Quick Question - Puma (?) ride height adjusters. Which way is up?

My IM roadster has the toothed type of ride height adjusters instlled in both front end beams and it would save me a lot of time and jacking to know ahead of time how they work.

It's fairly clear that they twist the torsion bars but wouldn't twisting both sides cause one side to rise while it's opposite side went down?

So, to make the car sit higher do I move the toothed outer pieces up on the fixed inner toothed pieces, or down?

A whole 'nuther topic is why would anyone want to adjust the top tube differently from the bottom tube? Seems like that would stress the trailing links and their ball joints unneccessarily, or am I missing something?

So....these are NOT Puma adjusters?

Is the bottom one adjusted for more height and the top for less tension and why would they differ?

I think I'm not getting how these torsion tubes work.

That looks like an Avis adjuster - same as my car. Moving the nut down lowers the car, while moving it up raises the car. That's basically the center housing that the torsion leaves are passed through. You have what amounts to a squarish bunch of flat spring steel bits that some (including me) refer to as "leaves". The adjuster rotates the leaves relative to the ground, adjusting the wheels on both sides at the same time. Since the wheels are suspended on trailing arms and the adjuster is on the front of the beam, rotating the adjuster in front up, rotates the rear of the trailing arms down, thus raising the front of the car. Rotating the adjuster on the front down obviously has the opposite affect.

Lane,

That's too simple...:D

Sheesh! I had it in my head that twisting the leaves in the middle would have opposite effect on each side but as soon as I saw you say pushes the arms down and up I realized I had been having another symptom of Alzeimer's or just old age dementia or something because your answer made it so simple that my reaction is "Of course - what was I thinking?

Thanks a whole bunch for the bonk on the head!

how the heck did you get them adjusted like that (or was it like that when you bought it)?

your suspension must be really stiff.

another tip: put the jack under your wheels to make the adjuster go up and down once it's loose.


edit: upon closer inspection - it looks like they are installed 90 degrees from each other. a good mod for a low-riding car

Ken:

Moving your adjuster stud UP makes the trailing arms go down and the car body go up and vice versa.

Both torsion bar adjusters work the same way, and are meant to be adjusted in tandem.

Having said that, some people try to think beyond the original German designers and adjust one torsion bar all the way up, and the other all the way down (yours look like that in the picture), thinking that this will cause a softer ride. I'm not a believer. All I think that accomplishes is to fatigue both bars prematurely, but what do I know?

Adjusting those adjusters is a trial-and-error process. Get them both about the same (they don't have to be precise), let it down, roll it back and forth 10 feet or so a few times (this is very important, as it settles your suspension to road height) and see where it is. Depending on the result, you may have to move both up or down a bit to get the front end height to where you want it. After a few iterations of moving one tooth at a time, you should be able to dial it in, then tighten both lock nuts and leave it.

The adjustment shown is how it was when I bought it. Henry described that those were adjusted to improve ride quality but he had not seen the above photo and they could have been reset since leaving IM.

The ride is very good this way, or was until I went over a guys self-installed and very sharp 'speedbump' where we got a taste of the "filling loosening" I've seen mentioned here several times.

The car is dead even/level but I'd like to try a little more front end height. A 1/2" or 1" at most because I've gotten some tire contact in the front wheel wells on full lock turns. The scraping is visible inside the well and I think a small increase in ride height will clear the wells.

From what you're saying I think I'll start by moving the bottom one down a notch or two and the upper up to it's midd point. Having them in tandem makes sense to me so that both bars and both sets of trailing arms work to suspend the car. There are other ways to improve the ride without disabling half of the spring force.

Setting the adjusters so the torsion bars push or pull against each other doesn't change the spring rate.

For example, if you had torsion bars that provided 100 lbs/in at the balljoints (200 lbs/in at the spindle):
Standard setup:
0 inch up -> T1 = 0 lbs down, T2 = 0 lbs down -> 0 lbs down total
1 inch up -> T1 = 100 lbs down, T2 = 100 lbs down -> 200 lbs down total = 200 lbs/in
2 inch up -> T1 = 200 lbs down, T2 = 200 lbs down -> 400 lbs down total = 200 lbs/in

Adjuster setup with top torsion adjusted up, bottom adjusted down:
0 inch up -> T1 = 200 lbs up, T2 = 200 lbs down -> 0 lbs down total
1 inch up -> T1 = 100 lbs up, T2 = 300 lbs down -> 200 lbs down total = 200 lbs/in
2 inch up -> T1 = 0 lbs up, T2 = 400 lbs down -> 400 lbs down total = 200 lbs/in
3 inch up -> T1 = 100 lbs down, T2 = 500 lbs down -> 600 lbs down total = 200 lbs/in

But by forcing the torsion bars to fight each other, the one supporting most of the load will be forced to twist more than normal, potentially fatiguing the bar.

What setting the adjusters at different positions gives you is finer control of ride height. For example, one set at 3 notches down and the other set at 4 notches down would set the ride height as though you were set at 3.5 notches down. Any more than 1 notch difference doesn't help.

Ken wrote: "The car is dead even/level but I'd like to try a little more front end height. A 1/2" or 1" at most because I've gotten some tire contact in the front wheel wells on full lock turns. The scraping is visible inside the well and I think a small increase in ride height will clear the wells. "

WHOA, THERE.....WAIT A MINUTE!!

Exactly where is the tire hitting in the wheel well? If it's not at the very top of the well (and the tire wouldn't hit there when cranked to the limit) and is rubbing 6-10 inches up from the bottom on the inside (frame side) of the well, it's NOT a ride height problem.

What'cha gotta do is adjust the steering limit stops on the frame right next to the steering box. They're not too bad to get at and are easy to adjust - loosen the lock nut, turn the bolt out about a turn and re-tighten the locknut, then road test and repeat until they don't rub any more. There are two stops, one for each side, but they're in two different places so look around and you'll find them. It's easy to screw up ride height adjustments so try adjusting the stops before you go for the Avis adjusters.

But then, Nolan took a chunk out of his wheel wells on his SAS when he hit a speed bump or something, so maybe I'm all wet, here......

gn

Justin, good info, and that's sorta' what I meant in mentioning spring rate - that the torsion bars would not carry equal or near equal amounds of the sprung weight. The bar with more tension would have the bulk of the load. It's not the spring rate but the spring loading.

Gordon, I looked high and low for a way to limit the steering but I'll have to look again at the areas close to the steering box to see if some mechanism is incorporated. Thanks, much.
The left wheel/tire scraped off the undercoating at about 11:00 on the wheel so I thought raising it might just clear. The car has molded-in cutouts on both sides for full lock rear clearance and I'm just hitting at the top of the leftside cutout. Mostly it's a noise that nobody would like but doesn't seem to damage the tire or the car.