Author Topic: How Rack and Pinion Steering was Installed on UV480 & UV500 by: Norm Standal  (Read 60 times)

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How Rack and Pinion Steering was Installed on UV480 & UV500
By: Norm Standal


In order to have good Ackermann steering geometry when the rack and pinion is
mounted forward of the spindles and the wheels are straight ahead, the steering
arm ball joints will be outward beyond the spindles and on a center line running
through the spindles and converging at the center of the rear axle. If the rack and
pinion is mounted rearward of the spindles, the ball joints should be on this same
center line but will be inward of the spindles. This means that if an Ultra Van has
the original drum brakes on the front and a person wants to install a rack and
pinion ahead of the spindles, the ball joints would locate within the drake drums.
The best solution is to install disc brakes which will clear the ball joints or install
the rack and pinion behind the spindles, where the ball joints will clear the drums,
as long as the ball joints are on the line, the steering geometry will be OK.

If the rack and pinion is mounted ahead of the spindles and the pinion is above
the rack (the usual arrangement), the pinion must rotate in the same direction as
the steering wheel and thus the steering shaft can be made up using only U joints.
If the rack is moved to the rear of the spindles, the pinion will have to be under
the rack, or a reversing mechanism will have to be installed in the sheering shaft.
With the wheels straight ahead, the rack is centered between the steering ball
joints and horizontally within an inch or so of their center line. That of course puts
the rack and pinion in the 33 5/8” outside width x 5 ½” deep compartment
between the wheel wells, a perfect area for it. Since this box is structural, we
don’t want to modify it anymore than necessary.

The inner tie rod to rack ball joints on the GM, rack and pinion are about 33”
apart and the compartment is about 33 5/8” wide, so we put a layer of 1 Ό” thick
oak in the bottom to strengthen the compartment, and raised the rack so when
the wheels are straight, they can drop the limit of the shocks without the boots or
tie rods rubbing on the compartment. The maximum travel of the rack (7.5”)
wants to limit the turning angle of the wheel spindles to the original 50 degrees.
(See Page 1-3 Ryerson).

The steering wheel is connected to the rack and pinion with preloaded, roller
bearing, steering shaft quality Cardan U joints. Properly installed, the steering will
have virtually no play for the long life of the bearings. The Ultras usually need six
U joints and four support bearings. Two U joints are mounted on and supported
by the lower end of the steering column shaft and the rack, pinion shaft. The
pinion U joint can be mounted in rubber to absorb road vibration. The center four
U joints are supported by two self aligning ball type pillow box bearings. Careful
alignment and angling of all of the U joints will assure good linear rotation
between steering wheel and the rack and pinion. On #480, the rack and pinion is
powered by the regular engine mounted hydraulic steering pump.

Some field measurements of rack and pinion are:
1. Length of rack travel = 7 ½”
2. Distance between ends of inner tie rods = 53”
3. Length of outer tie rods with female ends= 10” to 11”
4. Thread size of tie rods= 16 x 1.5mm
5. Center to center of steering arm ball joints= 71 ½”
6. Length of rack and pinion cylinder= 24”
7. O.D. of rack and pinion cylinder= 2.42”
8. Center line of rack cylinder to base of rack and pinion= 1.85”
9. Inside angle of rack and pinion= 82 degrees

See accompanying pictures, sketches & drawings entitled “#480 Rack and Pinion Specs.”
« Last Edit: November 23, 2018, 08:51:33 PM by Ultravan Owners »
Tony - US Army and ASE Mechanic, Retired.
Location - Ottawa, Canada

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Installing Rack and Pinion Steering in the Ultra Van
 
 The simplicity and low cost of manufacturing and installation and the precise steering control with rack and pinion (R&P) type steering have caused it to be used in almost exclusively in all modern, light, and medium duty highway vehicles. 

If you would like to use your Ultra Van to travel at highway speeds on our modern freeways, it probably will be safer and more comfortable driving if you have R&P steering and it is now easier than ever to install it because the units used in GMs ’07 to ’11 medium weight vehicles (like pickups) will fit very nicely under the floor between the wheel wells and toward the front where the original cross rod went through, and they have a long 7 ½” of travel (stroke). From there, the tie rods go straight out (when the wheels are straight) and connect to the steering arms with the outer tie rods (steering arm ball joints) to turn the wheels.

For power assist turning, the R&P is hydraulic connected to an engine or an electric driven hydraulic pump.

« Last Edit: November 23, 2018, 09:40:01 PM by Ultravan Owners »
Tony - US Army and ASE Mechanic, Retired.
Location - Ottawa, Canada

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Steering Wheel to R&P Connection
 
At the base of the steering column the steering shaft turns toward the rack pinion through preloaded steering shaft Cardan universal joints and about a 24” long shaft (all under the original floor boards) and connects to the pinion. Thus turning the steering wheel turns the pinion and moves the rack to the left or right turning the wheels. 

The design and drafting of the critical components and their layout to obtain the proper Ackermann steering geometry was provided by Glenn Lemke, Coach #247, using his CAD system. 

Installation of R&P steering on the Ultras is significantly simplified if it has 14” or larger front wheels and disc brakes, due to the forward and outward spread of the steering arms (relative to the spindles) interfering with the backing plate of drum brakes.   

On Coach 480 we had 15” wheels and good working drum brakes on the front, but always felt that disc brakes would be safer for hard braking, so we installed a ’64 to ’72 GM disc conversion kit that fits nicely, gives us the desired clearance for the steering components and keeps the coveted short Ultra steering radius, and the R&P steering. We now have 350 test miles on it.
« Last Edit: November 23, 2018, 09:40:51 PM by Ultravan Owners »
Tony - US Army and ASE Mechanic, Retired.
Location - Ottawa, Canada

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Out of Pocket Costs
 
The best place to buy the R&P is from your local auto recycler because when you buy the R&P you can often times get the outer tie rods (ball joints), pinion connector and ball joint, hydraulic fittings and tubing, and mounting bolts with it for a couple of hundred dollars, & rebuild it if necessary. A bare rebuilt unit will run up to $300.00. The disc brake conversion kit we used was $239.00 from Speedway and the 5 used (like new) 911 Porsche steering u joints were $35.00 ea. (EBAY) Add $200.00 for misc and you have about $900 to $1000 plus a hydraulic pump is needed.
    
This may sound like quite a bit of money but when you drive down the freeway and feel that sure, velvety, and wind defying steering or you ever need that extra braking, you will know it was worth every penny of it.

Norm Standal #480 & #500
« Last Edit: November 23, 2018, 09:25:37 PM by Ultravan Owners »
Tony - US Army and ASE Mechanic, Retired.
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More Pictures of the Install
Tony - US Army and ASE Mechanic, Retired.
Location - Ottawa, Canada

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I Offer New R&P Steering Arms.

I will also post the drawings (soon) - should anyone prefer to get them made on their own.
However, Keep in mind, it can cost more, when an individual has a set made using a different machine shop each time. Most machine shops have a setup up cost (divided by 1 vs dividing by more - reduces the cost) and you need a special tap (if the machine shop does not have one, you will pay for it) so the tie-rod ends to fit in the R&P Steering Arms. This normally adds cost to the one time order. I already have the $80 tap and wait until I get more than one order to reduce the cost for all.   

Video Link - https://youtu.be/-uBS7uTFy3g
« Last Edit: November 24, 2018, 07:50:48 AM by Ultravan Owners »
Tony - US Army and ASE Mechanic, Retired.
Location - Ottawa, Canada