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PostPosted: Sun Dec 16, 2007 6:26 pm 
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Probably 2 or 3 inches.

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PostPosted: Sun Dec 16, 2007 8:58 pm 
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sorry if I am being a little dense but I don't understand why that reindexing would change the spring rate of the torsion bar. spring rate should be determined by how much the torsion bar will twist. Unfortunately when we lower our trucks we do not have leave much upward suspension travel left to twist the bar.

I think reindexing or adjusting the torsion bolt only changes ride height and the amount or suspension travel you have.

Since the weight of the truck and the torsion bar are not changing the spring rate should be the same. I think.... Were is that mechanical engineering suspension expert when you need one..

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PostPosted: Sun Dec 16, 2007 10:15 pm 
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I know what you mean. My son and I talked this out for a long time.

When I think it all out in my head, it seems all I did was re index the rear adjusting end. Instead of it being up at the floor of the cab and at the end of the threads on the bolt, it is about mid way now.

Because "X" amount of twist on the bar will lift "Y" amount of weight to "Z" highth. It shouldn't matter how it is indexed, this much twist will lift this much weight this high. :? But it seems to ride better now. :? :o

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PostPosted: Mon Dec 17, 2007 12:01 am 
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gs11x wrote:
sorry if I am being a little dense but I don't understand why that reindexing would change the spring rate of the torsion bar. spring rate should be determined by how much the torsion bar will twist. Unfortunately when we lower our trucks we do not have leave much upward suspension travel left to twist the bar.

I think reindexing or adjusting the torsion bolt only changes ride height and the amount or suspension travel you have.

Since the weight of the truck and the torsion bar are not changing the spring rate should be the same. I think.... Were is that mechanical engineering suspension expert when you need one..


Think of it as similar to a valvespring. To get more spring pressure you shim it, same with the torsion bar. Raising or lowering the bar increases or decreases the spring rate/tension.

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PostPosted: Mon Dec 17, 2007 1:03 am 
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I need to do some more research.

F=kX force formula for springs

F=force
k=spring constant
x=distance

With adjusting or indexing torsion bars you are only changing the position of the torsion bars between the frame and the lower control arm. You are not putting in or taking out twist.

The torsion bar is only resisting the weight of the vehicle. The weight of the vehicle does not change.

The valve spring increases in force because you are pre-compressing it using the shim(increasing x in the formula). But the only way to put some pre-twist into the torsion bar would be if you were able to keep twisting the torsion bar against one of the bump stops.

I still think we are only changing ride height when we adjust the torsion bar. Although I feel a little out numbered here. I work with a couple of guys who race and know how to tune suspensions. Hopefully they can sed some light on the subject. Sorry I just gotta know the right answer I probably won't sleep tonight.

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PostPosted: Mon Dec 17, 2007 7:17 am 
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I found this on Wikipedia.......

A Torsion Bar Suspension, also known as a torsion spring suspension or incorrectly torsion beam , is a general term for any vehicle suspension that uses a torsion bar as its main weight bearing spring. One end of a long metal bar is attached firmly to the vehicle chassis; the opposite end terminates in a lever, mounted perpendicular to the bar, that is attached to a suspension arm, spindle or the axle. Vertical motion of the wheel causes the bar to twist around its axis and is resisted by the bar's torsion resistance. The effective spring rate of the bar is determined by its length, diameter and material.

Torsion Bar Suspensions are currently used on trucks and SUV's from Ford, GM and Dodge. Manufacturers change the torsion bar or key to adjust the ride height, usually to compensate for heavier or lighter engine packages. While the ride height may be adjusted by turning the adjuster bolts on the stock torsion key, rotating the stock keys too far can bend the adjusting bolt and (more importantly) place the shock piston outside the standard travel. Over-rotating the torsion bars can also cause the suspension to hit the bump stop prematurely, causing a harsh ride. Aftermarket forged torsion key kits use re-clocked adjuster keys to prevent over-rotation, as well as shock brackets that keep the piston travel in the stock position.

