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Old 05-28-2011, 06:13 PM
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1941 dodge business coupe

I'm in the process of putting a 1941 dodge business coupe onto a 1996 dodge dakota truck chassis. I've shortened the frame 10 inches to match the 41 dodge 119" wheel base. If anyone has done this, how far does the 5.2 dodge dakota motor have to go back as to allow the front of the 41 dodge to connect to the main body. The motor has to go back and I do have quite a bit of room to move it back to the firewall. If someone has any thought to this process. Let me know. Will I have to weld new mounts on the chassis or can I just move the motor back onto the factory mounts. Looks like I have some room for this process. Thanks

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Old 05-28-2011, 07:53 PM
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I found out many years ago after my first frame swap that this is not the way to do it. It almost always ends up looking clunky.

Here's the way I would do it next time....
With the Dakota chassis sitting on a level pad and complete with wheels and tires, remove the front and rear springs so that you can position the front control arms and the rear differential in the relationship that they will have when under load. This may mean finding a complete, running Dakota and taking some readings off the components with an angle finder and a tape. Make up whatever brackets you need to, using scrap steel and allthread to hold the components together at ride height. I CANNOT OVEREMPHASIZE THE IMPORTANCE OF GETTING THIS PART OF THE SWAP RIGHT. PAY ATTENTION.

With the Dodge on a level, flat pad, put jackstands under the frame just behind the firewall and just ahead of the spring arch in the rear just so that the tires are barely off the ground. Take measurements from the firewall to the location of the hood latch on the core support. Remove the hood and fenders. Leaving about 8-10 inches of frame stub in front of the firewall, torch off the front frame clip. Go to the rear and torch off the rear frame clip, leaving enough stub so that you can weld the Dakota rear clip onto it.

Now, drop the body down to exactly where you want it for ride height and level it side to side. If you want a little California rake to it, then position the body for a little rake. If you want the body to be level, then position it level, with whatever ground clearance you want. If you want the back lower than the front like a liquored-up Kentucky hillbilly, then position the body that way. What we're doing here is getting the exact ride height and body attitude we want without the use of Fosdick dropped spindles or cut spring coils or any other amateurish monkey business. It'll be all stock with the Dakota ride quality and Dakota steering geometry and Dakota brakes. Cool, huh?

Now, with the Dakota chassis secured at stock Dakota ride height, just like in a real, running example of the truck, mount the motor and transmission into the chassis on the stock mounts. Bolt headers that are made for this motor in a '96 Dakota onto the heads. At the engine crossmember, fabricate a caster wheel (pirate one off a derelict shopping cart or whatever) and attach it under the crossmember, having the caster wheel touch the ground and located slightly to the rear of the Dakota wheels and tires, so that you have a short tricycle. Cut the Dakota front frame clip off the chassis right behind the transmission crossmember. You want to keep the forward/rearward tilt of the front clip in the same position as it was on the Dakota chassis at ride height. If you allow the clip to tilt forward or backward from the factory-designed attitude, trust me, nothing will work properly. Been there, done that. PAY ATTENTION. That's why I use the third wheel and make a tricycle out of it, to keep everything like it's supposed to be.

As you move the Dakota front clip into position in the front of the Dodge, you may have to cut the transmission crossmember off and some more of the frame ahead of the crossmember, depending on what's in the way of letting you push the clip back far enough to get the motor up against the firewall. If you have to do this and the transmission wants to dangle, put the trans pan on a creeper and chock it back up to the proper height with wood blocks so you can still roll the Dakota front clip around. Make certain you put a level on the Dakota clip to insure it's not lower on one side than the other. If it's out a little, you can add or let a little air out of one tire to level it up. You will have to trim each of the two Dodge frame stubs and each of the two Dakota clip stubs as you move the Dakota clip into position. Just keep trimming and moving and measuring for equal wheelbase side to side until you get it there and you see how you are going to join the stubs together. You can be measuring from holes in the frame on the Dodge and the Dakota that you know are the same distance left to right in order to keep the wheelbase equal. Once you feel like you're close, have a couple of buddies hold one of the front fenders in position so you can eyeball the car from the side and check the position of the tire in the wheelwell. This is where you want to PAY ATTENTION, as this relationship will make or break the swap. Once you have the clip in place, make up your 2" x 4" "Z" components to join the stubs together. Tack them in place for now, you can finish welding them later and add flat "fish plate" reinforcements to the sides of the joints. You may have to make minor changes, so don't finish weld until you know that everything is absolute right. Cut out anything that gets in the way of the headers and re-construct it later.

Do the same with the rear, making a tricycle with a caster wheel so that you can just wheel the clip up into place, same way you did in front.

There it is. You have a roller. Mount the core support from the Dakota so you can use the Dakota cooling system, ALL OF IT. Use what has already been engineered at the factory to work, not some Fosdick cobbled up mess from a catalog.

