Front Suspension adjustment

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Mopar87

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I'm looking into making some new longer control arms with coil overs.And I was curious about how much adjustment I can pull out of the stock mounts?After all said and done the new A arms would be about 1.5" wider per side and the ride height would be 3" taller than stock.I'm looking to have final alignment numbers at ride height of:

Caster +6*
Camber: -1.0* to -1.5*
Toe in: 1/16"

Obviously I'm gonna have to build in some caster/camber but how much adjustment did the factory leave for my 73 Scamp?
 
Unsolicited advice;
Many folks will point out that a coilover style suspension may not offer you any benefits over the torsion bar setup and the chassis would need to be reinforced to carry the loads in the new locations.

Those alignment specs are within reach of aftermarket tubular arms...maybe even with stock control arms with the offset bushings (someone will have to verify that though)…

If you are looking to go 4x4 racing, I can't help...as a matter of fact, I'd urge you to consider doing this to a Chevy or something more replaceable.
 
I'm not converting it to 4wd.I'm keeping it 2wd.I would be using the car to go camping which will include alot of driving on rough roads, sometimes at speed.To help protect the car as much as possible from the football sized rocks that seem to grow on dirt roads around here I will run some LT tires with a suspension lift to get the body up out of harms way along with a full compliment of skid plates to protect the squishy bits under the car.The plan is a 3" suspension lift which will give just enough clearance to run 31" tires with little trimming.Sure I could crank up the torsion bars to get that much lift but suspension travel and ride quality would suffer.So I plan to redesign the suspension so it sits 3" higher in the middle of its travel at ride height and I can't really do that while keeping the torsion bars.

The obvious answer is use a truck or suv but their driving dynamics leaves much to be desired.Instead of enjoying the drive to the campsite it becomes more of a chore.A pickup's very nature means that it will understeer constantly due to the piss poor weight distribution when lightly loaded, and because its designed to be loaded heavily the rear end is too stiff so it tends to bounce around.Both of those issues can be fixed but then the truck can not be used as a truck anymore.A rwd car would have better balance and after installing subframe connectors,torque boxes,etc will be stiff to enjoy driving.Camping for me consists of a tent,sleeping bag,a cot to sleep on,and a camp stove to cook with, then going back to work when the weekend ends.So for that I might as well drive something that I enjoy.

Chevys are replaceable so much so that I would never consider doing all this work to one.I could camp with a chevy but because its so disposable I wouldn't bother lifting it or swapping in a late model fuel injected engine.I would put skidplates on it and run it until the body fell apart.Then go do it again.I want my scamp to last so I'm gonna take the time to do it right.I will even go so far as to stitch weld the chassis so it doesnt fatigue itself into an early grave.

So its looking like I will need to design a fair bit of adjustment into the suspension,I have a front frame section off a 2wd dakota that I could use some of its parts to get more adjustment.I was gonna use the dakota suspension as is, but it turns out the original suspension on the scamp would be much easier to modify for more suspension travel and durability.
 
That's why I own a Durango, BUT for that intended purpose I would find that I really miss my old '79 3/4 ton club cab Power Wagon...
 
kursplat said:
since your so intent on this, and going to be building from scratch anyway, bag it
Click to expand...

Bags sound ridiculously expensive and unreliable.The general consensus seems to be that airbags don't hold up to an offroad environment very well. I dont have any first hand experience so I cant expand from there.
 
Mopar87 said:
I'm not converting it to 4wd.I'm keeping it 2wd.I would be using the car to go camping which will include alot of driving on rough roads, sometimes at speed.To help protect the car as much as possible from the football sized rocks that seem to grow on dirt roads around here I will run some LT tires with a suspension lift to get the body up out of harms way along with a full compliment of skid plates to protect the squishy bits under the car.The plan is a 3" suspension lift which will give just enough clearance to run 31" tires with little trimming.Sure I could crank up the torsion bars to get that much lift but suspension travel and ride quality would suffer.So I plan to redesign the suspension so it sits 3" higher in the middle of its travel at ride height and I can't really do that while keeping the torsion bars.

The obvious answer is use a truck or suv but their driving dynamics leaves much to be desired.Instead of enjoying the drive to the campsite it becomes more of a chore.A pickup's very nature means that it will understeer constantly due to the piss poor weight distribution when lightly loaded, and because its designed to be loaded heavily the rear end is too stiff so it tends to bounce around.Both of those issues can be fixed but then the truck can not be used as a truck anymore.A rwd car would have better balance and after installing subframe connectors,torque boxes,etc will be stiff to enjoy driving.Camping for me consists of a tent,sleeping bag,a cot to sleep on,and a camp stove to cook with, then going back to work when the weekend ends.So for that I might as well drive something that I enjoy...
Click to expand...

Purely my opinion but it sounds like you're about to turn a running/driving Scamp into trash.

