LC-AHC with armor, difference between torsion bars (1 Viewer)

[Kanaljen]

Looking for LC-AHC owners with front bumper, winch, and HD sliders (E.g, with lots of extra weight added!) with experience between stock LC-AHC torsion bars cranked up a lot versus LC torsion bars, cranked a bit less.

One is preloaded, can provide the same support to get within the AHC spec, softer spring rate, etc.. The other is stiffer, has a higher spring rate and wouldn't need to be preloaded/cranked as much..

I like my cushy ride but I want the suspension to work as design while keepin AHC system within spec. My AHC system works fine today with my cranked TBs and spacers on stock springs in the back (can go to H no problem) but I want to get the AHC pressure measured and the springs adjusted now when my armor is on...

THanks guys!

 

[3D FJ]

i thought people said that on ahc trucks, adjusting the tbars is for adjusting left to right stance. Is this correct?

 

[agaisin]

i thought people said that on ahc trucks, adjusting the tbars is for adjusting left to right stance. Is this correct?

Sorta - there are two reasons to adjust torsion bars on the AHC equipped vehicles:
1) to adjust front height left to right to get it level
2) to adjust neutral pressure in the front

The typical reason folks crank the TB is to raise the front vehicle height and that will not work for the AHC equipped vehicles since the AHC system will automatically lower/raise pressure to adjust height to compensate.

I believe the OP was saying that he'd need to crank TBs to bring neutral pressure back to spec and that is correct and so is his reasoning of using stiffer non-ahc LC TBs.

To the OP - I do not have the specific experience you're looking for with using ahc tb's vs. non ahc tb's on an armour laden vehicle however I do have experience measuring and adjusting neutral pressure (using techstream lite s/w). The concern I would have with using less stiff ahc tb's is that I may not be able to crank them enough to bring neutral pressure within spec. You can always try and see how far you get and upgrade to stiffer TBs if you max out on your ahc tbs.... Make sense?

If you're planning to do the tweaking yourself I'd recommend techstream lite + tactrix openport 2.0 cable based on my experience. pm me if you want more detail.

Also, I believe this topic has been covered on other threads.
Additionally, I know for a fact that TexasOil (of B&B) has a writeup on how to accomodate a vehicle with lots of weight (he uses #1500 as an example) and iirc he says the solution is to swap ahc tb and ahc spring for non-ahc tb and non-ahc springs. So the approach you're considering has precedent.

 

[Kanaljen]

Correct, I will most likely need to make adjustments to bring the neutral pressure to spec and I'm wondering if that should be done with the AHC LC TB or LC TB.

My question in based on the added weight and that an AHC TB will have to be cranked quite a bit, which in turn makes it more pre-loaded.. I.e., I might be able to crank it enough (even re-index it) to take on enough weight to be within spec BUT at that point it would be so "twisted" that it's force will continue to torque through the entire suspension travel...

With an LC TB, I could obtain the spec neutral pressure but with less pre-load.

I wonder if a stiffer TB is preferred to deal with the extra weight and also if it would mean a harsher ride.

Must be someone out there with armor/extra weight on an AHC LC that first tried with stock TB then moved to LC TB..

Sorta - there are two reasons to adjust torsion bars on the AHC equipped vehicles:
1) to adjust front height left to right to get it level
2) to adjust neutral pressure in the front

The typical reason folks crank the TB is to raise the front vehicle height and that will not work for the AHC equipped vehicles since the AHC system will automatically lower/raise pressure to adjust height to compensate.

I believe the OP was saying that he'd need to crank TBs to bring neutral pressure back to spec and that is correct and so is his reasoning of using stiffer non-ahc LC TBs.

To the OP - I do not have the specific experience you're looking for with using ahc tb's vs. non ahc tb's on an armour laden vehicle however I do have experience measuring and adjusting neutral pressure (using techstream lite s/w). The concern I would have with using less stiff ahc tb's is that I may not be able to crank them enough to bring neutral pressure within spec. You can always try and see how far you get and upgrade to stiffer TBs if you max out on your ahc tbs.... Make sense?

