DOM tube

[Jesus_man]

See if you can find out what existing designs use as far as material. DOM is pretty strong stuff, but HREW may be plenty and cheaper. Also, what is your design? Just making sure you allow for the suspension to do it's thing.

J.D.

[Tom S]

Well there is one guy on PSN using the exact same brackets with the same truck configuration that had good luck with the set up. I am just moving the mounting point forward a couple of inches to be a better match for the suspension path when I mapped it out on a big piece of cardboard. It will also mirror the driveshaft angle.

http://powerstrokenation.com/forums/...ad.php?t=22953

Tom

[Jesus_man]

Tom, I was worried that this was the design you were after. I was looking at the pictures from the first 5 pages and the design is nearly all the same. Let me try to explain the design flaw.

With leaf springs, as the compress and re-arc in their cycle, the spring changes length. Since the shackle is on the rear of the spring, the spring gets longer as it's compressed and moves towards the rear of the truck, thus the axle actually moves back with it. If you put a solid bar between the frame and the axle, you stop that motion, which does two things, it makes the ride much stiffer because the spring can't move and it could break parts. What scares me is I see some name brands in there.

Measure your spring eyes center to center empty, now place 500+ lbs in there and see how much longer they are. You axle will move approx. half of that distance.

A better design is to put a shackle on the end where it attached to the frame. A little more involved, yes, but it doesn't bind the suspension at all.

Ahh, finally a link: http://www.4x4review.com/Reviews/Pro...3/Default.aspx
In your case, since you are not rock crawling you're truck, you don't need the fancy Johnny Joint at the frame end, you could use all spring bushings.

how this design works, is when you're rear axle is trying to wrap, it's pushing the nose up. So the shackle stops that, but still allows the axle to move forward and back as the suspension cycles.

That make any sense?

J.D.

[Jesus_man]

Oops, as I have gotten further down the post, I see you already purchased most of the stuff. It might work, but you're only saving grace as I see it is make the bars the right length to travel in the same arc as the axle does. You'll only know that by testing with heavy loads and lifting the truck up by the frame.

[Jesus_man]

Another example, however the shackle needs to be on top of the cross-member, not below.
http://forum.ih8mud.com/60-series-wa...ront-axle.html

Steel is stronger in tension than compression. That's why the desert racer guys truss the bottoms of their axles, to take the stress of big air. So you want your traction bars to pull on the shackle, not try to squish it.

[Tom S]

I actually have this layed on full scale on a big piece of cardboard. With the mounting points I selected the traction bar will follow the fore and aft movement of the axel as the suspension is compressed and relaxed. With the minimal arch in the springs on my truck the movement is not a lot compared to a vehicle with more aggressively arched springs. I also did some testing by jacking the truck up by one wheel or letting the suspension hang free. There is not the same degree of travel on a truck like mine that there is on a flexy rock crawler. I think I am going to try this route and see how it works. If it does not I will just re-engineer the design and go to a two point mount with a shackle like you are suggesting.

I would enjoy discussing this some more though as I am always open to alternate ideas.

Tom

[Jesus_man]

If I was more savvy in Solidworks, I'd model it for you and you could watch the movement on the screen, but I am not that good yet. It seems feasible to have the traction bar and the axle on the same circle radius, but honestly, I still worry about the bracket you added to your axle. That is attached near the center of the axis of your axle and won't control axle wrap nearly as good as something mounted above or below.

J.D.

[Tom S]

Originally Posted by Jesus_man

If I was more savvy in Solidworks, I'd model it for you and you could watch the movement on the screen, but I am not that good yet. It seems feasible to have the traction bar and the axle on the same circle radius, but honestly, I still worry about the bracket you added to your axle. That is attached near the center of the axis of your axle and won't control axle wrap nearly as good as something mounted above or below.

J.D.

I was wishing I had a CAD kind of program to model this on two but had to settle for just a layout. Basically it is just creating an arc that best follows the high point (compression) aft low point (droop) forward of the mounting point on the axle as the suspension travels. By having the front mount at the proper height you regulate the angle formed by the top and bottom points of the arc.

Tom

[Tom S]

Originally Posted by CGuava

Tom,
I always go to Hinton Steel off Santa Fe and Evans for all my steel. If you're just building a track bar, I'd say that 1.75 .120 wall should be enough. 2" .250 wall is HEAVY.

Christian

I called Hinton and it was $4.81 a foot $81.50 for a full stick and I think they said they only wanted to sell a full stick.

C & M on Old Hampden in Sheridan was just under $4 a foot and would sell half sticks. I will probably run over there in a bit.

Tom

[CGuava]

Really? I buy partial sticks from those guys all the time. But when I'm looking for 1.75, it's usually in whole sticks. It's the odd size stuff that I always buy 5' or 7', etc.

I was at C and M yesterday. I should have just asked and called you to let you to be sure you had the DOM stuff, as I'm headed to Littleton today.

Sorry I misinformed you, I'm surprised they don't sell it by the foot.