Howdy Moparts!

I built my 54 big block pickup out of stuff I could scrounge so the suspension is kinda oddball. The front is 1989 dakota 2wd with all new bushings & balljoints, no swaybar, and moog load handler coil springs. The rear is a 9.25 axle located by saggy A-body 6 leaf xhd springs. Ride height is set with helper airbags over the axle and wind up is controlled with slapper bars. With no air in the bags it sits just off the bumpstops. I usually run 25-30psi in them (individual schraeder valves) to get just a touch of rake for style and ground clearance.

When I built it I threw some $15 monroe shocks spec’d for a stock ‘89 dakota, just to get rolling and keep it cheap. It cruises fine and there is no problem there, but they’re predictably not amazing.

Here is a youtube link of a quick street launch- more of a rolling burnout. I used Imovie to repeat a zoom in on the launch- so first is actual speed, then slomo, then super slomo twice in a row so you have time to look at the front tire the first time and the rear tire the second time.

https://youtu.be/IGzZB3f1A-8

I only know enough to be dangerous concerning this stuff but what I’m seeing is the tires hit and the slapper bars give some chassis seperation and a tiny bit of nose lift, then it unloads the tire and I get a little rocking pourposing move going. Then into the rolling burnout it never hooks and steadily but barely carries a little weight off the front as it slips down the road.

My next move is M&H ‘rod-19’ DOT drag radials and probably a shock absorber upgrade as well.

Obviously there will never be a dead hook on the street but how can I use an adjustable shock to control what I got going on here? Easier extension and harder compression on both shocks? I don’t know how much looser I can get the front. I have an aluminum top end on my big block, 10” motor setback, and only 104” wheelbase plus a heavy 1” thick ironwood bed floor and the fuel cell & battery are behind the axle, so I do have some tricks up my sleeve already.


Thanks for looking

Radar

What is your intended use? Street only or street/strip

It might get a few rips down at atco for a laff but it’s a grocery getter. I know there’s no hooking on the street with a stroker but feathering it less would be good. I won’t be doing a ton of testing to get the 60’ up under 2 seconds where it belongs.

I’m mostly trying to learn how you tune shocks to help keep the tires loaded as much as possible. Of course I won’t be able to give it the beans on an unprepared surface.

On my old demon I put comp 90/10 shocks on with /6 bars and it launched totally different. That was fun. This has less tuning I can do but tires & shocks seem like the obvious next step. Tires are easy- biggest & stickiest I can fit. Shocks I need some edumuhcashun if anybody cam learn me on which ones to buy and how to tune them to hold the weight on the tire.

If your gonna tune it.. it right.. pull those air bags and start at zero.. you
have air bags.. you are doing the same thing with a few different
items.. shocks are control the wind up or slow the rear end down..
if you want to do it right you need some weights first then you can
look at the rest.. but from what I've read you wont want to do it
EDIT
you need a loose front end so you get the front lifting but a lot
of work in the rear

Ok I’ll bite- I’m always down to try stuff of at least understand more. My original plan was just the XHD springs and slapper bars but after it sat for a while while building it the springs reminded me why I took them off my demon and went 002/003 springs. They sagged down after a few weeks. But in theory once the slappers rotate up and lock then the stiff short front segments should be acting like a ladder bar with a too-high instant center then the chassis is just held up by the airbags and movement is controlled by the shocks right?

I like the bags because they let me set ride height depending on what I’m trying to do. It can go from flat and a little too low to an almost cartoonish rake and the lower it sits the softer the spring rate. I figured that would be easier than guessing on leaf springs or coilovers and a 4-link that could hold stroker power is an expensive deal plus I didn’t know if I wanted parallel or triangulated.

So what do you mean pull the airbags? Aired down they do nothing and aired up I can haul a safe with an elephant in it so what’s not to love? They aren’t even that heavy.

If they do nothing with no air in them what good are they With air in them they are not helping traction, are they
You need to figure out what you want the MOST, traction or a comfortable ride and changing the looks of the truck to impress observers with the air bags

Well I don’t have a fancy air system with switches pumps and dumps, just two schraeder valves to set the ride height.

