C-series build underway. Dakota chassis big block

Howdy!

So I posted a little bit ago about my plans and got a bunch of wisdom from y’all and Dabee even PM’d me his phone # and sent me a bunch of helpful pictures of a finished pilot house on a Dak frame. This will be my build thread so it can hopefully help others and give folks a chance to tell me I’m doing things bass ackwards

Things are moving along nicely. I have four or five days in so far. The dakota is stripped from the bed foreward, leaving the suspension and steering in place. That will all get rebuilt and rebushed later. The 54 has the fenders nose and rad support removed as a unit. It was two bolts in each doorjam and two bolts holding the rad support. They all fought mightily but none required the torch. The cab bolts were harder but the cab is off the 54 chassis as well.

Yesterday I got some help from a couple friends and we did a first mock up. The rear body mount pedestals which also hold the front bed mounts are too wide and need to get chopped off so the cab can slide back. I’m saving them and relocating the front portion to be reused with new poly body mounts for a dakota.

The front body mounts on the 54 cab are mushy and one is gone so I will probably be grafting in a bunch of the Dak firewall before I relieve it for the motor.

Also the front horns of the dak frame hit the tins all wrong so they will get chopped off and create a new bolt in bracket for the 54 rad support (thanks for the pics Dabee!)

That’s all for now. I haven’t figured out how to post pics here since photobucket screwed everybody so if you wanna see pics I have a bunch up on the flathead dodge truck forum
http://p15-d24.com/topic/47345-512-cid-c-series-on-dakota-chassis-build-thread/

Thanks

Thanks for posting and the link to pictures.
I had to move my 5.2 rearward in my '56 car.

More work done today- cab and fenders second mockup (close to final position) and bed first mockup (a mile in the air and I decided to go shortbed before I shorten the wheelbase).

Pics and more detailed blathering on the build thread in the flatty dodge truck forum:
http://p15-d24.com/topic/47345-512-cid-c-series-on-dakota-chassis-build-thread/

Your making good progress.

The idea of doing a completely new rear frame isn't a bad idea, given the power your about to feed this thing. It would be a lot easier to set it up now, rather then to wait and take it apart to change it later. Might be a good time to upgrade the rear axle now as well.

I'm a Mopar guy, but there are not many heavy duty Mopar rear axle choices available these days. If you don't have a more suitable Mopar rear end then an 8 /4, a Ford 8,8 out of an Explorer has the 5 on 4 1/2" bolt pattern, can be had with disc brakes, and 3:73 posi rear end, can be bought for pretty cheap, and the width should be pretty close to what you need. You can buy a flange that will accept the smaller Mopar U-joint. You would need to cut off the coil spring brackets and weld on the spring perches for the leaf springs if you were going with leaf springs on your new rear frame, but there may be advantages setting up the new rear frame to take advantage of the 8,8 coil spring setup. The 8.8 will hold up a lot better to the 512 then an 8 1/4 will. Gene

Thanks Poorboy

I’m conflicted about the rear. My one good buddy I wrench with keeps saying “stop playing around- do a 4 link!” but he also often thinks I should drink shots! I would love to do coilovers with a 3.90 gear dana 60 on a four link, but I still have to buy a cam and a rotating assembly. so it’s partly a $ thing. For now I think I’m counting on not racing it and having street tires slip before breaking stuff to make this rear live. It should be a fairly light weight truck. And if it breaks I already own 3 different 8.25 rears, one with discs, so there is that. If I thought I could easily sell them maybe I would buy a dana and 4 link it.

I want to move foreward quickly on this project and not get bogged down by the time and expense of bodywork or front suspension rebuilding but I also know that those things can easily happen later. Other more frivolous stuff like making it a shortbed need to happen early in the build so the wheelbase will only change once.

I grabbed another 400 shortblock last night. It looks super clean and already has a deep rear sump milodon pan and pickup which I can definitely use!

Howdy Moparts!

More progress! It seems like a cascading effect where small decisions eat up a week of wrenching time and each small decision blows up all out of proportion. Y’know like normal ‘project creep’. At least I’m still OK with the bodywork being terrible as long as the lines are good and everything is solid. Chewing this meal one bite at a time haha

I ended up getting a beat 9.25, then a good one- a sure grip 3.21. The gears got a thorough set up and it’s 1/2 way done getting new yukon axles and a disc brake setup off a jeep grand cherokee.

My plan is to use some xhd six leaf a-body leaf springs I had left over from my demon (dak 2wd rear leafs are similar eye to eye 54” iirc) with some comp slapper bars I got for a song. I am also planning to box the frame all the way up to the leaf spring hangers- the factory changes from box to C-channel under the cab and I ran a curved Z splice behind that when the chassis went from 124” to 104” wheelbase.

