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Discussion Starter · #1 ·
Hello, I am a newbie to this group. I have a 1941 Chevy Suburban that I am doing a frame off restoration on. It currently has the original 216 straight (gas) six, three speed, torque tube and stock rear. I was offered an additional 1941 1/2 ton frame with a 235 six, four speed, highway geared rear.
The problem is that once the resto is complete I want to be able to tow my Travel trailer during the spring and summer, it weighs 2900 lbs loaded. I am looking for for a motor that can pull at highway speeds up hills and still get decent fuel economy for everyday driving.
A friend at work suggested that I look into dropping in a diesel, and so I posted on the Stovebolt forum asking about it and was immediatly directed here.
I know absolutley nothing about diesels other than they are torque monsters!! I have have 15+ years expierience building cars but have never touched a diesel...but am interested.
Any suggestions?? Trannys? Rears? Installation??
Thanks in advance!!
Johnny
 

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A frame-swap for sure on that older vehicle if you're going with a 4BT b/c of the weight. A custom tube frame for strength & light-weight or swap something from a later model if the dimensions will work (1/2 ton truck, etc).

Transmissions? Possibilites are endless. If you're doing regular towing I'd recommend against a light duty automatic (700R4). A 4L80E, dodge auto from the 6cyl cummins, Allison, etc. would be better.
 

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I'm not familiar with the 41 frame, is it channel or boxed? If its channel than box it. The weight is the same as a big block chevy, lots of those in 40s chevs. Are you going to keep the stock front suspension or use a Camaro-Nova type clip? You will need better brakes and steering with the added weight. Personel taste taste on trans, I like a manual myself. Lots of options. Build it like you would a street rod and it will be a lot of fun. Don't forget your cruise rpms could be lower when choosing gears and rear tire size. If you consider a frame swap take a lot of measurements of your floors or you could end up doing a lot of carveing on them. Have fun.
 

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Are you going to keep the stock front suspension or use a Camaro-Nova type clip? You will need better brakes and steering with the added weight.
Agreed. If this vehicle will be used for anything other than a museum, plan on a lot of modern brake and suspension upgrades. I wouldn't trust that 70 year-old rear end, either. The torque of a 235 is less than 200 ft lbs, a 4BT would kill the stock rear in short order.

We had a '47 1-1/2 ton truck with a 216, it was a real work horse for anything under 40 mph. Forget speeds over that, though.

You might also want to look into the Japanese-built Cummins 4BT 3.3 liter.
It may be more closely matched for what you need.
 

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The diesel likes gearing that is close together. Large steps in gearing take the motor out of the power band. You don't rev the diesel like the gas motors. When you upshift it takes the rpm way down if the next gear is a big jump.
I think the 3.9 would be a better choice than the 3.3 since you will be towing.
Most rear axles will be to wide for your Suburban. I was recently told about a swap using Jeep parts. You may want to look at Wagoneer or Comando parts. I do not know how strong these are though.
You will have the same width problem on the front. These old trucks have narrow track width and unless you are going 4x4 with a lift they don't look good with the tires hanging out of the fenders. I'm a street rodder so I like my stuff LOW, but I realize that isn't for everyone. If you are going 2 wheel drive there are a few thoughts. Narrow a GM car subframe or find a heavy duty Mustang II aftermarket front. Either way you will need springs for a big block application. A stock MII crossmember will not support the weight. The aftermarket units are much stronger. If going the MII route buy one with the strut rods eliminated. The strut rod brackets would break off the frame with this service.
Frame swaps are a pain. Nothing ever fits like it should. If you can beef up your stock frame I would do that.
Since your truck had the 6 there will be plenty of room for the 4bt. I suggest setting it back as far as possible to lighten the load on the front axle as much a possible. The exhaust is the limiting factor on engine setback.
 

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The brakes and steering will need to be addressed.
I am not so sure I would box the frame right away. The old trucks are pretty sturdy to start with, and that 235 is a pretty heavy engine.