My explanation may sound simple to you, but believe me, this is the pinnacle of automotive fabrication and will take every ounce of your skill and determination to accomplish properly. But I'll tell you, when you get the old girl running and she handles, steers and stops properly, you'll be grinnin' from ear to ear.

Last edited by techinspector1; 05-28-2011 at 08:11 PM.
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Old 05-29-2011, 11:03 AM
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1941 dodge/dakota frame swap

Thanks! I will consider this since I still have the the old 41 chassis removed and the dakota chassis intact. I did lower the front 2inches of the dakota chassis with lowering spindles. Since all this is new, I will maintain the front drop. Not sure how the frame will match up to the 41 dodge after the I clip the front and rear of the dakota chassis. I know how important is is to keep the frame from twisting or moving and level. Not sure which way to go on this one. Thanks for the information.
Jim
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Old 05-29-2011, 11:35 AM
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Quote:
Originally Posted by midsota
Thanks! I will consider this since I still have the the old 41 chassis removed and the dakota chassis intact. I did lower the front 2inches of the dakota chassis with lowering spindles. Since all this is new, I will maintain the front drop. Not sure how the frame will match up to the 41 dodge after the I clip the front and rear of the dakota chassis. I know how important is is to keep the frame from twisting or moving and level. Not sure which way to go on this one. Thanks for the information.
Jim
Jim, if you follow my lead, take those dropped spindles off and sling 'em over the fence. The factory spent millions of dollars to hire professional engineers to CAD the front suspension so that it would work properly. You haven't even gotten started good and you've already fouled the whole scheme with some fosdick aftermarket crap. Love me or hate me, I don't care either way, but I will never intentionally lead you the wrong way.
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Old 05-30-2011, 01:57 PM
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41 Dodge

Just a thought. If I cut the dakota chassis and roll it back until it reaches the firewall, I will not have the 119" wheelbase and front wheels will not be in the right position for centering it in front 41 dodge wheel wells. I still will have to move the motor back. Maybe I'm missing something here since I'm new to the street rod build.
Jim
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Old 05-30-2011, 02:07 PM
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Before you cut that beautiful original frame all up REALLY think hard on this project. If this is your last step of the rebuild you may be out of time. But if you are just starting on this car and it needs body and paint and other things, go onto those other things and look around at these cars. Not many 41's with production stopping because of the war. There are many suspension kits out there to make that car drive and ride great, there is no reason to chop the frame in half an put something under that that simply doesn't belong.

Mating the frames is the easiest part of the whole project. The rad support, inner fenders and bumper mounting is where all the work comes in. Many times a LOT more work is involved with these mods than welding the frame sections together, that is the easy part!

Cutting that beautiful frame in half and putting on an ugly late model chunk would be the last thing I'd do.

Sell the Dakota frame and buy a nice Mustang II kit or something but don't cut that beautiful original frame up.

Brian
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Old 05-30-2011, 03:54 PM
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If I understand the question correct, you have already cut the Dakota chassis and set the wheelbase at 119", the original wheelbase length of the 41 Plymouth? Assuming this is correct:

Now with the rear tires centered in the rear fender openings (hopefully the front tires also are centered in the front fender openings?) the engine is located too far forward. There is a huge gap between it and the firewall. The radiator will have to be mounted out in front of the grill.

Assuming my understanding is still correct:

The next thing I would do is move the engine and transmission back. Measure from the back of the engine to the firewall (do this in several locations so you don't end up with a surprise interference). Then subtract about a half inch. The difference is how much to move the engine back. The crossmember for the transmission will probably be an easy move rearward assuming the frame rails go straight back. If there is a kick up or kick down, it may be more complicated, but still the easiest part of this.

I would then look at the possibility of removing the front mounts from the frame and relocating them rearward. If they are attached to the frame rails, this may be as easy as the crossmember. If they are attached to the crossmember, you are probably going to be modifying them or fabbing new ones. Love 'em or hate 'em, these guys built some slick mounts. Should give you some ideas. http://www.powerblocktv.com/video/?ep_show=TK

Make sure the engine is leveled side to side. Centering it would be nice, but not absolutely necessary. My 41 Chevy has the engine offset to the right by about half an inch to provide steering clearance. The important thing is that the centerline of the crank and tranny are parallel to the centerline of the car. The fore/aft angle will need to be set. They used 3 deg. which is probably close enough. Once you have the engine set, don't forget the pinion angle on the rear end.

I am also assuming you shortened the frame correctly. Offset cuts would be nice. Fish plates are an absolute necessity. The body and frame mounts are done correctly. In order to prevent it from looking like a car on a truck frame, did you channel the body over the frame?

Forgot one thing. You did check the track width, didn't you? Some of those 40's cars had a narrow track width. Some late model cars and trucks are an inch or two wider. Doesn't sound like much until you go to take a turn and rip the front fenders off.
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