I was conflicted about what wheels and tires to run until I came across a set of torque thrust IIs with almost new sporty tires for around the same price as just buying some new tires. And the measurements seem perfect for my tubs with a 64” rear. I might as well try and get some traction with the big block going in. Going to pick them up tomorrow. If that falls through I have a line on a set of OG hubcaps with 5.5” and 8” steelies.

I finished building a 727 with a shift kit and my 400 block is getting bored for a 512 kit. I got the crank and rods here so they can get measured for clearance and when my block and pistons get home I can start mocking up and measuring.

I’m not sure how much installing the driveline will change the stance- it should drop at least a couple inches. I kind of want to get the motor and transmission mounted before I finish shimming up the cab and front tins to their final position. I want to do all that before I mount the bed so I can match the body lines and line up the running boards. And I still have to box in the frame and swap out the rear suspension and rear.

Small bites! This week the goal is finishing the new 9.25 rear including axles with new bearings seals & brakes, and picking up some rad new wheels.

It always seems like we get nothing done with the time we have available, but any progress is moving the project forward. I like the little bites theme, that is how it will get done.

I think the front end is going to be a little low once the big block is hanging in the engine bay. I'm guessing that the motor will sit back a few inches then placement of the original motor, which will help. Was the Dakota a V6 or a 4 banger? The V8 front springs from a 91-96 Dakota might give you the spring capacity you might need, and that could leave the ride height as it is.

I'm guessing the motor will be sitting inside the cab about 6"! That will put the firewall about even with the bottom of the dash....
At least that was the way my 54 ended up. I had a hole cut in the firewall the width of the motor. It made for an uncomfortable for a rider in the center, but was OK for a passenger and the driver.
Pictures of my 54, that was sold 15 years ago. It was done with an F,M,&J clip, 360, 727, 9 1/4 w/3:12 sure grip. We put 40,000 + miles on it. Gene

Poorboy that thing is sooo clean! Part of my truck’s charm is that it’s a beater but in reality other than the floor (which is gone now) it is in pretty decent shape. Although I am planning on doing the ratty sleeper thing with it I do want to continue to improve the bodywork little by little. I wouldn’t have been brave enough to start cutting up a truck as nice as yours. I’m sure it was plenty of work getting it to where it sat in those pics.

I got the bed mounted this week. I set it on 4 poly body mounts and made a frame to support the wood floor and strengthen the bedsides. I did lose some depth but nothing like the ‘custom’ trucks you see with laughable bed floors that are 6” from being a tonneau cover.

The rear shock mounts are finally welded to the axle. I’m surprised that the stock 1st gen dakota had such a steep shock angle! They are laid back pretty far which definitely decreases their effectiveness, plus the stock replacement monroes are not very stiff.

My motor is sitting in the chassis and back probably as far as you thought. The rear two cyls are basically under the dash. It has the stock v6 mounts temporarliy bolted to the bigblock spool mounts which is all wrong- the motor is sitting up high and cocked to the passenger side. I’m hoping to be able to drop it far enough to use some kind of decent air cleaner without losing my fresh air vent in the cowl. 1/2” clearance from the crossmember to the flat front section of my rear sump oil pan is my plan. I’m hoping to use the female tops of the dak mounts and the bolt in plates from their bottoms and connect the two back up with plate but that remains to be seen.

I’m having trouble finding ‘v8’ dakota springs they all seem spec’d for v6 applications. The moog ones are listed as progressive rate so maybe they would give a little lift? I bought shocks and some 2.5” spring spacers- they are well built steel pieces but still kinda cheesy. The springs feel good and don’t bottom now with the driveline in so it *should* work.

The trans mount I have on the shelf already (just put a post on q&a but didn’t learn much) fits on tbe studs of the 727 with a rubber cube underneath, then a small stud pointing down. My motor and trans are located pretty well front to back (already having my driveshaft shortened) and the little mounting stud hits the rear flat of my existing dakota trans crossmember. Measuring the pinion of the rear I came up with 1.75” offset to the passenger side so I’m thinking I’ll just drill a hole to locate the trans mount, drop it in and verify my driveshaft is straight, then go about getting the front of the motor lined up in front of it. After the front is mounted it will be easy enough to shim up the trans mount or build a box and sink it into the crossmember if my driveline angle needs adjustment.

I’ve come so far and need to go so much farther! I’ve still been uploading a ton of pics on the flathead site- link in above posts.

radar, I wouldn't worry too much about the motor/trans being 1.75" off center line with the rear axle center line. You just need to be sure the trans center line is parallel with the center line of the pinion shaft in the rear end, and the final angle is still in the operating angle of the U-joints, which I think are 30 degrees or less. It doesn't matter which direction that U joint angle is in.
A 1/2" clearance between the oil pan and the frame using good spool mounts should be good. The motor torque tends to lift the left side of the motor (unless your doing burnouts in reverse...)

