Calling all Ford Rangers!

[gwittman]

Hi Scott, I am trying to wrap my head around your statement of losing compression travel when lifting with torsion bars. Maybe I am misunderstanding what you are saying but my understanding of the way the torsion suspension works would result in increased compression travel after a torsion bar lift. My definition of compression is when the wheel is pushed upward relative to the chassis. Lifting with the torsion bar should reduce the extension travel (wheel moves down relative to the chassis) due to the shock hitting the extension stop easier. Lifting with the torsion bar should put more stress on the bar because it will twist more due to the increased compression travel.

Adjusting ride height with the torsion bar does not change the overall travel limit points of the suspension, it just changes the neutral position of the suspension. If you raise it, you are closer to the extension limit. If you lower it, you are closer to the compression limit. I think you can get more travel by installing shocks that have more extension travel but that could stress the some of the suspension components resulting in early failure. The CV joints may not like that either.

Let me know if I am misunderstanding something about the torsion bar suspension or your understanding of it.

 

[Scott B.]

I meant to say droop (extension) travel. Sorry about that.

I should have clarified that a torsion "twist" or lift only moves the neutral (static) point of the suspension, it does not add travel.

That being said, I do not agree with your statement about the lift putting more stress on the bar. At any given static setting, there is the same static load on the torsion bar. At any given static setting, the torsion bar sits in the same position - with the same amount of "twist" holding the load. Sure, with a static setting at close to max extension, max compression travel will twist the bar more than with a neutral static setting, I don't think that is more stress. The torsion bar is designed to twist.

However, with a static setting set in the "extension-half" of the travel, you will see a rougher ride. (Not significantly rougher, but rougher none the less.) With a static setting giving a "lift", the A-arms are not parallel to the ground - the wheel ends are angled toward the ground. If the A-arms are parallel to the ground, when the wheel hits a bump, the arms deflect upward, twisting the torsion bar, etc. When the arms are angled, part of the impact goes toward moving the A-arms, part of the impact is transferred to/into the frame rail, (trying to) move the frame up and away. The reality is you will see less upward wheel travel.

Taking off my engineering hat, my 2006 has a torsion twist, and it rides just fine.

As for shocks, you don't want the shock absorber to be your limiter - you want the A-arms to hit bump stops. Using a shock as a limiter will cause early shock failure.

 

[h4rdflip]

Finally got my ranger paid off along with the old shoulder surgarized so Im looking fwd to finally do some stuff to my ranger and update my camper setup. Here what I rigged up last summer for it, judge me all you want but I needed a comfy bed for my weak back and shoulder. It was the best sleeping nights I had camping, in Jasper with my dog on her side of it.

 

[ihatemybike]

Looks like a great setup to me.

 

[thethePete]

Scott, when you crank your torsion bars you are preloading the spring to gain the height. That's why lift keys are a better option, they change the indexing of the spring so you can gain more height by changing the true neutral position of the spring, you're not getting it by increasing the preload.

You shouldn't really use the shock as a compression or extension limiter, though some do have built-in internal bumpstops. I believe gwittman was referring to gaining droop extension by using a longer shock, not limiting compression. ideally you'd have good bumpstops and limit straps to restrict the travel on either end.

Also, your rough ride doesn't come so much from where the arm sits in its travel, but the lack of droop left, which absorbs downward bumps, like potholes etc. Up travel will help with rocks and obstacles, but again, your rough ride is contributed to by your preload on the spring. It only has so much twist before it will snap and the harder you crank it to get that height the less twist it has left. It also imparts stored energy into the dropout when going over a pothole etc, more so than at zero preload. This can contribute to a jarring ride as well.

 

[Hawk136439]

Hey Everyone!

Just found this post and thought I'd try and contribute too. This is my 2006 Ford Ranger 4.0L 4x4 manual everything.

 

[gwittman]

Scott, when you crank your torsion bars you are preloading the spring to gain the height. That's why lift keys are a better option, they change the indexing of the spring so you can gain more height by changing the true neutral position of the spring, you're not getting it by increasing the preload.

Also, your rough ride doesn't come so much from where the arm sits in its travel, but the lack of droop left, which absorbs downward bumps, like potholes etc. Up travel will help with rocks and obstacles, but again, your rough ride is contributed to by your preload on the spring.

Pete, I agree with you about the jarring ride being primarily due to reduced droop left in the suspension when lifting with the torsion bars. I also think Scott has a point about the angle of the arms but I think it would be a minimal effect. If the angle change was very significant the affect would be significant but the change is minimal.
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I don't agree with the idea of preloading the spring to gain height. The torsion bar is preloaded due to the weight on the suspension. Raising the front does not add any more preload on the torsion bar because weight is not increased. In fact weight is slightly reduced when raising the front because that slightly shifts the weight to the rear. Again this effect is minimal but I use this approach all the time in balancing the corner weights of my race car.
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Adjusting the bolts on a torsion bar to lift the front is similar to adding a spacer on a coil spring suspension vehicle. The spring does not get any more preload or see any more load unless it is raised so much the suspension is binding. It does not take any more force to hold the front end 2 inches higher unless you have a very low ceiling on your garage. If the weight doesn't change the spring force doesn't change until you start getting effects from the angle of the arm that Scott was talking about.

