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Torsion bars breaking?

Discussion in 'Chevy Trucks' started by mkwl, Jan 22, 2008.

  1. mkwl

    mkwl 2000 Club Member
    Messages: 2,361

    Has anyone ever heard of (or experienced) cranked torsion bars snapping under load (i.e. plow) before? I wan thinking about it today and wanted to see what your experiences ahd been.

    Matt
     
  2. wild bill

    wild bill PlowSite.com Addict
    Messages: 1,239

    give me a break

    i have never seen one break from normal loading (ie) plow ,i saw a f150 break both one right after the other ,just pulling out of the drive with no plow .
     
  3. millsaps118

    millsaps118 Senior Member
    Messages: 694

    I never broke one but I know they will snap like a tooth pick if you crank the T-bars up and hit a pot hole or something to that effect, ie. sudden/brunt impact or jolt to the front susp. This can happen with or w/o a load on the front.

    Exact reason I never turn my T-bars any more than 8 turns-in.
     
  4. lehmand1

    lehmand1 Member
    Messages: 66

    I don't think cranking a torsion bar would make any difference wether on not it will break. I have never heard of it happening.

    Cranking the torsion bar doesn't put any more stress on it. The only thing that it stresses are the driveline angles of the cv shafts. You are just in a sense re-indexing the torsion bar, it still has the same spring rate and can carry the same load. It doesn't make it any stiffer. If your plow makes your front end drop 1", it will drop that same amount no matter where your torsion bars are set at.

    Some people think that cranking them up makes there truck ride rougher, this is not because it is stiffer. If you crank them all the way up, your suspension is close to reaching its maximum downward travel (shocks, a-arms, etc) then when you go over a bump or pot-hole, your suspension can't travel down far enough to compensate.
     
  5. millsaps118

    millsaps118 Senior Member
    Messages: 694

    I don't know where you get your Torsion bar info from but they WILL SNAP. "TORSION" is derived from the word "TORQ", so in relation to a torsion bar, a twisting or turning effect (torq) is being exerted on that log skinny piece of steel that connects from your lower control arm (susp. component) to a cross member . When your IFS moves up and down, that torsion bar twists.
    When you turn your T-bar bolt in (raising up) you are twisting/turning the T-bar through the "key" applying load to it causing the front susp to ride higher than stock. When you apply a load to something no matter what it is, it's just a matter of time before it fails.
    The tension on a torsion bar can only take so much and steel can only be twisted so far before it breaks.

    Lehmand...you be the ginnie pig and turn your T-bars in as far as they will go and drive around for a while over ruff pavement, post back and update us all when they snap.
    BTW turning the bars does make the truck ride stiffer and ride ruffer....., why do you think you feel it when its done????????:dizzy::dizzy:
     
  6. lehmand1

    lehmand1 Member
    Messages: 66

    First of all, I did not say that they will not snap. I said that they won't snap as a direct result from cranking them up. When you crank up a torsion bar, you are not putting any more twist into it than it had before. The amount you crank on the key is the amount it raises your lower control arm. The only way cranking it up would put more twist into the bar would be if your lower a-arm didn't move at all. But that wouldn't give you any lift would it.

    As to a truck not riding rougher I think I explained it pretty well in my post. It does feel rougher but it is not stiffer. If you hang an 800# plow on your truck and it drops the nose 2 inches you would expect if cranking them up made it stiffer it would then only drop 1 inch.
    But this is not the case, because the "spring rate" is the same. GM sets the suspension up from the factory for it to be able to travel a fair amount in both directions(bound and rebound). When you turn your bars up you are taking away a lot of downward travel and adding it to the amount of upward travel. Then when you go over a pothole or bump, your suspension and wheel do not travel far enough downward to take up the jolt, thus making the truck ride rougher because your suspension cant travel any farther.

    On a final note, I bought my truck new, I have 78,000miles on it, hauled countless loads of wood across rough fields with it, I live on a gravel road, and have plowed with this truck for the last 3 years, and I have had the torsion bars cranked all the way up since the first year I owned it. So I guess I already am the ginnie pig.
     
  7. NBI Lawn

    NBI Lawn PlowSite.com Addict
    Messages: 1,797

    X2, I cant understand why people dont get this. Cranking your T-bars is not a good idea :eek:! Sure if you do like one turn you would probably be fine but dont try to get a 3" lift out of it. Cranking them does cause added stress. When you turn the key you are just twisting the bar more, they can only twist so far before they fail.
    I have seen them break before. I dont think they will crack, with the stress on them they will probably just break right away.
     
  8. lehmand1

    lehmand1 Member
    Messages: 66

    But you are not twisting the bar more. The only way to twist the bar more is to add more weight to the front end. And then you would be twisting the bar regardless of wether you crank the key up or not. All cranking the key does is re-index the bar, it does not twist the bar or put anymore stress on it.

    The biggest thing that cranking them stresses is the CV shaft angles and it can sometimes over extend the shock absorbers.
     
  9. ticki2

    ticki2 Senior Member
    from NH
    Messages: 175

    When you adjust the rear of the torsion bar you are not twisting the bar , you are turning it , thats why it raises the lower control arm. If you add weight (plow) it will twist the bar ( more torque) . The harsher ride comes from the other front end compnents not being in proper position relative to each other. The only way to stiffen the suspension is to change the bar rating , or add a component. Then again, maybe I don't get it.
     
