Heavy Duty Torsion Bars???
05-08-2008, 04:56 PM
#1
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Heavy Duty Torsion Bars???
I've been looking at these "HD Torsion Bars" that Downey sells. They claim that if you run a larger tire that your stock torsion bars will become too weak.
I'm wondering how this is possible, since there is normally not any tire weight on the torsion bar, as is the nature of virtually all suspension components(to suspend the chasis over the axles).
I can see these things being virtually worthless unless you do EXTREME 4X4ing, like jumping it, or rock crawling with your IFS
...
The only real benefits that I can see is if you crank them up, that they would hold a slight lift(1") better than stock, and would be stronger than stock if you jump it all the time.
But on the down side, I can see them Destroying any ride quality, esp. if you have them cranked. Also, They probably wouldn't flex like the stock ones do. And the torsion bars are usually not the weakest link in the IFS.
Any comments on this???
Any Experience with these, good or bad???
I'm wondering how this is possible, since there is normally not any tire weight on the torsion bar, as is the nature of virtually all suspension components(to suspend the chasis over the axles).
I can see these things being virtually worthless unless you do EXTREME 4X4ing, like jumping it, or rock crawling with your IFS
...The only real benefits that I can see is if you crank them up, that they would hold a slight lift(1") better than stock, and would be stronger than stock if you jump it all the time.
But on the down side, I can see them Destroying any ride quality, esp. if you have them cranked. Also, They probably wouldn't flex like the stock ones do. And the torsion bars are usually not the weakest link in the IFS.
Any comments on this???
Any Experience with these, good or bad???
05-08-2008, 05:04 PM
#2
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No. They will wear out from time. Or if you have a big ol v8 and a big heavy bumper. All these HD torsion bars do is firm up your ride. They will not let you crank the t-bars higher then stockers would. Your CV joints will complain far before the stock t-bars do.
Stick with stock.
Stick with stock.
05-08-2008, 05:09 PM
#3
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I had a pair of Sway-a-way t-bars on my old 89 4Runner (which I think is the very bar that Downey sells) and I'll tell you what I think. They HATED potholes big time unless you were going pretty fast. They would be good for jumping in fact would probably compliment a long travel kit very well. One thing I did like was once installed they did provide about 1 inch of lift without any cranking over where the stock bars were set. As far as the tire being heavier, that does sound kind of stupid to me. If I were to buy another set of aftermarket T-bars I think the only route I'd go would be OME because they aren't as thick as most aftermarket bars I've seen. I'm not sure how much of a difference 1-2mm would make in stiffness but I'd probably never go with SAW torsion bars again.
05-08-2008, 05:11 PM
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No. They will wear out from time. Or if you have a big ol v8 and a big heavy bumper. All these HD torsion bars do is firm up your ride. They will not let you crank the t-bars higher then stockers would. Your CV joints will complain far before the stock t-bars do.
Stick with stock.
Stick with stock.
I didn't even think about the added weight of a V8 Swap tho. That's about all I'd want em for....but then again, if I was dropping in a V8, I'd do a SAS.
05-08-2008, 05:43 PM
#6
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If your truck is running stock ride height, you don't have a heavy bumper or bigger motor, you don't need HD T-bars.
Where they come in handy is when you use them to get the 1.5-2" of lift possible with the stock IFS. When you crank the stockers to achieve this, the suspension gets very stiff because they are so preloaded and it'll also lead to their early demise. Also very hard on mounting points and can break them.
When you run a HD t-bar it's not so preloaded to achieve the 1.5-2" of lift so it rides softer, has more travel and is easier on mounting points.
Where they come in handy is when you use them to get the 1.5-2" of lift possible with the stock IFS. When you crank the stockers to achieve this, the suspension gets very stiff because they are so preloaded and it'll also lead to their early demise. Also very hard on mounting points and can break them.
When you run a HD t-bar it's not so preloaded to achieve the 1.5-2" of lift so it rides softer, has more travel and is easier on mounting points.
Last edited by MonsterMaxx; 05-08-2008 at 05:45 PM.
05-08-2008, 07:17 PM
#7
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If your truck is running stock ride height, you don't have a heavy bumper or bigger motor, you don't need HD T-bars.
