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simplyconnected
02-24-2017, 06:37 PM
Rick raised an interesting question regarding the replacement of oem steering components with R& P.

In the OEM 'ball screw' system, the pitman arm and idler arm work on opposite frame rails to traverse a common 'back (or counter) shaft'. That is their only purpose in life. There isn't much geometry at play even though they turn in an arc.

This countershaft has tie rods. on both ends that connect to the spindles. So as spindles go up and down, so do the tie rods.

The real geometry is in those spindle forgings. Yes, they hold ball joints which allow the wheel to go up and down with suspension but equally as important, they have a trailing arm, set to a specific length and at a specific angle. This angle matches the wheelbase so that turning changes the radius of both wheels. Consider the difference in angle of both front wheels:
http://www.ijser.org/paper/Optimizing-the-turning-radius-of-a-vehicle-using-symmetric/Image_001.jpg
All this greek has been worked out by Ford when they manufactured your spindles.

Since Rack and Pinion only replaces that countershaft that traverses left and right, your geometry does NOT change.

Another important question is, how heavy-duty does your steering components need to be? I'm using a small Chevy rack gear in our Galaxie. BTW, my '59 Galaxie spindles are the exact same part number as Squarebird spindles.

Since the rack gear replaces and REDUCES the number of steering connections and joints, it feels much more solid. The rack gear is also in direct alignment with the spindles so it can be 'less beefy', let's say. The steering system only guides, which doesn't require much power.

Put it all together; no slave cylinder, no directional valve, fewer joints, more directly in line, less massive components, then you realize a manual R&P gear will work just fine. A power R&P system using any modern pump makes steering effortless in any parking lot. I'm using a pump from my Mustang GT. Works great and never any leaks.

Since Squarebirds (and Galaxies) didn't have R&P systems back in the day, a little fabrication needs to happen. I re-used the frame holes my steering box and idler arm used to populate for brackets that hold my new rack gear. I also CUT my steering shaft and ground two flats on the end to form a "double-D". I made a nylon 2" bushing for the steering column housing that the shaft goes through. The rest is easy. Simply buy pre-made U-joints such as these and bolt them together:
http://www.speedwaymotors.com/shop/sweet-mfg-steering-u-joints~8192-745

Replacement rack gears are very available at just about all auto parts stores and they are inexpensive. The gear I'm using is a Chevy gear and the hydraulic fittings are common A-N (army-navy) flare fittings. Only one line is high pressure, the other is 'return to tank' that uses common hose clamps. - Dave

Yadkin
02-24-2017, 08:58 PM
So you put the rack rear of the front wheels. I guess that makes sense since the OE spindle forgings are at the rear. So the pinion has to be on top of the rack.

Cars I've owned with OE R&P have all been at the front of the front wheels.

Yadkin
02-24-2017, 09:16 PM
Here's the rack in my '12 Jeep GC. The bellows for the passenger side is on the upper left, under and perpendicular to the tubular subframe. The big electric motor powers the hydraulics. Large #8 wires to it, so I assume it draws a lot of amps. There is a remote reservoir.

The newer mustangs are all electric.

simplyconnected
02-24-2017, 11:04 PM
Yes, the rack gear mounts behind the #2 crossmember.

http://squarebirds.org/images_steering_RackAndPinion/DSCN4956.JPG

Also notice, a rack and pinion gear unclutters valuable real estate for exhaust manifold and header placement. - Dave

Yadkin
02-25-2017, 02:26 PM
Is that a purchased kit? That looks like some pretty severe angles for the U joints. I count three. The center one looks especially tight.

scumdog
02-25-2017, 05:01 PM
Ideally the inner end of the R&P tie-rod should pivot at the same point as your cars inner A-arm pivot point if mounted at the same height as the bottom A-arm.
Otherwise when your car goes over a bump the outer end of the tie-rod will move through a different arc to the outer end of the A-arm and you end up with bump-steer and to a certain point tyre scuffing.

Looking at that set-up in the photo this will occur in that car with the outer end of the tie-rod moving through a 'lazier' arc than the A-arm since it looks to be mounted the same height above the ground as the bottom A-arm.
Look at a stock set-up to see where the factory put those pivot points.

I've been down that road with various projects ( not of mine!) over the years and the ideal set-up is the inner R&P pivot point should be in a straight line between the top and bottom inner A-arm pivot points.

My 2 Kiwi pesos worth!

simplyconnected
02-25-2017, 07:52 PM
You're looking at a setup with NO ENGINE or transmission. Trust me, there's no bump steer or any bad habits at all. I've been running it for years and my tires look even, all the way around. Where ever I put the steering wheel, that's where the car goes. Like a modern car, there is no 'hunting'.

