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DIY ladder bar/torque arm

Discussion in 'The Hokey Ass Message Board' started by ben s., May 6, 2013.

  1. ben s.
    Joined:
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    st. louis

    ben s. Member

    started making a ladder bar/torque arm for my 1950 pick up.

    1-1/4" x .120 DOM tubing (12')
    3/4"-16 threaded rod ends (x3)
    3/4"-16 Comp. Eng. solid rod ends (x2)
    3/4"-16 threaded bushed end (x1)
    1/4" mild steel plate
    leaf spring shackle, 90's chevy 1500 (x1)

    I decided on a torque arm style mount because it would rotate about the center of the rear axle and not bind during street use. Ladder bars tend to create a giant anti-roll bar out of the rear axle, limiting articulation.

    the hardware is for mock up, the non-hardened stuff will be replaced. I was having trouble finding hardened bolts with the correct shoulder length.

    the shape is basic, consisting of two triangles, one circumscribed about the other when finished.

    my truck is for street use. i plan on taking it to the track periodically. with this set up I feel that i can retain the stock style leaf springs.

    the front shackle mount is 1/4" mild steel. the rear axle mount will be more of the same.

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  2. ben s.
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    ben s. Member

    welded the ends

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  3. ben s.
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    ben s. Member

    the triangulated outside bar with ends welded on.

    i'm using a Hobart TIG for all welds

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  4. ben s.
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    ben s. Member

    i've been working on this for two days. i want to get it done this week.

    the bar is 34-1/4" on the top and 10-1/2" on center.

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  5. Motomike43
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    Motomike43 Member

    Looks good. You have not shown any pics of the actual welding process. I hope you are using a JIG. Its rather important that the are 100% equal side to side. And square. Even a very basic crappy jig you throw together fast is fine. As long as you can clamp the bars down so they do not move at all when you weld. and it make both sides the same. Good luck. They look good. You welds look good.
  6. ben s.
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    ben s. Member

    I'm only making the one bar so I don't have to worry about duplicating the exact shape. I don't have a jig (lesson learned now!) and should've put more thought into that. Sometimes I'm a dumbass. I used the bench vise and various squares. It turned out decent, although I did notice some movement during welding. Again, not that big a deal as I only need one, but something ill invest more time in for future builds.
  7. ben s.
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    st. louis

    ben s. Member

    I added another brace today. I've been fishmouthing the tubes with a grinder and such and it's proved to be a pain. the cuts aren't perfect but the weld fixes them right up ;).

    still no jig. Been doing all of the sizing and work on the bench with the bench vise.

    I'm going to add another brace in the back to complete the inner traingle and brace the axle side of things. The front might get a triangular gusset.

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  8. nailhead terry
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    nailhead terry Member

    late model camero firebirds used a simular setup and the origanal truck or you using a panard bar or just stock floaters
  9. ben s.
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    ben s. Member

    I'm not quite sure what you mean there. I got the idea from the Camaro rear end but I'm not using housing floaters or spring sliders. The axle is a ford explorer 8.8 mounted over stock rear leaf springs. The panhard bar reduces sway from the leafs and also provides some of a "jacking" effect that similar to what a j-bar does for dirt cars.
  10. nailhead terry
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    nailhead terry Member

    For the tourqe arm to be a three link the housing must be able to rotate on the outside axis you have created one large traction bar on stock ad trucks the rear axle housing had floaters that attached to the spring as it went through the arc it would allow the rear end to move back and forth and not bind on the springs this is fine for drag racing ! but for ride quility it should float .The camaro and birds used 2 more links and coil springs the way this is set up you are moving the lift point out front of the bumper sticky enough tires and enough horsepower wheel stands should be possible .How much flex will your rod end allow because you are going to have side to side movement ! great job hope it hooks hard !!
  11. ben s.
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    ben s. Member

    Right, I remember the stock axle having tiny shackles or something at the bottom (it is pictured earlier, the pic may be hard to make out) What I've done is put a late model 1500 Chevy leaf spring shackle in the front mount. There is a threaded, bushed end link at the front of the bar and the Chevy shackle uses a bushing to mount it to the chassis plate. With this enabling the arm to move fore and aft with suspension cycling, and with the bar being very close to the midline of the truck, I hope to mitigate the binding that occurs with traditional ladder bars.

    Thanks for your support dude!
  12. ben s.
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    ben s. Member

    Finished the bar. Added a vertical rear support and a gusset in the front. Going to make some end link safety straps because the new bars come with them and it seems like a good idea. Just gotta make the axle brackets now.

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  13. ben s.
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    ben s. Member

    used some string and a framing square to find the centerline of the frame. the explorer rear axle has the offset pinion so i couldn't run it parallel it to the driveshaft.

    the mount is made of 3/16'' angle steel that i trimmed down with grinder. rear bolts are 3/4". i plan on making a brace running around the back 180* of the axle housing. should be stiff enough.

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  14. ben s.
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    ben s. Member

    i used the TIG to weld the bracket on. no problems. instead of cast iron, the ford explorer axle is steel. welds pretty easily.

    the bottom bracket is probably going to be more of the same 3/16'' angle.