Where they come in handy is when you use them to get the 1.5-2" of lift possible with the stock IFS. When you crank the stockers to achieve this, the suspension gets very stiff because they are so preloaded and it'll also lead to their early demise. Also very hard on mounting points and can break them.
When you run a HD t-bar it's not so preloaded to achieve the 1.5-2" of lift so it rides softer, has more travel and is easier on mounting points.
Where they come in handy is when you use them to get the 1.5-2" of lift possible with the stock IFS. When you crank the stockers to achieve this, the suspension gets very stiff because they are so preloaded and it'll also lead to their early demise. Also very hard on mounting points and can break them.
When you run a HD t-bar it's not so preloaded to achieve the 1.5-2" of lift so it rides softer, has more travel and is easier on mounting points.
The thicker t-bars give roughlt 1.5" of lift with the same amount of adjuster bolt exposed because the thicker bars don't settle in (sag) as much as the thinner bars. Also, what's nice is that the thicker bars can flex more because they aren't over preloaded, so you achieve much better small bump sensitivity, and the rebound forces aren't as strong allowing a stock damper (shock) to work just fine.
If you run a thicker t-bar, but keep the stock ride height you might feel like the suspension is too soft or bottoms out easily. This is because the thicker t-bars need a certain amount of preload placed on them to function properly. Just like you can overload the t-bar tension for a harsh ride, if you don't add enough preload you get a sloppy, unresponsive feel. I hope this helps.
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05-09-2008, 06:15 AM
#8
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Very well put. Anytime you preload a spring (crank up t-bars) it looses much of its small bump sensitivity and becomes very harsh. Also, the rebound force increases, this is why they don't like pot holes, they rebound so fast that your shock can't slow the rebound because it is not valved for such rebound forces.
The thicker t-bars give roughlt 1.5" of lift with the same amount of adjuster bolt exposed because the thicker bars don't settle in (sag) as much as the thinner bars. Also, what's nice is that the thicker bars can flex more because they aren't over preloaded, so you achieve much better small bump sensitivity, and the rebound forces aren't as strong allowing a stock damper (shock) to work just fine.
If you run a thicker t-bar, but keep the stock ride height you might feel like the suspension is too soft or bottoms out easily. This is because the thicker t-bars need a certain amount of preload placed on them to function properly. Just like you can overload the t-bar tension for a harsh ride, if you don't add enough preload you get a sloppy, unresponsive feel. I hope this helps.
The thicker t-bars give roughlt 1.5" of lift with the same amount of adjuster bolt exposed because the thicker bars don't settle in (sag) as much as the thinner bars. Also, what's nice is that the thicker bars can flex more because they aren't over preloaded, so you achieve much better small bump sensitivity, and the rebound forces aren't as strong allowing a stock damper (shock) to work just fine.
If you run a thicker t-bar, but keep the stock ride height you might feel like the suspension is too soft or bottoms out easily. This is because the thicker t-bars need a certain amount of preload placed on them to function properly. Just like you can overload the t-bar tension for a harsh ride, if you don't add enough preload you get a sloppy, unresponsive feel. I hope this helps.
Guys, I'm afriad this is not correct. Stiff bars equal less flex at all height adjustments.
The preload on the bar is a function of the weight of the truck and the leverage on the bar. If you just install a new torsion bar, the truck does not get heavier so preload remains the same regadelss of how much thread is or is not exposed. The bar just "feels" and resists torque. If you adjust the height upwards, the preload goes DOWN NOT UP. The fact that the a-arm is less parallel with the ground reduces torque on the bar hence why it deflects less and you feel the bump more.
This means, when adjusting in lift, you need a stiffer torsion bar even less that you *might* have needed one prior.
The size of the tire has absolutely nothing to do with making the torsion bar weak. There is no engineering related support for that claim. They do put more load on shocks, but we get off road shocks and the the problem is solved.
There is on reason and one reason only to get a stiffer torsion bar and that is if you want less flex. That's it, period.
I hope this clears things up. The relationship betweel load on a torsion bar and ride height is backwards (higher = less load on t-bar) and so therefore not terribly intuitive.
Frank
05-11-2008, 07:59 AM
#10
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You're not considering swing weight, there is a lot of significant dynamics going on when the truck is moving fast on rough roads. Your statement is correct while the truck is stilling still (static). Keep in mind one of Downey's big markets is the desert racing group. But what's good for desert racing is not always good for rock crawling.
