5:1 High Speed TT Rear Gear Scrap or Serviceable?

[JoeBauer]

I have the 5:1 TT high speed rear gear shown in the pictures. I pulled it from a TT Ruckstell axle. Someone has filed the teeth. I have not seen this done before.
Why would someone file the teeth?
Is this gear serviceable or scrap?

[J Franklin]

It looks very damaged with broken teeth.

[A bones]

need better light

[JoeBauer]

I would like to send you better pictures. Please check your email

[rotorwrench]

I don't really have enough experience with worm screw drives to be able to judge the condition with just the photographs. I would need to see what an original gear in as new condition to tell what they originally looked like. The gear appears to have rather sharp edges on the sides of each gear tooth. This could lead to edges breaking off little pieces of the edge under load. I would have figured that Ford would have made them with relatively smooth and lightly rounded edges. The sharpness is likely due to wear and long service.

A worm gear under drive puts a lot of load on one side of the gear tooth depending on direction of worm rotation. A gear with very sharp edges on either side may experience some chipping of the contact side under drive. In reverse, the load is on the other end and opposite side of the teeth. The gears are first machined for the cup radius and tooth edge shape then they are gashed to set the tooth angle on the gear. They are then hobbed to get the tooth shape correct for the worm to run on. A lot of worm screw and gear designs use a softer metal for the gear but this wouldn't be practical for a rear axle gear that would be under heavy load. If the edges were better smoothed and rounded then it would give better service. I would say that it's likely on it's last legs and may have too much backlash between the worm screw and the gear.

A lot of trucks were still using chain and sprocket drive well up into the 30s so that drive ratios could be easily changed for the work at hand but this stuff took a lot of maintenance. The model TT and earlier AA trucks were lighter duty and were still using the worm screw drive but they likely were getting less popular due to the stump puller ratios. The high speed ratio was better for road driving but the engine would have to lug it's way along to get up to speed and likely didn't perform well during that highly loaded period of getting up to speed. The model AA trucks eventually went to a 4-speed with bevel gears and they performed pretty well but they still were no speed demons even with the tallest of ratios.

This is a good link on the AA rear axles. It has an interesting video.
https://aafords.com/aa-chassis/aa-4000-rear-axle/#bta01

[A bones]

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Originally Posted by rotorwrench

If the edges were better smoothed and rounded then it would give better service. I would say that is on it's likely on it's last legs and may have too much backlash between the worm screw and the gear.

This is a good link on the AA rear axles. It has an interesting video.
https://aafords.com/aa-chassis/aa-4000-rear-axle/#bta01

Pretty well says it. If you have better shots, more light, post them so everyone can see.
There are some TT owners here

[JoeBauer]

A bones -

I have much better pictures, but can't figure out how to post them. I will post them when I get some help later this week. In the mean time please check your email. I sent you an email which has my email address, if you respond I will have your email address, then I can easily send you better pictures! I would like to get some more opinions!
Thanks

[A bones]

Joe check your Email and send pics there; and I'll give everyone a look.
I messaged you yesterday, waiting on you.
Don't be too hopeful tho

Well 7 days passed, no Joe, suppose he will shop for a 'new' one.

[Hans hendrik]

I would guess that they have tried to smoothen the damaged teeth