I got these with some other model T parts and I have no use for them. These were bought a few years ago by the previous owner and never installed. They are the new high speed gear set made by Mike Hartman in Arkansas. The current price of the gear set is 1850.00. But I talked to Mike a few weeks ago at our local swap meet here in Arkansas and he said he is out of stock at this time, and it may be awhile till he has time to make another run. These gears are a side/hobby type of product and his main shop work comes first. He did say as of right now he plans on no price increase, when he does make another run. Even though his materials and tooling costs are increasing. I will take 1250.00 for this set plus shipping to anywhere. That is a 500.00 discount. I ship overseas on a regular basis, but even though I pack very well and I know how to deal with customs inspections, ect. International shipping is at Buyers risk. I have over 1000 e-bay auctions so far and 100% positive feedback. Over 100 packages have shipped to International sales, with only one damaged part. There have been many sales to Australian Model T owners and Forum users. The condition of these gears are as manufactured by Mike Hartman with no damage, and never installed. Here is a link to a earlier discussion about the gears. There are a few other discussions about them on the forum...
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Please excuse the dust and spots the flash made show up in the photos.
what is the ratio of this worm and gear set?
Jim. The ratio is 5.17 to 1.
This is the last new set in captivity. In Fort Worth 20 years ago there was a worm gear and wheel manufacturer who built a replacement bronze worm gear for us for an antenna gearbox for a reasonable price. The firm has since closed his doors. I don't know where his equipment went. Any more new sets are likely to be hard to come by and quite expensive.
Ted, Mike Hartman is the only manufacturer of these gears I know of. But they are a "labor of love" and are a side line to his real business. That is why they are made in limited runs. and are "out of stock" a lot of time. The time in making one set is extreme. He told me the machine "run time" to just cut the teeth of the ring is over 21 hours. He also makes and casts his own brass ring gear blanks. That alone is another major task, and the special brass stock he uses for the castings is also expensive. I am just an ameature machinest, but I know enough to be very impressed with what he does to make these gear sets.
If Mike Hartman is making new gears for the TT, why not make a faster ratio. There must be a reason.
Jim, I think part of the issue with the ratios is multi-faceted.
- I had been given the impression that the brass tends to wear at an accelerated rate compared to the regular steel gears in a T.
- The design of the worm gear system (including pitch, profile, and curvature of teeth) has its limitations. One can only make teeth so big/small before they will not adequately mesh.
- If speed is a major issue, there are numerous solutions. You could: trade a TT for a T, purchase an auxiliary transmission, or do some fabrication and install a regular T axle. TT's were built for hauling a lot of weight. I almost bought a 1921 TT that had a high ratio rear axle (like 6 and change :1) AND a Ruckstell. Imagine the Ruckstell in low with 1st gear engaged. 0 to 3 mph in 1 second!
If one really had the time and money, a custom rear axle could be cast that had all of the mounts for a TT suspension with the differential design of a regular T.
Jim, I have been on a camping trip for several days so sorry for the slow response. I believe when Mike started making the gears he had a NOS set of 5.17 to 1 gears to "reverse engineer" for making his. That is probably the main reason, and also that the 5.17-1 gears were an option from Ford as their high speed gears ... ???
These have been spoken for, pending payment ...