This was the second best modification I ever did on this car. Disk brakes was the first and electric wipers, third. - Dave

scumdog
02-25-2017, 08:45 PM
You're looking at a setup with NO ENGINE or transmission. Trust me, there's no bump steer or any bad habits at all. I've been running it for years and my tires look even, all the way around. Where ever I put the steering wheel, that's where the car goes. Like a modern car, there is no 'hunting'.

This was the second best modification I ever did on this car. Disk brakes was the first and electric wipers, third. - Dave


I figure that if your tie-rods and A-arms are the same overall length there's less likelihood of bump-steer? i.e they move through the same arc.

simplyconnected
02-26-2017, 06:14 AM
That's wonderful theory Tom, but our upper and lower 'A' arms are not the same length (and never were). The lower is much longer. And again in theory, outer tie rods should be the same length as the lower arm but they never were.

Our 'A' arms (especially the lowers) are exceptionally long, so long that we don't need a spring compressor to change coils. Consequently, when the car rolls over bumps, lower arm motion isn't much. In fact it's so little that urethane bushings (where just the rubber moves) lasts decades.

Bump steer you are talking about, when severe, affects toe-in. My tie rods are slightly longer than the center line of the lower arm pivot axis but they are in-line with the spindle arms, so if there is any toe-in change at all I cannot detect it. The arc radius is wide making steering rock solid, even around high speed corners like freeway exit ramps. In a more perfect world, I could have spaced the heim joints out 1-1/2" more but it makes no difference. - Dave

OX1
02-26-2017, 08:44 AM
I figure that if your tie-rods and A-arms are the same overall length there's less likelihood of bump-steer? i.e they move through the same arc.


That's what I thought at first too, but you look at
where the stock tie rods are, not more than a couple
inches off center also.

http://luxjo.supermotors.net/59%20T-BIRD/STEERING/STEERING%20REBUILD/STEERING%20REBUILD.jpg

Sometimes stuff just works. If I wasn't trying to
keep mine sort of period correct looking, I'd be all
over this mod.

I went to painstaking lengths to make drag
link and track bar angles correct on my early
bronco, but it bump steers like crazy..........
Eventually going crank in a crapload of caster
(need to cut and turn ends of axle)
and toe and see what happens.


http://luxjo.supermotors.net/70%20EB%20SPORT/STEERING/TIE%20RODS%20_DRAG%20LINK/CHEBBIE%20TIE%20RODS_DOM%20LINKS/DCP04573.jpg

And I have no problem with the three U-joints.
Not crazy about how it looks, but we used to do
stuff like that with body swaps of smaller bodies on
fullsize chassis's (is that a word?? :D) on offroad mud
trucks.

They typically had 400 HP BB's, front driving
axles, and 44-62 inch tires. We didn't use anything
beefier than what is shown there, and that was
with a constant bathing of mud and fine sandy grit
from the NJ pine barrens.

Anyway, think you have before, but would like to
see more pics of the frame brackets, just for
S and G's.....

terribleterry
07-05-2017, 06:09 PM
Iv'e used a dodge omni r&p it works fine but the turning radius is ugly 22 degrees right or left of center Do you know what your chevy rack has? terry

keith
07-11-2017, 01:49 PM
Dave,

I want to use your method on the bird. As I get closer I would like to ask you for more info and if you would do anything different.

Keith

simplyconnected
07-11-2017, 09:30 PM
I'd be glad to help you, Keith. Remember, I have a full-size Galaxie but others have done Squarebirds. The system is very similar. I made brackets using my existing frame holes; from the steering box and the idler arm. The rack gear is rubber-mounted to the brackets just like modern cars.

All of my steering connections are done in 'double-D' joints. Tie rods and heim joints are also readily available at places like speedwaymotor.com. When properly fitted, no welding is necessary but I did use double set screws on the steering joints.

The hardest part (mentally) is cutting your steering column. I added a simple nylon bearing on the end of the housing for the steering shaft. The steering housing needs a simple bottom support because Ford used the steering box (that is now gone).

The rest bolts together. I used a power steering pump from a 1990 Mustang but just about any pump will work. The pump and R&P housing both use modern AN hydraulic fittings. Only one line is pressurized, so that line required a simple elbow at the gear and two hose clamps.

No leaks. Just like you would expect from a modern car, power rack and pinion steering works very well and lasts a long time. If you ever need parts, all the parts stores have them. - Dave