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Old 04-23-2011, 08:56 PM
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straigth axle cars with rack and pinion steering

Has anyone installed a rack and pinion steering system on a straight axle car? I have a 29 Chevy that has a leaf spring front end with a straight axle , I plan on keeping all original suspension and only replace the steering box with a new rack. Before I go too far I thought I would see if anyone has any advise on this.

I did call a very popular speed shop and the sales rep. stated it was not safe to use a rack under a straight axle car? I did not understand why it would be any less safe than an steering box and I would like to get your opinions on this.

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Old 04-23-2011, 09:59 PM
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There is a cross-steer R&P made by Unisteer. They show units for early Fords, don't know why it wouldn't work for early Chevys. Call 'em up and chat....
http://www.unisteer.com/search_by_pr...1928-1932.html
I was reading that the only way to do a conventional R&P with a straight axle is to mount the R&P to the axle. I'm thinkin' that would probably be butt-ugly, but hey, whatever.
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Old 04-23-2011, 11:38 PM
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Tech's right. if you mount the rack to the frame, it'll bump steer.. has to be on the axle to work..

The Unisteer setup, basicly replaces the Vega box and drag link with a single sided rack.. if you could accomodate that in your frame, then it would work.. I would think the cross steer setup would be most adaptable
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Old 04-24-2011, 12:09 AM
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Rack & pinion steering is for independent front suspension, using it on a solid axle car will cause MASSIVE amounts of bumpsteer

your only bet is to use the Unisteer (or similar) and maintain the factory design of the steering links (IE: spindles tied together w/ a drag link w/ a tie rod connecting the rack to one of the wheels)
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Old 04-24-2011, 06:07 AM
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Hold on people!!.. You guys are thinking rack mounted to frame..

I ran a rack on an anglia front axle back in the day. Steering was fine..

I believe it was an Opel rack. Mounted directly to the axle. I had to use a splined coupler as there was a very small for and aft movement in the shaft as the suspension went thru its 3 1/2" travel. NO bump steer and handled about as well as a short car with a big block hanging over the front axle could be expected to.
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Old 04-24-2011, 06:30 AM
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Quote:
Originally Posted by techinspector1
There is a cross-steer R&P made by Unisteer. They show units for early Fords, don't know why it wouldn't work for early Chevys. Call 'em up and chat....
http://www.unisteer.com/search_by_pr...1928-1932.html
I was reading that the only way to do a conventional R&P with a straight axle is to mount the R&P to the axle. I'm thinkin' that would probably be butt-ugly, but hey, whatever.
Here's center steer rack mounted on axle
Butt Ugly??????
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Old 04-24-2011, 06:35 AM
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As stated by a few, bump steer can not be an issue when the rack is mounted on the axle. How to mount it on the axle is the first issue. How to align the caster and camber in this day becomes a real issue. Toe is easy once you locate the position the rack in its centered position. The location and the quality of shocks you install will become key to handling.

Trees
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Old 04-24-2011, 02:12 PM
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Quote:
Originally Posted by da34guy
Here's center steer rack mounted on axle
Butt Ugly??????
That particular installation is aesthetically pleasing. Maybe I was a little hasty in my assessment.
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Old 04-25-2011, 09:53 PM
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I've seen a few of the unisteer racks installed instead of a vega box, everyone seems happy with them. For rack and pinion on a solid axle, that's the way I'd go. As far as mounting a normal rack on the axle, it's not without problems. First, when the rack is mounted to the axle, the rack is closer to the axle center line than it would be on an ifs application. Assuming the rack is rear mounted, your tie rods angle back to the spindles, instead of straight out, causing some odd ackerman angles. Granted, it's more of a problem at large steering angles, but it's still a problem. Second, the u joints from the column to the rack aren't really designed for that application. Typically, steering u joints make small turns from a supported column to a supported box or rack. The shafts only rotate, they don't move with suspension movement and they don't have to change length. Mounting the rack to the axle means the shafts and joints have to allow for movement of the rack with suspension movement, and have to allow for the change length that movement brings. More like a CV joint than a u joint.
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Old 04-25-2011, 11:01 PM
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Rack steering on axle

In order to function correct the rack has to be mounted on the axle for the geometry to be correct. With a straight axle and a rack and pinion steering, the rack needs to move with the axle or you will have serious bump steer that can be dangerous at highway speed. This then requires a steering shaft that allows sliding up and down movement. Early Ford Taurus had a steering shaft that used a nylon bushing with a sliding shaft that works well with this set up.

Last edited by Studebaker; 04-25-2011 at 11:06 PM. Reason: correction,
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