Title pretty much says it all. A few weeks ago I purchased a 88 pickup and I'm considering lift options. Is there a way to tell if the torsion bars have been adjusted by the previous owner?

 

Yes. It's what's commonly called ride height. Though the FSM refers to the specification as vehicle height. Regardless of what you call it, it's why the torsion bars are adjustable. But being out of spec doesn't necessarily mean they've been adjusted. It could just as well mean that they haven't been. However, it's more than likely they have, if the vehicle height is higher than stock.

Vehicle height specs are:


See illustration here:
http://personal.utulsa.edu/~nathan-b...axle/2-4wd.pdf

What that means is A needs to be 58.5mm(2.303") higher than B. B is raised/lowered in relation to A via torsion bar adjustment.

 

Wait, so you can lift your front end with stock torsion bars?

 

Yes, roughly 1.5"

 

So I measured mine and I've only got .5". According to that, they've never been adjusted and they seem to be sagging. I did see this note which makes me think maybe the 2.303 isn't the correct measurement for my truck. It's a base model, so maybe there's a different number for mine.

HINT: For the vehicle height of non–loaded vehicles for
each model and the alignment standard values, refer to
page A–25.

 

Oh, I guess you're probably right. I'm a total idiot when it comes to these things. What-the-hell would I know about it anyways?

...good grief!

Looks like the easy way was a little more than you could handle. I guess we'll have to try the hard way then. Since you're NOT going to find the "non-loaded" vehicle height specs in the 93 FSM(not that they'd do you much good if you could). So let's take our vehicle height/chassis ground clearance specs from the 88 FSM instead. Remembering, of course, that without stock size tires installed, they aren't going to be correct. And you'll need to accomodate for any difference in the measurements that might exist because of that fact. Good luck...

 

I have always adjusted mine so there is 1/4" - 3/8" space between the upper bumpstop and the upper controlarm.

 

but how do you actually adjust the torsion bars?

 

If you have 4wd, you just tighten or loosen the adjusting bolt until your ride height meets the spec. As Mudhippy posted above, you will want 2.303" difference between the height of the driveshaft tip and the center of the adjusting cam bolt.

For a 2wd, the spec might be a little different. Not sure, as I never needed to look it up. You should consider putting the details of your truck in your signature, so we don't have to make assumptions.

It really is super easy. If it seems difficult, you aren't doing it right. If you want to be even more particular, you could make sure your fuel tank is filled up half-way. That way the ride height will be a bit low on the right with a full tank and bit high with an empty tank, but will about average out over time.

 

Just remember that when you adjust tbars that they change the wheel camber too, so alignment is necessary to keep tire contact/wear happy. Stock height on front end is right around 20" from center of axle to bottom of fender lip as another means to measure from.

 

mine is only 1.5", the suspension has been feeling very rough, like I feel the tiniest bumps, I loosened it to 2.3" and it feels smoother (it could just be my imagination;-)