Opinions needed on which AFCO leaf springs to buy

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lee g

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Getting ready to pull the trigger on a new set of leaf springs so here is what I have so far:
72 Dart, 360/around 300HP maybe a little more, seam welded and reinforced K-member, reinforced lower control arms, 1" Just suspension torsion bars, Steer and Gear Stage II steering box, B body 8 3/4 rear with 2.9? with suregrip, monroe shocks (will upgrade to Bilstein in a few months), 2002 Mustang Bulleitt wheels with Michelin Pilot 245/45/17 tires. It will be driven on the street (no drag strip) but I want it to handle the curves and road course.
Looking at the Afco 20231M 120# spring rate or the 20231 142# spring rate. I know Hotchkis springs are around 130# spring rate (in the middle of the two listed above). At a later date I want to relocate the springs and do a 3" mini-tub but that's a few years down the road.
 
Not opposed to other brands but just researching found a couple of folks with similar set ups that liked them.
 
I'm running the 20231M's (121 lb) on my Duster. I think the 121lb springs are fine, especially if you're planning on running a rear sway bar. And paired with a set of 1" Just Suspension bars the 121lb springs would be a better match to the front rate of the car. I ran the 1" Just suspension bars for a bit before I went up to 1.12" Firm Feel bars. The 1" bars are fairly soft for their size, I would estimate their wheel rate to be around 190 lb/in. The 1.12" bars I run are 300 lb/in, and the 121 lb AFCO's still work well with my rear sway bar. They actually worked ok without the sway bar, although the addition of the sway bar did reduce some body roll.

If you do want to go with the 142 lb springs, I would be inclined to try the 4" arch 20230 springs instead of the 20231's with a 5" arch if your car is lowered at all. The 5" arch on the 20231M's ends up being pretty close to zero arch (a little higher) on my Duster, but I'm also about to install 1/2" lowering blocks, so with a higher spring rate I think you'd want the lower arch. The longer wheelbase on the Dart would effect that too, but I'm not sure it would make a big enough difference to go with the 5" arch. And with the 142 lb springs you probably wouldn't need a rear sway bar, especially with the front bars you have.

You'll also need to make sure you get a set of rear shackle bushings, the AFCO's use a 1" rear eye. Energy suspension 2-2117G bushings will fit the AFCO rear eye and the A-body shackles.

I'm pretty happy with the 20231M AFCO's. They've sagged very little since I've installed them, unlike the mopar XHD's I put on my Challenger which lost almost 2" in ride height in the first few weeks. The ride height works pretty well, with 26" rear tires I've got about 26.5" to the wheel arch, although that's with a Duster. As I mentioned I'm going to add a set of 1/2" lowering blocks to put it exactly where I want it, but my car sits fairly low. Only 1.5" from the LCA to the frame stop in the front, just under 1" to the bumpstop. The spring rate seems to work pretty well, the body roll was much reduced from the stock springs. The rear sway bar helped reduce that further, and I don't seem to be too far into oversteer with it set up the way it is. But I haven't pushed the car really hard yet so its a little hard to tell.
 
I'm interested to see how your setup works for you.
I'll be doing something similar.
I'm still buying part at this point.
So far I have:
Rebuilt frontend in rubber
1" Just Suspension bars
1"1/8 Hellwig front swaybar
7/8" Addco rear swaybar
KYB shocks
16:1 Firm Feel manual steering box.

Need frame connectors and the SS springs have to go.
I'm also considering a spring relocate.

So I'm very interested in your results as I may follow suit if
you have good results.
 
think i'm gonna go with the eaton 69 383 dart #ML229 springs.. they are like 130 lb pound rate... supposed to have a stronger front section then a 340 sprong..
 
abodyjoe said:
think i'm gonna go with the eaton 69 383 dart #ML229 springs.. they are like 130 lb pound rate... supposed to have a stronger front section then a 340 sprong..
Click to expand...

The Eaton springs are great, but they're also an extra $180 for the pair. The AFCO's also have a reinforced front section, making them better at controlling spring wrap than the stockers. I would hope that the Eaton's would be better, but I haven't had any issues with my 121lb AFCO's either.
 
I havent gotten them installed yet. Will be soon, frame connectors are going in this week then will get the rear suspension going. With the offset hanger kit from Dr Diff, i have an inch of ride height adjustment built in to them.
 
Fisher said:
I havent gotten them installed yet. Will be soon, frame connectors are going in this week then will get the rear suspension going. With the offset hanger kit from Dr Diff, i have an inch of ride height adjustment built in to them.
Click to expand...

That's a good point. I have the Mopar Performance hangers, so there's no adjustment there. But I don't think the MP hangers actually have the eye bolt in the middle height wise compared to the stock hangers, I think they may have a little drop to them. It would be less than a 1/2" though.

I have a feeling the 167 lb, 6-5/8" arch springs will be like +1.5" compared to stock, maybe more. The 1" drop with the hangers will help, but you may still end up with some extra rake.
 
I will install in the lowest hole that should give me the correct ride height. Will post some pictures as i go along.
 
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