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Discussion Starter #1
I'm wanting to make a set of lift/ladder bars for my 63 Chevy II gasser, I have not been able to find much tech on these. I have some 2x2x120 tubing that I'm using for my sub-frame connectors, I will be installing a 2x3 dropped cross-member. From what I have been able to measure and figure out my cross-member will need to be 34" in front of the rear axle C/L to put the cross-member where it need to be for the main hoop in the cage. My plan is to use some of this tubing and make lift bars (like the old thunderbolts used to have) that are welded to the axle and have a mount on the cross-member. I'm thinking on using a rubber or poly bushing that will fit in the bars, and will be easy to replace if worn out. To mount the bars to the axle I planned on using 1/4" plate with a 1.5" radii to fit the axle and extend down low enough so that at ride height the bars will be parallel with the ground, is any of this correct? any help will be much appreciated
Thanks
 

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machinist & fabricator
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when i designed my rear suspension, i used 2 x 3 box tubing for trailing arms,
welded them to the rearend and mounted them off the tranny cross member like your talkin about...
the only diffrence is that i hate bushings... so i used stainless steel bungs for the mounting point to the cross member. and 1/4 plate tabs to mount them.
sounds like your on the right path... but remember... its a gasser, not a street rod.... use a solid mounting point! IMO

you can see the front end bungs sitting on the frame, same as thats in the trailing arms



 

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Discussion Starter #3
Thanks for the help, as for the bushing go I want to rid my self of the binding during body roll that you have during normal street driving
 

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Philippines Cowboy
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888 Posts
Since ladder bars are solidly attached to the axle housing, the "parallel to the ground" business is unimportant (except, of course, aesthetically). In other words, they could...if it were possible...be 45 degrees from the ground and the car would behave exactly the same. What's important is the location of the pivot points relative to the no squat/no rise (100% anti-squat) line. It's hard to tell, from your description, whether the pivot points will be above or below the line. If above, the rear of the car will rise on launch; if below, squat. You'll have to figure it out for yourself. There's plenty of information at my blog:

http://home.earthlink.net/~whshope

(You might also consider positioning the right side pivot higher than the left to cancel driveshaft torque effects. I know I discuss this sort of thing for 4links and 4bars, but I don't think I cover ladder bars. If you want to do this, just PM me with specifics and I'll help you.)
 

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Discussion Starter #6
correct me if I'm wrong. If the bars are below parallel (nose down) the will tend to unload the rearend during hard breaking??? where do I set the pinion angle? If the bars are welded to the rear there will be no "twist to the rear" (pinion moving up and dow, like in a leaf spring) but correct will change on the natural arc of the suspension travel???
Thanks
 

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Philippines Cowboy
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1963duce100 said:
correct me if I'm wrong. If the bars are below parallel (nose down) the will tend to unload the rearend during hard breaking??? where do I set the pinion angle? If the bars are welded to the rear there will be no "twist to the rear" (pinion moving up and dow, like in a leaf spring) but correct will change on the natural arc of the suspension travel???
Thanks
Since the ladder bars are solidly connected to the axle assembly, you can consider the entirety as just one big piece acting on the remainder of the car through the front pivots. So, as far as the rest of the car is concerned, it doesn't know if the ladders are parallel to the ground or not. Again, the important matter is the location of the front pivots.

Yes, the ladder bar arrangement magnifies the pinion angle changes during suspension travel. But, with a front pivot as far forward as you describe, this is nothing to worry about. Just be certain that the pinion is aligned at ride height.
 

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Discussion Starter #8
I'm going to gun leafs with sliders, ir will be easy to set the pinion angle at ride height. Thanks for the help. Any more incite before I cut and weld???
 
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