4BT swap questions.....

[slozukimc]

Hey All,
Located a running and driving Frito Lay van today for $2000. It has the 4BT and automatic tranny and the engine has a new head and sleeves. I have a few questions about putting it in my M37.

Has anyone used the automatic trans in an M37 swap? I know it's not as good as a 5 speed but will it work?
If I do use the automatic, what gears would I want with what tire size for best highway driving? I assume 4.89's with 11.00-16's would be in order.

Has anyone done a writeup on how to do the swap? Does anyone sell premade motor mounts or trans mounts?

Can I use the original fuel tank and lines or will I need bigger lines to feed the Cummins?

What is the best choice for a radiator?

Where can I find info about upgrading my brakes?

What kind of performance should I expect as far as mileage? I want to be able to travel at 60MPH pulling my car trailer on trips up to 1000 miles......Am I being realistic?

Mike(with too many questions...) Canfield

[JimmieD]

Hey All,
Located a running and driving Frito Lay van today for $2000. It has the 4BT and automatic tranny and the engine has a new head and sleeves. I have a few questions about putting it in my M37.

[COLOR="SeaGreen"]Man, that's CHEAP!!!

Has anyone used the automatic trans in an M37 swap? I know it's not as good as a 5 speed but will it work?

It's physically possible but I don't personally know what it would take to mate to the M37 transfer case. The TH400's were hard pressed to ahndle the Cummins torque in a large delivery truck. Others disagree but I'm thinking the TH400 would last a lot longer in a lighter truck like an M37. I would rebuild with new clutches, bands and a new heavy duty performance type torque converter.

If I do use the automatic, what gears would I want with what tire size for best highway driving? I assume 4.89's with 11.00-16's would be in order.

I haven't driven mine yet but from what I hear the 'sweet spot' is around 1,900 to 2,000 rpm for cruising. You can play around with the ratio converter at the link to see what you'll have to do to get there.

http://www.4lo.com/calc/gearratio.htm

Has anyone done a writeup on how to do the swap?

Paul in NY and Cabell Garbee have websites at the links:

http://imageevent.com/moosecreekmaple

http://www.garbee.net/~cabell/

Does anyone sell premade motor mounts or trans mounts?

No. Not all that hard to fabricate though, or use the ones from the stepvan.

Can I use the original fuel tank and lines or will I need bigger lines to feed the Cummins?

I was able to install the 25 gallon aluminum tank from my donor stepvan to fit between frame rails in rear of my truck. 3/8" minimum on supply, 1/4" minimum on return line. Diesel fuel injection needs a return line from pump back to tank again. If you clean your old tank well it can be used for diesel but you'll go through quite a few fuel filters from what I hear.
What is the best choice for a radiator?

4BT diesels don't need a whole bunch of radiator.

Where can I find info about upgrading my brakes?

Dunno.

What kind of performance should I expect as far as mileage?

25-30.

I want to be able to travel at 60MPH pulling my car trailer on trips up to 1000 miles......Am I being realistic?

Reality is a relative thing dependent on personal reactions to various sensory perceptions and tactile stimulations causing perceptual cognizance of various orders of magnitude within the cerebral cortex such that one may experientially realize events at the moment. That's why you can't tell if you're nuts, if you are, and it's also why people who are actually quite nuts can make very good sense from time to time. Something to think about I suppose, but be mindful of the conclusions you draw. :~ )

Mike(with too many questions...) Canfield

Jimmied [with not 'nough answers.....]

**********

[MoparNorm]

12:04 am! Let me guess, it's snowing again, you have no fire and the 'puter screen is the warmest thing you have? ha!ha!
MN

[JimmieD]

Close! Steering column and shaft fought me like a wild colt and some wiring didn't want to get with the electron program so late knocking off. No snow predicted for the next couple of days so may have her running by Sunday? If not I'll tie a rope to the wheel chocks, get in and yank the rope and make little diesel noises while it rolls down the hill or something....virtual reality?

