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Thread: Torsion bar reaction lever adjustment

  1. #1 Torsion bar reaction lever adjustment 
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    Apologies if this has been covered on the forum before, but I've tried searching and can't find the specific info I need.

    I'm trying to increase front ride height using the adjusting bolt in the torsion bar reaction lever, which is currently screwed fully 'in' i.e. suspension as low as possible for the current spline positioning. I want to try this before resorting to turning by a spline (which seems like a bigger job), to see what effect it has.

    I jacked and axle-standed the front so that suspension is at full droop, but the bolt head still seems to be under some compression against the chassis plate against which it bears - presumably as there's still some torsion applying through the torsion bar. As there's very limited room to get a spanner on the bolt head, I can't turn the bolt, even with the adjusting nut backed right off.

    Am I right in thinking that it's as simple as needing to remove the damper so the suspension droops even further? After all, thinking of the process in reverse, when a kit is built then you'd adjust the ride height first via the torsion bar setting, and then bolt up the damper - is this correct?

    Cheers,

    Gerry
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  2. #2 Re: Torsion bar reaction lever adjustment 
    club member Club Member jon_cox's Avatar
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    Hi Gerry
    First of all make sure you have completely removed the clamp bolt. This will allow the adjuster to actually move.
    For every 4mm of movement at adjuster bolt you will get a 10mm ride height change.
    For every full spline adjustment you will see 40mm ride height change.
    The reaction lever can be simply pulled forward (toward the front of the car) off the splines then rotated and refitted. Removing the damper is also a must for this job.

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  3. #3 Re: Torsion bar reaction lever adjustment 
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    That's great thanks Jon, much appreciated. How does the clamp bolt work then, presumably there must be a slotted hole in the chassis so that it can be retightened in a different position (sorry not with my car now so can't check for myself but would be useful to know in advance of my next visit my garage)
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  4. #4 Re: Torsion bar reaction lever adjustment 
    club member Club Member listerjp2's Avatar
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    I don't know if this will help?

    202109281528_00.jpg
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  5. #5 Re: Torsion bar reaction lever adjustment 
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  6. #6 Re: Torsion bar reaction lever adjustment 
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    Thanks, that's very helpful.

    Gerry
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  7. #7 Re: Torsion bar reaction lever adjustment 
    club member Club Member stevejgreen's Avatar
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    It’s not a difficult job.
    Take your time, as always.
    Try to take as much load off the torsion bars as possible, they don’t move much but there is a lot of torque in them.
    Possibly worth a total refurb of front sipuspension with nice stiff superflex bushes for the tie bar and lower eyebolt.
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  8. #8 Re: Torsion bar reaction lever adjustment 
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    A quick update as I got the job done last Sunday. Jack up under the chassis and after removing the damper bottom bolt and reaction arm clamp bolt it was pretty easy to turn the reaction arm adjustment bolt. The adjustment bolts on both sides were screwed almost totally in i.e. lowest ride height and I was aiming to raise quite a bit without going over the top for a first try (the aim is to convert to a trials car so I'm just experimenting for now and will make some more scientific decisions about ride height further down the line).

    Anyhow, I measured the length of the reaction arm from torsion bar pivot to the centre of the adjustment bolt head, then measured the length of the lower suspension arm from its inner pivot to the centre of the front tyre tread - can't recall the exact measurements but the latter was around 3 1/2 times the former, so basic geometry suggests that any upward movement of the reaction arm will be translated into around 3 1/2 times that amount of ride height increase...

    So I screwed the reaction arm adjustment bolts just over half way through their sensible range of adjustment, which equated to around 20mm of thread showing between the bolt head and the reaction lever, making sure I raised each side equally. And the resulting increase in ride height? - just a shade under 70mm on each side....!

    So the 3 1/2 : 1 ratio checked out - although the reaction lever is moving in an arc and angular movement doesn't translate perfectly into linear, so won't necessarily hold over the full range of travel - but a good rule of thumb.
    Last edited by gerryrichards; 07-10-2021 at 09:59 PM.
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