05-11-2008, 07:59 AM
#11
Contributing Member
Guys, I'm afriad this is not correct. Stiff bars equal less flex at all height adjustments.
The preload on the bar is a function of the weight of the truck and the leverage on the bar. If you just install a new torsion bar, the truck does not get heavier so preload remains the same regadelss of how much thread is or is not exposed. The bar just "feels" and resists torque. If you adjust the height upwards, the preload goes DOWN NOT UP. The fact that the a-arm is less parallel with the ground reduces torque on the bar hence why it deflects less and you feel the bump more.
This means, when adjusting in lift, you need a stiffer torsion bar even less that you *might* have needed one prior.
The size of the tire has absolutely nothing to do with making the torsion bar weak. There is no engineering related support for that claim. They do put more load on shocks, but we get off road shocks and the the problem is solved.
There is on reason and one reason only to get a stiffer torsion bar and that is if you want less flex. That's it, period.
I hope this clears things up. The relationship betweel load on a torsion bar and ride height is backwards (higher = less load on t-bar) and so therefore not terribly intuitive.
Frank
The preload on the bar is a function of the weight of the truck and the leverage on the bar. If you just install a new torsion bar, the truck does not get heavier so preload remains the same regadelss of how much thread is or is not exposed. The bar just "feels" and resists torque. If you adjust the height upwards, the preload goes DOWN NOT UP. The fact that the a-arm is less parallel with the ground reduces torque on the bar hence why it deflects less and you feel the bump more.
This means, when adjusting in lift, you need a stiffer torsion bar even less that you *might* have needed one prior.
The size of the tire has absolutely nothing to do with making the torsion bar weak. There is no engineering related support for that claim. They do put more load on shocks, but we get off road shocks and the the problem is solved.
There is on reason and one reason only to get a stiffer torsion bar and that is if you want less flex. That's it, period.
I hope this clears things up. The relationship betweel load on a torsion bar and ride height is backwards (higher = less load on t-bar) and so therefore not terribly intuitive.
Frank
Great post.
However, a thicker torsion bar DOES have one more use, and that has been already stated above: heavy bumpers/winch or bigger/heavier motors. They will keep you from bottoming out on big bumps with the extra weight.
I do not recommend the Downey bars at all. If you want a slightly stiffer bar for the bumper/winch thing, the OME bars are perfect. Only slightly thicker than stock, giving a good ride while stiffening the front end enough to allow the truck not to bottom out while bumping.
05-11-2008, 08:14 AM
#12
Contributing Member
BTW I've been using Downey bars for many years, I wish they were a little softer myself but I do like the way they stiffen up the handling at higher speeds. So its a trade off, do you want soft & flexy or do you want stiff & racey?
I guess I've learned now not to critize a manufacturer for making a product that fits a certain niche just because I don't fit that niche (I'm not saying anyone here was critizing
).
Last edited by mt_goat; 05-11-2008 at 08:49 AM.
05-11-2008, 04:37 PM
#13
Registered User
See, where less flex is desirable (desert racing, heavy winch/bumper) stiffer bars are good.
It's good to keep that in the cross hairs when considering them.
What will get worked in the desert though are shocks. They get hot, fade, and then the bumpstops get beaten to death not to mention the truck becomes hard to control.
Stiff bars will absorb more energy when jumping too. They just flex very poorly on the trial unless you have increased the front end vehicle weight.
Our suspensions even with spacers don't have a very large window of travel so you aren't going to break either bar, though, the stiffer bar is under more stress at full flex than is the stock bar. That will *technicall* make it more likely to fatigue though it's high unlikely either will.
Frank
It's good to keep that in the cross hairs when considering them.
What will get worked in the desert though are shocks. They get hot, fade, and then the bumpstops get beaten to death not to mention the truck becomes hard to control.
Stiff bars will absorb more energy when jumping too. They just flex very poorly on the trial unless you have increased the front end vehicle weight.
Our suspensions even with spacers don't have a very large window of travel so you aren't going to break either bar, though, the stiffer bar is under more stress at full flex than is the stock bar. That will *technicall* make it more likely to fatigue though it's high unlikely either will.
