Torsion Bar Suspension Droop

knipper_03 · December 18, 2009

There's ton of questions on torsion key level kits. My old 2000 truck I had enough thread to jack up the front end maybe 1.5 inches.

My question is now that I have since replaced that truck are there any kits on the market that replace the droop stop on the UCA?

I understand that in highly abused cases you MIGHT wear out CV joints and ball joint which in my opinion are simple maintenance issues.

These leveling kits have addressed shock length issues yet I have yet to see any kit that is trying to get the same amount of factory droop.

My understanding is basically you have so many inches of overall suspension travel...by jacking up the torsions (thread or key) you are just off centering your static ride height. Im thinking that by replacing the upper control droop stop that I can achieve stock riding results without sacrificing any wear and tear other than maybe ball joints, tie rod ends, and what not not lasting 150,000 miles but only 100,000 miles for instance.

Also I dont see how cranking or reindexing a torsion bar actually stresses the bar itself. The front end weighs the same either way. I dont think cranking or reindexing a torsion key adds anymore stress its just changing ride height. (Although I'm not sure if the compression bump stop is actually taking some load off at its stock static ride height) Maybe the actual extra stress is caused by the extra 1-2 inches of up travel in the suspension? For instance instead of twisting the torsion bar the same number of degrees in both directions (compressed suspension vs drooped suspension) cranking or reindexing allows lower degrees on the droop and the extra degrees of rotation in the compression side of the suspension basically "over rotating" the torsion bar.

So whats the maximum "rotation deflection?" from a torsion spring and are these trucks even coming close to what a torsion can rotate before it can't return to center based off of exceeding the elasticity of the steel in the spring itself.

Are my observations correct? Just seems that there are a lot of misconceptions and myth with what is really being affected and would like to clear those up. Thx for the input.

Matt_ · December 18, 2009

a lot of what you said is right on track. the stress in the components (balljoints & such) is from the angles. the added stress to the torsion bars is due to exceeding the rotation they're desiged to see.... hence why a lot of people have sagging issues a few years after cranking their bars, it makes them wear quicker (all springs wear)

if you want increased down travel... cut your droop stops. how long will parts last??? lets just say this isnt a new question and theres a reason that a lot of smart people havent tried increasing travel before you.

in the grand scheme of things, the $1500 for a good suspension lift pays itself off really quick.

knipper_03 · December 18, 2009

a lot of what you said is right on track. the stress in the components (balljoints & such) is from the angles. the added stress to the torsion bars is due to exceeding the rotation they're desiged to see.... hence why a lot of people have sagging issues a few years after cranking their bars, it makes them wear quicker (all springs wear)

if you want increased down travel... cut your droop stops. how long will parts last??? lets just say this isnt a new question and theres a reason that a lot of smart people havent tried increasing travel before you.

in the grand scheme of things, the $1500 for a good suspension lift pays itself off really quick.

good point. I signed up for all data diy. it gives the max trim specs I'll post once I get through the info.

knipper_03 · December 18, 2009

a lot of what you said is right on track. the stress in the components (balljoints & such) is from the angles. the added stress to the torsion bars is due to exceeding the rotation they're desiged to see.... hence why a lot of people have sagging issues a few years after cranking their bars, it makes them wear quicker (all springs wear)

if you want increased down travel... cut your droop stops. how long will parts last??? lets just say this isnt a new question and theres a reason that a lot of smart people havent tried increasing travel before you.

in the grand scheme of things, the $1500 for a good suspension lift pays itself off really quick.

good point. I signed up for all data diy. it gives the max trim specs I'll post once I get through the info.

Trim Height Inspection Procedure

Trim Height Measurements

Trim height is a predetermined measurement relating to vehicle ride height. Incorrect trim heights can cause bottoming out over bumps, damage to the suspension components and symptoms similar to wheel alignment problems. Check the trim heights when diagnosing suspension concerns and before checking the wheel alignment.

Perform the following before measuring the trim heights:

1. Make sure the vehicle is on a level surface, such as a alignment rack.

2. Remove the alignment rack floating pins.

3. Set the tire pressures to the pressure shown on the certification label.

4. Check the fuel level. Add additional weight if necessary to simulate a full tank.

5. Make sure the rear compartment is empty except for the spare tire.

6. Close the doors and hood.

Z Height Measurement

Important: K models only the Z height must be adjusted before the alignment.

The Z height dimension measurement determines the proper ride height for the front end of the vehicle. Vehicles equipped with torsion bars use a adjusting arm in order to adjust the Z height dimension. Vehicles without torsion bars have no adjustment and could require replacement of suspension components.

1. Place hand on the front bumper and jounce the front of the vehicle. Make sure that there is at least 38 mm (1.5 inch) of movement while jouncing. Important: All dimensions are measured vertical to the ground. Cross vehicle Z heights should be within 12 mm (0.47 inch) to be considered correct.

2. Allow the vehicle to settle into position.

3. Measure from the pivot bolt center line (2) down to the lower corner (5) of the steering knuckle (1) in order to obtain the Z height measurement (4).

