I'm thinking about getting a Gear Vendors unit to put behind my 460-C6. I mostly want it for the overdrive to help with highway speeds and gas mileage, etc. But I can't find anything specifically stating how the setup shifts. Will it automatically shift gears for me or will I need to do it manually between gears or into overdrive and all?
I've also considered a newer transmission with overdrive instead, but I'm told they aren't very sturdy. (I believe it's the E40D or something?) Could I buy one and have it beefed up for possibly cheaper? Maybe find one that's already blown up or something and then have it rebuilt to be stronger?
I have an older Doug Nash overdrive unit behind my C-6 in my '66. It was the parent of the US Gear OD, which is similar to the Gear Vendors one. They both are 2 gear transmissions only - straight drive and OD.
You have to tell it when to shift via a switch setup.
I do not know how the GV unit works, but the Nash unit has a gear motor inside, turning a worm gear. This worm gear moves a pawl back and forth into or out of OD and straight drive.
I am happy with mine. I bought it used, and had to find the connectors for the wiring where it plugs into the tranny; they are mid '70s GM grey 2-prong connectors.
I wired up the relay, and a switch system I found in an old bus. It had red and yellow lights (one for straight and one for OD) already wired up. Looks vintage too.
I could have bought the entire wiring system for $400, but this was a LOT cheaper.
I have never checked out my mileage. My Nash OD was behind a tired 352 and an LTD C-6, so my mileage and performance was pretty poor.
I blew the 352 in my '66 last December, and am near the end of an engine/transmission swap of a 460/C-6. I'll have the better power while in OD, and I hope to gain better highway mileage as well.
Hope this helps.
I forgot to add that they show up on Ebay frequently. Even if you bought one new, I believe you would be ahead of the game to do so, rather than go through all the trouble to adapt a different transmission to your vehicle.
I am not saying it cannot be done, this would be a lot easier and faster, and almost as economical to go with the US Gear or Gear Vendors unit.
The was an article in a hotrod mag a while back (not sure when) on the gear venders overdrive unit and I believe it is electronicly shifted and you can choose between it automatically shifting and shifting it when you want it to.
Yeah, I read the Gear Vendors site you referenced but they didn't answer the question that clearly. I seemed to gather it would shift automatically but I wanted to be sure cause it really doesn't say it clearly.
Thanks for all the input. I've been watching the overdrives on ebay. I don't know that it would be much more trouble to convert to that newer trans than the gear vendors, I'm just worried it wouldn't be tough enough from what people say.
well the way i understand it, if u put it on automatic it will automaticly shift into od at 47 mph, and then shift back out at a slightly lower speed. if u switch it to manule u can choose to shift it when u want it to shift. hope that helps
i would go with the us gear unit to the other gear vendors unit u cant shift under load.
I have a manual for a GV unit, since one came with a parts truck I have, I got the book from them free of charge. Any way, it will shift automatically, or if you choose, ti will shift manually. It uses gears similar to your automatic trans, and the clutches like one as well.