[CGarbee]

JimmieD has most of the answers covered... I'll add that the stock gas tank does work fine, and if you take it to a radiator shop and have it boiled out you will not have any problems with junk in the filter... You will have to run a return line to the tank, but that is easily done...
Stock radiator provides plenty of cooling for a 4BT. I have an electric fan installed on my truck and hardly use it, road draft over the radiator works great in spring, summer, and fall, and I run a radiator blanket in the winter so I can get some heat on the way to the office (I live in NC)...
Brake upgrades: Ray at Helitool provided a wonderful disc brake conversion setup. Hopefully, he will make some more sets in a year or so once he gets settled in his new digs overseas... Meanwhile, I know of more than one machinist who has looked at what is involved who is willing to step up if Ray does not. Meanwhile, Ray's site still has info not only on the disc brake conversions, but on the dual circuit master cylinder conversion (a great improvement all by itself).

I've been working on website updates this weekend. Most have been for events, but I have promissed a couple of folks some dimension and part numbers for things like my intermediate drive shaft (ZF S5-42 to NP200).

Good luck.

[slozukimc]

JimmieD has most of the answers covered... I'll add that the stock gas tank does work fine, and if you take it to a radiator shop and have it boiled out you will not have any problems with junk in the filter... You will have to run a return line to the tank, but that is easily done...
Stock radiator provides plenty of cooling for a 4BT. I have an electric fan installed on my truck and hardly use it, road draft over the radiator works great in spring, summer, and fall, and I run a radiator blanket in the winter so I can get some heat on the way to the office (I live in NC)...
Brake upgrades: Ray at Helitool provided a wonderful disc brake conversion setup. Hopefully, he will make some more sets in a year or so once he gets settled in his new digs overseas... Meanwhile, I know of more than one machinist who has looked at what is involved who is willing to step up if Ray does not. Meanwhile, Ray's site still has info not only on the disc brake conversions, but on the dual circuit master cylinder conversion (a great improvement all by itself).

I've been working on website updates this weekend. Most have been for events, but I have promissed a couple of folks some dimension and part numbers for things like my intermediate drive shaft (ZF S5-42 to NP200).

Good luck.

Hey All,
Thanks for the info so far!! I have been reading through more info than I though could possibly exist on this subject just in Paul and Cabell's links and what I can dig up in the posts here on the forum. EXCELLENT GUYS!!

I still have some questions.......

I don't recall where but I saw reference to a suspension lift and/or modifying the Cummins oil pan to fit over the front axle......Is this an issue I am likely to have to deal with?

I still have not heard from anyone who has used the TH400 automatic in thier swap.....Has anyone done it? I have run TH400's in 1 ton dumps and beat the snot out of them without a failure so I think for what I intend to do with the truck the automatic should be more than strong enough and should keep my installation costs to a minimum......I really can't afford the Cummins let alone an NV4500 and all to go along with it.

Gearing is my major concern with the automatic.......I know it will be plenty low enough offroad but will it be geared right for ON the road with only a 3 speed auto? I am looking at 4.89's and 11.00-16's to help but is that going to be enough to keep the Cummins at 1900 RPM or so for cruising?

NOW>>>My truck is FULLY functional and drives well as it is. I have gone to the trouble of making ALL of the 24 lights work as they should and would like to keep it that way. I have a brand new turn signal box and switch and all of the wiring in the entire truck is in excellent condition so I would like to know how hard it would be to convert the Cummins to 24V?
Would it be possible to run 24V lighting and charge the batteries with 12 somehow? Maybe a large diode to keep the 24V from the alternator? Can I get a 24V alternator for the CUmmins? Could I just use my stock generator on the Cummins?
(By the way.....If anyone needs to locate the rare as hen's teeth manual turn signal control box for the M37 just order one for an M715.....THey are the same thing and when ordered for the 715 instead of the 37 costs less than half the money.)