The main advantages of torsion bar suspension are durability, easy adjustability of ride height, and small profile along the width of the vehicle. It provides a longer travel than leaf spring systems, and takes up less of the vehicle's interior volume compared to coil springs. A major disadvantage is that torsion bars, unlike coil springs, usually cannot provide a progressive spring rate, forcing designers to compromise between ride quality and handling ability—progressive torsion bars are available, but at the expense of durability since they have a tendency to crack where the diameter of the bar changes. In most torsion bar systems, especially Chrysler's, ride height (and therefore many handling features) may be adjusted by bolts which connect the torsion bars to the steering knuckles and require nothing more than crawling under the car with a wrench in hand. In most cars which use this type of suspension, swapping torsion bars for those with a different spring rate is usually an extremely easy task.

Some vehicles use torsion bars to provide automatic leveling, using a motor to tighten the bars to provide greater resistance to load and, in some cases (depending on the speed with which the motors can act), to respond to changes in road conditions. Height adjustable suspension has been used to implement a wheel-change mode where the vehicle is raised on three axles and the remaining wheel is lifted off the ground without the aid of a jack.

Before World War II, the front wheel drive Citroen Traction Avant (1934) had independent front torsion bar suspension and a trailing dead axle, also sprung by torsion bars. The Czechoslovakian Tatra cars designed by Professor Hans Ledwinka in the mid 1930s used all round independent torsion bar suspension, along with air cooled rear engines. Also in the 1930s, prototypes of the first Volkswagen Beetle incorporated torsion bars—especially its transverse mounting style. Ledwinka's concept had been copied by Ferdinand Porsche, whose successors later had to acknowledge the influence of Ledwinka's Tatra models on the Porsche-designed Kdf-Wagen of 1938 (later known as the VW Beetle), a post-war lawsuit resulting in a DM3,000,000 settlement paid by Volkswagen to Ringhoffer-Tatra in 1961.

The system was applied to many new armoured fighting vehicle designs during the Second World War. It was used extensively in European cars Renault, Citroen and Volkswagen, as well as by Packard in the 1950s. The Packard used torsion bars at both front and rear, and interconnected the front and rear systems to improve ride quality. The most famous American passenger-car application was the Chrysler system used beginning with the 1957 model year, although Chrysler's "Torsion-Aire" suspension was only for the front; the same basic system (longitudinal mounting) was maintained until the 1981 introduction of the K-car. A reengineered torsion bar suspension, introduced with the 1976 Dodge Aspen, introduced transverse-mounted torsion bars (possibly based on the Volkswagen Type 3 passenger car) until production ended in 1989 (with Chrysler's M platform). Light-duty Dodge trucks however continue to use torsion bars on their front suspension.

General Motors has used torsion bars since 1966, starting with the E-platform vehicles (Oldsmobile Toronado, Cadillac Eldorado), 4 wheel drive S-10 pickups, and since 1988, full size trucks (GMT400, GMT800, and GMT900 series).

Some front-wheel drive automobiles use a related type of torsion BEAM suspension, usually called a twist-beam rear suspension, in which the rear wheels are carried on trailing arms connected by a laterally mounted torsion beam. The torsion beam functions both as wheel-locating arm and as an anti-roll bar to resist lateral motion of the wheels as the body leans in turns. Its advantages are that it is inexpensive to manufacture and install, and engages a minimum amount of interior volume, leaving more space for the carriage of passengers, cargo, and other components. Because the torsion beam acts in the lateral plane, not vertically, the twist-beam axle cannot provide ride-height adjustment, and it suffers, to some extent, similar car handling limitations as other beam axle suspensions. However these limitations may not be apparent on the road, because of the trend towards firmer, more sporty suspension setups with more limited wheel travel. Torsion-beam rear suspensions were pioneered on the Volkswagen Golf[citation needed] in the early 1970s, and remain common on compact cars and minivans.

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PostPosted: Mon Dec 17, 2007 1:04 pm 
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uhhh, thats alot of reading!! lol

anyways, ron the truck looks great! just watch out for that exhaust now. when i lowered my luv, i ripped the exhaust off the manifold!!

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PostPosted: Mon Dec 17, 2007 2:05 pm 
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rondog wrote:
I know what you mean. My son and I talked this out for a long time.

When I think it all out in my head, it seems all I did was re index the rear adjusting end. Instead of it being up at the floor of the cab and at the end of the threads on the bolt, it is about mid way now.