  10. NBI Lawn

    NBI Lawn PlowSite.com Addict
    Messages: 1,797

    Incorrect, so why is it that when you lift it properly with a lift key it doesnt ride like crap? You are changing the angle of the front end components.
    http://images.google.com/imgres?img...v=/images?q=gm+lift+keys&gbv=2&svnum=10&hl=en

    Every turn of the key twist the bar more. So lets just say as you tighten it the rear part of the bar closest to the key rotates 1/2 turn, the front has only turned 1/4 turn, the t-bar is twisting and under more stress in an attemt to raise the front more.
     
    Last edited: Jan 23, 2008
  11. ticki2

    ticki2 Senior Member
    from NH
    Messages: 175

    If by lift key you mean the green keys it will ride like crap if you don't some other things , like shocks and bump stops. If you go aftermarket lift , it will have a new control arm plus shocks.

    If you rotate the rear a 1/2 turn , the front will rotate a 1/2 turn . The front weight is the same no matter what height.
     
  12. lehmand1

    lehmand1 Member
    Messages: 66

    The link to those keys didn't say anything about not "riding like crap". Them keys do exactally the same thing that the adjuster bolt does. It re indexes the rear of the torsion bars. The only difference is "without the chance of stripping out the stock adjusting bolt."
    They lift the vehichle at the same point, in the same way(by re-indexing the rear of the bar).

    They even admit that the angles in the front end will be changed, but they say "PLC believes that the small increase in driveline angle is not enough to cause concern among 4wd owners, however a slight increase in CV boot wear is possible and should be watched.

    There is absolutly no difference in this lift and a "crank them up" lift as far as your front end and ride quality is concerned. The only difference is the method as to how they re-index the torsion bar.
     
  13. lehmand1

    lehmand1 Member
    Messages: 66

    ticki2- Im glad someone out there agrees with me on this on.
    I was begining to think I was fighting a loosing battle.:gunsfiring:

    Well off to go cut firewood for the daywesport
     
  14. NBI Lawn

    NBI Lawn PlowSite.com Addict
    Messages: 1,797

    They call them keys, did you follow the link? Real lift kits do not come with new control arms, not for a 4x4 anyway. They lower the cross member for the control arms. Some come with taller spindles.

    They do not turn equally. As the stress is increased one side will rotate more.
     
  15. NBI Lawn

    NBI Lawn PlowSite.com Addict
    Messages: 1,797

    Unfortunatly you guys are wrong. The reason the ride is stiffer is because the t-bar cannot twist much more.

    Lift keys are made so the t bars are not twisted more than stock while at the same time allowing the the position to be in a lower spot. Make sense? Here is a picture that may help.

    I dont care what you do but you are twisting the t-bars more than they should be especially after you put a load on them, ie plow.

    chevy-vs-ford.jpg
     
    Last edited: Jan 23, 2008
  16. JD Dave

    JD Dave PlowSite Fanatic
    Messages: 11,045

    I'm not exactly sure what your talking about. When you buy a Cognito Leveling kit it does come with new UCA's. They move the bump stop so when your bars are cranked, your truck isn't resting on the stops. The kit comes with shock extenders also but I would recommend longer shocks. Another thing is on most 2001 and up 3/4 and 1 ton pickups your stock keys are fine. There is nothing wrong with running your tb adjusting bolt all the way in if that's the height you want. I wouldn't run fully cranked with my blade on the truck though but some guys do. I've levelled alot of trucks over the years and I've never needed green keys. A spindle lift is for a 2wd truck if I'm not mistaken and I'm running the new UCA's on the 4" Cognito on my new GMC 4x4.

    On edit. I just read your link and I guess some 4x4 lifts are knuckle lifts. I would like B and B to give his thoughts on this but I see no use to putting the keys in unless you can't get enough height out of the old ones. I have never stripped my t-bar bolts and my truck did ride like crap untill I put the shock extenders in. I'm just debating this, not trying to start a fight. BTW I've never even heard of a t bar snapping.
     
    Last edited: Jan 23, 2008
  17. JD Dave

    JD Dave PlowSite Fanatic
    Messages: 11,045

    I should have just agreed with you, instead of posting. These shops selling keys lifts like to really stretch the truth to get you to buy something you don't need. JMO:drinkup:
     
  18. millsaps118

    millsaps118 Senior Member
    Messages: 694

    Little article from Truckin' mag.
    http://www.truckinweb.com/tech/susp...pension_handling_performance/torsion_bar.html

    Who ever wrote this must have miss-informed A LOT of people then.........:dizzy: :waving:

    Here's another link to a thread on PS back in JAN '08. go down to post 15 and check the link out. http://www.plowsite.com/showthread.php?p=487781
     
    Last edited: Jan 23, 2008
  19. NBI Lawn

    NBI Lawn PlowSite.com Addict
    Messages: 1,797

    I guess I dont know but if you raised the truck wouldnt the control arm be further away from the bump stop, not resting on it?

    Why do they even make a leveling kit if all you have to do is crank the piss out of you t bars :confused:
     
  20. saabman

    saabman Member
    from Maine
    Messages: 70

    When you crank the bar, it moves the lower control arm down (raising the truck). This moves it away from the bump stop. When the jacked suspension compresses, the lower control arm has more distance to travel before hitting the OEM bump stop. As such, it sweeps a greater angular distance, it will twist the TBAR more than it could of when the lower arm sat closer to the bump stop. This is why new bump stops are offered on some lift kits. They make sure the suspension does not "over travel". If you the suspension twists the bar to much, it will break.

    This is similar to putting lift blocks on a leaf springs and not lengthening the bump stops. In this case the spring can "invert"