mild street suspension question

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4tez

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ok guys, I don't usually post on the forums but I read these things religiously. Heres the back story, I have a 1970 Duster with a /6 in it, car only has 46k original miles on it, and has been well taken care of for years. The issue I am running into is the suspension is giving, and the car is my daily driver, so I'm in the process of rebuilding the suspension.

To start I have 4 normal gas shocks that my father picked up online, the ones on the car are completely shot and the front end bounces pretty good over bumps. Second, I recently install some used v8 springs off a dart, which seemed to raise the rear and stop the back from just floating around.

Next for my car will be a disc brake swap which i got from a 73 dart, and since Im going to be doing the work up front I was wondering what would be the best way to stiffen up the suspension to give me the best turn-in and overall performance.

I know these cars arent the best around turns, but i would like to do my best to keep the car on track, and just make it feel more solid. I dont want to turn this car into a drag racer, rather a decent street car that can take a turn at a decent speed.

So far from what I gathered, the first thing i should do is get a sway bar for the front, some new bigger torsion bars, a set of xhd springs out back, and what ever else you guys could recommend to help me.

thanks for the help, mark
 
Don't put bigger torsion bars in if you're keeping the /6. New shocks and a swaybar should be all it needs to drive like a whole different (new) car.
 
ok, you used two different terms for your duster, rebuild and upgrade. lets address both.
as far as rebuild, after 38 years, your duster is going to have a lot of worn out parts. so those need to be addressed first. take care of your ball joints, pitman and idler, tie rod ends, and bushings. buy quality stuff where you can, as it sucks to have to do it twice, even when the parts are under warrenty. for a full rebuild kit, look at either PST or Just suspension. ive used both with fair success, though lately i have been doing stuff piecemeal with manufacturers i like. after everything else is up to snuff, check out the stering box and coupler. sometimes the box can be adjusted to get rid of slop, sometimes it can't. the coupler is a snap to rebuild.

as far as upgrading to turn, theres many options depending on budget and preference. i'll give you my OPINION on what should work well, but just remember, its my opinion, based on what ive tried and liked. it is not the gospel.
1. after a thorough rebuild of all the non-bushings (using my favorite brand, MOOG), buy an energy suspension bushing kit. fire up the belt sander and shave down the strut rod bushings by "i think" 1/8th of an inch. someone will correct me on this im sure. use 80 grit, it seems to work best on their poly. also, toss the upper control arm bushings (and remember to get the big ball joint control arms with your disc spindles)and install the moog offset ones. i wish i had done this on the current suspension in my duster, but you live and learn.
2. add the ADDCO 1 1/8 front sway bar, and a small rear. ive had good luck with addco, and the one for the 70 will clear the 73 calipars in the stock location.
3. upgrade to the 340 duster torsion bars and leaf springs. should be just stiff enough for the /6.
4. add a set of KYB shocks. theyre inexpensive, and work reasonably well.
5. if a poer steering car, swap in a FFI stage 3 box. i just finished mine, and LOVE it!
6. upgrade to 15 inch wheels. i use the wheels off a diplomat, 15X7. theyer cheap, readily availible, and fit right. i can fit a 235/60.15 front and 275/60.15 rear on my duster.
7. add subframe connectors. i did that, and it really helps. i did mine like the big block dart website says to.

except for the upper control arm bushings, and spring rates this is roughly what i currently run in my duster. i am still dialing in the alignment specs for my driving style, but it handles pretty fair. still think my wheel/tire combo is holding me back, as well as too soft a spring. but that should get you in the ballpark for minimum investment.

hope that helps
Michael
 
4tez, Welcome to FABO! Since I see you are relatively new, how about some pics of your ride? BTW: Glad to see another member from the Peninsula here.
 
Thanks Ace and dusterbd13, I kept hearing that the sway bars would really help, so thats first on the list with the shocks.