Because "X" amount of twist on the bar will lift "Y" amount of weight to "Z" highth. It shouldn't matter how it is indexed, this much twist will lift this much weight this high. :? But it seems to ride better now. :? :o


Hi Ron you are great at explaining something complex very clearly. this is a tough conversation to have online. much better to have this in the garage looking at the truck with beer or wrench in hand. I believe you that the truck rides better. Just trying to get my mind wrapped around why.
Lowered truck should handle better because of lowered center or gravity.

the problem I am running into is with low profile tires is that I only have about 1 inch of suspension travel left. so if you hit a bump of any significance I bottom out the suspension. with you higher profile tires you still have. 2-3" of travel. so your truck has 2-3" to absorb the bump I only have 1"

I still think indexing only affects what point you are at in the adjustment. The only way to increase the spring rate in a torsion bar should be to change it to a thicker/stiffer bar. Wish I lived closer I grew up in Pasadena.

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PostPosted: Mon Dec 17, 2007 11:31 pm 
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Heres how i see it, if this helps anyone. If I just add more confusion i apoligize in advance.

You are under your stock truck(i.e. tortion bars have NEVER been touched) and you look at your adjuster for your tortion bar, its probably screwed in about half way or more. Now unscrew that bolt out NEARLY all the way. You'll notice the one side sag considerably. Put a low profile jack under the front end and give a little pump on it. Now WATCH OUT and screw out the adjuster all the way, you'll notice at the last second a big bang, or snap; that is the tortion bar straightening and probably smacking the bottom of the cab. Now take the tortion bar, as a whole, and slide it out of the lower control arms back to the rear of the car (adjuster cam and all!). Now lower your jack as low as it will go, maybe even take it out. Now your shock MAY bottom out before max travel is reached, if this is the case, just simply remove the shock at the top then proceed to attempt to completely lower the vehicle again. At this point your wheel is super tucked under the front fender. Now slide the tortion bar back into the lower control arm hole, while maintaining the alignment nesecary to get a thread or 2 started on the adjuster bolt. Once you get your bar in the control arm with your bolt started, get crankin'. By the time you get the adjuster bolt all the way in, or at least 3/4, you should be at your desired LOWERED ride height with preload to spare!

Hope this helps! It worked for me! I have a great ride and never bottom out. I'll admit tho, i did have a drive on rack to do this on so i just hit the bolt with an impact for about a minute or 2. Also I noticed it helped a lot to put a washed between the adjuster bolt and the frame.

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PostPosted: Tue Dec 18, 2007 2:41 pm 
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I got it!!
Think about it in lifting the truck terms. I found it easier to understand this way.
Lets say the front of the truck weighs 500lbs.
500lbs on the torsion bar puses the a arm up when you set the truck on the ground. Doesn't matter where the torsion bar is placed in the a arm, the truck will only push down 500lbs.


OK It's jacked up in the air, wheels hanging. 5 inches between top of tire and fender well. Lower the truck. the tire/fender gap is now 3 inches. The truck drops 2 inches.
Jack it back up, pull the bar out, let the a arm drop all the way down, and reinsert the bar. You now have 10" tire/fender gap. Set the truck down, and you now have 8" tire/fender gap, with 500lbs of pressure on the bar.

Make sense?? I The weight on the bar will always be the same, it's just where the starting point is, that changes.

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PostPosted: Tue Dec 18, 2007 6:54 pm 
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Hi Ron,
Yes I agree. That is how I understand the front suspension to work.

But back to the original question Why would the ride improve if the torsion bar is reindexed?

Claims were made earlier in the thread that
"I lowered my truck using the torsion bar and the ride felt like crap. Then I reindexed the torsion bar for the same lowered ride height and the ride improved."

If weight, the torsion bar and the ride height stayed the same and the only thing that changed was reindexing. Why would the reindexing improve ride quality? The only thing I could think of is that reindexing is changing the spring rate on the torsion bar in some way.

Here is the only way I can think of to test the spring rate of the torsion bar.

1. remove shocks-just in case they will interfere
2. keep ride height constant
3. add weight to the front of the truck until it bottoms out
4. re index torsion bar, adjust to same ride height
5. add weight to front end again until it bottoms out.

Compare the weight it takes to bottom out the truck. If it takes more weight to bottom out the truck with the t-bars reindexed then the spring rate did increase....

another quick test might be to reindex one side and not the other. adjust to the same ride height. Push down on each side and see if you can feel a difference.