I don’t see how the bags are hurting me? To my thinking it’s just an adjustable spring rate? Shouldn’t the shocks control any bouncing? The reason I have them is I’m not 17 and trying to look cool with a 3” ride height. The bags let me set the rear with a little ground clearance. If I wanted to impress other people I would take them off and ride 1/2” off the bumpstops. They were an economical solution to the problem when I realized I needed stiffer springs. :

I’m not trying to say they are helping my launch- I just want to understand how they could hurt? Maybe if I have them set too high/hard the resulting stiff raked chassis would be harder to get weight transfer?

Here’s a shot from when I put the bags in- no air and 40psi

The shocks single purpose (for which you have the air bag if I'm following) is to control the motion of the axle/spring. Your bag doesn't do that.mit controls ride night. The shock doesn't do that.

You can't have both. Either live with the air bags, or get rid of them and buy a good shock and live with one ride height.

The airbags are only there to add to the spring rate. The bottom bag brackets are curved to mate to the axle but not welded- they do maintain contact and don’t float around but don’t pull down or act as shock absorbers. I have conventional shocks using the top frame bracket from a dakota and ears welded to the axle tubes.


I have heard of people replacing shocks with airbags on IFS and not bothering to relocate the shocks (running without them) or running adjustable air shocks to lift a muscle car (getting a rock hard ride and eventually punching thru the top brackets). This is not that. I have my axle located with leaf springs but they’re saggy ones that lost arch after a year or so. The axle wind up is controlled by the short stiff front segment combined with the slapper bars, so under power the pinion angle is lifted to match the crankshaft angle.

Like I said I still have conventional shocks. I am not trying to get defensive and I think I understand the compromises I made with this setup but I want to learn the basics of rear shock tuning for traction.

My concept of how it works now is that since my leafs and slappers converge too close to the axle it is going to make my instant center too high, hitting the tires really hard. If they are triangulated in action they will act like a ladder bar but I would have pointed a ladder bar a bunch further up the chassis and probably a couple inches lower. So that isn’t ideal but I wasn’t willing to run a ladder bar on the street and end up constantly twist stressing the axle housing back and forth like a giant sway bar and I don’t have the know how or money to throw at doing a 4 link that could hold up to stroker torque. I never set up coilovers either and the choices are intimidating and expensive for trial and error.

Was all the ‘ditch the airbags’ talk because y’all thought I was running with no shocks? I have shocks they’re just stock replacement $15 blue ones that barely make the chassis not bounce a couple times after a bump. They work fine for cruising but I want to upgrade the shocks and want to understand more about where to start with settings.

From what I’ve learned on here and from books I want the shackles angled to separate the body upward on launch, pressing down on the tires. Check. I want the pinion rotation to stop with good driveline alignment and begin applying only forward and upward rotation with no oscillating wheel hop. Check. Then I want to hit the tires as hard as possible without spinning and keep them planted with as much weight transfer as I can muster. This is the area that needs work.

I figured the next obvious step was more and stickier rubber, and shocks to control the movement of the chassis relative to the suspension. I know the object in the front is to make it as easy as possible to lift the nose and to come back down slowly. There is only so much I can do with the dakota suspension without re-doing all the bushings etc but it’s all new and greased with decently light wheels, as much aluminum as I could get on the big block to replace iron, and the motor is moved back 10” too.

I have a much foggier idea of what you want the shocks to do in the rear. Is it the same as the front where you want soft extension and harder compression?

Thanks and sorry if I’m being hard headed I am still not understanding why helper bags are bad? How are they different than just making my leafs have a variable spring rate? In fact isn’t that a good thing if I can drop it down low for better weight transfer then air it up a few inches for a longer drive or something?

Radar

Here’s a shot of when I was building it. You can see the leafs and slappers a little- they were CE bars for a 60s mustang that I adapted is why the goofy brackets on them in this pic. The shocks are cheap stock replacement 1st gen dakota stuff.

No takers huh?