 

[ExplorerTom]

How can you increase height WITHOUT adding a spacer? Obviously you can't with a torsion bar.

Weight on the front doesn't change appreciable. Let's consider it constant.

Imagine for a second a coil spring suspension since it's easier. Replace the springs with new springs that are the same natural length as the originals except these springs are super soft (think ball point pen springs). Now put the weight back onto the suspension. Does the truck sit higher or lower than before? All we changed was the spring constant. In this case it would be lower- much lower, like on the bumpstops/frame. Now do the same with same length springs that are much stiffer than stock. How does it sit now? Higher, correct.

Now back to torsion bars. Since when you adjust the torsion bars, you aren't replacing the spring, you are effectively changing the spring rate. Nothing else has changed: the spring remains the same length, attach points front and rear are the same- yet the truck sits higher/lower depending on which way you go with the adjustments. Only way for this it to sit higher is for that spring to be stiffer.

 

[Scott B.]

How can you increase height WITHOUT adding a spacer? Obviously you can't with a torsion bar.

Weight on the front doesn't change appreciable. Let's consider it constant.

Imagine for a second a coil spring suspension since it's easier. Replace the springs with new springs that are the same natural length as the originals except these springs are super soft (think ball point pen springs). Now put the weight back onto the suspension. Does the truck sit higher or lower than before? All we changed was the spring constant. In this case it would be lower- much lower, like on the bumpstops/frame. Now do the same with same length springs that are much stiffer than stock. How does it sit now? Higher, correct.

Now back to torsion bars. Since when you adjust the torsion bars, you aren't replacing the spring, you are effectively changing the spring rate. Nothing else has changed: the spring remains the same length, attach points front and rear are the same- yet the truck sits higher/lower depending on which way you go with the adjustments. Only way for this it to sit higher is for that spring to be stiffer.

Sorry, but no...

Using your example, put a spacer block under the coil spring. You have increased ride height with the same spring rate.

 

[thethePete]

Then why do you have to crank your torsion bars when you add a plow to the front, and then when you take the plow back off, it rides like a lumber wagon? This is regardless of whether you have stock keys or lift keys. And why does the ride quality improve when you use lift keys to attain the same height as stock keys cranked up? You are increasing the spring preload to gain height with stock keys and turning in the adjusting bolts. You are changing the natural position of the spring (think a spacer on a coil spring) when you use lift keys. This is the way torsion bar springs work. It is the same if you are looking to gain height on the front of the truck or compensate for added weight. Turning in your keys increases preload on the spring to attain height, using lift keys reindexes the spring to attain the height.

 

[BigOrca]

Whether you use aftermarket keys, or stock ones there is no difference in spring rates (so long as the suspension travel is not at max either up or down). The difference is now where the suspension arm sits in its total range of motion. Look at it this way. Pretend a vehicles suspension arm is perfectly level to the ground and has 4 inches of up travel and 4 inches of down travel. If I re-index the torsion bar to gain 2 inches of lift I now effectively have only 2 inches of down travel, but now i have 6 inches of up travel. The total travel has not changed. In the first 4 inches of up travel my springs are at the exact same rate they were when stock. The difference now is that I have 2 extra inches to the upper bump stop. This is more than the original, and if/when I get into this range of suspension travel it will feel rougher because it is stiffer. Now remember that our down travel has been limited by 2 inches which means that we will top out the suspension a full 2 inches before we did when we were stock. This also creates a rougher more jarring ride. Scott B. hit the nail on the head with his comparison of adding a coil spring spacer. And whoever made reference to the geometry of the suspension also made a good point. The vehicles suspension was not designed to work at that angle all the time. Independent suspension is just made up of levers. When you lift it the end of the lever (spindle, wheels, etc.) move more in line vertically with the pivot point, which means force is applied more vertically. The force of the bumps are now moving more "into" the frame than they were at stock. I'm not arguing that the numbers I used above work in real life, but I hope they can be used to make more sense of what is happening.

 

[thethePete]

Preload!= spring rate.

 

[Jgranger]

Wow what a discussion... Just SAS it and call it a day


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[schaefer21285]

Well, here is my new to me 1999 Ranger. It was an unlikely purchase because I was looking for something different but I am really liking it. Oh yeah, and it is manual with a turbo diesel too!

 

[thethePete]

Nice. Where was it imported from? CC Rangers didn't exist state-side, neither did the diesel option. How did you skirt the 25 year rule? Or are you not in North Carolina?