Handling upgrade...what parts?

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goldduster318

goldduster318

Overzealous Car Modifier
Joined
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Lake Orion, MI
Alright guys, now that I have a nice drivetrain in my Duster, I'd like to make the handling quite a bit better.

The thing I hate most about the car is the wandering feeling it gives during suspension motion. Since I live in Michigan, the suspension works pretty hard.

Currently the car has:

Front:
Stock 70 K-frame
Stock 70 Front sway bar
Rubber bushing rebuild kit with 8k on it
RMS strut rods
0.920" Mopar T-Bars
HD Replacement shocks
73-76 Disk Brake swap with '80 Volare rear mount calipers and 11.75" rotors
Delphi 800 Steering box

Rear:
8 3/4
MP offset shackle kit
ESPO HD 340 leaf springs 6 leafs per side.
HD Replacement shocks

225/60-15 tires all around.

Eventually, I will change the car to 17" rims and stickier rubber (hopefully 245/45-17 front and 275/40-17 rear). I would very much like to make this car handle better.

Which UCAs? Hotchkis? Firm Feel?
Change the Torsion bars?
I was looking at the Hellwig sway bar kits as it appears theirs will work for me in the rear especially with the offset springs.
Are the Bilstein shocks I saw at FirmFeel any good?

Looking for everyone's thoughts. The car has 470hp so I'd also like to be able to plant the power (it's not as bad as I expected now actually).
 
I would start with a 'good' alignment job with a nice dose of caster, provided all the balljoints and bushings are in very good condition.
How much does the idler arm bushing resist when pushing it up & downwards?
 
goldduster318 said:
MP offset shackle kit.
Click to expand...

Anytime you start moving the rear leafs towards the middle, you increase body roll

Maybe a rear anti sway bar

Sounds like you have some pretty good parts already

Upper A arms are not necessarily going to help handling.

I'm gonna say tires, depending on the shocks, better shocks.

After that, maybe a stiffer front anti sway

I agree, alignment (and tires) can make "a whale" of a difference
 
Idler arm is brand new, Moog brand and is very tight. it used to be A LOT worse. It went from totally wondering all over the place to only a little funky when the road changes (and I have to counter steer). It seems like what I am feeling is just how these cars would normally be but with better steering feel, but it's still not a great feeling car when compared to my 04 Colorado ZQ8 pickup or 12 Chevy Cruze.

I suppose I should elaborate...it feels pretty good at lower speeds, just not ultra fantastic at faster speeds (feels a little darty at 70 mph when changing lanes).

I don't think I'd get an alignment without changing the UCAs anyway, The passenger side one was stripped and the ball joint is welded on. All the front end is tight. It has stock alignment specs
 
Oh, the current tires are BFG G-force Sports 225/60-15

The shocks are some 14 year old HD Tennico Gas shocks.
 
Stock alignment no good, New spec alignment with front and rear sway bars you will feel like the king.
 
The stock alignment specs ARE your culprit. The stock specs call for little to no caster, which means the car WILL wander with modern tires. Dial in as much caster as you can with about 1/2 degree negative camber and 1/16-1/8" toe-IN. You won't believe the difference. A little lower in the rear will probably also help.

It is fairly easy to do this at home. Set the ride height (I recommend about an inch between the LCA bumper and frame, make sure it is equal side-side from the frame to the metal part of the arm). Then set the upper control arm cams with the rear all the way in and the front all the way out. Adjust the rear cam out until you have your 1/2 degree negative camber. That is the most positive caster you can get out of the parts on the car. Then set the toe.
 
I think I'd upgrade to a 3/4+ rear sway bar and a larger front sway bar. Re align the front end as suggested above and use offset upper control arm bushings. They will get you some more camber. How do you like the Delphi 800 steering box?
 
Get one of them cool coil over suspensions. Front and rear. Some coil over shocks too. Go with tubular a arms upper and lower. Make sure it's all red. And make sure you have plenty of stickers. Yeah. Stickers.
 
I doubt I have an inch of travel between a stock LCA bumper and frame at ride height. It's more like 1/2". I don't want to raise the car up either. The tires are tucking by about 1/32" on each side which is how I like it.

The Dephi 800 steering box is very good. The car actually has steering feel now, and the quicker ratio makes it a lot more enjoyable. Since I have a 340 and TTI headers, and with this k-frame, I had to grind one section of the box on the mounting face to make it sit tight, and I changed one of their hex bolts to a socket screw. You actually have more room than with a stock box as well. Well worth it.
 
1/2" is fine. You might bottom out with that and stock bumpers. My son's Barracuda sat that low so we just cut the bumpers shorter...
 