I guess I’ll get a set of rancho 9000 rear shocks and start at 8. The fronts I’ll leave the cheapies in- they’ll only get better as they wear out. I also ordered the M&H 275/50r17 DOT drag radials today. More sidewall and a bias ply like a 10.5x28 drag slick would probably help absorb the hit a little at the track but these are the best compromise money wise with the staggered wheels (16f 17r) I got off craigslist. I must have filled and emptied a summit cart a hundred times- I can fit up to a 13” tire in my tubs but would need a 6.5” offset to fit it on a 10.5 or 11” wheel. Even if I went 15” or steel wheels it was like $1500-2k.

Wish me luck and if I somebody wants to chime in again about the bags or whatever I’m interested in opinions or experience.

Those rear shocks will never work.. the angle of them is all wrong.. I
dont care if you had the best shocks on there.. remember the the rear
is rolling upward.. if the springs are near right you wont need the slapper
bars or the air bags

That’s disappointing to hear but I really appreciate the feedback. They are in the stock location for the ‘89 dakota which as far as I know is not exactly known to tear up the dragstrip. A thirteen second pass won’t hurt my ego and the truck is a blast to drive. So maybe I’ll see what it does how it is and either start making changes or just be happy if I scoot it down the track safely a few times and have fun. After I have more seat time I can decide if I want to start re-working the rear suspension and keep making passes in it, or just enjoy it as a warmed up street cruiser.

What would you do? I’d like to find somebody with scales and weigh the truck including total and each corner. Then I would know which springs to pick. Then I’d have to decide what to do with the suspension- leafs 002/003? 002/002? Or the stiffer B body super stock springs? With a more upright shock angle? Parallel 4 link with coilovers or bags and shocks? Or triangulated 4 bar setup? It’d have to be stout to hold 500+ ft/lbs so no cheap parts on a 4 link. And it’s already set up for A-body super stock length springs so I could just change the shock angle if that’s the problem and SS springs are not that expensive.

I did already pull the trigger on a set of drag radials but I didn’t buy any shocks yet.

First off, I have to say I really like the truck!

But, I would ask... Whiskey Tango Foxtrot was wrong with the original springs? Sat too high?

One thing about the A-body rear leafs is that the front section is short - really short.

Putting a slapper bar on that spring is going to try and lift the vehicle at the front spring eye of the rear spring. I would imagine that a system that would try and lift up the chassis at a point further forward would tend to lift the entire vehicle, instead of just picking the back end up. Hopefully putting a little more weight on the rear tires while it's lifting.

Unfortunately, my project has been stalled by a move across country, a career change, and a home purchase.

So, I'm gonna' have to subscribe to this thread and live vicariously...

Hi Carfarmer! Thanks.

The original leaf spring setup had about 9” higher ride height plus it was equal length front and back sections of spring, not a short front segment like the SS springs. The Dakota came with an 8.25 axle and a really dinky spring pack with a super heavy overload leaf to keep it from flipping inside out. The reason I re-worked it was because I put a 512 motor in it and figured the 30 year old setup spec’d for a v6 driveline wouldn’t get er done. And I already had a set of 6 leaf xhd springs that I ran for a year on an a-body before switching to 002/003 leafs. Turns out I forgot they were already losing arch and sagging.

I also channeled the body down over the frame, shortened the frame a couple feet, boxed it, shortened the bed a foot, and set the motor 10” back into the firewall. Basically just got carried away working in my driveway last year and having fun. I already had the ‘54 and always wanted to build a stroker B engine.

I think you’re right- my instant center is too high and far back.

I agree with Mr P, your going to have to get the rear shocks into the right geometry- as they are, they will always be to slow to do anything effectively.
Would also suggest a double adjustable front shock set pretty loose on extension.
Might actually loosen it all the way up, see what you get from it, then start tightening it up until you have the right combination of front end travel and ride stability since your street driving.
I don't think much is going to help until you resolve the shock geometry in the rear.

Just my opinion.

Shocks are useless mounted like that. Until the mounting is corrected, housing and crossmember, nothing will work right. The rest of it has potential. Air bags are an old trick on Stockers with coil springs. I don't know what benefit there would be on that set-up beyond covering up for dead springs or carrying a load of firewood without dragging the bumper. Swapping the slappers (I assume they're slappers) for a C-E Adjust-a-Link or Cal Tracs would be money well spent.

