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512 cid C series on Dakota chassis- build thread


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Speaking of u-bolt plates I have a set of plates off my demon that have the stud for mounting a shock but I decided to weld tabs to the axle like the dakota had and use the stock upper shock mounts. 

 

I scored these slapper bars which also act as the bottom u-bolt plate. They are for a late 60’s mustang but they seem custom made for using  dodge dart leaf springs on a 1st gen dakota chassis to fit a sectioned ‘54 3/4 ton C-series hahah. They’re heavy duty Competition Engineering bars I saw on sale $40 shipped on amazon. Slappers must be out of style for the late ‘60s mustang guys.

 

They are already made for axle over spring and the bumper hits my leaf right under the front eye AFTER drilling a 1 1/2” offset centering pin hole! 

 

I’m hopefully not going to have any wheel hop and it will have an oldschool hotrod look too.

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I got the first mock up of my ‘hanger flip’ lowering and beefing up tried out. The front  spring eyes will be around 8” up and 1.5” back from their original location.

 

A full upside down flip would have blocked the slapper bar from hitting the spring eye so I went with a 90° rotation. The top half will get tied in to the bed support pedestal and reinforced later.

 

I located the two hanger brackets by running a straight piece of allthread through the bolt holes so I could measure and square up the axis to the chassis

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I am waiting on spring eye bushings in the mail- I had the wrong ones. 

 

The perch which is just clamped in until I set the pinion angle later is drilled to move the axle 1.5” behind the spring centering pin but the slapper/u-bolt plateis not clearanced for the bottom of the pin yet so the slapper angle is way off.

 

But I’m 2/3rds of the way there on proof of concept- set down on it’s weight it has 4” clearance axle to frame and with my 300lbs bouncing hard right over the one spring I couldn’t get it to touch the bump stop. If it sits too low with full curb weight I can always add a little shackle length.

 

Hopefully my buddy is stopping by later tonight to help me throw the bed back on. If I like where the wheels sit in the tubs it will be all systems go to forge ahead and  mount the bed. If not then it’s 3 steps forward and 2 steps back!

 

On a more positive note, sort of, I got the cab and doghouse mounts sorted for good after chasing my tail for a half a day. Somehow I didn’t notice that one fender the wheel arch was pulled out 3/4” more than the other. I finally figured out better reference points for measuring and got all the holes slightly slotted and marked with a die grinder & carbide burr. 

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Well I figured out that if I take the wheels off I can wrestle the bed on by myself.

 

There is good news, bad news, and more bad news.

 

The good news is my complicated algebra problem for how to get a 5” drop was exactly on the money. I nailed the ride height right at 4” and with my 300lbs bouncing directly over the spring it didn’t even touch the rubber bumpstop. 

 

The temporary bad news is that my simple subtraction problem to get the wheelbase right so the wheel looks good in the wheel arch didn’t work out. That’s why I just tack welded it! I’ll be able to pull it back where I want it and move the hangers back without too much drama. The shackles are perfect now so I’ll have to move them back the same amount and I will probably also drop them an inch or two to get 3/4” more lift or so in anticipation of the weight of the bed, wood bedfloor and some % of driveline weight too.

 

The other bad news is kind of just the cost of doing business when you want tires that tuck in and fill up the tubs. Just like a tubbed racecar or prostreet setup I will be dropping the springs down and lifting the chassis up every time I want to change a tire or take off a wheel.  Not the end of the world.

 

It’s the first time I had my new 64” wide 9.25” rear with 9.5” alloy wheels under the tubs and thank goodness my backspacing math and tape measure work all checked out. The tires really fill up the tubs, have a comfortable amount of clearance to the lip, and the rims just barely tuck like I wanted. By my next post I should have the wheels centered in the tubs and on my way to buttoning up the suspension. 

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I dont remember the width of the stock rear end. With the offset I went with on mine running 225/60/17's, I has to roll the front and rear fender lips for clearance. I can just get my fingers between the wheel and fender in the back.