If you're planning to do the tweaking yourself I'd recommend techstream lite + tactrix openport 2.0 cable based on my experience. pm me if you want more detail.

Also, I believe this topic has been covered on other threads.
Additionally, I know for a fact that TexasOil (of B&B) has a writeup on how to accomodate a vehicle with lots of weight (he uses #1500 as an example) and iirc he says the solution is to swap ahc tb and ahc spring for non-ahc tb and non-ahc springs. So the approach you're considering has precedent.

 

[jOnathN]

That's easy to calculate *if* someone knows what percent if load the AHC carries at Neutral in a stock truck.

E.g. Assume the truck is 5000 lbs and AHC carries 20% at neutral (1000 lbs). To achieve the same ride on non-AHC springs you would want AHC to carry the same weight post change (load and new springs), 1000lbs.
The non-AHC springs design load is 100% of the stock truck weight so the truck would need 1000lbs above stock to get the AHC back to design load and stock ride characteristics... Probably a little less actually since the non-AHC/non-Lexus truck weighs a bit less; 200lbs less? So maybe net 800 lbs load required.

If the permanent load (armor) is less than that you can raise the height some by adjusting sensors to get the neutral pressure back in spec.

Adjust numbers above to suit the facts; everything above is SWAG.

Now that i am looking at it that sounds pretty good: add armor (500lb for F&R bumper/sliders/skidplates?) switch to stock springs, AHC lift to get back in spec and you have a cost effective, lifted, armored, stock-riding truck.

J

 

[Kanaljen]

I see where you're going but i think it's a similar way to articulate what the measurement of the neutral pressure is intended to do; it shows the pressure on the AHC system at neutral, with "the rest" being supported by the spring. And of course, the way to get the pressure in AHC to spec, you baalance the truck's weight between shock/AHC and springs correctly.

Now, this can be done with cranking up existing (and thinner) T-bars OR by putting in TBs with higher spring rate and crank them less. I think the existing/thinner ones will be cranked so much that they produce a downward torque way through the suspension travel.. A thicker TB would probably give a tad harsher ride but wouldn't have to br ceanked so much and thus wouldn't create the same torque all the way through the suspension travel.

I figure I just have to try it, pick the setup that is best but I wanted to ask for people that have done this exact comparison before (LC vs LX TBs after armor). FOund one guy, but have yet to receive a PM back.

THanks for all the input!

That's easy to calculate *if* someone knows what percent if load the AHC carries at Neutral in a stock truck.

E.g. Assume the truck is 5000 lbs and AHC carries 20% at neutral (1000 lbs). To achieve the same ride on non-AHC springs you would want AHC to carry the same weight post change (load and new springs), 1000lbs.
The non-AHC springs design load is 100% of the stock truck weight so the truck would need 1000lbs above stock to get the AHC back to design load and stock ride characteristics... Probably a little less actually since the non-AHC/non-Lexus truck weighs a bit less; 200lbs less? So maybe net 800 lbs load required.

If the permanent load (armor) is less than that you can raise the height some by adjusting sensors to get the neutral pressure back in spec.

Adjust numbers above to suit the facts; everything above is SWAG.

Now that i am looking at it that sounds pretty good: add armor (500lb for F&R bumper/sliders/skidplates?) switch to stock springs, AHC lift to get back in spec and you have a cost effective, lifted, armored, stock-riding truck.

J

 

[Fuge]

Did you ever replace the LX TBs with LC TBs? I just replaced my rear springs with King Spring KTRS-79 springs. It improved my ride significantly. Before I had stock springs with 30mm spacers and I feel that the pre-load made the AHC not dampen the way it was designed to. I have no empirical data to reinforce that but this much stiffer spring brought my pressures way down and the ride better. With the spacers wash board roads were painful. They are less painful now. Therefore, I am curious that if I went to a stronger TB would it have the same effect as the stronger springs in the back? My TBs are turned quite a bit and I am hoping that a stronger TB without the pre-load will actually be a better ride than a harsher one. Just curious if you have tried this and what results you found?