It's your car of course and you can light it on fire if you want...but I'm also free to say that this is just sad.

Also, on what planet would the driving dynamics of a hacked up antique car be better than a more modern vehicle that was actually made for this purpose?
 
Mopar87 said:
Bags sound ridiculously expensive and unreliable.The general consensus seems to be that airbags don't hold up to an offroad environment very well. I dont have any first hand experience so I cant expand from there.
Click to expand...
ok. but considering you essentially just want to put an A-body body on a lifted 2 wheel drive custom suspension, i thought we were looking a little out side the box.
 
Mopar87 said:
Obviously I'm gonna have to build in some caster/camber but how much adjustment did the factory leave for my 73 Scamp?
Click to expand...
Are you asking about range of caster and camber in the cams? About 1.5 camber and 3.5 caster. That's range of adjustment. The actual numbers depend on the ride height (because they change as the arms go up and down.) By ride hieght I mean shop manual ride height method- not clearance.

As far as your goals, its a little confusing. Most off-roading is not brisk in the challenging sections - it's often slow and steady, big on torque and articulation but depends alot on where you're at. Muddin and rock crawling are different setups, etc.

If you're looking for something more like rally, then find everything you can on the rally cars - the Shell 4000 website has some great articles on/by Scott Harvey from back in the day. There's also the Rally bulletins from DC/MP. Later ones include the Colts but still have the A-body stuff. Also I'm pretty sure the photos of Beckman's FIA car prep are still on line. Basically for current FIA Historics alot more safety is not only allowed but required. Back to your area of interest - stock based suspension is great for rally. Save yourself a lot of engineering and development time. As soon as you start playing with a suspension like your talking about (ie moving attachment points) then roll centers, center of gravity relative to roll centers, toe changes, scrub, etc all have to be figured out again.
 
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This may be fun
upload_2019-8-23_17-15-56.png

but don't be under any illusions.

Off pavement speed is brutal on vehicles, all vehicles.
Even if you don't crash, catch a ditch wrong, clip a tree or any of the other things that happen.
I first realized this truth at SCCA regional club meetings talking with a guy who ran closed section rally. He was going on about repairing this and that on his Quattros body and structural like it was a normal thing - because it is when you play in that sandbox.

When I go off pavement, its pretty well thought out. Its either pretty known course and conditions like at the rallycross in my avatar, or drive it slow and careful enough to not to risk anyone else on the road or the car. If something looks like it could do damage or strand me I stop and walk it first.
 
Yes,what I would be doing would be more rally than true offroading.Pick a spot on the map to go camping,Then figure out what roads are roads and what "roads" are actually goat trails, then head out while avoiding the truly rough sections.

I know how rough rally actually is on vehicles.At some point the chassis will be thoroughly used up and worn out, so I plan to delay that as much as possible by strengthening the body as much as possible before its put together.I plan to have this car for a long time.In its current state if someone else had they *MIGHT* restore it if they had a lot of disposable income, but most likely it would be a parts car.Currently its engine got water in it from sitting for 10 years so its done,the upper control arm on the passenger side has ripped out of the sheetmetal,and a couple panels have some pretty good dents/crumpled areas.

So it looks like if I design the control arms to have -1* camber at ride height and +5.5* of caster I should easily be able to adjust it using the factory mounts.
 
I'm gonna fix the suspension and replace the engine and then I will go from there.I just realized that all of my builds that I tear into without driving it for a while turn to S***,Now to figure out why the passenger side front tire has like 30* of negative camber...
 
I think if your frame/suspension is in that bad of shape, I’d see about getting a 2wd Dakota or S10 frame and set the body on that. I just picked up a 2wd short wheelbase s10 and the wheelbase is 108” same as a Duster or barracuda. The short wheelbase 1st gen dakotas have a wheelbase of 111.9” so that’s be perfect for a Scamp. And they have rack and pinion steering and 5x4.5” bolt pattern as well
 
I thought about running a dakota frame and suspension, but in stock form they actually have less suspension travel in the front, and they would be much harder to modify to get better travel because of the spring perch that is also the upper bump stop and because the upper A arm mounts are inboard on the frame, the frame would need clearancing as well.That being said,I have a front section of a 2wd dakota frame that I was planning on using some parts.
 
on closer inspection someone monkeyed with the torsion bars and cranked them way up.The passenger side is missing the upper bump stop but its two inches away from the pad and the driver side upper bump stop is squashed completely flat. I have a set of slant six rear leaf springs I got so I will install those in the back to replace the negative arch leaf springs currently on the car.Then I will lower the front down to match and that should fix the funky camber.
 
I Adjusted the front end down so the control arms are about 1/2" away from the bumpstops and that fixed the camber.Took all the weight off the trunk and the rear springs are still sagging but not as bad.Now I just need to find some a couple of tires that hold air so I can move it around and start working on it.Replacing the solid rust seized engine would be a good start.
 
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