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PostPosted: Tue Dec 18, 2007 10:24 pm 
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:smt017 I keep thinking about it.

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PostPosted: Wed Dec 19, 2007 12:31 pm 
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The tortion bars will have the same tension!!!!! You just start winding them at a different position in the lower control arm. Same tension, different stance.

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PostPosted: Thu Dec 20, 2007 7:20 pm 
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its like all it is in your mind if the bolt and bar stay in the same place then (in your mind) lift up the a arm just make a good mark so you keep them even so it depends on how low you wont it one time in my 82 chevy 1/2 ck i slammed it by cutting a 1 ton coil spring the same hight as my slammed 1/2 spring but it had a bigger spring rate so it gave me more ride with torsion bars you don't change the springs you just reindex them i hope this will help sum.now that i understand this better as soon as i fix the trans in my luv(while its in the air ) i am going to do mine to ok ttyl

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PostPosted: Sun Dec 23, 2007 8:18 am 
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Still lost here. I thought you raise and lower with the torsion bar. If not how are you raise and lowering the control arms. Can this be done with just a floor jack and stands andnot taking the whole front apart.
Also how did you lower the back. I have some 2 inch blocks from my sons s 10 we took out when his was real low.
Do I just put those on top of my rear axle and go.

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PostPosted: Mon Dec 24, 2007 7:45 am 
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So basically to lower my front a bit I just scew the front bolts in a bit on the torsion bar or unscrew them a turn or so.
Doesn't seem too hard to take the bars out and reinstall if i want to reindex them either. They come out and go back in pretty easy i assume.

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PostPosted: Wed Oct 08, 2008 2:41 pm 
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gs11x wrote:
Hi Ron,
Yes I agree. That is how I understand the front suspension to work.

But back to the original question Why would the ride improve if the torsion bar is reindexed?

Claims were made earlier in the thread that
"I lowered my truck using the torsion bar and the ride felt like crap. Then I reindexed the torsion bar for the same lowered ride height and the ride improved."

If weight, the torsion bar and the ride height stayed the same and the only thing that changed was reindexing. Why would the reindexing improve ride quality? The only thing I could think of is that reindexing is changing the spring rate on the torsion bar in some way.

Here is the only way I can think of to test the spring rate of the torsion bar.

1. remove shocks-just in case they will interfere
2. keep ride height constant
3. add weight to the front of the truck until it bottoms out
4. re index torsion bar, adjust to same ride height
5. add weight to front end again until it bottoms out.

Compare the weight it takes to bottom out the truck. If it takes more weight to bottom out the truck with the t-bars reindexed then the spring rate did increase....

another quick test might be to reindex one side and not the other. adjust to the same ride height. Push down on each side and see if you can feel a difference.


HAHA old post but it's relevant for me, when you re-index you are changing the amount of torsion in the bar at a given height... Thats how it allows you to change ride height and keep ride quality.

Nick


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PostPosted: Wed May 01, 2013 7:52 pm 
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I can't seem to get my bars out :esad what's the best way to get them out? Have the truck up in the air, adjuster bolts all the way out....wouldn't budge. I ended up just lowering it al the way with the jack and putting the adjuster bolts back in and cranked it to where the bolts are about flush wth the end of the round nut at the end of the cam


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PostPosted: Thu Jan 16, 2014 6:11 pm 
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so i just need to remove the torsion bars and take a floor jack and raise the control arms with the jack to the height i want then reinsurt the torsion bars and tighten everythin back down. set the truck down and look to see if its at the height i want if not just loosen the torsion bars a lil to make small adjustments, am i getting it or am i just lost?


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PostPosted: Fri Jan 17, 2014 4:27 pm 
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zmcleod+Luv wrote:
so i just need to remove the torsion bars and take a floor jack and raise the control arms with the jack to the height i want then reinsurt the torsion bars and tighten everythin back down. set the truck down and look to see if its at the height i want if not just loosen the torsion bars a lil to make small adjustments, am i getting it or am i just lost?


You want to lower yours? Remove the bars, lift the control arm as high as you can, insert the bar, set the truck on it's wheels, tighten the bar to the lowered height you desire.

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