4. Repeat the jouncing operation 2 more times for a total of 3 times.

5. Use the highest and the lowest measurements to calculate the average height.

6. The true Z height dimension number is the average of the highest and the lowest measurements. Refer to Trim Height Specifications.

1. For vehicles equipped with a torsion bar suspension turn the bolt (1) that contacts the torsion arm clockwise to raise the and counterclockwise to lower the height adjustment. One revolution of the bolt (1) into the nut increases the Z height by approximately 6.0 mm (0.2 inch) .

2. For vehicles without torsion bars, replace damaged or worn components as necessary.

knipper_03 · December 18, 2009

z height chart

1. For vehicles equipped with a torsion bar suspension turn the bolt (1) that contacts the torsion arm clockwise to raise the and counterclockwise to lower the height adjustment. One revolution of the bolt (1) into the nut increases the Z height by approximately 6.0 mm (0.2 inch) .

2. For vehicles without torsion bars, replace damaged or worn components as necessary.

zaac · December 19, 2009

in the grand scheme of things, the $1500 for a good suspension lift pays itself off really quick.

skier, can I quiz you on this comment? How is buying an aftermarket key any better than cranking up the original key for 1-2" extra lift? Either way the end result is the torsion bar is twisted more to raise the truck. Am I correct assuming this?

When you say a good suspension kit do you mean one with longer control arms or more ball joint movement range or higher rate torsion bars? Really trying to learn this as I could use some more clearance to get through snow but don't want to be replacing parts every year. I've got the bicycle tires on it (235's) but the front diff is pushing snow. Thanks in advance.

Matt_ · December 19, 2009

in the grand scheme of things, the $1500 for a good suspension lift pays itself off really quick.

skier, can I quiz you on this comment? How is buying an aftermarket key any better than cranking up the original key for 1-2" extra lift? Either way the end result is the torsion bar is twisted more to raise the truck. Am I correct assuming this?

When you say a good suspension kit do you mean one with longer control arms or more ball joint movement range or higher rate torsion bars? Really trying to learn this as I could use some more clearance to get through snow but don't want to be replacing parts every year. I've got the bicycle tires on it (235's) but the front diff is pushing snow. Thanks in advance.

Buying aftermarket keys is NO different than cranking the original torsion bar keys.

When i say a "good suspension kit", im talking about a real suspension lift that drops the lower control arm, diff, etc to maintain factory suspension geometry... NOT a POS kit that just has a longer upper control arm.

There are quite a few affordable 3-4" lift kits for your truck.

Rough country makes a quality 4" suspension kit that will outperform ANY "wannabe" leveling kit/lift... and its only $1000

There are a few other nice 3-4" kits on the market for your truck (superlift, rancho, skyjacker, trailmaser, tuff country).. but for $1000 which includes 4 shocks, this is a hard kit to pass up IMO. You'll spend $1000 in one front end rebuilt after driving around with your torsion bars cranked for a few years

zaac · December 19, 2009

Ok, I see what you mean. I guess I'll continue shoveling snow out from under my truck as the good kits that prevent premature wear will do me no good as it's the low front diff that causes problems. Seems retarded to lift a truck and still get stuck all the time. I guess it would allow taller tires but even at that a 3" taller tire will only give 1.5" more clearance. Also the taller tires all seem to be wider which ain't the best in snow.

If your gonna go through all the trouble of dropping down the front diff why not just go with a body lift? What's the benefit?

Matt_ · December 19, 2009

.... Seems retarded to lift a truck and still get stuck all the time....
If your gonna go through all the trouble of dropping down the front diff why not just go with a body lift? What's the benefit?

Using that logic, you also think its useless to put a suspension lift on a SFA (solid front axle) truck???

A suspension lift gets the frame higher off the ground which prevents getting high-centered... which helps a lot offroad but may not be that much more helpful in snow. How deep is the snow you're driving through?

zaac · December 19, 2009

Using that logic, you also think its useless to put a suspension lift on a SFA (solid front axle) truck???

A suspension lift gets the frame higher off the ground which prevents getting high-centered... which helps a lot offroad but may not be that much more helpful in snow. How deep is the snow you're driving through?

For me, putting a suspension lift on a SFA would be pretty much useless. Not interested in how it looks, just want to do my job which involves going through lots of snow.

Lifting the frame would help some I think as I've dug out a few times with snow packed up to the fuel tank and spare tire.

If the snow gets up to 12" the front diff starts pushing pretty good. I have to stay on the trails and some are getting worn fairly deep and the wind blows the snow in them. 12" of snow plus trail worn in another 3" and it gets to be tough going. Then I made the dumb mistake of putting in a trutrac after the G80 wore out and now I'm in 4x4 more than ever. I'm not much better than the Fords out there.

Reason why I've been considering this is because when I load the box with 1500lbs the frame is sitting on the rear diff. Not sure if that will hurt anything. Wanted to add a leaf but what I have read it raises height 2". Wanted to lift front to match and as a plus have more front diff clearance. But now it's not sounding like such a good idea.