 

[ihadmail]

I've read of a lot of people swapping to the LC torsion bars when adding a lot of weight and some lift to an LX.

I have a set of LC bars waiting to go on while I'm doing some other maintenance.

With 2" sensor lift, Dissnet front bumper, sliders, Gamiviti rack and Smittybilt H2o 12k winch my AHC torsion bars cannot keep up. I can get my pressures in spec while stationary but they cannot respond to dips in the road well enough. Once the LC bars are in, the FSM neutral pressure spec is no more than a starting point for experimentation to get a good pressure for comfort and suspension response.

Hope this helps some, sorry I cannot comment on my personal experience with the LC torsion bars since I havent gotten to installing them yet.

 

[MastiffDad14]

Just bring up an old thread. Has anyone actually put in non ahc bars and what are your experiences? My truck is lifted 1.5", with a 12k winch and metal front bumper.

Stock torsion bars are maxed out and front pressure is a little over the recommend pressure range.

 

[Rolocado]

Just bring up an old thread. Has anyone actually put in non ahc bars and what are your experiences? My truck is lifted 1.5", with a 12k winch and metal front bumper.

Stock torsion bars are maxed out and front pressure is a little over the recommend pressure range.

Don't do it. Get TB bars that are for a LC. They are different thicknesses and the LX one's aren't strong enough. Ask me how I know.

 

[Fuge]

I have a pair of LC bars sitting in my garage to try this but haven't had the time to swap them out yet. I will post back when I do.

 

[Moridinbg]

Yet another bump. How did it work for you?
I had to crank my driver side TB more or less to the maximum to bring my pressures to neutral and level the car, after putting a bumper and a winch. The passenger side has a lot more adjustment left.

How do the stock torsion bars work with bumper, winch, roof tent, extended tank, etc?
This probably are the original 250k miles torsion bars, so I am wondering if a fresh AHC pair will get me to neutral pressure with less cranking? Or should I get the non-AHC bars?

 

[SlowBuild]

Yet another bump. How did it work for you?
I had to crank my driver side TB more or less to the maximum to bring my pressures to neutral and level the car, after putting a bumper and a winch. The passenger side has a lot more adjustment left.

How do the stock torsion bars work with bumper, winch, roof tent, extended tank, etc?
This probably are the original 250k miles torsion bars, so I am wondering if a fresh AHC pair will get me to neutral pressure with less cranking? Or should I get the non-AHC bars?

Doubtful you need new bars. Just re-index, crank to pressure, and keep driving.

 

[Miljack]

I recently swapped a stock set of LX bars for stock LC TB and noticed a huge difference! The PO had changed out the rear springs and shocks to bypass the failing (failed?) AHC system. They left the stock front bars which were tweaked a little to adjust the ride height. What was happening under acceleration, the front would unload, and the pre-loaded TB's would start to "lift" the front in addition to the weight transfer and ring and pinion "climb." The beast would do some strange things under acceleration.
Once I swapped to the stock LC TB's, a huge difference in driving dynamics!
I would say if running a loaded/armored rig and one wanted to keep the AHC system, the stock LC TB's would be a good step to take...

 

[bamabrock]

I recently swapped a stock set of LX bars for stock LC TB and noticed a huge difference! The PO had changed out the rear springs and shocks to bypass the failing (failed?) AHC system. They left the stock front bars which were tweaked a little to adjust the ride height. What was happening under acceleration, the front would unload, and the pre-loaded TB's would start to "lift" the front in addition to the weight transfer and ring and pinion "climb." The beast would do some strange things under acceleration.
Once I swapped to the stock LC TB's, a huge difference in driving dynamics!
I would say if running a loaded/armored rig and one wanted to keep the AHC system, the stock LC TB's would be a good step to take...

Thats because the stock AHC TBs only have a fraction of the spring rate of normal non-AHC TBs. What the PO did was dangerous and cheap.