Frank
05-11-2008, 05:01 PM
#14
Thought I'd link this old thread as it has a lot of info about different sizes on the T bars and who makes what, just in case someone is trying to make a particular decision. Sizing info starts around post 16.
https://www.yotatech.com/forums/f31/...on-bars-28507/
https://www.yotatech.com/forums/f31/...on-bars-28507/
05-11-2008, 05:57 PM
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Everything I've ever heard about springs, torsion or otherwise, says that you should only use a spring stiff enough to support your vehicles weight at the desired height. Using anything stronger or higher-rate is generally only recommended when there is limited travel and shocks/struts don't have the proper valving on the jounce and rebound strokes to sufficiently slow down the wheel's upward / chassis downward travel to prevent bottoming out, or to compensate for your vehicle's gained weight.
I could understand a slightly stronger torsion spring on our trucks when a long-travel suspension kit is installed due to the fact that the control arm is longer than stock and increases the leverage of the suspension against the torsion springs (although not that much, relatively speaking: would another 3" on that big-a**-breaking bar give you all that much more advantage?) or when necessary, as mentioned, to counter any additional weight being carried such as heavy tube bumpers, winches, etc. However, for most stock, or semi-stock situations like 'differential drop' IFS lift kits where the control arms sit at the stock angles, the stock torsion bars are actually more than adequate.
The whole concept of 'preload' on these springs means little-to-nothing since it is not a valid argument with regards to the operation of the torsion spring. The only 'preload' the spring has is whatever tension is on the spring when the suspension is at full droop. When the vehicle is placed on the ground the springs become 'loaded', not 'preloaded'. Adjusting the torsion bars does not add any additional tension to the spring once the vehicle is on the ground- it is carrying the same load if the suspension is 1/8" from the droop-stop or 1/8" from the compression-stop.
Does the truck magically gain weight if you crank in that extra 1" or so lift with the bars or add ball-joint spacers? NOPE. The difference is once lifted, the torsion bar has an extra 1" or so of compression travel to cope with, not any extra weight. That extra travel equates to a few extra degrees of rotation which puts additional stress on the bar that it didn't have to cope with to begin with. This extra stress may be enough to fatigue the bar and eventually cause its failure since the extra stress is something the bar wasn't designed for in the first place. Your real options here are install a 1" taller compression bump stop, a bar capable of handling the extra twist- which counter-intuitively means a softer bar, or a stiffer bar that won't break when over-leveraged. Ask any SAS equipped truck what stiffer springs would do to their ride and they'll probably say it would limit travel and flex. Well, no wonder IFS trucks don't have much articulation. Imagine if that torsion bar was strong enough to support the truck at the proper height on flat ground but soft enough to let that wheel climb all the way up the wheel well without upsetting the chassis. What we're dealing with here is called 'spring rate' or how quickly does adding tension to the spring cause it to get more firm.
On a related note, it is the shock/strut's job to respond to the bumps in the road and help slow down the lifting wheel and falling chassis, not the springs. The springs are there to keep the wheels on the ground and the chassis off of it. If you find yourself bottoming out too often, get more appropriately tuned shocks for your driving style. If you can't get the shocks to meet your needs, then a progressive rate spring is in order, but good luck finding a progressive rate torsion spring.
There are a few notable exceptions to what I've written above which I won't go into now except to say that a purpose-built vehicle has different requirements for operation than many of our trucks which operate on the highways as well as off-road. Everything is a balance and choosing only what you need and not what some marketing spin says you have to have is the better way to go. Stiff springs, in my opinion, are only useful as mentioned above- for carrying extra weight, or when it is not possible for the shocks to sufficiently dampen the suspension movement.
/me steps off of the soapbox
I could understand a slightly stronger torsion spring on our trucks when a long-travel suspension kit is installed due to the fact that the control arm is longer than stock and increases the leverage of the suspension against the torsion springs (although not that much, relatively speaking: would another 3" on that big-a**-breaking bar give you all that much more advantage?) or when necessary, as mentioned, to counter any additional weight being carried such as heavy tube bumpers, winches, etc. However, for most stock, or semi-stock situations like 'differential drop' IFS lift kits where the control arms sit at the stock angles, the stock torsion bars are actually more than adequate.
