Fitting new worm gear to steering shaft.

Henry Hopper

Henry Hopper

Senior Member
I have a 37 steering box that Im fitting to the Cabriolet.I bought a rebuild kit for the box and it arrived on Thursday.I commenced trying to remove the existing worm gear!!!..no ammount of persuasion would shift that sucker so I split it with a cutting disc in the angle grinder and off it came..result!... Next it was time to fit the new worm gear....man 'o man what a struggle..heat and pounding,no good...hydraulic press ,no good..it would go so far but stick solid about 3/16" short.

I tried plan C this morning....polished the shaft to mirror finish...put the worm in the oven in the kitchen at max heat for half an hour.Next I called my old apprentice to bring me a bottle of refrigerant over....I froze the shaft good and proper..then placed the worm onto the shaft...it dropped straight on and even went a bit too far..no force, just fell into place...I adjusted it until in the proper position.

So, I hope this helps someone in a similar bind.
 
This reminds me that in my high school physics classroom there was a device that looked like two old time soldering irons (the kind that you heated with a blowtorch to use). The both had standard wooden handles, and one had a ring on the end, the other had a ball. On the first day of class, the teacher would give them to the biggest guy in class and tell him to take them apart (the ball had been pushed through the ring). It couldn't be done. He would then turn on a Bunsen Burner (remember them?) and heat the ring up for a minute or so, and the ball slipped right through. I will always remember that demonstration and have always been ready to use heat in sticky situations.


(BTW, I wasn't the kid the teacher gave it to on that first day to try.)
 
Henry Hopper said:
I have a 37 steering box that Im fitting to the Cabriolet.I bought a rebuild kit for the box and it arrived on Thursday.I commenced trying to remove the existing worm gear!!!..no ammount of persuasion would shift that sucker so I split it with a cutting disc in the angle grinder and off it came..result!... Next it was time to fit the new worm gear....man 'o man what a struggle..heat and pounding,no good...hydraulic press ,no good..it would go so far but stick solid about 3/16" short.

I tried plan C this morning....polished the shaft to mirror finish...put the worm in the oven in the kitchen at max heat for half an hour.Next I called my old apprentice to bring me a bottle of refrigerant over....I froze the shaft good and proper..then placed the worm onto the shaft...it dropped straight on and even went a bit too far..no force, just fell into place...I adjusted it until in the proper position.

So, I hope this helps someone in a similar bind.
Click to expand...

If the gear turned any color when heating, it won't last very long.
Those gears are normally pressed off and on with a fixture.
 
Heated it in the oven in the kitchen...I doubt very much that it could make enough heat to damage the integrity of the part.
 
Henry Hopper said:
Heated it in the oven in the kitchen...I doubt very much that it could make enough heat to damage the integrity of the part.
Click to expand...
Considering that most if not all kitchen ovens may achieve 500°F, there is a coefficient of expansion figure that can be used for steel to determine how much a given dia. will expand at 500°F.
That figure is (.0035).
Multiply the figure (.0035) times the diameter of the fitting diameter to determine how much the diameter will expand.
For example the .75 dia worm gear would expand (.0026)
The appox. 14 inch dia flywheel gear would expand (.049)
So it isn't any wonder that the flywheel gear would just "fall on"
 
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Did the same thing with a ring gear awhile back only Momma's stare motivated me to use my old school charcoal bar-b-que to "gently heat the ring without discoloring it She didn't know that my son had already placed the flywheel in the freezer.
If anyone shares this with my wife I will quickly become political..."I do not recall'''...
 
Neal in California had posted pictures here some time ago, with details of his press fixtures and how he presses these gears on/off the shaft. Then I followed up later with pictures of the tooling I made based on Neal's idea. I've done several of these worm gear swaps for my cars and other folks.
You could be do a forum search to find these posts.
 
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On heating critical parts, all my instructions from various manufacturers use no more than 275 degrees F for heat. Freezing is the key. You can get it as cold as you can and not worry. I have simple equipment to make dry ice with a bottle of CO2 and that works for most assembly procedures.

This is a very good thread with Neil in CA's and JM 35 Sedan's information and tooling. Neil does this stuff more than most. https://www.fordbarn.com/forum/showthread.php?t=215074&highlight=steering+worm
 
I took My 32 Shaft to a Tractor (John Deere) dealer. He pressed the old one off & the new one on is about 5 minutes. Charged me NOTHING
 
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