Steering Box Geometry

FUMMER

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I have been playing around with using a steering box for my A-arm car and have found it to be entertaining. I have seen a few photos of the swing sets and several using varied methods of achievement. Does anyone have some principles or guidelines to narrow my modeling down a bit. I have heard that matching the KPI into the swingset and a few other tips, but they way they were explained was in one ear-scrambled-out the other. Thanks
 

FUMMER

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Ok, here is where I am at. Trying to make a clean drawing with proper relations and references to keep things simple (yeah right). Will add some more so I am more clear on what is occuring and how to counter it. The UCA/LCA/KPI/Ackerman is set for my tire, wheel base and brakes. Hopefully post some more pics soon.
 

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FUMMER

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A little history. This model was a "pre-run" and I realized that the width of the Howe 2.0 made it difficult to have A style arms. The rack would collide with the arm on full bump. I also wanted to find a more "affordable" steering system. A manual Howe rack is not bad, and would be easier to just make the front of the arm perpendicular to the center line. It is going to be about 22-2500 pounds i am guessing.
So far. 19" travel. 8* on bump with .33 scrub/5.25* on Droop with .06 scrub. 1*ride/0
.83 scrub radius.
 

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Scott_F

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Are your tires available in 37"? ha

Your arms look mighty beefy to be using heims as ball joints. I would redesign those arms for uniballs. Use the heims for your UCA pivots.

Since you are apparently building everything from scratch, why not centermount those LCAs?

A horizontal swing set, with or without matching the KPI, should work nicely for you.
 

FUMMER

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There are so many configs. of the basic design I can hardly keep them organized. Uniballs are in the most current. A horizontal swinger like the -dont remember whos truck that is in the pic. Being a buggy do you think I could 86 the sector shaft reinforcement? No unfortunately 37 is not an option for a bug with a "reasonable" track width.
 

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Scott_F

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The tire comment was a joke about your tire model. You never said what you are building (Baja Bug?).

With a rear engine, I think your sector will survive without the support. I am considering the same option on my project.
The main difficulty I see is getting the support tube and bearing to be perfectly aligned axially with the sector shaft, so there is no radial run out.
 

FUMMER

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It is a Bug. I would like to run a bigger tire since my beam car has almost 18" of clearance at ride height. The arm set up is at best 16 or so. Is there a preference on which box to use. I was thinking a 525 manual box, borgeson has them in a 16:1. I figure I can quicken it up in the pitman and swingers. Re laying out my assembly without frame rails and adding some new planes and mates. Yeah the runout is always fun. Even machining a 0 clearance step is not always perfect. If I did need the support I figured the obvious start would be some lathe time, step, and truing again after welding.
 
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