Rack and Pinion with i-beams??

[billymanfroy]

We are wondering if it's possible to use a rack to replace the stock, leaky, bulky steering box on a beamed ranger. We would like to ditch the box if at all possible. Do you need swingset steering, or can you just "crossover" the links to opposite sides of the rack to reduce bump steer? I hate to admit I've never studied other vehicles for this.

Any help, suggestions or pics would be greatly appreciated. As it is, the oil pump hits the box on our new engine. (Yes, we can fab new brackets to raise the oil pump up a few inches.)

Billy

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[ntsqd]

Bumpsteer will be your enemy. I would guess that your best bet would be to drive some sort of swingset type linkage with the rack as most of the racing racks aren't wide enough to get the inner TRE/SRE's anywhere close enough to the right place. I'm not all that fond of the swingset design as it forces a compromise due to the arc that the vertical components travel in. This moves the inner pivots vertically away from their ideal location.

My last year at Chico State I was asked to sporadically advise the fledgling SAE Mini Baja Project. Their steering system consisted of a ''rack'' that had the inner SRE's attached to it. This consisted of a square tube that slid thru brass bushed square bearings. Perhaps something like this could be made to work better than a swingset ? Maybe it doesn't matter.

The way the Mini Baja drove the tube back and forth I thot was novel and has absolutely no bearing on what you need to do. They built what amounted to a Capstan Winch. The end of the steering shaft had a spool on it with 3-4 wraps of cable around it. One end of the cable was anchored to the tube and the other had a turnbuckle anchoring it to the tube. Changing the spool's OD changed the steering ratio.

[billymanfroy]

Thom,,

We built a stand alone rack using two .750" shafts, mounted one in front of the other which looks like this from the sideview: o=o

We ran cromo tubing with linear bearings in each end for a total of 4 bearings. We had to use two shafts to keep the twist out of it like your square bearings. It would have had the TREs attached in a crossover-style to make the links as long as possible. We still had to rely on the stock box, though, which defeated the purpose. We were originally going to sell them as a bolt in crossover alternative. Maybe a ram attached to this slider would work?!?

Billy

[ntsqd]

I think you're on the cusp of something. Can you make your parts also hold one of the heavier duty buggy-type racks ? If so then you have a bolt-on bumpsteer eliminator kit that includes a low turns Rack & Pinion. Using such a rack would elim the need for a ratio qwikener and has the ports for a slave cylinder.

[Greg]

Any thought about ditching the whole steering box completely and doing something like Nye Frank has done? Just a lever arm through a steering quickener in reverse. And Thom, what if you were to design the swing-set on teh x-over steering to actually correct for lost ackerman do to moving everything forward? just a thought.

[ntsqd]

Going to a rack would loose the stock box. Mount the rack to the slider's frame work and drive the slider with it.

I've not seen Nye Frank's design so I will only comment that ratio quickener's are designed to have the steering box btwn them and any impact loading. They aren't designed to be the primary steering gearbox. Unless you've done the math, the destructive failure testing, and know that it won't fail; I wouldn't go there. Nye Frank can because he undoubtably has done all of the above.

Lost Ackerman due to moving what forward ? Moving the steering linkage around w/o also moving the spindles the same amount messes with a lot of things, but Ackerman isn't one of them. Primarily bumpsteer would be the issue at hand.