Turns : Inches for torsion bar adjustment?

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Trevor B

Trevor B

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I'd like to bring the front down an inch or so (back springs are sagging but their replacement is much further down on the list). 1973 Duster, 318 no AC, stock everything except the 15" slot mags I'm about to put on. Will get an alignment on Friday after the new tires are mounted but I wanted to do any adjustment beforehand.

What is the right place to measure before and after and is there any formula for how much twist per inch?
 
The factory manual tells you to take measurements at two places and the difference is the spec. I don't know the exact measurement points or the spec.

I just turned in the preload bolts until I liked the way it sat, bounced it up and down a couple of times to make sure and repeated it on the other side. Took it down to get it aligned. That was over 20 years ago.
 
I dont believe there is a formula as it depends on a bunch of factors.... Car weight, wheel offset, age of bars, to name just a few.
 
Yes, there is no formula for number of turns as stated above. rklein is also right about the factory method, which I find cumbersome. I try to set about an inch between the LCA bumper and the frame. I then measure from the metal part of the LCA to the frame in the same place on both sides and make them even.
 
Depends on your lowest hanging parts.
Oilpan and header damage really sucks,
tearing off muffler/exhaust system aren't
fun either.
 
You can measure from the ground to the bumper or K-frame for reference, just keep using the same reference points for consistency. I think that it's easiest to use the bottom of the front bumper.


Also bounce the front end up and down a bit after each adjustment before measuring.
 
The problem with using the bumper or fender is that they may not be even side-to-side. Use the frame to ground, frame to LCA, or some other fixed point.
 
When the torsion bars are being adjusted I like to have the front wheels hanging in the air to take some load off the suspension whenever I tighten or loosen the torsion bar adjusting bolt.

Although I've seen lots of guys just adjust them with the wheels on the ground!
 
Keith Mopar said:
When the torsion bars are being adjusted I like to have the front wheels hanging in the air to take some load off the suspension whenever I tighten or loosen the torsion bar adjusting bolt.

Although I've seen lots of guys just adjust them with the wheels on the ground!
Click to expand...
Same here. If I'm going up I take all the weight off the front. If I'm going down I leave it on the ground. I also just do it in increments side to side and settle the front end each time until I get the height I'm looking for. I normally go up high and then drop until I like what I see.
 
Thanks for the help! I can measure from the K-frame and was ready to do some adjusting but then I decided to see what the stance looked like with the new wheels and tires on.

Got them on there (225/60R15) and have to wait... tire guy told me the upper control arm bushings need replacing and he didn't want to do an alignment before they were taken care of.

Gonna ask about that in a new thread... the quote of $375 labor to replace those parts didn't make me very happy.
 
Trevor B said:
Thanks for the help! I can measure from the K-frame and was ready to do some adjusting but then I decided to see what the stance looked like with the new wheels and tires on.

Got them on there (225/60R15) and have to wait... tire guy told me the upper control arm bushings need replacing and he didn't want to do an alignment before they were taken care of.

Gonna ask about that in a new thread... the quote of $375 labor to replace those parts didn't make me very happy.
Click to expand...

can buy all the bushings for both upper arms for $20. not hard to do yourself really.. if i'm pulling the upper arms i'm doing the upper ball joint while i have the arm out..

https://www.rockauto.com/catalog/x,carcode,1088186,parttype,7532
 
Depending on how far the rear has sagged, and how much f/r rake you like, the front may get so low that caster will go negative,leading to speed related stability issues and camber change on turns or bumps may get bothersome,and with the accompanying reduced suspension travel,speed bumps can be a treat. Bottom line is;be careful how low you set the front. I have found 5.75 +/- .25 inches between earth-plane and lowest point of K on vehicle center-line, as a comfortable target, with 235/70-14 tires(about 24 inch diameter).
-If this nets a negative rake, fix the back.Re-arching and adding a leaf is not that pricy.
-Dont forget to roll the car back and forth after each adjustment to relax the suspension, before measuring the side to side for level(I use the wheel openings on my car).Mopar uses a measurement where the ground-plane to lower surface of LCA inner bushing minus the ground-plane to lower BJ equals "X", and X needs to be the same on both sides.The problem with using that method is that the two measuring points are too close together and tiny errors in measurements get amplified to where you could be chasing the level factor for a while.I used it to ballpark it; then switch to the fenders. When youre done both ends of the car should be level from side to side. IIRC that "X" was 1.375. IDK, not sure.That was 1999.
-If you have a lot of difficulty getting both ends level, the back may be sagged unequally between sides, another reason to fix the back.
-Take all the junk out of the car that wont normally be in there. I put 180 pounds in the drivers seat on my car when I aligned it.
-If youre replacing UCA bushings, get the "problem solvers".At least you might get some positive caster with those.And if its apart this far, have your guy take a real good look at the LCA bushings. They usually wear out first and they are extremely important for the alinement to last. If/when they move around while driving the alinement feels terrible, and the tires burn off quick. And then he gets to do it all over again. MO MONEY.
 
New plan... I'm going to try to nail down all the suspension stuff all at once:
1) New springs in the rear
2) New upper control arm bushings in front
3) Check out the stance and then adjust accordingly (and big thank you, AJ/FormS - definitely want to do this on a level plane and check the side-to-side!).

I found a pretty great video for popping out the bushings, by the way:
[ame="https://www.youtube.com/watch?v=aPbL9HTHZg0"]How to Replace Control Arm Bushings (EASY) - YouTube[/ame]
 
Several things I don't like about his video. First is his tool did not fit the bushing properly. Second is that he did that on the ground (clamp the tool in a vise). Third is that he left the rust on the bushing. Clean the arm (that's why I own a hot tank) and bead blast it.
 
Way back when I was drag Racing my 69 Bee,I would always measure the front wheel well opening when changing the bars. That was the easest place I could find. Didn't take me long to find out the higher the front was the better. :) Like one of the posts above, when raising the front take the weight off by jacking it up. When lowering, leave the weight on the front. Much easier that way with the weight working with you. Good Luck

Jim
 

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I think my guy charged me 400 to change mine. Then we found rust and hadto do some major surgery while we were in there.
 
Thanks for the link - I procrastinated buying the tool kit and the price dropped $30 over night! Now no excuse to not to replace the entire suspension.
 
Just lowered my front end yesterday so thought I'd post my finding on this. '74 Dart, 225/6. One full revolution of the T-bar adjusting bolt achieved roughly 1/4" drop at the fender well. I lowered mine around 1-1/2"+ and was 6 full revolutions, give or take.
 

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