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Horn Mods for PW/WC with Power Steering
Saginaw Power Steering Horn Modification

When you add Saginaw Power Steering to a Power Wagon or WC or M-37, you loose the ability to use the stock horn button on the steering wheel.  Power Wagons and WC's have a hole that goes threw the steering box.  This allows the horn button wire to exit the column and not get twisted as the steering wheel is turned.  The Saginaw Power Steering Box does not have a threw hole for the horn wire.  As such without some type of modifications you will not be able to use the standard horn button as the wire will get wrapped up in both directions as the steering wheel is turned.

I made a commutator for my Power Wagon and Carryall and M37 to eliminate this problem.   Many people have asked me for information on how I did this so that they could also regain use of their horn button.  The one on the Power Wagon  is enclosed in a boot and I did not feel like tearing it all open for pictures.  Today I made one for my Carryall and took pictures of the modification.

I selected materials that everyone should have access to.  Here is a step by step description of the conversion.  It is assumed that you already have the Universal joint mounted on the Saginaw Power Steering Box.
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1. Remove the .250" Grade 8 Bolt that goes thru the Universal Joint and Steering shaft and safe for re-use.

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2. Buy a coupler joint for 1.500" copper pipe and cut a piece off 1.000" long.  This will be the part you will be working with.

3. Find a Plastic Video Cassette case (white ones are the right thickness) and cut a strip of the plastic  4.875" long by 2.000" wide.


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4. Put the plastic inside the copper pipe coupling piece you cut off.  It MUST extend to the front inside leading edge and the rest will stick out the back of the coupling almost like a funnel.

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5. You are going to be working with a TIGHT interference fit so use pleanty of oil on the end of the steering shaft housing and the inside of the copper fitting with the plastic.

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6. Now start the fitting with the plastic insulator over the steering column housing.  You will only be able to start it.  Then it will take a hammer and piece of heavy metal stock to drive it on.  Use the metal stock against the copper fitting and hit on the metal stock.  Do NOT hit on the copper as it will deform.  You will be able to drive the fitting on the column until its flush with the bushing end of the steering column housing.  Take a sharp Box knife and cut off the excess plastic on both sides of the fitting.

7.  Use a Ohm Meter or test light and be sure that the new copper  jacket is totally insulated from the steering column housing.  On a Ohm Meter, you should read a open, on a test light the light should not light when one end of the test light is touched to the Bronze bushing/column housing and the other end to the insulated copper jacket.  If you read the open circuit you have done well.  If you read a short ...


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8.  At the rear edge of the copper jacket, solder a 12 gauge wire,  cut the wire long enough to reach your horn.  Make sure you solder it only along the rear edge so it will not interfer with the brush your going to add.

9.  Once again check for continunity between the end of the wire you just soldered on and the brass bushing in the end of the steering column housing.  it MUST read open !!!!!

10.  Now take a 3.000" x 3.000" angle bracket and cut one end off .5000" past the first hole.  Enlarge the hole to .2500".   For fabrication only, take a .2500" bolt and run it thru the steering shaft and thru the hole you just englarged and bolt it snug.  You will see what this looks like in the pictures.


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11.  Now you must find a motor brush.  You can not use small ones as they will not carry the needed current to operate your horn.  I will leave it up to you on finding the motor brush.  However the motor brush must be enclosed in plastic to insulate the brush from the holder.  The brush you see in the picture came from a burned out
2 hp motor.  Any motor shop should be able to give you a single brush.  Compare the size of the brush I used to the picture of the small brushes with the dime for reference size.  The small brushes wont work !!!  The brush that I used has a contact area of .3750" x .2500"


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12.  You will need some insulating/shock type material that is about .5000" wide by .2500" thick.  I just happened to have a key holder that made a great donor to cut up for the shock material.  I cut 2 strips .5000" wide by 2 inches long.

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13.  Get a stainless steel hose clamp.  Put the clamp around the bracket, with the 2 pieces of insulating/shock material and then the brush, and tighten it down.  Watch the contact of the brush with the copper jacket.  Align the brush for full contact with the copper jacket and tighten down.  Be careful not to tighten to much and bind the brush.

14.  Your fabrication is now done.  Its time to test.  Take a ohm meter or a test light and connect one end to the wire coming from the brush (in the picture its the yellow clip).  Connect the other end to the wire coming off the copper jacket ( in the picture its blue).

15.  The ohm meter MUST show a short, the test light must light.  If it does turn the steering wheel and be sure you have contact through its entire rotation.  Go back and forth with the wheel to check it out.  If you have good contact and show a short or light the test light, you HAVE DONE WELL.  You are now ready to install.


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16.  Re mount your steering wheel/shaft/column in the dash bracket.  The far end of the steering shaft in re-inserted into the Universal Joint on the Saginaw Steering box.  Put a GRADE 8 .2500 bolt through the Universal joint/steering shaft, then put the angle bracket (as shown in the picture) and tighten with a GRADE 8 Locking  nut.

17.  Once again a final test, re do the test in step 15.  If all is well your ready for final connection to your horn.

18.  Take the wire from the horn button that comes down the inside of the steering shaft, bring it out through an opening in the Universal and solder it to the wire coming from the brush or the brush holder.  The other wire (blue in the pictures) goes to your horn.  A positive wire either 6 or 12 volts (depending on your truck) goes to the other connector on your horn.


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19.  I have found on the Bumblebee that a LARGE size Mr Gasket shift boot, when a cut is made on one side will totally cover the modification you have made.  Lace up the  back of the shift boot to close it up.

20.  CHECK FOR ANY BINDING OF THE STERING WHEEL, AND CORRECT IF ANY IS FOUND.

21.  Enjoy your horn button, now back where it belongs on the steering wheel.


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Modification March 23, 2006 to use a very small brush and relay.  The large brush originally used is shown for comparison to the smaller relay now being used.

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PW/WC/M37 horns have voltage applied to one horn wire.  The other horn wire goes thru the horn button on the steering wheel to ground to operate the horn.  By using a relay, we can use a much smaller motor brush to operate the horn.  All relays will be marked with the terminals and their assignments.  You need to use the normally open contacts for horn operation.

On the Potter Brumfield relay Pin # 30 goes to the horn ground wire.  Pin # 87 goes to truck ground.  Pin # 85 goes to the copper ring you mounted on the steering column ( described  eariler). Pin #86 goes to 12 volts thru a 1 amp fuse.  The wire from the horn button attaches to the motor brush which rides on the copper ring.

When you push the horn button, the relay is operated, closing the normally open contacts and operating the horn.  The relay used for 12 volts is a Potter & Brumfield VF4-45F11.  For 6 volts, you will have to buy a relay rated for 6 volts with...


 
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