Worm Drive Condition

AA Ford Discussion Group relating to the repair and restoration of your AA Ford.
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RJ Scott
Posts: 16
Joined: May 27th, 2004, 4:20 am
Model Year: 1930
Location: Olathe, KS

Worm Drive Condition

Post by RJ Scott »

Can anyone tell me how to determine whether or not my worm dirve is good shape or not. I have it disassembled and everything looks like it's in pretty good shape, But I just don't know for sure what I'm looking at....
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Neil Wilson
Posts: 3062
Joined: February 5th, 2003, 9:42 pm
Body Type: 82-A/89-A
Model Year: 1930
Location: Boulder, CO
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Post by Neil Wilson »

RJ,
The worm gear is usually the first part to ware. This is the large round gear which is driven by the worm. A new worm gear will have a flat area on the top of each tooth. As the gear wares, the flats of the teeth are reduced until the top edges are a sharp peak. Further ware results in the top edge becoming jagged due to peaces of the teeth flaking away.

The worm is normally not worn but should be checked for any rough spots which will ware the worm gear.

The high speed 5.17:1 gear is more frequently worn than the low 7.25:1 gear.

The seals inside of the axle housings usually need replacement. They really can not be see very well due to there location.

I am not an expert on examining bearings. But, there should not be any pitting on any of the rollers. The ball bearings should spin freely.

The housing for the spider gears seems to be a weak part. I have found many cracked housings. The housings need to be very clean for inspection.

Hopefully others will have more input on this subject.
Regards, Neil Wilson
______________________________________
aafords.com@gmail.com - use this email for contact
https://aafords.com/
User avatar
RJ Scott
Posts: 16
Joined: May 27th, 2004, 4:20 am
Model Year: 1930
Location: Olathe, KS

worm drive

Post by RJ Scott »

Thanks for your response, Neil.
The main gear is smoothly worn and the top edges of the gear are somewhat concaved evenly across the tops of the teeth. Since it sounds like I need to replace it, any ideas of where a new gear can be obtained??
Also, I have not taken the gear completely apart yet, The axles are still attached. With the unit setting on the floor balanced on the main gear, should the entire unit be ridgid, or should there be some flexibility from center to ends?
Thanks again,
RJ
User avatar
RJ Scott
Posts: 16
Joined: May 27th, 2004, 4:20 am
Model Year: 1930
Location: Olathe, KS

worm drive

Post by RJ Scott »

Thanks for your response, Neil.
The main gear is smoothly worn and the top edges of the gear are somewhat concaved evenly across the tops of the teeth. Since it sounds like I need to replace it, any ideas of where a new gear can be obtained??
Also, I have not taken the gear completely apart yet, The axles are still attached. With the unit setting on the floor balanced on the main gear, should the entire unit be ridgid, or should there be some flexibility from center to ends?
Thanks again,
RJ
User avatar
Neil Wilson
Posts: 3062
Joined: February 5th, 2003, 9:42 pm
Body Type: 82-A/89-A
Model Year: 1930
Location: Boulder, CO
Contact:

Post by Neil Wilson »

RJ,
Once the axle housings are separated, the worm gear and axle shafts are no longer supported by the tapered roller bearings on the axle shafts. So, there will be some play in the assembly.

Finding a new worm gear will be close to impossible. Send me an e-mail to wilsmor@juno.com with a close up picture of the teeth on the worm gear. If you can't send a pictures, then just send me an e-mail and ask for pictures of the worm gear. I have one which is in very good condition which I can show you.

If the tops of the teeth are not sharp then there is still some life in the gear.

The model TT worm gear will also work in an AA. The TT worm gear is about 1/4" smaller in width but it is the same size otherwise.
Regards, Neil Wilson
______________________________________
aafords.com@gmail.com - use this email for contact
https://aafords.com/
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