Nice car goldduster i have mine set with about .5 between bump stops n frame rails with 1.03 t bars takes a hard bump to bottom it out i ve goin with pretty much a hotchkis tvs set up on my car with exception of upper control arms i didn't want upper heim joints hear to many people say they wear out fast. I went with pst uppers they look to be well made. I bought all my stuff individually cause didn't have money to dump all at once so i got to feel the difference of each component sway bars made the most improvement on mine my car originally didn't come equipped with one at all
 
The alignment is killing you. You've got great parts already. Jim's right on, you need modern alignment specs.

-.5* camber, +3 (or more) caster, 1/16 to 1/8 toe in.

With stock UCA's and offset bushings you should be able to get at least +3 on the caster. I have +5 on my Challenger, but it has Hotchkis UCA's. They're awesome, but I wouldn't run heims on the street again. Stick to a tubular arm with bushed ends for street use. It'll last longer, and with poly bushings you won't give up all that much flex anyway.

Bilstein shocks are amazing. I've heard the Fox shocks from Hotchkis are better, but even with 1.12" torsion bars in my Duster the ride is fantastic. Much better than my Challenger, which also has 1.12" bars but KYB shocks at the moment.

The tires will also help a lot. 245/45/17's shouldn't be a problem at all, a 17x8 with 5.25 to 5.6" backspace will work great. In the rear, with an A body 8 3/4 and an offset shackle kit a 17x9 with ~5" of backspace should work great for a 275/40/17.

I would go up to 1.06" bars in the front. That'll help with your lowered stance as well, as it will reduce the amount of suspension travel needed. The bilsteins will handle those just fine. They'll help improve handling, and will deal with the improved traction better. But the torsion bars aren't the source of your current problems.
 
Thanks for the input. I actually have a '68 B-body rear axle in the car...so I'll need more rear backspacing :)
 
goldduster318 said:
Thanks for the input. I actually have a '68 B-body rear axle in the car...so I'll need more rear backspacing :)
Click to expand...

Hey so do I! Yes, you'll need a lot more backspacing. On a 17x9 I'd say between 6.2" and 6.8" of backspace, or 30 to 45 mm offset.

Although I wasn't of the opinion that 295's would fit on a Duster in a stock wheel tub, I'm beginning to think its possible if the quarter lips are trimmed and re-welded. That would need a 10" rim and about 38 to 40mm offset.
 
Instead of new UCA's just install Moog offset bushings in the uppers. Press them with one in and one out on each UCA so the UCA is tilted to the rear at the upper ball joint. Since you are in Michigan, check with Mancini Racing or order from any place that carries Moog. (Rockauto probably has them)

Then get it aligned with 2* or so of positive caster, 1/16" toe-in, and 1/2* of negative camber. (much more camber than that on a street car will wear the tires) The key is the increased caster and you will NEVER get anywhere near that with stock bushings. I think when I first got my 68 aligned w stock bushings, the tech could barely get 0* in CA. Do NOT get it aligned to old factory specs.

My 68 w/ (4) 215-60x15 tires on 15x7 steelies tracks like a freight train even in big cross winds. (.92 bars, 73-76 K-member, lowered w/ cut down stops, Moog LCA and strut rod rubber bushings, stock size front sway bar, HD rear springs w/ poly shackle bushings, 16:1 manual steering)

(I know Lusk doesn't like them but...they've gone over 160 MPH on a racetrack in the Green Brick and I like them)
 
We got 2-3 degrees caster on both of my sons' cars with stock control arms AND stock bushings. The reason I don't like the offset bushings is the thin side and my BELIEF that this MAY shorten their life. I'll find another way to get more caster (like adjustable arms).
 
I don't recall any wandering steering from bumps on my Mopars. I drove my son's Chevy Cruze on windy mountain roads a year ago, and the steering felt more vague, probably because it has electric assist. I used to drive my 69 Dart on the very windy Angeles Crest Hwy and it handled the curves great.

It would be easier to set more caster had you used Moog "problem solver" offset bushing on the UCA (installed as you can find here, not the included instructions). An after-market UCA might help for that, but is an expensive way to get there. You want to move the upper ball joint as far aft as you can.
 
Like I mentioned before - my ball joint is welded in because its turned its way out more than once. I need to get new UCAs anyway. If I replaced that one, it would be the 3rd one I've used on this car on the passenger side...first one cracked...

Personally, I think the factory ones around are pretty shot...and its a chintzy design as it is. I'm willing to pony up some money for good parts for sure.
 
For tubular UCA's I'd look at Firm Feel, PST, RMS, or even Magnumforce's bushed versions. I would skip anything with a heim joint instead of a bushing on the street.

If you do go RMS, make sure you get the "later" version that looks more like a "V" than a "U". The earlier "U" versions limit the amount of backspace you can have if you run larger rims and tires.
 
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