Posted By: RUNCHARGER
Rack and Pinion on a beam axle? - 09/08/10 04:39 AM
Has anyone run a rack and pinion on a beam axle? Just curious if I can do this to gain power steering on my 70 Sweptline. I want to keep the front leaf springs and beam axle as that is part of what makes the truck. It seems simple enough, mount the rack to the frame, match up some tie rod ends that fit the knuckles, make sure nothing interferes. Anything else?
Sheldon
Posted By: poorboy
Re: Rack and Pinion on a beam axle? - 09/08/10 05:27 AM
Yes there is something called bump steer. With the frame mounted rack, the tie rods can cause a strange and unwanted steering effect should one side hit a bump and move the suspension that the other side doesn't. The change in suspension travel in effect, shortens the distance from the rack to one wheel and lengthens the distance to the other wheel. This turns the wheels without turning the steering wheel. Very bad news. For it to not have a bump steer, you would need to attach the rack to the axle, so the distance between the tie rods and the rack remains consistent as the suspension travels, but then you would need a slip joint in the linkage from the column to the rack to adapt the column to suspension changes. Such a thing does not exist that works well long term. Column stuff is just not designed to shorten and lengthen constantly as it would have to do as the suspension works. Sorry, Gene
Posted By: 36PLYM
Re: Rack and Pinion on a beam axle? - 09/08/10 01:46 PM
I am using a cross steer rack and pinion made by Unisteer. In use for about three years and no problems. This unit is made for 32 fords. To use it on the 36 I made a bracket to adapt it to my frame. The ford frame is primarily straight where the Plymouth has a good kick up. The rack is one sided and works like a vega box with the drag link going to the passenger side steering arm. It is not power but steers easy.
Posted By: John_Kunkel
Re: Rack and Pinion on a beam axle? - 09/08/10 07:00 PM
To make an axle-mounted rack work you'd need both a u-joint and a slip-joint, the Borgeson slip-joint should work if it's enclosed in a boot and kept lubricated.
http://www.summitracing.com/parts/BRG-450024/
Posted By: RUNCHARGER
Re: Rack and Pinion on a beam axle? - 09/09/10 02:01 AM
Hmmm. In the 80's Pro Gas cars used a flexible shaft to snake around the headers, probably wouldn't have enough free movement though. Maybe have to rethink the Toyota PS box idea.
Sheldon
Posted By: moparx
Re: Rack and Pinion on a beam axle? - 09/09/10 02:10 AM
if my foggy memory is correct, that flex shaft was from a pinto
