how much stiffer will the ride be after a torsion lift?

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rusty_tlc said:
F=-kx
for a torsion spring
t=-k(theta)

As we increase theta t will increase
Force would be the first derivative of theta right?
something like 1/2k(theta)squared
As we increase theta the rotational opposing force increases which would change the ride, no?

It's been something like 25 years since I took any ME courses so I could be wrong.
Click to expand...

I too would have to pull out my books to validate the equation.

However, what everyone is missing is that there is zero change in force! The only thing that has changed is the neutral point. Vehicle still weighs the same, same radians of twist on the spring, same spring force opposing the LCA rotation. Everything is exactly the same as a standard height vehicle except the neutral point. Only exception is the effects of suspension angle and how that affects ride quality (y'all are on your own with that one!)
 
OregonLC said:
what everyone is missing is that there is zero change in force! The only thing that has changed is the neutral point. Vehicle still weighs the same, same radians of twist on the spring, same spring force opposing the LCA rotation. Everything is exactly the same as a standard height vehicle except the neutral point. Only exception is the effects of suspension angle and how that affects ride quality (y'all are on your own with that one!)
Click to expand...

agreed with all of that. i'll take a shot at the last part... the (tangential) force is greatest when the (lever) arm is at 90 degrees, anything more or less than 90 produces a lesser component of the force (or torque in this case) acting on the spring, hence the perceived stiffer ride.

the remainder component of the force becomes lateral which you do not feel in your butt :cheers:
 
Mxndrnks said:
If all we need to adjust is the torsion bars, then it will be a really quick job as long as the bolt isnt too seized up. Has your truck always been in CA? If so, I dont think rust will be a big deal. Just hit the adjustment bolt with some PB Blaster for a few days before coming down. That will break loose any corrosion before hand. With no corrosion and as long as the tbars don't need to be re-indexed, it shouldn't take more than a 1/2 hour....and that is being generous.

You could drive back to Oceanside, however, there is a Firestone in PB like 2-3 miles from my house you could hit up before you head back north. Just dont do a ton of driving before getting the alignment done.
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Truck was an East Coast Rig all it's life up until July 2011 :) Mechanics said there isn't rust, shocking!

I could do some PB Blaster for you, lord willing I get the right bolt.
I'll try and find a pic of where these bolts are do that for you...

Think we can raise it more than an inch???
That won't do anything to it right?

I was hoping for 1.5".....

what happens if the bars need re-indexing? are we screwed?
 
pfran42 said:
No re-re-hashing...My whiteboard diagram clearly explains what you people are sensing as the "difference". Management Degree > Engineering Degree FTW!!!





But still... BOW TO OREGON!
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[strike]When you lift your truck without re-indexing you pre-load the springs, no? [/strike]

Never mind I get it now.


BTW I'm pretty sure they scramble the engineering part of your brain when you get a management degree. :flipoff2:
 
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RobRed said:
Man you guys over complicate everything.... You can do all the math you want... when you change that angle it changes the ride quality. Leverage.
Click to expand...

I be agreein with RR on this one... Cranking TBars changes other things related to front suspension geometry (CV angles, toe in, steering, etc)... Tiny adjustments may not be very noticeable but once you go up an inch or two it will ride different... An alignment will offset some of these changes but it still won't feel stock again... I've had all kinds of different setups at this point on my 100 and they all feel a little different...
 
LCbruiser2000 said:
Truck was an East Coast Rig all it's life up until July 2011 :) Mechanics said there isn't rust, shocking!

I could do some PB Blaster for you, lord willing I get the right bolt.
I'll try and find a pic of where these bolts are do that for you...

Think we can raise it more than an inch???
That won't do anything to it right?

I was hoping for 1.5".....

what happens if the bars need re-indexing? are we screwed?
Click to expand...

The bolt is almost as easy as the tire to find. Ok... maybe not quite that easy but pretty easy. Go to the front door handle and look under the truck at that spot. Just on the other side of the frame you will see a pretty big bolt head staring right at you. It is connected to a bar that runs up to the front of the truck (the torsion bar). Just spray the threads as good as possible. While you are there, see if you can tell if the bolt as equal threads on top and bottom of what it is attached to. If not, no big deal, we will look when you come down. If you can get an idea though.... it may help with knowing if we need to re-index or not.....

With the stock tbars you can get a good bit more than 1.5" of lift. However, we want to make sure you keep at least 60mm of droop for the ride quality. Although I have no experience with having the front higher than the rear, most have reported that you want to keep the front at least 3/4-1" lower than the rear for driving manners. The truck just seems to like it that way.

If the tbars need to be re-indexed we are not screwed, but it will take a bit longer. Here is a great thread in the FAQ to read up on it:
https://forum.ih8mud.com/100-series-cruisers/491948-those-torsion-bar-questions.html
It also has pictures of the bolt that should be hit with PB blaster.
 
jgray said:
I be agreein with RR on this one... Cranking TBars changes other things related to front suspension geometry (CV angles, toe in, steering, etc)... Tiny adjustments may not be very noticeable but once you go up an inch or two it will ride different... An alignment will offset some of these changes but it still won't feel stock again... I've had all kinds of different setups at this point on my 100 and they all feel a little different...
Click to expand...

Different feel and ride...but better or worse? Specifically I am talking about after cranking the stock t bars an inch or 2 (soaking in more pb blaster as we speak--affordability wise can't beat the mod). Appreciate the input at this late hour.

Sent from my mudPhone using IH8apple
 
10080 said:
Different feel and ride...but better or worse?
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What do you mean? Your better and my better could be worlds apart.

I'm my opinion, if you just crank the OEM TBs, it is just as "springy". It just takes a little more of a jolt to get them into their spring mode (vs. their static mode of just holding the vehicle a certain distance from the ground).
 
pfran42 said:
What do you mean? Your better and my better could be worlds apart.

I'm my opinion, if you just crank the OEM TBs, it is just as "springy". It just takes a little more of a jolt to get them into their spring mode (vs. their static mode of just holding the vehicle a certain distance from the ground).
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Ok Pfran...Just trying to understand what Jgray meant by "different". Better or worse is also non-specific--my question did not help much. My bad.

Guess the question to Jgray (and others) is after adjusting t bars what change in feel and ride did you discern, and, for the hell of it, did you you think it was a good adjustment--subjectively better or worse? I am willing to hear opinions about better or worse notwithstanding the inherent vagaries and personal preferences.

Thanks Pfran for the answer provided after your initial disclaimer (to which I generally agree). That helps me understand what to expect if I crank the t bars. Thanks.

Sent from my mudPhone using IH8apple
 
OregonLC said:
I too would have to pull out my books to validate the equation.

However, what everyone is missing is that there is zero change in force! The only thing that has changed is the neutral point. Vehicle still weighs the same, same radians of twist on the spring, same spring force opposing the LCA rotation. Everything is exactly the same as a standard height vehicle except the neutral point. Only exception is the effects of suspension angle and how that affects ride quality (y'all are on your own with that one!)
Click to expand...

I agree with this. "Zero Force Change" in the TB.
So for different reasons the ride will change mainly due to the negative effects by taking the torsion bars out of the preload range they were designed to operate in.
 
RobB said:
I agree with this. "Zero Force Change" in the TB.
So for different reasons the ride will change mainly due to the negative effects by taking the torsion bars out of the preload range they were designed to operate in.
Click to expand...

Also, for AHC this is not the same. There the cranking has no effect on height, but only affects the force imparted...
 
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