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Thread: Resplining torsion bars

  1. #1
    Van Addict boogieman's Avatar
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    Resplining torsion bars

    is it possible to respline the front torsion bars to lift or lower the van instead of just cranking the adjusters?

  2. #2
    Van Addict boogieman's Avatar
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    Re: Resplining torsion bars

    this would be a much better way to keep a decent ride quality..no one has tried this?

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    Re: Resplining torsion bars

    Gosh that seems like a good question. I don’t know enough to answer that one but hopefully someone who does can see this and chime in!
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    Re: Resplining torsion bars

    Are you refering to pulling tbe torsion bar and rotating it one or two slines?

  5. #5
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    Re: Resplining torsion bars

    right, so ride height is changed with out preloading the spring anymore...my 4runner kybs might be partly to blame but id like the front end to feel less harsh...

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    Re: Resplining torsion bars

    Most splines are designed to avoid that, a steering column spline has one wider tooth, so the steering wheel always lands in the same position related to the shaft, I would think it would be the same thing on torsion bar so it is impossible to mount the arms at a different angle at each end of the bar, but that is pure speculation. I didn't get into the torsion bar yet so when i do i'll check. I sure hope I'm wrong as it would be a great way of lifting without loosing ride comfort .
    Somehow, something tells me that, if possible, one of the clever people on here would have found out already.....
    LG.
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    Re: Resplining torsion bars

    Quote Originally Posted by Carbonized View Post
    Somehow, something tells me that, if possible, one of the clever people on here would have found out already.....
    thats what im saying! trying to save myself some grief as i havnt messed with the torsion bars on these either...did a ton on old 911s tho...german shyte

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    Re: Resplining torsion bars

    Resplining, re-indexing, or re-clocking the torsion bar would have no effect. To get lift from a torsion bar you must apply more torsional pressure or twist are use a bar with a higher spring rate. On old air cooled Volkswagens and other similar vehicles(like Porsches)you would pull the torsion bar and re-index to cause the trailing arm to sit higher or lower than normal depending on whether you wanted to lift or lower the vehicle. When you set the vehicle back on the ground the static or resting position of the trailing arms would be changed within it's range of motion, either higher or lower. You have not changed the range of motion in any way , mearly the starting point within that range. When you turn the adjuster nuts on the van(or bolts on old Chrysler products) you are changing the control arms static position in its range of motion. What makes the van ride rough in this new position is a lack of suspension down travel. Typically when the torsion bars are cranked the upper control is at or near it's travel limiter(bump stop). This means the suspension will cycle up into the wheel well like when you hit a dip in the road but the rebound back up is abruptly cut short when you hit the bump stop. At stock ride height the suspension is more centered in it's range of motion at rest so it has more equal up and down travel. The only other way to achieve lift without altering torsion bar settings would be to raise or lower the steering knuckle either with ball joint spacers(upper control arms mut be modified like this),raised spindles(not available), or a full suspension lift.

  9. #9
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    Re: Resplining torsion bars

    right, i dont want more range of motion, i realize there are upper and lower limits in the front of our vans, i want more ground clearance and maybe room for a bigger tire, both of which are achieved by a higher resting point. but i want the spring to not be all wound up stiff...for me big woops are not bad, its the small cracks in the road and washboard that shake my fillings....again my shock i think are too stiff too

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    Re: Resplining torsion bars

    ...but i think i get what youre saying and maybe it doesnt really matter, the spring at rest will still be the same...i guess maybe time to delete this thread....

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    Re: Resplining torsion bars

    When I initially lifted mine I had the torsion bars wound so tight that when I lowered the jack the weight of the van didn't compress the suspension at all. I went a couple days like that and then backed them off some. Maybe you could try your old shocks to see if the harshness improves or try no shocks. If it's not shock related then like I said before, the only options would be ball joint spacers or fabricate a full lift.

  12. #12
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    Re: Resplining torsion bars

    right, unless one is cranked up on the stop its still the static weight of the van on the spring...i guess if you were out of adjustment on the screw then it might make sense to respline but not otherwise...thought i was onto something....a couple too many beers i suspect

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    Re: Resplining torsion bars

    Wouldn't re-clocking the torsion bar at least reset the spring rate? In effect making it progressively stiffer as the arm approach the bump stop, hitting it at a lower rate of speed, lowering the force of impact. By the way on the 4WD the full suspension travel is only 4". Not much if you ask me. If I could lift and at least keep the static torsion bar adjustment at "neutral" that would be great! I don't know, in my mind, if the spring (bar) is already full stiff and only has .5 inch to go, (or less), it's going to hit a lot harder than progressively gaining stiffness over a greater distance. Right?
    LG.
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    Re: Resplining torsion bars

    After more thought on this I think I may be incorrect. Carbonized's last statement made me rethink this all. If you re-clocked the bars than the static or resting position would be altered up or down as desired without the need to crank up the bar for lift. You would still be maxed out or close to it at the UCA bump stops but you wouldn't have the torsion bar wound so tight. Perhaps Boogieman, you had just enough beers and I should have had a few. The question now would be if there is an indexing spline on the torsion bars which would require cutting the sleeve off the adjuster arm rotating it slightly and rewarding. I think the 4runner torsion bar swap thread has some pics of the bars and associated hardware.
    Maybe you are on to something after all.

  15. #15
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    Re: Resplining torsion bars

    it is a bit of a brain teaser but I started to think, whats the difference between a spline and lets say 4 turns of the adjuster? assuming this is all done with the van unweighted, when it is set down the spring is under the same load all be it a different position...now, is there a difference in the geometry of the a arm acting on it? prolly not....ive been too busy grinding and welding up my trick new bumper...and now is beer thirty

  16. #16
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    Re: Resplining torsion bars

    Looking at the 89 repair manual, page FA-97 to FA-101, it became clear that:

    _ there is no indexing in nether splines of the torsion bar so it is possible to "re-clock" it at ether end. No cutting, no welding needed.
    _ One reason to do it would be if your 30 years old bar has softened and/or twisted so much that you are running out of threaded rod adjustment.
    _ the other reason would be, of course, to get more lift but you are running into a plethora of issues:

    1) Since you have already forced the suspension close to full droop, any additional cranking might bring it hard on the droop bump stops allowing the shock internals to do the job instead: NOT GOOD!
    2) Ball joints maxed out.
    3) Drive shafts sliding splines over-extended.
    4) Same with the steering link.
    5) Alignment Problems.

    _ Ride quality is, by design, directly related to ride height, witch brings me back (after re-reading it) to Original's post #8
    LG.
    "perfection is achieved, not when there is nothing more to add, but when there is nothing left to take away." A. de St Exupery.

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