better. Snappy shifts that you can feel. If you like that sort of thing, that is. Granny might complain about it.



The next step up from a shift kit is the TransPak, which is what I prefer for serious off-road because it allows you to take manual control of the trans when you want. Most auto trans won't down shift above certain speeds, and will automatically upshift at certain speeds - no matter what you have the gear selector set at. With a TransPak, if you downshift, the stupid tranny WILL do it and it will STAY in that gear. I like that. A lot.

http://www.bmracing.com/PRODUCTS/Kits-Accessories



I very much prefer a well-built auto trans over a manual trans. Controlled with a B&M ratchet shifter is best. I prefer the Quicksilver shifter. Works great for daily driving in automatic, but it's also a ratchet shifter that can lock the trans into any gear (if the trans can be locked into gear, such as with a TransPak or B&M valve body) and cannot be accidentally shifted into reverse or park.

http://www.bmracing.com/PRODUCTS/Performance-Automatic-Shifters/Quicksilver



Then there is the torque converter - which not only converts torque, it INCREASES torque at low speeds. Woot. For wheelin', I like that. A lot.

http://en.wikipedia.org/wiki/Torque_converter


I generally go with a Traveler with a lower stall speed. Since I usually build engines for bottom end torque rather than top end horsepower, I generally don't need a high stall speed to get into the powerband.

http://www.bmracing.com/PRODUCTS/Torque-Converters



My normal setup (when I was into building wheelers) was to add a Traveler, TransPak, Quicksilver and deep pan.

Then cut into the hot line coming out of the trans and splice in a remote filter (usually frame mounted):

http://www.amazon.com/80277-Universal-Remote-Transmission-Filter/dp/B000CIKJMY

and also a fitting for a temp guage (I like the Auto Meter liquid filled mechanical gauges):

http://www.autometer.com/cat_gaugedetail.aspx?gid=2724&sid=9

After reading the temp at its hottest point* coming right out of the trans, then run to the biggest, most horribly humongous trans cooler that will fit in the truck.

(Use the dinky stock cooler for the power steering. Power steering fluid gets amazingly hot. The old Lincolns in the 60's and 70's used the power steering pump to "hydro-boost" the brakes instead of using a vacuum booster, and they came stock with power steering coolers.)

That giant cooler can easily make the tranny temp too low, so I run out from the mega cooler through the tranny cooler loop in the radiator to bring the fluid back up to the same temp as the engine (usually 180) and then feed it back to the trans.

For the most part, I would see the water temp and tranny temp guages basically locked together at 180. I like that. A lot.



* I don't like tranny temp gauge kits that stick the sensor in the pan - like the kit that B&M sells. That's not where the fluid is at its hottest. The fluid is dumped into the pan by the return line from the cooler and then sucked up by the pump and through the trans where it gets hot. Reading the temp of the fluid in the pan (after it has been through the cooler) isn't the right way, IMHO.

I once spoke to a B&M engineer about that, and he agreed. But, says he, they have to make a kit that the Average Joe can install without hacking things up too badly. Drilling a hole in the pan is the easiest way, and the temp reading is close enough to know if you're about to ruin the hydraulic fluid.

 

[Brooksbank]

a few thousand miles ago(10 years hahaha) i changed the tranny filter. so the fluid is newer...it shifts like it may already have a kit(very tight).

i mostly want to get better mileage to sell my subaru and use this van as my sole transport. thats why i wanted to put a cummins in it and a new tranny. ppl have been saying forever that it might not add up as far as swapping engine and tranny compared to just buying gas. that made more sense 10 years ago. but if i woulda done it many years ago it would be fine too. i dont really care. i may keep this van going for the rest of my life. im pretty dedicated to things i enjoy and this is one.

my tranny downshifts when i tell it to, another reason it may be fine.

not into wheeling as a hobby. but i need to access certain areas for camping etc. i live in south lake tahoe, california area if that helps. lots of snow here.

anyone know where to get rare as hell weatherstripping? this is something ive had a very hard time finding for the doors. its obvious that no one/few ppl make this stuff. today i did find a place that, to my good luck, is thinking about manufacturing my exact stripping for side and back doors this winter. heres there link:

http://www.metrommp.com/

also, not to disrespect this site, anyone know of another site where this type of thread will do well? just looking for as much input as possible. not easy at all to find the type of info im looking for.

thanx again guys,
scott