I looked at the video (which was done nicely by the way), before I read anything. I thought to myself... "WOW... those rear shocks are WAY too loose".

Fast forwarding down to your picture... it's hard to say if the shock is too loose or too tight, but because of the steep angle it's making it "act" too loose.

Think of it this way. If the shock is straight up and down, the axle separation feels whatever force the shock puts on it. As you rotate the angle of the shock (in any direction... rearward, forward, inboard, outboard...) it begins to loose effective force on the angle. If you were to think of the extreme where the shock was mounted completely horizontal, it obviously wouldn't have any effect on the up/down vertical motion of the axle housing at all.

Because of the angle it's mounted at, the shock can't control the up/down housing movement during any kind of launch situation. It's unlikely any shock could/would be valved to fix this at the angle it's currently at, which is why guys are saying you need to fix that first before you do anything.

The A-body spring segment length is fine. That truck has a fairly short wheelbase, so it will work without issue... meaning don't worry about the instant center right now. Fix the shock location first, and that will help you a whole bunch with the traction.

Right now since the shock can't control the body separation, it basically uses up all of the travel right away, and then once it's out of travel it just spins the tires.

Yup. Thanks Dizuster. I came to the same conclusion and I’m disappointed in myself that I didn’t move the shocks forward when I lowered it- I tried to angle a set of harley shocks 25 years ago making my first custom bike frame/suspension and found out that when shocks are diagonal to the action they resist it makes them useless. I know better but just thought well it’s still almost the stock location and Ma Mopar knows what she’s doin. Detroit didn’t anticipate me moving the axle forward an inch and up 8 or more.

I really appreciate your saying that it uses up all the travel then it’s done. That’s the kind of info I can sink my teeth into. I don’t have a good understanding of the shock’s role in a launch other than ‘controlling the movement’. I guess I want to allow but slow down the separation then have it fairly stiff as the weight transfers? I might have it backwards but start 3/4 stiff and meep adjusting stiffer tlll it spins then back it off a touch softer? Is that the correct tuning strategy?

The stock crossmember takes the shocks with the 2 bolt bar thru the top and I would just move it forward except I tied it into the fuel cell mount. The upper mounts are pretty close to the inside frame rails so now I’m looking at just welding little boxing plates and bolting on aftermarket shock studs to hole eyelet style tops.

I don’t know which shocks I should get. The bottom ears I welded on the axle are for eyelet style and I gotta measure but it’s not much more than a foot to the top of the frame. I might have to extend the axle mount down if I can’t get a shock with short enough travel. I’m guessing like most things you probably want to use the middle 80% of shock travel and not need the top and bottom 10%? I looked at 9 way ranchos and they are real long which makes sense for like a dart with 30” slicks but I don’t know what shocks I should be looking at.

I want to spend no more than $300-400 on the whole shock swap. I want something adjustable so I can tune it. I need half decent street manners and an occasional shot down the strip.

In other traction news my drive to work today was my first experience with drag radials. I just put on 275/50-r17 M&H racemasters and I didn’t expect a big change, especially with 27psi in them for street driving and the crap shocks, but wow I gave her a launch and it takes off WAY harder from a dig now. A new shock setup can only make that better. In the meantime the laid back $15 shocks ride kinda like a normal 80s truck which is very livable.

Any more pointed advice or recommendations are more than welcome- I don’t wanna sound like I think I know what I’m doing here!

You are willing to learn, that is the first step to knowledge, correct?
Test, test and test some more until your happy

I posted on the streetrod build thread but I’ll put this here to keep the conversation going until I resolve this problem.

I went underneath the truck with a tape measure. At my preferred ride height with the airbags- the height I used when I welded the perches to set pinion angle- I have 3” of compression available, getting into the progressively resistant wedge of the stock rubber bump stop after 2”. The video shows around 2” of seperation at launch so I need 5” of travel. On a lowered pickup I think I can live with a little stiffer ride and 27psi in a DOT drag radial should already ride softer than 38 psi in a nitto summer tire which is what I started with.

