Well, anyone have any experience with these units? Gear Vendors under/overdrive transmissions the most awarded auxiliary transmissions.

Soon with the new 3000 Circle-D stall, we're going to be prepping the truck for the Texas Mile.

We have a severe advantage over most who run because of having 4x4, and 4:10 gears so far as out of the hole acceleration goes. However top end is mathematically limited to about 175 with a locked converter. This unit gives us the total of a high performance seven speed, or better known, a 4+3 transmission that can be used everyday, and/or whenever is needed. (4L80E with 3 overdrives) At least that's how I understand it from about a day's worth of research and an episode of Overhaulin'. Not only that but at highway cruising speeds we'd gain a ton of fuel economy by dropping the 70mph 2200rpm down to about 1700 or so. (Camshaft willing)

The unit is also fully programmable so far as shift speeds and what not.

I understand that the downside is that both driveshafts, and all differential input shafts will be rotating at almost twice the speed of normal operating at 200+ mph due to the low rear end gearing. (Horsepower/Aerodynamics limiting.) However the launch benefits would be amazing, and if everything doesn't fall apart make for a better top end run.

So anyways, back to it. Has anyone used one of these units? How do they hold up? What do you think of my theory?

Thanks,
-Robbie.

 

Maybe not such a good idea?

 

Not any more so than going that fast in a truck…………….LOL

Seriously though, it should work quite well. The last one I worked on was behind a 6.2L diesel / Turbo 400 combination back in the ‘80’s. It had more of a PTO type engagement for simple split shifting and from my understanding they are not near so clunky in operation these days and very tough.

 

Lol, true that.

And that would be sweet. I hear many great things about the overdrive unit and I dont think one has yet been applied to a Silverado for land/speed purposes. So yeah I'm excited!

 

Sounds like a cool idea...I've heard good feedback about Gear Vendors Overdrives

 

Anyone hear any complaints about strength and/or reliability?

 

I understand that they are very strong. I'm considering one for my Muncie 4 speed in the '67 Camaro.

 

Ive always heard they were extremely strong, but expensive. Something I would worry about is hanging all of that stuff off the end of the trans... a transfer case weighs about 80lbs and this is about 40lbs...lot of torque on the trans mount going over bumps and stuff....

 

Good point. Another cross brace would be in order to aide with the trans twist and support.

 

I want pics when it's done!