My 54 wasn't a pretty truck before I started on it. I had to buy the front sheet metal from Texas to get something good enough to work with, the original metal was bent up rusty stuff. Unfortunately, nearly all my pictures went with the truck, which I sold about 15 years ago. Gene

Thanks Gene

My math was off I re-measured a bunch of times and caught my mistake- it is 3/4” offset not 1 3/4”. Anyway I think we are saying the same thing- the pinion is offset to the passenger side so the entire driveline needs to be offset the same amount to the passenger side.

The driveshaft will be 90° to the axles and parallel to the framerails.


The only plane that I want to work the U-joints is vertically as the rear suspension goes up & down. I’m using slapper bars so I’m going to set the pinion angle parallel with the crankshaft angle with the slapper bars jacked into the spring perches to simulate torque/traction.

I have the motor/trans closer to where it will go now it is 1” offset to the passenger side. I gotta pull it out one more time so I can notch the driver’s side motor crossmember and get it real clean bare metal for welding up the mounts.

Things are looking really good but I know the detail and sheetmetal work will be a bug job too!

the driveshaft should not go straight from the transmission to the pinion-----chrysler made them a little crooked so as to make those little needle bearings rotate around in the u-joint caps-----if the driveshaft goes straight and true it will have a very bad vibration and the u-joints will get destroyed......

If there is a difference between the height from the ground between the center line of the trans and the center line of the rear axle pinion, that will be enough to allow the needle bearings to rotate in the caps. He also stated there is a 1" offset, that would in itself also be enough for the needle bearings to rotate in the caps. The drive shaft doesn't really care which angle it sits at in relation to the trans or rear axle, as long it the angle is within the operating range of the u joint movement, and as long as there is some angle of movement. This is, of course that the trans center line and the rear axle pinion center line are parallel with each other in what ever plane they are in. Gene

Well the driveline and suspension are pretty much all done. I set the pinion angle and welded the perches in this morning. I ended up putting in some helper airbags to make the ride height adjustable. It goes from almost on the bumpstops to way too much rake. I set the pinion angle at a 1” raked ride height. The front suspension is completely rebuilt too- moog springs, new bushings and balljoints. I haven’t touched any steering stuff but that can happen later if it needs to.

The steering is figured out- I have the stock dakota column stripped and shaved with a wood 500 wheel and grant horn and have a support bracket welded in for the rod end that holds my shafts as they curl around the header to the rack and pinion.

The gauges are all swapped out for autometer ‘old tyme’ series with a mechanical speedo/odo and a 5” tach. The accessories and belts are all figured out and mounted. My radiator is mounted in the front sheetmetal with an hhr fan sealed up to it and b&m’s biggest trans cooler strapped to the front.

I started making the exhaust downpipes and locating my H pipe and mufflers. Once that’s done I’m going to start plumbing the trans hard lines and brakes.

Progress!

I like it, its looking good.
Gene

Nice

looks real good ! should be a great ride when done !

Some more progress! Got the bumpers on and almost done plumbing everything except brakes. I have to make a new firewall so I’m going to try and punch out the driver’s footwell a little to get some more legroom.

Once the driver’s side firewall is in and painted I can start running wires, hanging my booster, and finalize the lower bracket for my steering column. I am also seriously considering a removable transmission hump for ease of maintainance without a huge amount of relief in the front of the firewall.

Got a wood bed built, removed, & finished the wood. Once I plumb and hang the rear brake lines and calipers, and finish welding up the bedside sectioning it’ll be ready to bolt in permanently. It’s ipe wood finished in penofin with mar-k strips I bought undrilled.

Pics of full mockup unfinished then an indoor mockup with the oil finish.

Hey Moparts

I got a bunch of stuff done. The bed is done, suspension, fuel, and brakes done too. The cab floor is almost finished then I have to tackle the set back firewall. I shortened up a zj jeep e-brake and worked it into the console next to the ratchet shifter mount.

Some more pics

Nice work, I always did like those style Dodge trucks.

More progress shots- they’re all out of order but you can see a bunch of different systems and stuff getting installed and fabricated. Man it was cold out today welding the console in my driveway!

Here’s what I was working on today

i like the way you did the e-brake handle. nice job, and the wooden handle is a nice touch !

The 10” setback firewall is done! The middle swoops up to just behind the carb so that my stock cowl fresh air scoop linkage will stay. What a pain in the butt getting it all made in paper then steel- lotta shapes to cut and bend.

I also made a new gas pedal and cut out a ribbed rubber mat for the floor.

