Installing a Gear Vendors Overdrive to C6

[66FAIRLANE]

Hi Jay. Yeh I took your earlier advice and used Dexron III. I did give them a call first to confirm and they are fine with that. I think its just a low speed, pump pressure thing. It isn't exactly mushy just doesn't shift in instantly like I expected. It will probably hit harder as speed and pump pressure rise. I also need to do some more 'testing'.

[jayb]

None of mine will shift instantly either.  I have to wonder about the gear splitting thing; on the track with any reasonably fast car, I think you'd have to be pretty good at timing the shift just right to get the overdrive to turn off and the transmission to shift to the next gear at the same time.  I've never really tried the gear splitting technique, but it seems like it would be problematic because there is a slight delay when you hit the switch.

If you do any gear splitting tests, let us know how it works...

[66FAIRLANE]

I know this is one hell of a thread mine but figured this was an important note to add.
Before cutting & modifying the floor (if you need to) ensure your transmission mount is as new. Mine felt fine & was of course still in tact but it had sunk/settled over the years & not having a new one to visually compare it to I did not know the difference.

I have now purchased a new mount & it is nearly 5/8 higher than my old 'collapsed' one. Guess what hits the floor now! 

[475fetoploader]

The gas pedal. The gas pedal hits the floor.

[BruceS]

Andy, the same thing happened to me when I replaced the rear mount on my '66 after going thru the C4.  The fan started hitting the aftermarket rad and I didn't realize it until I tried starting the car for the first time after putting the trans back in.  So a word of caution to anyone who is replacing their rear mount even if they're not making any other mods.   

[RustyCrankshaft]

Gear splitting works great on the one I have installed behind a NP435! Never really tried it on the C6 one and it was a used one that didn't have the fancy control box. I just turn it on when I want it and off when I don't.

I've used MercV and it seems to be in between a regular ATF like DexIII and the syn Dex. I've also used RedLine Racing hi temp ATF (which I also use in all the modern chain drive transfercases with really good results) and it shifts better than the synthetic Dex or Mercon stuff but it's also a touch thicker so in colder weather (freezing) it's a bit grumpy for the first few miles. But that's only a problem for the pickup since it's the only thing that gets driven when it's that cold usually.

[gt350hr]

   I have one in my '78 F350 enclosed car hauler and love it. It has the C6 wide ratio kit also and I use the OD in manual only and only on the highway. It drops from 3,000 to 2,500 and saves gas for sure. Very smooth and trouble free. Having to add the speedo cable extender was unexpected but turned out fine. I too used zip ties to keep it all together. WELL worth the time and effort. I have three drive shafts due to the long wheelbase and chose the keep the original front (and stock tailshaft) driveshaft "on board" , just in case. That way I could convert back to stock and keep going in an emergency.
     Randy

[Hipopinto]

Very nice write up!

I added one to my toploader 66 Galaxie before I joined this board

Mine fit perfectly and I always use the push button when driving. I tried the auto shift feature that will switch to OD when 25mph is hit and it’s VIOLENT if you don’t push the clutch!

Gear splitting or just OD as a 5th works like a charm

Thank you for the great info

Dave

[Jb427]

66FAIRLANE do you think your car being converted to right hand drive had anything to do with you having to cut your floor to get your drive line angles i am thinking of buying a gear venders overdrive for my fairlane but i was thinking the short kit may place the venders unit in a better spot for a floor cut if needed and for exhaust X or H pipe
short kit works out at around 4 inchs longer then a std c6 car transmission length.

[Stangman]

i dont have a fairlane but I would think whether its a right or left hand drive the tranny tunnel would be the same.

[Jb427]

i dont have a fairlane but I would think whether its a right or left hand drive the tranny tunnel would be the same.

Yes me too i am not sure if they just used a xt falcon firewall and dash or if they front clipped it with one of our Australian xt falcons i may be wrong but pretty sure they never came out with c6s and they only came with biggest 302ci w and there are small things not the same on our Australian falcons but looking you would think they are the same

[66FAIRLANE]

The area of the tunnel where it hit is still US. The Aussie bit starts much further forward in front of the shifter area. Having said that my car has a lot of hand built stuff including engine mount brackets and at the time the trans cross member was an Aussie one too (now custom) and there is a slight difference. So not sure how it would all fit in an unmolested example. I still love the GV but if I was doing it again I would probably pull the trans and fit the shorter one.

[Jb427]

Thanks 66FAIRLANE i might be very wrong but i just can't see any bonus to running the long one. But the short if there are things like floor in the way i would think is is a better area to cut and gives more room for exhaust x or h pipe

Cheers for that info i think you made my mind up

[66FAIRLANE]

Only bonus is not having to drop and rework the trans.

[Jb427]

Only bonus is not having to drop and rework the trans.

True