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Technical Lowering with torsion bars

Discussion in 'The Hokey Ass Message Board' started by 392_33, Apr 15, 2014.

  1. A Boner
    Joined: Dec 25, 2004
    Posts: 7,444

    A Boner
    Member

    If you crank it down, count the number of turns.....if you don't like it, crank it back up the same number of turns.....no alignment needed. If you like it lowered, you can either watch for tire wear, or have it aligned right away.....depending on your tires, the better they are the more you might want an alignment. Drove a 57 Plymouth for over a year without an alignment......the tires were sort of old though.

    After I lowered the Plymouth it rode like a Caddilac.....cut the coil springs to lower a Chevy, it rode like a truck! Torsion bars are great!
     
    Last edited: Apr 26, 2014
  2. 327Eric
    Joined: May 9, 2008
    Posts: 2,125

    327Eric
    Member

    I know the toe changes when you lower it. My 69 Imperial had no issues whatsoever, my 71 Newport wore the tires real quick till my buddy realigned it for me.
     
  3. 68vette
    Joined: Jul 28, 2009
    Posts: 306

    68vette

    I would say camber for sure...it has to. When it wears the edges of the tires you will know...of course...then its too late to align and save the tire.

    When you cut a coil spring....you have to have enough sense to know that less than one coil is probably max...or it will ride rough as it changes the rate unless the spring is way to soft for the application....in that case, coil springs are cheap and usually there are many spring rates to choose from...not like a torsion bar....when I had the gibbons junk torsion bar in my f100, there was only ONE torsion bar for a choice...again...if you check...there is only ONE setting that provides the correct suspension for that particular car and weight.
     
  4. Ned Ludd
    Joined: May 15, 2009
    Posts: 5,051

    Ned Ludd
    Member

    Definitely camber. A-arm front ends have been set up to recover camber from very early on. The idea is that the front end should gain positive camber with roll, but less than the roll angle. Consequently it gains negative camber with bounce/pitch, in both directions, up and down. Lowering the front end duplicates the bounce/pitch condition (geometrically but not elastically), so it makes the front end go to negative camber unless it's adjusted back to stock (or what you want).

    In my student days I had a BMW 2002 which I lowered in front by having one coil cut out of each front spring. This increased the spring rate (by a bit over 10% IIRC) but didn't really affect the ride, due to the forward weight bias. It did increase front roll stiffness, though, which decreased understeer, despite greater loading on the outside front tyre, because it decreased roll overall and, hence, decreased front camber gain. I ended up with a damned-near neutral-handling car. I'm not claiming that I knew that this would be the result; I did it because the car would look better with the front a bit lower, and it did. But the dynamics did work out better than stock, and it's possible to understand why.

    I relate this because there isn't only one combination of spring rate, ride height, weight distribution, etc. that can work with any given car. Not only does it depend on what you're trying to achieve, there is also more than one way to skin a cat.

    I said before that torsion bars have a constant spring rate, no matter what height they're set up at. You can raise the front end of a torsion-bar-sprung car by rolling the front wheels up onto bricks. The effect on the torsion bars would be the same, whether that extra 3" is under the wheel, between the A-arm and the spindle, or (proportionally) between the torsion bar rear adjuster and the frame. The torsion bar sees the three conditions identically. What you are effectively doing is adding or removing spacers, and that does not affect spring rate. And note that this is the true no matter whether the torsion bars are longitudinal or transverse.

    The angle of the A-arm when seen from the front does have a small influence. To illustrate how small, suppose the arm is 12" long, measured perpendicularly to its pivot axis, and is horizontal at stock ride height. Suppose we want to lower the front end 3". The effective lever arm length goes from 12" to 11.62", a reduction of around 3% for a huge drop: not enough to feel in your butt.

    So, the spring rate of a torsion bar front end stays constant over a certain range, as long as the suspension is clear of the bump stops. How wide that range is depends on how much space there is for travel before you hit the bump stops.

    Of course it could be that the bump stops aren't what is acting as bump stops. You can raise the bump stops by a foot, but this would mean that the bump stops become mere ornaments because the suspension bottoms on the dampers' upper limit of travel. You are effectively using the dampers as bump stops, which is worse than riding just clear of the bump stops, because at least rubber bump stops have a (sharply rising) spring rate and a small degree of internal damping. Dampers aren't designed to do that so, not only do you have rigid suspension after half an inch of travel, you also have no damping because you ruined the dampers after two blocks' driving.

