C6 Overdrive
Thread Starter
|
Senior User
Joined: Jan 2007
Posts: 122
Likes: 0
C6 Overdrive
I just bought a Gear Vendors OD on Ebay for my '77 250 Supercab's C6. I'm hopeing it's small enough in diameter that it will fit without moving the upper frame crossmember just behind the trans. Anyone have one of these on a Supercab?
Thread Starter
|
Senior User
Joined: Jan 2007
Posts: 122
Likes: 0
I got the Gear Vendors OD/electronic controller w/C6 adapter. Says good condition w/50K miles. paid 1500, so I hope it really is in good condition... GV says it's pretty cheap to rebuild in any case. Seems like you can get new ones on ebay for around 2200, but I'm not sure if that includes the C6 adaptor. The big blocks have a lot of torque so you may as well use it to pull a tall top gear when unloaded - not screaming away burning excess fuel and wearing out your engine. With the 4:11's it should drop from ~3130 RPM @70mph to around 2470 RPM.
Posting Legend
Joined: Sep 2001
Posts: 30,255
Likes: 37
Sounds OK then! 
You may want to change out that 4.11 with a 3.07~3.50 or so. You can also get wide ratio gears to give more low end grunt for the C6 from a later tranny or just a kit from Ford or a tranny shop. An auto tranny already gives torque multiplication thru the converter so you really don't need a real high numeric ratio rear axle. With the OD unit you can split every gear and now have a 6 speed.
New OD units usually come with a choice of adapters.
You may want to change out that 4.11 with a 3.07~3.50 or so. You can also get wide ratio gears to give more low end grunt for the C6 from a later tranny or just a kit from Ford or a tranny shop. An auto tranny already gives torque multiplication thru the converter so you really don't need a real high numeric ratio rear axle. With the OD unit you can split every gear and now have a 6 speed.New OD units usually come with a choice of adapters.
Lead Driver
Joined: Nov 2000
Posts: 6,635
Likes: 349
From: Albuquerque
I have the C6/OD with 4:11. It works out to about 3.25 in overdrive. The unit can last forever if treated right. Or not. I went 80,000 on my first one with lots of abuse. It was still OK untill I changed to synthetic fluid (per factory advice). The clutch went away soon after so I would put in fresh tranny fluid, non synthetic. I paid around $800 for a rebuild. The only thing I had to do was shorten the drive shaft on my F-100.
You can shift on the fly but at full throttle it's problematic to get it timed with the tranny shift.
You can shift on the fly but at full throttle it's problematic to get it timed with the tranny shift.
Lead Driver
Joined: Nov 2000
Posts: 6,635
Likes: 349
From: Albuquerque
Trending Topics
Senior User
Joined: Jan 2004
Posts: 367
Likes: 1
From: denver
I have often wondered about that GV overdrive. Does it really work well as a 6 speed? How does the unit know how to shift out of OD for the 1st w/ OD to 2nd w/out OD shift? same for the 2nd w/OD to 3rd w/out OD? Plus, with downshifting, which out of the 6 gears does it go to?
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
Lead Driver
Joined: Nov 2000
Posts: 6,635
Likes: 349
From: Albuquerque
The OD is just a two speed tranny on the back of your 3 speed. The first shift can be automatic at around 20mph or 40 mph or when you push the button. Pushing the button again shifts it out if your in manual mode. Otherwise it only shifts out as your speed gets very slow.
Posting Guru
Joined: Nov 2005
Posts: 1,302
Likes: 0
From: Madison, SD
You're going to really like the od unit. I've had one in a toter truck, and one in a Super Comp dragster behind a 2 speed 'glide with a stroked big block Ford dishing out the abuse. With the extra gear in the dragster I was able to go from 4.88 gears to 5.13's, which took dang near a tenth off my 60 foot time. With the OD comin on after drive, I also managed another 12 mph on the big end. Never had a bit of trouble with either one of them. My toter had 70 some thousand on it when I sold it and got my new one 4 years ago. the guy who got it from me has driven another 50K on it, and still no problems.