Are there any year or model trucks that I can get 4.89 gears from that will work in my truck?

How well will the stock case hold up to the Cummins? Any suggestions to make it quieter than it is? I heard it used to be common to fill the case with STP in the motor pool to quiet them down......Any words of wisdom here or should I be looking at a 205? I believe I know where one is with a passenger side drop front and rear........

THANKS GUYS!!!!

Mike(WHo will have a million more questions before this project is done....)

[MoparNorm]

Hey All,
Thanks for the info so far!! I have been reading through more info than I though could possibly exist on this subject just in Paul and Cabell's links and what I can dig up in the posts here on the forum. EXCELLENT GUYS!!

I still have some questions.......

I don't recall where but I saw reference to a suspension lift and/or modifying the Cummins oil pan to fit over the front axle......Is this an issue I am likely to have to deal with?

I still have not heard from anyone who has used the TH400 automatic in thier swap.....Has anyone done it? I have run TH400's in 1 ton dumps and beat the snot out of them without a failure so I think for what I intend to do with the truck the automatic should be more than strong enough and should keep my installation costs to a minimum......I really can't afford the Cummins let alone an NV4500 and all to go along with it. ........

THANKS GUYS!!!!

Mike(WHo will have a million more questions before this project is done....)

Paul has modified all of his oil pans to clear, I don't know about Cabell and Charles. The TH400 comes behind the 4bt in some of the "bread" vans, but crossmember and transfer case connection are uncharted waters, unless Cabell and/or Charles have converted one. The auto will compensate, somewhat, for the low gears and make the truck a tad more driveable but it won't help you with the top speed unless it has a lockup overdrive.
MN

[Keith in CO]

Th400

I still have not heard from anyone who has used the TH400 automatic in thier swap.....Has anyone done it? Gearing is my major concern with the automatic.......I know it will be plenty low enough offroad but will it be geared right for ON the road with only a 3 speed auto? I am looking at 4.89's and 11.00-16's to help but is that going to be enough to keep the Cummins at 1900 RPM or so for cruising?

How well will the stock case hold up to the Cummins? Any suggestions to make it quieter than it is? I heard it used to be common to fill the case with STP in the motor pool to quiet them down......Any words of wisdom here or should I be looking at a 205? I believe I know where one is with a passenger side drop front and rear........

I use a TH400 with a big block in my M37 and that transmission is plenty tough enough for a 4BT. Since 3rd gear is 1:1 (rather than the .75:1 fifth gear of the NV4500), you will have to crunch the numbers on various tire sizes to get the RPMs you want on the highway. I used a double cardan joint with a slip yoke on the front and stock style yoke on the rear to hook up the 2wd TH400 to my NP200 t-case, and this same method would work on a 4bt/TH400. I also use synthetic gear lube in my t-case to help it stay effectively lubed at highway speeds, but I also use ear plugs during sustained highway driving.

http://home-and-garden.webshots.com/...64381057IVHZEV

Never heard of an NP205 with a passenger side rear output - please fill us in on that application.

[slozukimc]

I use a TH400 with a big block in my M37 and that transmission is plenty tough enough for a 4BT. Since 3rd gear is 1:1 (rather than the .75:1 fifth gear of the NV4500), you will have to crunch the numbers on various tire sizes to get the RPMs you want on the highway. I used a double cardan joint with a slip yoke on the front and stock style yoke on the rear to hook up the 2wd TH400 to my NP200 t-case, and this same method would work on a 4bt/TH400. I also use synthetic gear lube in my t-case to help it stay effectively lubed at highway speeds, but I also use ear plugs during sustained highway driving.

http://home-and-garden.webshots.com/...64381057IVHZEV

Never heard of an NP205 with a passenger side rear output - please fill us in on that application.

So, IIRC, the 4 speed in my truck has a 1:1 final drive as well. That is better than I expected. I like the way you mated the trany to the case....Very simple and very strong. I will likely do the same. As far as the case goes I know what you mean about the earplugs on the highway and that IS my major concern.....I plan to drive alot of highway miles with it and the noise is going to be an issue for sure.