 

[Moridinbg]

Doubtful you need new bars. Just re-index, crank to pressure, and keep driving.

I would like to avoid too much preload on the suspension. That's why I am considering non-AHC torsion bars - Currently I have cranked the driver side all the way in. Even if I reindex it, it would be just as preloaded.

 

[Joe Bob]

im in the same boat as many here. driver's side is maxed. i have dissent front and rear bumpers with 12k winch, dissent skids, white knuckle sliders, gobi roof rack.

• i cant find for the life of me instructions to reindexing. anyone have a link?
• whats the consensus on upgrading torsion bars to prevent excessive loading with armored rig?
• anyone here actually runing upgraded tbs that can comment?

thanks

 

[brauski]

im in the same boat as many here. driver's side is maxed. i have dissent front and rear bumpers with 12k winch, dissent skids, white knuckle sliders, gobi roof rack.

• i cant find for the life of me instructions to reindexing. anyone have a link?
• whats the consensus on upgrading torsion bars to prevent excessive loading with armored rig?
• anyone here actually runing upgraded tbs that can comment?

thanks

For those with torsion bar questions

Torsion bars 101 FOR NON AHC VEHICLES First some terms so the search function picks this up: - help with torsion bars - how to adjust torsion bars - reindex torsion bars This all went in Amy's thread but I thought those who weren't subscribes may like to see it. Ok lets try get to the...

forum.ih8mud.com

I sat down the other day to try and calculate what TB I would need for my steel armor & rack, 12k winch, sound deadening, and a 1.5-2" lift. Then I realized the last time I did engineering was 5 years ago and I've forgotten everything I knew. lol It seems like there were some solid rules of thumb regarding the relationship between additional weight over the rear axle/springrate/and AHC pressures, but no one to my knowledge has put out anything like that for the front. Here's what I was working with for my failed endeavor.

LX weights:
Empty - 5500 lb
GVW - 6500 lb
Allegedly it's a 51F/49R split (some basically a sports car? lmao)

MUDers have figured out:
-1" increase in the front = 2.2 Mpa-g
-1" increase in the rear = 0.6 Mpa-g
-210lbs over the rear axle = 1 Mpa-g

Common Available TB diameters (mm):
-AHC - 25.5
-NON AHC - 28.87
-OME - 30.5
-Sway Away - 31
-TJM - 32
-Ironman - 32

TBs are much harder to figure out spring rate on than a coil. But, if anyone can still math, lemme know what you figure out!

 

[suprarx7nut]

For those with torsion bar questions

Torsion bars 101 FOR NON AHC VEHICLES First some terms so the search function picks this up: - help with torsion bars - how to adjust torsion bars - reindex torsion bars This all went in Amy's thread but I thought those who weren't subscribes may like to see it. Ok lets try get to the...

forum.ih8mud.com

I sat down the other day to try and calculate what TB I would need for my steel armor & rack, 12k winch, sound deadening, and a 1.5-2" lift. Then I realized the last time I did engineering was 5 years ago and I've forgotten everything I knew. lol It seems like there were some solid rules of thumb regarding the relationship between additional weight over the rear axle/springrate/and AHC pressures, but no one to my knowledge has put out anything like that for the front. Here's what I was working with for my failed endeavor.

LX weights:
Empty - 5500 lb
GVW - 6500 lb
Allegedly it's a 51F/49R split (some basically a sports car? lmao)

MUDers have figured out:
-1" increase in the front = 2.2 Mpa-g
-1" increase in the rear = 0.6 Mpa-g
-210lbs over the rear axle = 1 Mpa-g

Common Available TB diameters (mm):
-AHC - 25.5
-NON AHC - 28.87
-OME - 30.5
-Sway Away - 31
-TJM - 32
-Ironman - 32

TBs are much harder to figure out spring rate on than a coil. But, if anyone can still math, lemme know what you figure out!

I think the metallurgy will dictate the spring rate enough that you can't really figure anything out until you have test data or spring rate provided by the manufacturer.