The whole concept of 'preload' on these springs means little-to-nothing since it is not a valid argument with regards to the operation of the torsion spring. The only 'preload' the spring has is whatever tension is on the spring when the suspension is at full droop. When the vehicle is placed on the ground the springs become 'loaded', not 'preloaded'. Adjusting the torsion bars does not add any additional tension to the spring once the vehicle is on the ground- it is carrying the same load if the suspension is 1/8" from the droop-stop or 1/8" from the compression-stop.
Does the truck magically gain weight if you crank in that extra 1" or so lift with the bars or add ball-joint spacers? NOPE. The difference is once lifted, the torsion bar has an extra 1" or so of compression travel to cope with, not any extra weight. That extra travel equates to a few extra degrees of rotation which puts additional stress on the bar that it didn't have to cope with to begin with. This extra stress may be enough to fatigue the bar and eventually cause its failure since the extra stress is something the bar wasn't designed for in the first place. Your real options here are install a 1" taller compression bump stop, a bar capable of handling the extra twist- which counter-intuitively means a softer bar, or a stiffer bar that won't break when over-leveraged. Ask any SAS equipped truck what stiffer springs would do to their ride and they'll probably say it would limit travel and flex. Well, no wonder IFS trucks don't have much articulation. Imagine if that torsion bar was strong enough to support the truck at the proper height on flat ground but soft enough to let that wheel climb all the way up the wheel well without upsetting the chassis. What we're dealing with here is called 'spring rate' or how quickly does adding tension to the spring cause it to get more firm.
On a related note, it is the shock/strut's job to respond to the bumps in the road and help slow down the lifting wheel and falling chassis, not the springs. The springs are there to keep the wheels on the ground and the chassis off of it. If you find yourself bottoming out too often, get more appropriately tuned shocks for your driving style. If you can't get the shocks to meet your needs, then a progressive rate spring is in order, but good luck finding a progressive rate torsion spring.
There are a few notable exceptions to what I've written above which I won't go into now except to say that a purpose-built vehicle has different requirements for operation than many of our trucks which operate on the highways as well as off-road. Everything is a balance and choosing only what you need and not what some marketing spin says you have to have is the better way to go. Stiff springs, in my opinion, are only useful as mentioned above- for carrying extra weight, or when it is not possible for the shocks to sufficiently dampen the suspension movement.
/me steps off of the soapbox
05-11-2008, 06:05 PM
#16
Registered User
People are running up to 22 years on stock bars without failures with 1 or more inches of ride height over stock. Bar fatigue is not something I would worry about. Even if they do fatigue, gosh they last decades longer than a coil spring under similar off road circumstances (or even on road for that matter). Want an example, check out coil sprung 4runner rear end sag.
Frank
Frank
05-12-2008, 03:54 AM
#17
Contributing Member
So replacing the stock Tbars with OME Tbars would be the next best thing for added weight up front then? is that what i am understanding? since i have a winch on the way and soon going to make a thick and heavy winch bumper. and running bigger tires/wheels. and soon looking into lockers/gears and possibly a suspension upgrade (coil sprung hilux SFA or Coil-Over kaddy kit).
So i guess my question is...OME bars would perform better under more weight than stock bars?
So i guess my question is...OME bars would perform better under more weight than stock bars?
05-12-2008, 05:19 AM
#18
Contributing Member
So replacing the stock Tbars with OME Tbars would be the next best thing for added weight up front then? is that what i am understanding? since i have a winch on the way and soon going to make a thick and heavy winch bumper. and running bigger tires/wheels. and soon looking into lockers/gears and possibly a suspension upgrade (coil sprung hilux SFA or Coil-Over kaddy kit).
So i guess my question is...OME bars would perform better under more weight than stock bars?
So i guess my question is...OME bars would perform better under more weight than stock bars?
Lesson learned: The front suspension has a lot more weight on it when going down a steep trail.
You'd think I would have learned that the first semester of Physics LOL.I made these heavy duty bump stops to replace them:
BTW you can cut a lot of weight out of the winch by running a synthetic winch rope and aluminum fairlead.
Or you can take it a step further and make the winch removeable and just carry it in the back.
Last edited by mt_goat; 05-12-2008 at 05:43 AM.
05-12-2008, 06:08 AM
#20
Contributing Member
Do you travel that jungle by yourself? Sometimes I think it would make more sense to have the winch in the back. That or back into the bad trouble spots, especially deep water with big snakes LOL.
Last edited by mt_goat; 05-12-2008 at 06:11 AM.
