torsion bar adjustment - firmer when higher?

[Ozwiz]

Hi all,

I recently compared the ride comfort of my 1993 SSR-X with one of my mates and discovered that my suspension is significantly firmer than his, especially the front. Whilst he's still got the whole factory suspension set-up I did a couple of mods including 2in suspension left at the back, new polyurethane LC bushes at the front new ARB OME shocks and I suspect the previous owner jacked-up the front by adjusting the torsion bars by ~1-2in.

My question: Do the torsion bars get firmer when adjusted to higher ride height or is it normally just the same?

[NiftyNev]

They can't get firmer. You are just rotating them.

Nev

[Paul G]

Dont Pollybushes firm up the ride to a degree?

[NiftyNev]

Dont Pollybushes firm up the ride to a degree?

A little but if the shocks have been changed that would make a difference.

Nev

[wishbone]

The upper wishbone is probably sitting on the bumpstop, causing a crap ride.

Rob.

[Ozwiz]

I heard that the poly-bushes make the ride rougher - but I wanted to be cheap and could not get hold of aftermarket rubber bushes... I don't think the bump stop is the problem. It stays clear of the wishbone and I don't have much problems with suspension noise when going over bumps. I guess Nev is right, might be the shocks. They give me good handling when going fast on dirtroads. They're just slightly too firm when in the city. Good to know I can leave the torsion bars as is! Will get used to the firmer ride! Thanks for the feedback!

[an1mal_69]

I'd argue the bar does 'firm' up when you raise the vehicle this way..you're effectively increasing the preload of the spring (to lift the truck) which ultimately alters the characteristic of the spring. Its not really a case of firmer, or stiffer tho because the spring/bar is rated at what it is. Just feels stiffer because you've shifted the springs working range higher.

[wishbone]

I'd argue that altering the t-bars is like fitting a spacer...

Main reason for crap ride after raising is top wishbone sitting on bumpstops. (cut down bumpstops or fit bj spacers),

Other explanation is the wishbones are more vertical than before, therefore putting more 'jolt' into the frame.

Rob.

[Ozwiz]

Thanks, guys! So adjusting the torsion bars means twisting them? (sorry my ignorance) Is that what increases the preload when you raise the vehicle? I would understand that this would change the ride if the spring constant of the bars is not linear in the amount of twist (basically the amplitude) you put on them. Is that the case?

About the upper bump stops. I removed them completely to see if they cause the rough ride. Seams to be slightly better but no magic yet. In any case I'll cut them in half just to be sure. Is there any danger in driving w/o bump stops. Would it put too much stress on the CV joints because of the longer wheel travel?

[Ozwiz]

Ah, sorry, bullshit! I meant the firmness would change if the spring constant is not a constant but changes with the amount of twist... never mind!

The bump stops are cut in half and put back - no major change.

While poking around under the car I found that the exhaust down tube (hope that's what it's called) was not firmly attached to the bell housing anymore. Fixed it up. Ride's still firm but a lot quieter!

Thanks for the feedback!

[wishbone]

How much space you got between the upper wishbone and the bumpstop ?