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  15. DICK SPADARO
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    DICK SPADARO Member

    Ben s, no reason to use the panard rod the installation will create a bind in the suspension as it operates against the spring shackles and should be eliminated. The torque arm should be mounted at the front on a toggle not a fixed point so the swing of the rear axle is complementary to the spring rotation and displacement.
  16. ben s.
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    ben s. Member

    Dick, there is a reason for the panhard rod. The leaf springs are thin as far as leaf springs go (~1-5/8", instead of 2-1/2") and they sway. They do not locate laterally with the stiffness of new springs. There's should be no binding as the panhard arcs through the 'sway' of the springs laterally.
    All three mounts for the ladder bar are bushed. The front mount is another leaf shackle from a newer Chevy truck. It has two bushings. The panhard will displace the axle no more than 1/2" at max travel (which is rarely encountered). The 'sway' without the bar was worse. The maximum articulation about the front mount is less than the two bushings can move. All of the bars have bushed ends, I fail to see how they will bind.

    As the leaf springs compress it will displace the axle rearward, what... Like an 1" at most? The shackle can soak that up. They used to do it on old gassers and still do it on big 4x4 street trucks. I don't anticipate any problems with this, but thank you for your comment. I had considered this during the initial planning.
  17. DICK SPADARO
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    DICK SPADARO Member

    Nope, Doesnt matter if the springs are 2.5 or 1.5 wide springs, if it moves side to side the mount bushings are too soft or shackles are too loose. The springs locate the rear axle and only move front to rear if yours rock side to side bolted to the rear axle something is wrong. Addition of a panard rod is a band aid to another problem.

    Ok the front of your torque arm is toggled with a shackle, two points of movement, cant see that in the picture.

    If you are experiencing a roll or sway as you say this is usually due to too soft a spring combination, what did these come from and did you remove any leafs? This can be cured with a stiffer spring pack, stiffer rebound shock absorber or anti roll bar. You experience the lesser roll with the panard rod because it binds everything up, eventually something will break.
  18. ben s.
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    ben s. Member

    The springs are stock. Had a local spring shop go through them and check them out. New clamps, bushings, all hardware, shackles.... It's all new. Shouldn't be any different than normal except for the age of the springs themselves. The shocks are new. There are no springs missing.

    Yes, regardless of width, the springs do locate to the center, but their width is a big factor.
    http://www.engineersedge.com/material_science/leaf-spring-design.htm
    They locate to the center, but given their width, spring eye height, and shackle thickness, they're not nearly as rigid as newer, wider springs. I've been considering new sprigs for sometime, and I am fairly sure that I will adapt newer springs from a truck (explorer, s10). they will enhance the ride and I suspect that I will no longer need a panhard. If I have new stock style sprigs made, the bar stays and I leave the rubber bushings in the shackles to allow them to flex and let the bar do the centering. As it stands now, it stays. If the suspension has a propensity for some lateral movement, then the bar shouldn't bind it. Another option is making a new rear cross member and mounting the shock perpendicular to the springs like a coil over set would look like.

    Is it a band aid? Yes and no. New shit costs money, and I had the bar laying around. After a bunch of reading on the issue I didn't think it'd hurt much. There's some interesting threads on rear panhards by the ford lightning guys. Their bars are longer and move half as much, but i don't think I'm in danger of breaking anything. I'll figure out something to do with it and post it down the road.
  19. marks73turbota
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    marks73turbota Member

    The panhard bar will impart some sideways movement of the rear axle as it goes thru it's travel/arc. But, it will depend on the length of the bar (mount to mount point), the length of rear axle travel, and the stiffness of the spring pack and mounting eyes/shackle how much that is. You said the rear already exibited side to side motion so you should not see any binding if it was already present. The only down side is, if you have a lot of suspension movement, the side movement will cause a loose rear end feeling, although it will be the same all the time and predicatable. Without it the sideways motion would be different at each encounter. Vehicle speed, road surface, and aggresiveness of the cornering changing the effect. The front bar/rod end inclosure is a good idea but not a big deal on your setup. On many suspension setups, the ladder bars are the only means of attachment for the whole rear end to the car. Thus, you don't want the rod end/mounting bolt to break and allow the rear end go drastically out of position. If yours breaks the rear end is still fully mounted and wiill not dangerously affect the handling of the vehicle. But if you have the room it does not hurt anything either. The front of the stock torque arms on the GMs does not solidly mount but is mounted in a rubber lined bracket that allows the arm to move in and out (forward and backward) within the rubber. But it restricts the up and down movement within the thickness of the rubber. Your short shackle will do the same thing just fine although you may notice some road/suspension noise transfered thru that all metal mounting. If you were to make the top shakle mount a rubber bushing, such as the bushing used on suspension arms etc. That could cut even that noise down a lot, if not eliminate it, without hurting the effectiveness of the bar.
    Mark L
  20. ben s.
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    ben s. Member

    finished everything up today. got the lower mount done and bolted on the shackle mount. it started raining so I didn't get a chance to test drive it. i'm calling it done for now, although I noticed some hot cracking (+1000*F; happen instantly) on the lower weld and some cold cracks (-1000*F; takes days to show) in the upper. gonna grind those out and use the MIG on 'em. from what I've read, I should use a lower amperage setting and adjust my weld pool to something that isn't is wide, even layered in some areas.

    live and learn I guess. the lower mount was more of a pain than the upper. I had a suspicion that I should use a different machine for the brackets, but I figured i'd give it a go with what I had on hand. i'm picking up my MIG in the next few days so i'll get it sorted out then.

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