D30 questions

I am a new member to the forum. I have just purchased my first IH product, a late 30's D30 truck. I has been sitting for a very long time. I have a few questions for those who are more knowledgable on these trucks.

Year of production? How do I tell? I never noticed the tag on the firewall.

I am wondering about the wheels. They are split rims but what type are they? How safe are they?

The original sales brochure lists the rear ratios as: 5.28:1, 6.16:1, or 6.60:1. My curiousity is how long this rear axle stayed in the IH lineup and if a more modern ratio (4.10) might be available to get the RPM down on the highway. A 12V cummins wants to slip into the engine bay.

If the axle has higher gears (lower numerical ratio) in it, you might be able to get away with a 5-speed overdrive transmission and be able to get highway speeds. But then the rear end was designed for 80 or 90 hp, so it might not stand up to 200+ if you haul any kind of weight.

Here's a gear calculator I just remembered I had saved. It's kinda fun to play with and dream about all the great gearing options you could put in your truck. http://www.grimmjeeper.com/gears.html It's aimed at 4 wheel drive applications but you can just ignore the transfer case fields.

Some quick number punching shows with 8.25x20 tires (~37" diameter), 6.60 rear end and a transmission with a .8:1 OD will go 55mph turning 2650 rpm.

Remember, we wanna see the diesel swap.

If the axle has higher gears (lower numerical ratio) in it, you might be able to get away with a 5-speed overdrive transmission and be able to get highway speeds. But then the rear end was designed for 80 or 90 hp, so it might not stand up to 200+ if you haul any kind of weight.

Here's a gear calculator I just remembered I had saved. It's kinda fun to play with and dream about all the great gearing options you could put in your truck. http://www.grimmjeeper.com/gears.html It's aimed at 4 wheel drive applications but you can just ignore the transfer case fields.

Some quick number punching shows with 8.25x20 tires (~37" diameter), 6.60 rear end and a transmission with a .8:1 OD will go 55mph turning 2650 rpm.

Remember, we wanna see the diesel swap.

My initial thought was to remove the old axles (gasp) and swap a chevrolet P30 disk brake straight axle in the front, and a cab and chassis full float GM 14 bolt in the rear, 3.73 gears and 8x19.5 tires with a cummins and an NV4500 5 speed (.77 OD). I have even found a strange intercooler that might fit the D30 fairly easy. It would be set up to tow if it could stay cool. The cummins won't be stock they drive and tow great at 300+ HP. It looks like the D30 frame should be able to handle that.

Option B, is to just put a Chevy D60 dually front under it and make it 4WD. I already have the D60 and the 4WD NV4500 for a cummins.

I was thinking of trying to keep it looking like a little old semi tractor as much as I can. If it gets 19.5's I'll paint and stripe the wheels to try and make it look believable. I was thinking of a single 5'' stack with a rain cap behind the cab, old road flares, and am thinking about a visor. I'm thinking I will need to put the air cleaner outside the engine bay to unclutter things under the hood. Might touch on some old early custom mods from street rods etc. Wish I could find some old beer kegs for fuel tanks...

Glad to see you here, will leave the intro where it is at. Look forward to pictures.

Lloyd

I've bored everyone here but here I go again. I swapped 1968 IHC drivetrain (304 V8 Auto) including front and rear axles, wheels and tires into a D-30. I shortened the wheelbase while I was at it. It all fit like a glove. It drove like a dream.

1968 IHC 1 ton. Dual wheel rear axle.

Maybe some pictures would help out the conversation some more...

Best thing you can do right now is dig out around the wheels and jack it up so they are not in the moisture any longer. It's probably already too late, but you could be lucky. Thing is you don't want what ever damage is done to get any worse. Good luck on your project! MM

Looks like a decent place to start. No apparent rust-through. I really like the look of the D series. That's a unique fender brace you have on the passenger side. How much room is there between the radiator and the center of the firewall?

Dean

Looks like a decent place to start. No apparent rust-through. I really like the look of the D series. That's a unique fender brace you have on the passenger side. How much room is there between the radiator and the center of the firewall?

Dean

There is some rust through inside the cab in the area around the wiper motor from birds nesting up there. I should be able to find a donor cab or the panel somewhere. I also need to find another set of D30 headlights... apparently they are larger than a regular pickup? and the current owner wants to keep them for another project.

Those fender braces are on both sides. They will be removed and braces will be built under the fender. Apparently, this was a common modification on heavy trucks in this area back then, rough washboard roads are common even now.

There is 33" between the radiator and firewall, I need to stretch that to about 37". I will alter the recess in the firewall to make room for the rotary pumped 12V cummins 6BT. I will be able to run a clutch fan and have about a 1/2" between the radiator and fan clutch, just like the 1992 dodge the engine came out of.

Oh, I got a barrel with the stainless trim for the grill and hood in it in the deal. I think one piece is missing.