Thread: rack and Pinion movement

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I installed a brand new T-Bird Rack and Pinion and bushings in my 40 ford truck. Its powered by a GM pwr steering pump with reduction valve installed.
With the tires on the ground I get what seems to me a lot of movement of the rack when I turn the wheel. ( engine running). ( Yes everything is tight as can be)
At the first knuckle/ end of output shaft of the rack there is movement of about 1/4" to 3/8" up and down. All is tight, I can't budge it by hand no how.
What is wrong with this ?
Is it supposed to be like that ?

I'm confused. If you can't move it by hand, how do you know that it moves up and down. Are you having someone turn the steering wheel while you look at the rack? Not familiar with the T-bird rack, but no rack that I ever owned moved up and down.

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Your talking about the rack/joint and not the housing?

Is the rack input shaft bent maybe?

Originally Posted by jerry clayton

Your talking about the rack/joint and not the housing?

Yup I'm talking about the rack /joint. I'm turning the steering shaft by hand on the 1st segment of the steering rod just before it gets to a Heim joint thats bolted to a bracket on the frame. The housing stays put for the most part, its just the outer limits of the rack out-put shaft that moves. Of course the housing must be moving a little bit or the shaft wouldn't move. Should have taken a picture, my pictures communicate better than I.
The shaft is not bent.

Navy, looking at the rack there are the two threaded "steering rods" that attach to the spindles, and then there is the splined shaft that you turn to affect movement of the steering rods. When you say "output shaft" are you talking about the splined shaft that attaches to your steering via DD u-joints, and saying that it moves in & out radially from the rack housing, basically the shaft pushing back towards the firewall 1/4" to 3/8"? Just trying to understand what you're trying to communicate.

Originally Posted by rspears

Navy, looking at the rack there are the two threaded "steering rods" that attach to the spindles, and then there is the splined shaft that you turn to affect movement of the steering rods.
When you say "output shaft" are you talking about the splined shaft that attaches to your steering via DD u-joints, and saying that it moves in & out radially from the rack housing, basically the shaft pushing back towards the firewall 1/4" to 3/8"? Just trying to understand what you're trying to communicate.

Ok I found a picture of the rack with out the pump installed.
Its not moving in and out but up and down. The splined shaft and the housing move together, its like its rocking on the rubber bushings, but only when turning the wheel.

Is the angle too steep on your u joints?

Originally Posted by 36 sedan

Is the angle too steep on your u joints?

No thats not it, there is only a short shaft coming off the rack that I turn by hand to turn the wheels at this time.

Have you checked the gear lash adjustment?
Rack-and-Pinion Service

Navy, I'm having a hard time understanding how a force can be generated to cause the whole rack to rotate against the bushings. Unless I'm wrong the rack & pinion are both simple straight or spiral cut spur gears which don't cause any torque load. The gear lash adjustment on the rack & pinion is only to deal with excess play in the wheel, as I read about it (at the very end of the link 36 sedan posted above).
The only thing that makes any sense to me is that maybe your steering arms are describing a vertical arc as they turn, imparting a "twist" on the rack? I'd try loosening the lock nuts on the threaded steering rods to allow them to rotate a bit as you turn and see if the housing movement disappears. If so you may need to tweak your steering arms for better alignment? Does that make sense to anyone else?

I'm sorry, I missunderstood, I thought he was saying just the input shaft was moving?, not the rack itself.
I believe a power steering rack operates differently without fuild and pressure and could be torquing on its bushings due to this, JMO.

I suspect that a number of small items are adding to this pile---------

Incorrect bushings and/or improper mounting--check out a T bird ( maybe also Lincoln) to see EXACTLY how they are mounted-probably against a crossmember that can't twist or flex.

If the steering/suspension geometry has even one little varient incorrect it will take a significant amount of force to turn them and that will cause the back feed that will necesstate enough torque to twist the housing(applied thru the spiral/bevel to rack will cause rotation in that direction mentioned.

And -------are you setting down????? If the power steering is powered it will generate the force internally in the box and this won't happen-I don't think you have a problem

In Navy's original post he says that

Originally Posted by Navy7797

...Its powered by a GM pwr steering pump with reduction valve installed. With the tires on the ground I get what seems to me a lot of movement of the rack when I turn the wheel. ( engine running). ( Yes everything is tight as can be)

He also says in the post with the picture,

Originally Posted by Navy7797

Ok I found a picture of the rack with out the pump installed.

This says to me (could be wrong) that the system is totally plumbed, engine running, pressure to the rack unit when it twists, which adds to the dilemma. With that I'll await the next installment from Navy.

Originally Posted by jerry clayton

And -------are you setting down????? If the power steering is powered it will generate the force internally in the box and this won't happen-I don't think you have a problem

That's pretty much what mine does and, when you operate it manually (without power) it messes up the fluid balance inside the rack and will not operate correctly until you rebalance (bleed as some call it) the fluid inside. Usually all it takes to rebalance the fluid is to crank the steering wheel under power left to right (full stop to stop) several times until it starts driving correctly.