76 duster. 416/727..3.55 rear. street car with a few passes yearly down the strip.

currently on original T-bars and leaves with air shocks to clear 275-60 15 rear tires.
car has always handled poorly,i installed new front rod ends/bushing/ball joint kit and magnumforce non adjustable upper arms. was told by shop that car must of been hit at some time(core support is wrinkled a bit) and couldnt get the extra caster thats suppose to be built into the magnum uppers.
So time to lose the "jacked up 70's" look, i want to go to maybe 17x7 front 17x8 or 9 rear wheel. first ? is which height leafs to get to clear 17", +1 or 2" over stock ? standard or heavy duty? i want to get this car handling decent.
second ? the shop said should be able to get more caster if i had adjustable uppers so recommendation on which brand of adjustable upper cntrl arms and torsion bar size?

maybe take it to a frame specialty shop & get the subframes checked/straightened. there's the Moog "offset" UCA bushings meant to sideways kickout for more camber & you turn one around before pressing it in to get more positive caster. On the rear suspension I am out on a limb but just me if getting 1 or 2" over is a good plan I would get the 2" more arched ones & you can lower it later if needed. I wondering if the jacked up back is contributing to this but if the tires are huge then either that or fender mods and or wheel offset/pad perch relocating.

The jacked up look is definitely contributing. Whether that is the entire problem, I do not know.

Fully adjustable UCA:

https://www.jegs.com/i/Specialty-Product...UxoCc9sQAvD_BwE

If the aftermarket UCA that was built correctly to give you more caster couldn't get you close, you’re going to need a lot of trial and error. It must be pretty far off.

Don’t know how friendly you are with you alignment guy. But I talk with him before you take the car with fully adjustable arms. Try to get an idea what he is going to charge you. You might run up a steep alignment labor bill. For $300 you can buy a nice home alignment tool.

Need to ask this question and move this thread to the Suspension Board

Goldduster318 has a Duster just like you. He’s got 275/35/18 on all four corners.

https://board.moparts.org/ubbthreads/ubbt...tml#Post2547550

I would not go smaller that 8” wide wheel and 245 wide tire in front.

245 45 17 on 8" Bullitt rim fits fine on the front of a duster. I ran around with them all around for years. i liked the convenience of the same size all around but don't like the look. I had 275s On the back for a while and that looked good. On the rear you can go big if you get creative. I now have 315s on the back of mine with offset hangers. I removed the outer wheelhouse and trimmed the excess lip off the wheel opeming, the lip is about 1/2" now. If I go on some crazy incline turn the inside top of the tire will just touch the inner wheelhouse, but it has to be extreme. It looks kind of funny to me with tires that wide. Like steam roller. A 295 or something would probably look real good.

I would not get any additional arch built into the springs to run a 17. I have had expo hd leaf for like 10 years on mine.

How high is the back now?

its 29" from ground to center of rear wheel opening lip,tire is 27" tall,springs and shocks are so soft a dip in the road at speed and the tire will rub the inner lip ocassionally.
i just want to get it down in the rear and have it more stable at highway speeds.

what alignment numbers were you able to get?

Why not take it to a frame shop and have them measure up what you have and pull it square again if it's off a little? Not much money in the big picture and the car will be better for it. Hardest part is getting the frame specs for something that old.

I once took an old Mustang coupe to the dealership I worked at in the late 90's to have the alignment verified right after I got it back together and was also told that it would not adjust to his exact book specs. I have heard more than once about techs not being able to align old cars very well. Not sure why that is????

I think the old specs were a bit more loose then the current specs. It the old days, the alignment was by "close enough" and were adjusted to drive the way the alignment guy (or the customer) likes them to drive. The new specs are digital and printed out, per wheel. If the car is just outside the limited spec window, the out of spec wheel is flagged on the printout. I had one wheel once that was .001 out of the spec range. The tech had to point it out and make a big deal over it to cover his butt, and the company's butt. If the tire showed any wear outside of normal, they would point out they couldn't get it back within specs. Any abnormal tire wear wasn't their fault. Gene

The height of the rear will affect the front alignment. So, decide on your final height before you do anything with the front.

You absolutely have to find an alignment guy that is familiar with our old Mopars. That is very important.

I have had several Mopars aligned that to get them to drive straight, some of the specs ended up "in the red". That's what it took to get them to drive straight and there were no down sides.

If it were me, I'ld get a starting point on the alignment. Set your rear height where you want it to end up, then take it to the shop and have your front end specs measured where they are now. Maybe even have him see if it will come in as it is now.

That way you know how much additional adjustment you might need. The offset bushings may well do it by themselves. For most of us street guys, I have always felt that the adjustable uppers was money wasted. If the car needs more than the offsets offer, I have 1/4" or so cut out of the rear UCA.

One last thought; I have often struggled with getting the rear height just right. And then you have the possibility of it settling down over time after I get the height I liked. So I have went to using leaf helper springs from Helwig that I mount on top of the rear segment.

They stiffen the rear some, are not visible, and I can adjust it up and down exactly like I want any time I want. And at the drag strip, I can still pull 1.5 60 foots. What's not to like?

^^^ Dave good info