I only have a couple hundred miles on the rig so far and my plan was to kind of let it tell me what it wanted when the time came to upgrade shocks. I didn’t get a lot of direction concerning which shocks would work well for me in this thread but it was super helpful to know that the coming shock swap would need a simultaneous re-working of at least the top mounts.

I did a lot of searching on jegs summit speedway and here. Different vendors have different ways to narrow the choices and it can be daunting to find something that will fit, have eyelets top & bottom, and is not spec’d for dirt track or something specific. I was looking for at least single adjustable with 5”+ of travel and a ride height length of 12”-15”. Double adjustables were out of my price range.

After talking to a tech at Qa1 he agreed that unless I needed more travel and wanted to extend my bottom shock mount down closer to the scrub line so I could run a longer overall shock that a 5” travel star stocker 18 way single adjustable would work fine for what I’m trying to do. I went with the ts504 which is an 11” to 16.35” length eyelet to eyelet shock. They were on sale at $160 each which is cheap but hopefully not ‘these suck and now good money has to follow bad’ cheap.

The wimpy cheap stock replacement shocks that are laid back in there now are just enough to keep the empty bed from bouncing after a bump and with the stock sprung bench seat it’s not obvious that the shocks are way inadequate. I drove around 500lbs of music gear to a local show my band did (no highway) and the truck did awesome but showed early signs of squirrely handling around 50mph. This was my first longer trip with the DOT drag radials but they were not aired down for launching and I had them balanced ao I’m blaming the shocks and shock angle. It previously felt great hitting 80mph with nitto summer tires and an empty bed. The single adjustable shocks might not yield my combo’s ultimate 60’ but I hope they make the truck more versitile nimble and quick from a dig.

Hopefully testing will begin in a week or so!

I’m not sure how the brackets will end up but I’m considering making them bolt on the frame instead of pulling the bed and efi computer again in this heat for chassis welding. I have some ideas but it’ll talk to me after the shocks are mocked up off the bottom ears.

Rear shocks came in! TS504 stocker star QA1 single adjustables. I mocked them up at ride height and they still need a little angle but I think they will work much much better. I have some double adjustables coming for the fronts too. I’m hoping to be able to adjust a compromise between launching and handling for street duty and have some adjustablity for the track if I ever get her down the 1/4.

I’m waiting on a set of bolt in eyelet mounting pins in the mail and I can fab up some upper brackets.

You can see the old shock hanging by the top mount in the picture- it’s way back there!

is that a new lower bracket ? looks good. however, i would add a boxing tab from the rear housing to where it starts the curve to the eye of the mount.
approximately 1 1/2" [?]. that little bit of extra material will help a lot with the strength of the mount. [my opinion]

Those are the lower ears I put on when I built it. Boxing in the mount is not a bad idea with the amount of stiffness I can get with the qa1 adjustables

Got the bed pulled, extended the 3/16” frame boxing plates back farther, and welded in a CE coilover crossmember to relocate my upper rear shock ears about 6” forward. They still lean back around 20° but I’m thinking that’ll be just fine with the much stiffer shocks. I got the bed back on but have to button up the mounts, wires, & fuel system. I am also going to install the front double adjustables. I am looking at splitting the difference between drag racing and mild street handling settings as a starting place for the knobs- like 10 compression 2 extension. I don’t mind a little stiff but I’ll have to see if it’s awkward and stays nose up after a little dip like the comp 90/10s were.

I really didn’t want to pull the bed in this heat let alone do all the fabrication work but it wasn’t too bad now that that heat wave let up some.

I can’t wait to feel the difference in handling and hopefully the launch will transfer weight a little better or at least take off a little smoother. I’m already loving these M&H racemasters.

The front shocks required a little whittling on the lower control arms so the knobs would fit up into the spring pocket but it was no big deal with a little carbide burr.

I have all four shocks in now. I started the rear single adjustables at 10 clicks and set the fronts to 10 compression 5 rebound. Now to get some seat time and mess with them once I get a feel for how they act.