As far as the 205 goes I will have to go look at it. I was told that's what it is and was going on his say so. It is a divorced case for sure but he may be mistaken on the output being offset. If it does have an offset output what case would it be if it is not a 200? Is there a solution to my problem without going to a centered diff setup?

Thanks again, Mike

[slozukimc]

Paul has modified all of his oil pans to clear, I don't know about Cabell and Charles. The TH400 comes behind the 4bt in some of the "bread" vans, but crossmember and transfer case connection are uncharted waters, unless Cabell and/or Charles have converted one. The auto will compensate, somewhat, for the low gears and make the truck a tad more driveable but it won't help you with the top speed unless it has a lockup overdrive.
MN

HHHMMMMM..........A crossmember should be a breeze and I like Kieth's solution for connecting the tranny to the case. The oil pan is a concern as I am doing all of this in my driveway, in the dirt, and I would really rather not have to mess with taking the pan off if I don't absolutely have to. The Frito-Lay van I found has an automatic, I would assume the TH400 but I haven't looked to be sure. I am still trying to come up with the cash to go buy the darned thing......Anyone interested in any of my stock parts let me know. Runs great, smokes a bit, probably valve seals.

Thanks, Mike

[JimmieD]

Don't know if it will help you for your swap but I have the complete GM/Cummins changeover parts available:

http://www.powerwagonadvertiser.com/...ead.php?t=4991

I would use nothing less than Spicer 1350 u-joints behind the Cummins, and I used Spicer 1410 on trans output. I have a Pontiac TH400 output splined yoke for Spicer 1350 included in parts listed above.

Diesel smoking can be a bad sign or maybe not. There are adjustments on the Bosch VE fuel injection pump to increase power and if these are tweaked incorrectly it causes black smoke. Also installation of fat sticks like Lucas POD injectors cause clouds of smoke. Turbo/intake leaks might contribute to smoke but only rarely. Question is, are we talikng diesel fuel black/grey smoke and haze, or is it blue oil smoke? I'd shy away from an engine with blue oil smoke under your circumstances. Not fun to rebuild in the yard on the dirt, but kits are only about $600. Careful.......

[slozukimc]

Don't know if it will help you for your swap but I have the complete GM/Cummins changeover parts available:

http://www.powerwagonadvertiser.com/...ead.php?t=4991

I would use nothing less than Spicer 1350 u-joints behind the Cummins, and I used Spicer 1410 on trans output. I have a Pontiac TH400 output splined yoke for Spicer 1350 included in parts listed above.

Diesel smoking can be a bad sign or maybe not. There are adjustments on the Bosch VE fuel injection pump to increase power and if these are tweaked incorrectly it causes black smoke. Also installation of fat sticks like Lucas POD injectors cause clouds of smoke. Turbo/intake leaks might contribute to smoke but only rarely. Question is, are we talikng diesel fuel black/grey smoke and haze, or is it blue oil smoke? I'd shy away from an engine with blue oil smoke under your circumstances. Not fun to rebuild in the yard on the dirt, but kits are only about $600. Careful.......

It's not the diesel that smokes it's the M37 engine that I am removing that needs the valve seals. I will have all of those parts as well when I pull the van apart.

Thanks, Mike

[Keith in CO]

4BT M37 tow rig?

As far as the 205 goes I will have to go look at it. I was told that's what it is and was going on his say so. It is a divorced case for sure but he may be mistaken on the output being offset. If it does have an offset output what case would it be if it is not a 200? Is there a solution to my problem without going to a centered diff setup?

I've seen divorced 205s with passenger side front output, but never with a offset rear output. Don't know of any NPs with offset rear outputs other than the 200.