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I really like the Dakota Chassis also.  My 1995 Dakota, 5.2L, handled like a car, and hauled well too.  Way better than a crappy S10 or utilizing a mustang 2 kit.  There are many reasons why the Dakota is better than the "popular" choices...  But you obviously know this.  I can't wait to see the finished product.

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Thanks for the responses fellas! It’s good to know this mic is on!

 

A little more progress today. I moved the spring hangers back so the wheel would center better in the tub and welded them in solid. The tops still need trimming and reinforcement but it’ll do fine to hold up the truck while I get the height and angle of the bed just right.

 

With this more radical hanger setback I will need to move the shackle hangers back and down a little to get their range of motion and my ride height back but I know from my 1st failed front hanger relo attempt about how much they flex under a neutral load.

 

Now I have to get those shackles moved and I’ll be ready to make a bed floor/frame and mounts. It’s a balancing act lining up the running board mounts and matching the angle of the bed to the rake of the cab.

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On 7/27/2018 at 9:52 PM, 59bisquik said:

I dont remember the width of the stock rear end. With the offset I went with on mine running 225/60/17's, I has to roll the front and rear fender lips for clearance. I can just get my fingers between the wheel and fender in the back.

The OG rear axle was about 61” wide to the WMSs. I have a 64” wide 9.25 rear running 255/50r17 tires. I think these torque thrust IIs are 9.5” wide with 5” backspace but I bought them used with tires so they could possibly be 8”. 

 

My axle was tight but the drums were an ordeal. I don’t miss it.

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Here’s what the tire looks like in the tub. I measured approx 74” from the fender lips this just makes it. If I ordered a wider tire combo I would have to add only to the back side- probably fit a 12.5” in there no problem.  These are a craigslist score- beggars can’t be choosers and these are plenty wide. Any shorter on the sidewall and they’d look silly too. 

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Thanks Wayfarer!

 

It was supposed to rain cats & dogs here in philly today but never did so I hauled the bed off again and got to work on the shackle hangers. Cutting off factory rivets and air hammering them out is much more fun when I can find my ear protection but I was too dirty to go back into the house and dig around.

 

I got them off and the 1989 upper shackle bolts were much easier to get out off the truck in the shop press. Those 1/2” bolts get stuck good over a few decades.

 

I ordered a set of poly bushings for a dakota which only ended up fitting the upper shackle pins. So I ordered a set for ‘72 dart leaf springs. The rear spring eyes are the only part that’s going to work using the factory dodge dart sleeveless bushings for 1/2” lower shackle pins. 

 

It turns out that the mancini extra heavy duty (super stock but not offset like 002 003 muscle car springs) front leaf eyes are 1.5” ID. The standard Dart bushing set is for 2” ID front spring eyes. D’oh! Also the dart bushings are 3” wide with 5/8” pins while the Dakota hangers are only 2 7/8” wide with 1/2” pins. Ugh make up your mind mopar!

 

I considered chucking up the fat front eye bushings in a drill and trying to remove 1/2” of diameter but after five minutes of slow slow progress shaving urethane on the belt sander I called RuffStuff in Cali and ordered some 1.5” OD by 2 7/8” wide poly bushings that take 1/2” pins. I’ll have to shave 1/8” off the 3” inner metal sleeves to fit them but the $20 shipped pricetag is worth a few minutes of fitting.

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I have to wait for my spring bushings come in to get the chassis sitting on the suspension. I think I’ll shift my focus to the bumpers and running boards.

 

My front bumper and frame stubs needs to get located and welded to my rad support crossmember and shouldn’t be too bad to do. The rear bumper is basically a pretzel. I’m not sure what I’m going to do about it. The dakota bumper was too modern looking for me. The rear looks good with no bumper. I’ll probably see if I can’t straighten it out some in the shop press before I give up on it. 

 

The running boards need to be sectioned the same amount as the bed sides, which also need final fitting and welding since I took 12” out of them and just tacked them back up for mockup.