For my 48 Chevy (Detroit) Diesel project I decided to keep the original frame, as it is well built, fits the truck, and looks better than a newer frame. It is a 2 ton, so plenty strong, and even a 3/4 ton I feel would be strong enough.

A 1941 1/2 ton with a 4BT, depending on it's use, may be fine with the original frame as is. Part of the equation is how you make the mounts. If they are like original, one at the very front, and two at the flywheel, I bet the frame will be OK. If you use the two mid side mounts some work will have to be done in those areas.

Grigg
 

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Discussion Starter · #7 ·
Before investigating the diesel option I was thinking aboyt a 292 inline six with a NV4500 tranny and a newer rear with at leat a 3.55 ratio.
I was also think about a Heidts Mustang 2 front end.
Some specs are as follows the wheel base is 115", the rear axle is approx 55" from the inside plates, the stock engine dry weight is 563 lbs (for the 216) the 235 weighs 273 lbs dry.
What I am interested in figureing out is the best way to mount the engine into the old frame. I don't mind spending time welding, measuring etc. my goal is to do it right once. I'm not into frame swapping I've seen it done and helped friends do it and I would rather beef up an old frame than cut and grind on a stock body. I also want to keep it at the stock height, basically I want it to look bone stock from the outside. The 1/2 ton frame is not boxed but appears pretty stout, boxing it would not be terribly hard and is totally do-able if necessary, I also realize that I would probably need a beefier rear and will need to beef up the springs etc. (it currently has 8 springs in the back) I would like to keep the chevy six lugs pattern and use older rims if at all possible. The max wheel/tire sise that the Burb can handle is 16x6.75 (I think it may be 16x6.50 it currently has 15" artillery wheels).
I am also open to different trannys other than the NV4500 my goal is to get the best fuel economy for a daily driver and be able to haul my trailer over Donner Summit with no trouble. Closer gearing makes sense what are some common combos with the 4TB? What about rear gearing?
 

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I have been through classis builds, race truck, and a diesel transplant stuff. FWIW, my advice would be to keep and modify the existing frame. I did a frame swap on a 57 truck and wish I had modified the original instead. It just works better if you have the original rails and all the mouting hardware to work with. You can easily box it and add bracing to handle the 4BT.

Being a chevy build, and me being a chevy fan myself, I would suggest a 4l80e. I am currently building one for my 6BT converted truck. It should hold well if properly built and with the lockup converter and .75 OD you will get great mileage....which is what I am after as well.
 

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Most rear axles will be to wide for your Suburban. I was recently told about a swap using Jeep parts. You may want to look at Wagoneer or Comando parts. I do not know how strong these are though.
Ford 8.8" rear from an Explorer or Ranger for the win!
Custom length/flange/bolt pattern axles are cheap for the 8.8 rears.
 

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Before investigating the diesel option I was thinking aboyt a 292 inline six with a NV4500 tranny and a newer rear with at leat a 3.55 ratio.
I was also think about a Heidts Mustang 2 front end.
Some specs are as follows the wheel base is 115", the rear axle is approx 55" from the inside plates, the stock engine dry weight is 563 lbs (for the 216) the 235 weighs 273 lbs dry.
What I am interested in figureing out is the best way to mount the engine into the old frame. I don't mind spending time welding, measuring etc. my goal is to do it right once. I'm not into frame swapping I've seen it done and helped friends do it and I would rather beef up an old frame than cut and grind on a stock body. I also want to keep it at the stock height, basically I want it to look bone stock from the outside. The 1/2 ton frame is not boxed but appears pretty stout, boxing it would not be terribly hard and is totally do-able if necessary, I also realize that I would probably need a beefier rear and will need to beef up the springs etc. (it currently has 8 springs in the back) I would like to keep the chevy six lugs pattern and use older rims if at all possible. The max wheel/tire sise that the Burb can handle is 16x6.75 (I think it may be 16x6.50 it currently has 15" artillery wheels).
I am also open to different trannys other than the NV4500 my goal is to get the best fuel economy for a daily driver and be able to haul my trailer over Donner Summit with no trouble. Closer gearing makes sense what are some common combos with the 4TB? What about rear gearing?
The NV4500 would work fine with the 4BT.

