Twin High HI-LO TT transmission

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Jeepbone1
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First Name: Brad
Last Name: Kirtner
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Twin High HI-LO TT transmission

Post by Jeepbone1 » Fri Aug 30, 2019 2:23 pm

I’m picking up a ton truck chassis next week with this aux transmission and I don’t know anything about it. Anyone have some enlightening information to share?


mtntee20
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Re: Twin High HI-LO TT transmission

Post by mtntee20 » Fri Aug 30, 2019 9:26 pm

Hi Brad,

Since no one has replied, I'll tell you what I know. Up until about a week ago, Twin High transmissions were extremely rare. Now there has been three pop up since then. They're multiplying like bunnies.

Henry "Hank" Lee appears to be the resident heavy on these. Evidently, they were built by an aircraft engineer. He drew his aircraft background into the transmission business. The transmissions are way overbuilt as in bulletproof. Top dollar, high-quality bearings, excellent sliding planetary gearing. I think you get the idea. These have a fourth main engine bearing built right into the front of the transmission. SWEET.

Technically, they are an underdrive and direct drive transmission. They are about 10 1/2" long which makes them shorter than a Warford. A neat feature is the shift lever. I can see both sides of this, both good and possibly bad. The shifting lever rotates 360 degrees. This will allow excellent access for entering or exiting the vehicle. BUT, I can see where that rotation might cause minor problems with shifting. Speaking of shifting, the designer was aware of the potential dangers of getting an auxiliary transmission stuck in neutral. So, there is NO neutral in the Twin High. One other thing I can tell you; for an aluminum cased transmission, they are almost as heavy as a cast iron Warford. I'm looking forward to seeing how well it performs.

You should contact Hank through the forum and get the straight poop from him. He's a great guy and very knowledgable in many different areas. A great guy to know.

Looking forward to seeing photos of your TT and transmission.

Good Luck,
Terry Miller


Topic author
Jeepbone1
Posts: 222
Joined: Sun Jan 06, 2019 6:10 pm
First Name: Brad
Last Name: Kirtner
Location: Salem, Virginia
MTFCA Number: 50618
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Re: Twin High HI-LO TT transmission

Post by Jeepbone1 » Fri Aug 30, 2019 10:40 pm

Thanks Terry. I think I was talking to Hank as you were typing this. The one I’m referring to isn’t the same one you mentioned, it’s the longer “inline” unit that bolts directly to the rear axle with the driveshaft actually I front of it. I’ll know more when I get it in front of me.

Brad


26modeltt
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Re: Twin High HI-LO TT transmission

Post by 26modeltt » Sat Aug 31, 2019 9:24 am

Our '26 Model TT equipped with the high speed rear end (5.16 to 1) and Twin High HI-LO rear axle mounted auxiliary transmission, provides an approximate 3.1 to 1 final drive ratio, when the auxiliary transmission is in "Over Drive". The beauty of the Twin High HI-LO transmission is the ability to "shift on the fly" and the Ford designed drive shaft speed is maintained. Auxiliary transmissions mounted to the Ford transmissions increase the drive shaft speed and have the tendency to promote drive train vibration.

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Henry K. Lee
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Re: Twin High HI-LO TT transmission

Post by Henry K. Lee » Sat Aug 31, 2019 9:47 am

Thank You Jack, I heard that once upon time! Makes total sense.

All the Best,

Hank

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