How to tell if torsion bars are worn out?

My front end keeps sagging. I can set ride height take it for a spin come back front end settles an inch. The car is a 64 belvedere with a BB alum heads and crossram. The front end was rebuilt 15 years ago bars are original 318 bars. the rear has super stock springs (15 years old) and rear is also sagging more than before. The car sits a lot. I have only been to the track once in 5 years and maybe 100 street miles.

Do you have any travel left on the adjusters? You can just keep screwing the adjusters in and eventually the car will stay at ride height.

If you don't have any adjustment range left then you need thicker bars. For that engine you should step up to BB or Hemi bars unless you have the car setup for maximum weight transfer.

I have some adjustment left. I will try and see if it will settle down before I run out of adjustment. This is a strip/street car more strip then street. If I run out of adjustment what diameter bar are guys running car weighs 3700Lb

3700 lbs.? for a 64 , I don't think so. I used 6 cylinder bars in my 64 BB car, no sagging. But anyway, do a inspection on the bushings, if all good,crank up the bolts some more .

A coil spring will lose free length when it goes away. I would think a torsion bar would also not come back to it's original state. Been awhile since I've fooled with them, don't recall if the hexes are perfectly aligned when new and I don't have any laying around, but I would compare the alignment of the hexes with the alignment of a known good or new bar.

If you keep tightening and it keeps dropping, my guess would be that they are toast.

I had a 65 Coronet that kept sagging, found the anchor welds had cracked in the cross member. This allowed them to rotate, dropping the front end.

Yes it is with me in it we weigh 3680. Car alone is 3455. I will have to start looking closer at mounts and bushings. Just wasn't sure if it was common for bars to wear out. Thanks Mike

Bars don't really wear out, they are either springs or they are not. If they haven't been damaged then they should still have the same spring that they did when new.

If the bars have been overloaded at some point and twisted then that is a different story. You could have something else that is moving around or some other sort of issue.

The SB bars are too small to control a BB car for normal street driving but they'll work okay for drag racing. For street driving you should use the BB or the Hemi bars. I have the 0.960 bars in my '65 Coronet and they work nice on the street with a high quality shock. It just all depends what you are trying to do with the car.

Living where you live I would measure the bars thicknesses in several places to see if they have corroded and lost diameter It will only hold the most load it can at its narrowest point, I think
I would tighten them up and see if it continues to sag, if so replace them

I had /6 bars in my 64 for over 15 years, not sure how long before that since it was a race car forever, sat outside most of the time. Race only but it never settled. I'm thinking what poboy said, something broke, never seen a bar keep twisting.

Mine continue to settle. 6 cylinder, dedicated drag car. Last car did it as well.
Doug

Mine have been in a 3800 lb car for 20 years, no settling at all. 28" front tires.

The car came from South Dakota so rust isn't a problem. I had bars out 15 years ago could I have screwed up putting them back in? The car is strip/street car but more concerned with strip. Some say they settle. How often do you have to readjust them?

You need to follow the FSM install procedure. L bar on the left side, R on the right side. Front suspension should not be torqued in place while hanging off a lift. The front suspension needs to be at ride height before it is torqued down. If the front suspension is installed correctly and torqued at ride height then the car should not settle.

If you lift the car in the air so the tires are hanging and then drop it on the ground the car will settle since the bushings have been twisted out of shape. Usually you can settle the car by bouncing it a few times.

The torsion bars should not settle. They are just springs. Force equals deflection and all that. The spring rate doesn't change over time, the only thing that moves with time is the rubber bushings in the control arms.

My guess is that your front suspension was torqued with the arms hanging down and now everything is just trying to get back home. Loosen up the lower control arm pivots with the car at ride height and then re-torque them.

Thanks Andy I will try re-torque arms and make sure adjusters and mounts look ok. Thanks

Also you can not adjust the front end and then measure with out moving the car so that it settles. usually you need to move it about 10 ft. unless you have plates to put the front end on then you can adjust to the height then it will stay there.

I jack car up let front hang turn adjuster set car down then bounce front end before I check my height.

still have to roll it to make it settle. what is happening is when you raise it up the tires come in and there for it has to be rolled to make it settle. there is too much friction on the tire for it to spread out on the ground with out rolling it.

you still have to roll it to get it to settle down. what is happening is when you raise the front end up the tires come in and when you let it down they cant slip on the ground to spread out so you have to roll it to get it to settle. that's why slip plates work.

I disconnect the shocks. With .812 bars, I can almost bounce the front wheels off the ground. I also roll it back 5-6ft and roll it forward to a mark on the floor.