And thanks for the kind words Moparx

If you read unlawfls you probably saw me having some small setbacks getting my fresh driveline broke in and driving. I’m still fixing an exhaust leak and a weepy water neck but thats normal stuff. All combos have their own combination like a safe to get them started and it took a little bit to figure out this one likes no gas until after it starts to spin, then it comes right to life. The motor feels really strong! No noises or clunk from the rear I set up. The trans doesn’t slip and shifts are smooth- probably especially because I haven’t been shifting manually yet or trying to chirp the tires with high rpm shifts. I did a short burnout in rainy weather in front of my house- spinning them was pretty effortless! I am also happy the front IFS ended up being juuust tall enough for how far I channeled the body. Gotta go slow turning into driveways but no rubbing just driving.

Very COOL!

Some more progress.

I had trans problems and ended up calling that version a mockup. I pulled the body, fixed the trans, installed a holley sniper setup, and laid stripes all over my neighborhood. Then I shattered the slip yoke doing a holeshot and the driveshaft loop wedged the carnage and took out the transmission tailshaft and main case. I have the old trans out and a new one built with some help from the board.

In the meantime I got door cards done and fixed my tired latches, along with fresh glass in the vent windows (passenger side had a bullethole!). I’m planning to do the headliner next in matching diamond pleats.

https://youtu.be/xP9orqM1tyI

More pix

Got some more work done on the interior. Lizardskin insulation, headliner, and lights.

nice job ! i always liked diamonds.

Thanks man!

guys like you keep my motivation up for getting my charger back out, and finishing my humpback project, even when my health issues say no !
so keep up the good work !

Nice tasty, well thought out build .. good job sir

Thanks Bigdad. Dunno if you read Unlawful’s but I have a thread on there with a launch video asking for shock recommendations and after some confusion my takeaway knowledge was that my shock angle is laid back way too far after radically lowering the ride height. I got a set of 275/50-r17 M&H racemaster dot drag radials on there yesterday but haven’t driven it yet. It runs hard for a mild street deal and I’m hoping a little more gas pedal will be usable in 1st & 2nd gear with the softer tires.

I tried to think ahead building the chassis but I didn’t even think about the shock angle- just left the stock dakota crossmember and welded ears to the new rear. I’ll have to pull the bed- again- to weld in a new shock crossmember farther forward. No point in buying shocks till I get ready to do that. Probably put another post on unlawful’s about it 😂

Anyway, I spent the past couple thrashes messing with trimming out the rear surround. It’s looking much more finished now.

I got the fit around the window and reinforcement bar pretty good too. It’s not perfect but the price was right.

Nice. I like that rear window panel. It make the interior look more complete.

Without looking back through your build, did you weld in the rear shock crossmember? The 88-96 rear shock crossmember originally bolted to the frame, moving it would only involve drilling 4 new holes in the top frame flange. Gene

Yeah I wish I thought to move them when I was building it. The front fuel cell mount is welded to the stock shock crossmember. Gonna have to start from scratch. Luckily I planned for a shock swap later when I spent $30 total on the rear shocks- not a big deal to fabricate a new crossmember while I’m at it.

I gotta figure out how much shock travel I need, what style of top mounts I want, what amount of fanciness I can afford, whether or not my ears on the axle will still work, and make it happen. There’s actually some space between the bedside and the frame that I want to look at- the wider they’re spaced the more leverage they’ll have to soak up uneven road bumps right?

i would start by making the shock angle similar to the A & B-body angle, only with a little less angle. a shock works best vertically, but that is in a drag setup.
i don't know what the dak uses for a rear spring plate, but a shock plate for a common B-body may work, and you could then make a simple upper mount with the angle you want the shocks at.
just throwing something out there.

Thanks moparx

I got under there with a tape measure and after I got my measurements I got busy exploring my options. The best price, adjustability, and quality I settled on was the QA1 star stocker single adjustable ts504. I needed at least 5-6” travel in a package with 12-15” eye to eye at ride height. I need 3” compression to get well into the rubber bump stop and 2” of extension is about what I have right now in body separation on launch which should be tamed a little once I have a shock in there that actually does something.

The options are a little daunting when looking for shocks- a lot of shorter shocks are spec’d for IRS and have very little travel, then lots are spec’d for dirt track cars or have different mounts than I want. I called QA1 tech with my numbers and needs and he recommended the same shock I had been looking at. Getting more travel would mean extending the axle mount down closer to the scrub radius which I don’t think will be necessary for a lowered street strip type build.

I’m going to wait to make top eyelet mounts until I have the shocks in hand but I’m considering making them bolt to the frame to avoid having to remove the bed and efi computer for welding a whole new crossmember.

not going below the scrub line is absolutely important, and i'm glad you thought of that.
however, i'm wondering just how much body rise you really will end up with, because your shock angle now limits the rise when the shocks top out.
how much difference in your spring drop is there when you unbolt the shock, as opposed to when the shock is bolted in place ?

Dunno how the top mount will end up looking but there’s plenty of room under there.