As mentioned, an 8.8" Ford rear from a Ranger or Explorer would provide adequate strength, and the right width.

The turbocharger will take care of the mountains - with no problems, Donner is not that steep - it is nothing compared with heading up to the Eisenhower tunnel in Colorado.

Gears, 3.55 are the lowest (highest numerically) that I'd go. Somewhere between 3.55 and 3.08 is probably the sweet spot with the tires you are planning. You want to be under 2000 rpm at 65mph in top gear.
 

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Discussion Starter · #11 ·
Ford 8.8" rear from an Explorer or Ranger for the win!
Custom length/flange/bolt pattern axles are cheap for the 8.8 rears.
I've been looking into the Explorer 8.8 rears and they seem like the way to go...the only problem is the 5 on 4.5 bolt pattern I need to use the 6 on 5.5 chevy pattern on the flange to use the artillery wheels that I have for the Burb and are currently in use on the restored travel trailer. Who makes these flange converions? So far I have had no luck finding anything... I have been looking but have only seen a two piece wheel adapter that looks dangerous for my application....any idears??
Any other rears you guys would suggest?
 

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I've been looking into the Explorer 8.8 rears and they seem like the way to go...the only problem is the 5 on 4.5 bolt pattern I need to use the 6 on 5.5 chevy pattern on the flange to use the artillery wheels that I have for the Burb and are currently in use on the restored travel trailer. Who makes these flange converions? So far I have had no luck finding anything... I have been looking but have only seen a two piece wheel adapter that looks dangerous for my application....any idears??
Any other rears you guys would suggest?
Get a set of custom axles made. Check out Moser engineering.
 

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I think that the Ford 8.8 or 9" rears are no problem to have custom axles made with the bolt pattern of your choice.
Try:
http://www.dynatrac.com/products_sstshocks.html

Also pick up a copy of "Peterson's 4 wheel & off road" magazine, many advertisers who may have axle and bolt pattern solutions for you.

Grigg
 

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For your rear axle, look into the rear from an old Jeep Wagoneer. It will be a Dana 44, or a AMC 20. They are narrow, have 11x2 drum brakes, and have the same 6x5.5 bolt pattern than Chevy uses. If you source one '80 or later, it will have 2.73 (standard) or 3.31 (towing package) gears.
 

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Seamed to me the Dana 44 rears proved themselves less than worthless under every fullsize truck they went under in the 50's through the 70's. They're an upgrade for a Jeep, but probably best not applied to bigger animals. 8.8 has proven to be pretty good chunk of iron, all except Fords plastic diff cover they used for a few years.
 

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In a light 1/2 ton that was not worked everyday I would have no problems with a Dana 44.

I had one in an IH Scout pickup, plenty of power with the 304 V8, but no weight in the rear, you can't tear up a rear axle if it can't get traction....

Depends on the use as to if the 44 is a good idea or not, I think in this case it may be.

Grigg
 

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Being a Jeep fan I have messed around with the many versions of the Dana 44 Jeep offered. Depending on which t-case there were several different offsets as well as a centered pinion model, also several different widths. Most of the Jeep Dana 44 axles were thin wall tube housings, thus low GAWR. Moser eng. , Yukon gear, Summers Bros., and Alloy USA all offer custom axle shafts at a decent price for the Dana 44. But IMO I would stick to something that is a stock length. That way if a shaft breaks you can get one from a junk yard or NAPA, etc. and not have to reorder a custom shaft.
I skimmed over this thread and I didn't see any WMS dimension for your stock Suburban rear axle. Like others have mentioned I would favor the Ford 8.8 over an AMC/DCX version of the Dana 44. Besides you will end up with a free rear disk brake upgrade in the process.
 
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