Will defer to the people with 4BT experience here, but I am not sure the 4BT has enough power to pull a loaded car trailer at highway speeds, other than down hill. I've logged thousands of highway miles in my M37 because I had to in order to get to trailheads, and although the M37 is more comfortable that you would think, it is not a highway cruiser, and certainly not what I would choose for a tow rig. IMO, M37s are fun in the dirt and a drag on the pavement, and converting an M37 into a quiet, comfortable, highway tow rig is more work that it is worth -you could just buy a used Dodge CTD and be way ahead of the game in money, work, time and end results.

[JimmieD]

Stock 4BT is around 105-120 hp, 300 ft lbs torque. some very simple adjustments can bring up the power but you need to be careful on EGT's Exhaust Gas Temperatures. Almost all of the 1st Gen 6BT performance tricks are identical for a 4BT or 4BTA. Not hard at all to get 150hp and near 400 ft lbs torque with simple adjustments, and with performance parts you can get into the 250hp/500 ft lbs torque area. This torque is virtually off idle so it's far more available compared to a gasser engine.

You can go ahead and tweak the 4BT's Bosch VE injector pump and then use a larger turbo setup, like HTT High Tech Turbo, to cool it back down. A further option is water/methanol injection. This adds more power from injected methanol while the injected water cools the EGT's.

4BT is the same engine as a 1st Gen 6BT except for 2 less cylinders.

[slozukimc]

I've seen divorced 205s with passenger side front output, but never with a offset rear output. Don't know of any NPs with offset rear outputs other than the 200.

Will defer to the people with 4BT experience here, but I am not sure the 4BT has enough power to pull a loaded car trailer at highway speeds, other than down hill. I've logged thousands of highway miles in my M37 because I had to in order to get to trailheads, and although the M37 is more comfortable that you would think, it is not a highway cruiser, and certainly not what I would choose for a tow rig. IMO, M37s are fun in the dirt and a drag on the pavement, and converting an M37 into a quiet, comfortable, highway tow rig is more work that it is worth -you could just buy a used Dodge CTD and be way ahead of the game in money, work, time and end results.

I LOVE THE WAY MY M37 DRIVES!! It just needs to be a bit quiter. It is a real truck and handles as such. I drive mine every day until they start salting the roads and I am not afraid at all of long trips with it the way it is. With the better gearing, more power from the Cummins, better tires and some sound deadening work I will be glad to drive it at 55MPH all day long pulling my trailer. Also bear in mind I only haul 2500-3000 pound vehicles on a lightweight utility trailer....Total load including the weight of the truck is less than the GVWR of the Frito-Lay van.
Also I have the M37(It has less than 20K miles on it)(I need to get some pics of her posted for you guys to see), I can get the Cummins cheap($2000 for the truck-scrap aluminum after I am done with it) and I can do almost all of the work involved myself(I am self employed and have lots of time to work on it) and come out with a better all purpose truck for way less money than buying someones worn out CTD Dodge for 5 grand. From what I have heard here I can expect better fuel economy from my M37 with the 4BT than I have heard of anyone getting with a modern diesel truck of any sort. Parts for the M are readily available and comparably cheap to the newer trucks. It is much easier to work on for major repairs and service. I have no objection at all to checking the fluids in everything once a week(engine oil much more often) and going over the ole gal with the grease gun at the same time. I realize that the maintenance is the lifeblood of the truck and if maintained properly it will last my lifetime and perform any task I throw at it.....Newer trucks just can't do that. I love pulling newer "small tire" 3/4 and 1 ton trucks out of the same mud I just wallowed through with a 2000 pound diesel welder on the back.....SUCH FUN!!
All of this goes right along with the fact that I am just crazy enough to spend the time riding across the country or around the continent in my M37 if I can make it economical enough to do so....It is surely durable enough for the task. ;>) Somehow she just turns driving from work into pleasure even when we are working hard. Must be some wierd old truck fetish or something...LOLOL

Mike(who thought about swapping his M37 for a 3/4 ton CTD Dodge and then realized just how foolish that would be in the long run......)