 

Today I sandblasted the shackle hangers and painted them john deere blitz black. I’ve been using the JD  chassis paint on clean parts and por15 on rougher stuff. 

 

It takes a little effort but working with clean restored parts is always nice.

 

 

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One step closer to having the rear suspension all done! The shackles are rebuilt, I pressed the rubber and chiseled the steel sleeves out of the front spring eyes, and pulled the rubber bushings out of the rear eyes. All my new poly spring bushings are ready to get lubed and installed once the fresh paint dries on the springs. 

 

The axle will have to just get clamped to the perches for now until I set the driveline angle- then I’ll be able to set the pinion angle and weld in the perches.

 

I liked the shackle angle on my first stab at locating the front hangers so I moved the shackle hangers up the same 2.8” and down a smidge to leave compression room for a heavy wood bed and frame.

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My good buddy had some ipe (ironwood) stashed he’s going to hook me up with. 

 

It’s 3 boards 1” thick by 11” wide so I’ll need to buy two more (at $90 each!), four bed strips, and some stainless hardware but I should be all in for around $400 said and done which isn’t too bad for heavy duty premium hardwood. The ipe will look great with an oil finish and last forever.

 

I’m pretty excited about it!

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So it’s sitting on the springs again and somehow I lost 1.5” of travel. The axle is 1/2” away from the rubber bump stops, with no bed or driveline installed. Too low. The front spring hangers couldn’t go any lower and still provide access for the bolts and the shackle hangers I didn’t want to hang way off the frame so all the welding is done and those points aren’t moving again.

 

The wheel hits the tub how I want and the shackle angle is good so I ordered a set of longer shackles to get a little bit more lift and travel.

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15 hours ago, Radarsonwheels said:

So it’s sitting on the springs again and somehow I lost 1.5” of travel. The axle is 1/2” away from the rubber bump stops, with no bed or driveline installed. Too low. The front spring hangers couldn’t go any lower and still provide access for the bolts and the shackle hangers I didn’t want to hang way off the frame so all the welding is done and those points aren’t moving again.

 

The wheel hits the tub how I want and the shackle angle is good so I ordered a set of longer shackles to get a little bit more lift and travel.

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nice!  I did the deck at my first house out of IPA...good stuff!  I used Penefin oil on it.  WHEN I get back to the FEF Caboose projects, it will get an IPA floor.  That stuff is tough as nails.

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Ggdad I bet that deck still looks good! Penefin is exactly what I was looking at to finish it. Maybe some paint for the end grain.

 

I got both running boards shortened up today using the scraps from sectioning the bed as a template for how much to cut off.   The driver’s side board is muuuch rougher than the PS board. I guess all the years of stepping wore the paint off and let the rust in. At least now they will fit lengthwise and I can start making brackets for them. 

 

 

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On 8/7/2018 at 7:49 AM, Merle Coggins said:

How has all of this spring anchor relocation effected your pinion angle?

 

Good question Merle.

 

I cut the perches off the top of the 9.25” rear that located it on a 70s ramcharger. Right now the new perches are just pinched inbetween the axle tubes and the springs with the pinion facing generally forward. 

 

Once the motor and transmission are mounted I will see how the angles want to play. Then the perches will get welded in along with some shock mounts so I can use the dakota upper shock crossmember.  I’m very visual so I drew a picture to explain what I’m dealing with.

 

Fig. A top view

The motor transmission and driveshaft are all offset to the passenger side. Mopar offset most stuff but it’s not always the same amount. When I make motor and trans mounts the driveline angle must be parallel to the frame. How much offset will be dictated by the rear axle housing. I haven’t figured out yet if a 70’s RC has the same offset as a 1st gen dakota but the engine will need to move rearward so sideways at the same time won’t be a big deal.  This is the ‘easy part’ haha

 

Fig. B side view

two styles- production and race:

 

In a production car the driveline angle (3°ish down) matches the pinion angle (3° up) but their parallel lines don’t intersect. The universals only have to correct on one axis so their phase cancels itself out. They don’t vibrate but they have to work enough to keep the needle bearings moving around enough to not seize up.