Hopefully when i start getting that stuff in, I have some more money to get one of those suspension rebuild kits.

heres a pic, its an older one. I have new wheels on the back, running 15in and 265s, looks alot better. Hopefully i can get some new pics up this week

IMG_0365-1.jpg
 
For a everyday useable street car suspension, I would certainly use better shocks. than standard off the shelf units. Even a set of cheap KBY's is a nice thing to do and worth it. I do like mine on my Magnum. (1979 Magnum)

Anti sway bars are a great idea. The T-bar, if upgraded should be up one size from standard at max. Going up two sizes creates a bit of a stiff ride most do not like for an everyday use car, even if only used on weekends.
In example, the car is a /6, use 318 T bars. Gong to a 318, go up one size. etc....

Wider tires are allways done on my cars. It not only improves grip in trun handling very well, but overall, IMO, a nicer ride feel than skinny's all around. Car feels more stable on uneven roads.

After all those major upgrade parts are done, new bushings and worn out parts should be replaced. I did a PST suspension and loved that new and tight feeling all over. No squeaks! Gotta love it.
 
Not to influence you or anything, but I just pulled a pair of .87 torsion bars from my 67 Barracuda. These are the small block heavy-duty (Formula S) size, and would make a great upgrade for a /6. I am upgrading to the big block size (.89).
 
mvh said:
Not to influence you or anything, but I just pulled a pair of .87 torsion bars from my 67 Barracuda. These are the small block heavy-duty (Formula S) size, and would make a great upgrade for a /6. I am upgrading to the big block size (.89).
Click to expand...

what would it take to acquire those torsion bars mvh?

Also is your barracuda in a body shop up in san mateo? I just saw one when I was bringing mine in to get appraised on some damage at the rear.
 
4tez said:
what would it take to acquire those torsion bars mvh?

Also is your barracuda in a body shop up in san mateo? I just saw one when I was bringing mine in to get appraised on some damage at the rear.
Click to expand...

Well, I just calculated my tax bill and it looks like I need about 5 grand... <LOL>

Oh, I don't know... 50 bux as is? They could use some paint.

No, my fish is in my mother-in-law's carport in a Menlo Park cul-de-sac, up on jackstands.
 
4tez said:
the rear one will be straight bolt on? or is there some other modifying necessary
Click to expand...

I don't know about "bolt on". I know I guy who mounted one of those on a Barracuda 'vert and he described it as a major pain. The ends apparently had to be bent either in or out to line up properly.

One of the aftermarket outfits offers a frame mount rear bar that pretty much is the same thing, but made to fit A-bodies. I can't recall if it's FirmFeel or Just Suspension off the top of my head.

The axle mount rear bars (ADDCO-style) are pretty common, too.
 
Rear bar will definitely reduce understeer (plow). Rear spring spacing between the F/M/J is not the same as the A-body. Ends of the rear bar won't line up with the A-body without some torch time. The A39 Dart cop car ('76 option, I think) had a rear bar, most delivered in SoCal. The bar was body mounted. I'd like to find part numbers for the spring plates for mounting a bar on my car.
 
P-S-T or Just Suspension sell front end rebuild kits for all cars. I bought the polygraphite kit from P-S-T and it made a huge difference in tightness and gave a firm fell. Yes shockes and sway bars should also be used but this is another way that many dont attempt. I did the entire front end over my Spring Break from college so its not to bad.
 
There's more to getting around a corner than springs and tires. You didn't say if you had power or manual steering. If you have power, and want to keep it, recommend a cop car steering box. Spot 'em yards by a cooler on the Saginaw pump. The Dip & Fury boxes work fine though you'll need to swap the pitman arm.
If you have manual and want to speed things up, use the Mopar worm & nut package, P4007612. Changes ratio from 26:1 to 20:1.
Going to a smaller steering wheel will increase steering effort regardless of assist or non. It decreases the leverage you have over the steering box. It won't necessarily change the feel. Personally the stock power box is too light with the standard bus sized steering wheels.
I agree with suggestion to change to polygraphite bushings. It makes steering much more precise, improves road feel, and doesn't seem to make the ride any more harsh. I've used PST & Just Suspension kits in the past with satisfying results.
 
Thank You once again for all the help, most of the upgraded parts will be going in this weekend if not next. Pics will be up as i go along.
 
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