    Get bump stop positions and damper configurations right, and torsion bars can act consistently over a huge range of ride-height adjustment.
     
    Kodak Jack likes this.
  5. 392_33
    Joined: Nov 30, 2010
    Posts: 175

    392_33
    Member

    Ned, I highly appreciate your input but it's way over my head. I'm just going to turn it down 2" and then back to reload the springs. It will be according to CEE aka close enough engineering. I will post some picks and a report once it's done.


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  6. Ned Ludd
    Joined: May 15, 2009
    Posts: 5,051

    Ned Ludd
    Member

    Just make sure you've got space under your bump stops, and you're good.
     
    Kodak Jack likes this.
  7. I had someone come in for tires and an alignment years back, a '65 Chrysler and it was jacked up ridiculously. SOP was to first correct the ride height to factory specs. Then align it. We would mark on the receipt "corrected ride height" in those cases.

    Sure enough, the car comes back in within a couple of months, new tires wiped out. The owner went under the car and cranked up on the torsion bars again. He wasn't happy when we told him we wouldn't honor the tire warranty... but the manager did offer a free alignment.

    Bob

    Bob
     
  8. 392_33
    Joined: Nov 30, 2010
    Posts: 175

    392_33
    Member

    Thanks Ned


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  9. flathead4dr
    Joined: Nov 15, 2010
    Posts: 15

    flathead4dr
    Member

    I recently acquired a '55 Ford pickup that had been modified with a Volare front clip assy. It's been a real trying experience for the last couple of months. The thing "wallered" and wandered, dipped and dove all over both lanes. It pulled hard to the right, and wouldn't return to center after a right turn. Went to the alignment shop and found out there was negative camber and no caster on the right side, with no adjustment left to correct. After studying the whole mess, I ended up taking the adjustment slide plates loose far enough to add two washers underneath the plate, just on the front side. This immediately looked better, at least to the eye. A test drive showed a marked difference and actually felt like a real vehicle now. I will put new heavy duty shocks on next and then take it in for another alignment check. Great Relief !
    Bill
     
  10. tattoos by brandon
    Joined: Jun 28, 2011
    Posts: 541

    tattoos by brandon
    Member
    from salem ohio

    I have a 59 Chrysler and went all almost 3 inch of drop to match the rear until I had it bagged ... rode fine and no problems

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  11. greybeard360
    Joined: Feb 28, 2008
    Posts: 2,079

    greybeard360
    Member

    You can buy some upper control arm bushings that are made to allow for more caster/camber adjustment if needed. Before you start lowering it and counting turns, look close at the adjuster bolts.... the threads. I have found there are some fine thread and some are coarse thread. Not sure if it is a year of car difference or not but I have seen 2 Mopars that had one of each in them. If they have the same thread pitch, start counting!
     
    loudbang likes this.
  12. okiedokie
    Joined: Jul 5, 2005
    Posts: 4,785

    okiedokie
    Member
    from Ok

    Fatman dropped spindles on my Volare front suspension in my 53 F100. Work great.
     
  13. on almost any raising or lowering will effect the camber , toe and caster any suspension that bottoms out will not handle so any part that hits will cause problems control arms hitting snubbers, shocks too long or to short, and a torsion bar is just a spring, like a coil or a leaf i have turned torsion bars down in dia to soften the ride.and playing with the adjustment screws up and down at will even if you count the turns will get you close but it won't get it right on spec.
     
  14. unclescooby
    Joined: Jul 5, 2004
    Posts: 4,993

    unclescooby
    Member
    from indy

    Helpful post! I want to lower this over the weekend. My question though is "does anyone have a good swap for front disc brakes on these mopars?"
     

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  15. chopolds
    Joined: Oct 22, 2001
    Posts: 6,214

    chopolds
    Member
    from howell, nj
    1. Kustom Painters

    I used Fifth Ave, from the late 80's, spindles, on my 61 Dodge. Bolts right in.
     
    unclescooby likes this.
  16. garyf
    Joined: Aug 11, 2006
    Posts: 288

    garyf
    Member

    Cordoba is unibody (no frame). I wonder why, now gm and other makes are using torsion bar suspension?
     
  17. unclescooby
    Joined: Jul 5, 2004
    Posts: 4,993

    unclescooby
    Member
    from indy

    Thank you!
     
  18. scrappybunch
    Joined: Nov 16, 2011
    Posts: 415

    scrappybunch
    Member
    from nj

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