 

In a race setup (also usually centered from the top and custom length axles to center the pinion) the driveline is aimed right at the pinion and the working angle is one straight line. This doesn’t waste energy working the U-joints but is better suited to 1/4 mile at a time than thousands of trouble free miles. The U-joints don’t do much.

 

Fig. C dynamic flex

Even in a four link race car the pinion will rotate up a little under power as the ring gear is pushed down. My setup is looser with leaf springs. Either way the pinion needs to be set a few degrees down at rest so that it becomes ideal under load.

 

Leafs can move a lot and if they stress the leafs too far the spring power will eventually break traction and snap the pinion back down. When this happens over and over real fast you get violent wheel hop instead of a hard launch or smooth burnout.

 

I’m fighting this two ways- first my 70s mopar muscle car xhd (super stock) springs have a short front segment- 20” out of 54” are in front of the axle. This makes it stiff. The second thing is the ‘slapper’ bars. They are welded to the U-bolt mounting plate and when the springs wind up it forces a rubber bumper into the bottom of the front spring eye, theoretically putting that rotating force into the chassis instead of the spring and further planting the tire.

 

The shady thing I did and why most folks do a 4 link when lowering a truck or adding big power is I changed the spring angle when I moved the front hanger. This will accentuate roll steer in a turn- when the suspension compresses the wheelbase will increase by up to 1.5” at full travel, causing understeer as the outside wheel moves back in the chassis. I’m counting on stiff springs and shocks along with limited travel to minimize this effect. A sway bar would be another band-aid for roll steer.  

 

These are the compromises I made in order to use the parts laying around my garage and my welder instead of giving my checkbook the workout. In any case I plan to be hazing the tires more than practicing for the Nurinburgring.

 

Sorry for writing an essay to answer a simple question- but there’s not really a simple answer!

 

radar

 

 

 

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Edited by Radarsonwheels
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Man it just started pouring here in Philly. It’s really dumping! Here’s a pic of my shortened running boards including the scrap pieces. The outside edge needs a little hammer and dolly work but they’re welded up flat and straight. I will probably use the dimpled leftover sections to repair some of the rust in the driver’s board it is rusted through with bondo frisbees under the door area.

 

I chose not to make myself crazy trying to make the dimple spacing line up- it would have affected the way the boards interacted with the door & fender in the front.

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Edited by Radarsonwheels
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Just now, Radarsonwheels said:

 

Good question Merle.

 

I cut the perches off the top of the 9.25” rear that located it on a 70s ramcharger. Right now the new perches are just pinched inbetween the axle tubes and the springs with the pinion facing generally forward. 

 

Once the motor and transmission are mounted I will see how the angles want to play. Then the perches will get welded in along with some shock mounts so I can use the dakota upper shock crossmember.  I’m very visual so I drew a picture to explain what I’m dealing with.

 

 

 

Sounds like you have a good handle on it.

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13 hours ago, Radarsonwheels said:

Ggdad I bet that deck still looks good! Penefin is exactly what I was looking at to finish it. Maybe some paint for the end grain.

 

they make a wax for the end to prevent checking...

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Thanks Ggdad- looks like the wax sealer is the way to go.

 

I’m getting closer on the running boards. They fit great now that they’re shorter. I have them mocked up- pinched onto the rear fenders and cribbed up to meet the cab. They have 6” ground clearance in the front and 6.75” in the back- nicely raked and above the scrub line. It’s low but still practical for drivability.

 

I fabricated some brackets to hold them up. They should be cooled down enough to paint in a little while then I’m going to weld them into the frame. 

 

The bed is sitting a little lower than it will end up so the fender’s board mount holes line up which is good because every bit I can move the bed up relative to the chassis gives me more cargo room. As it sits now I was going to have to raise the bedfloor 6” or so from stock inside the box. Lifting the bed also means less or no clearancing the inner tubs for axle travel and the bed front for driveshaft clearance.

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