700r4 conversion questions
02-20-2018, 06:21 PM
#1
700r4 conversion questions
I'm contemplating putting a 700r4 overdrive trans in my '69 and have some questions. If I'm not mistaken the '82 vettes came with a 700r4 from the factory, can I use the crossmember and driveshaft from an '82 in a '69? What about the shifter, would I need a shifter and cable from an '82 or do I grind another detent notch for the extra gear in the the '69 shifter? If I can modify the '69 shifter to work what exactly needs to be done to it? What about the trans lockout cable that goes from the trans to the steering column, does anyone make a cable bracket for a 700r4 so that I can keep the lockout cable? By the way, can a 700r4 handle a mildly modified 454 big block? I do know that the '88-'92 700r4's are the ones to look for because they have some stronger stuff inside them. The 700r4 I have is a '90 trans that I got for free from a friend (the price was definitely right, lol) so at least I don't have to go out and buy one. But I am worried about it's ability to handle a big block, especially if I decide to hop up the motor some more. Or would I be better off going with a Gear Vendor overdrive on the turbo 400 that's in the car right now? Speaking of which, what needs to be done to the car to put a Gear Vendor overdrive in it besides a shortened driveshaft? Does the floor need to be modified to make it fit? How much power can they handle? I want overdrive in the car but I don't want to go broke doing it which is why I haven't bothered to consider putting a 4L80E trans in it because they're expensive to buy and expensive to install. I don't want to have to spend a lot for a good 4L80E trans and then have to spend a bunch more money to make a 4L80E work in the car (getting an expensive aftermarket computer for it, getting a new tailshaft housing and the stuff required to connect a cable drive speedometer to it, etc) on top of needing a shifter, a crossmember, and a shortened driveshaft. I don't have money to burn, I don't want to blow thousands of dollars on the overdrive conversion. Any advice from those on here that have done an overdrive conversion? Should I do the 700r4 or the Gear Vendor conversion? Are there any other aftermarket overdrives available for a turbo 400 besides a Gear Vendor? Any advice/help/etc is greatly appreciated.
02-20-2018, 06:40 PM
#2
Melting Slicks
here is my thread about when i put a 700r4 into my '72.
https://www.corvetteforum.com/forums...ddly-bits.html
bought shifter kit, yoke and other bits thru BTO.
i used the tail extension from a early caprice, made the mount holes the same length as the T400.
i modified my lockout bracket, sort of works, allows you pull into reverse, but no other gears.
never did finish fully setting it up. just needs a bit of time to work out the bracket on the box to cable travel angle...
heard that the Gear Vendors box will take a lots of modifications to the tunnel.
https://www.corvetteforum.com/forums...ddly-bits.html
bought shifter kit, yoke and other bits thru BTO.
i used the tail extension from a early caprice, made the mount holes the same length as the T400.
i modified my lockout bracket, sort of works, allows you pull into reverse, but no other gears.
never did finish fully setting it up. just needs a bit of time to work out the bracket on the box to cable travel angle...
heard that the Gear Vendors box will take a lots of modifications to the tunnel.
Last edited by riverracer au; 02-20-2018 at 06:44 PM.
02-20-2018, 08:39 PM
#3
Drifting
you may need to beef up the 700r4 a little to handle a Big Block torque, depending on what it was behind before. .. you can get a shifter conversion kit from Shift Works .com that comes with everything including a new shift position indicator for a nice clean job.. or grind on yours if you prefer .. A Gear Vendor unit requires additional room in the tunnel. Fiberglass modification will be necessary . I did mine 9 years ago..from TH350 . very happy. I did change rear Ratios from 2.87 to 3.31 at first.. wasn t right with my big cam so I pulled them and went 3.73 .. just right.. in 4th or Overdrive at 80 mph, I m only turning 2550 rpm .and I can go down to 35mph in 4th .. I installed a manual defeat for Lock-up convertor for slow in town driving..it just shuttles back and forth too much in lock at low speed . My stroker cranks out 525HP.. no issues with the 700r4 in 9 years
02-21-2018, 08:28 AM
#4
Le Mans Master
I'm contemplating putting a 700r4 overdrive trans in my '69 and have some questions. If I'm not mistaken the '82 vettes came with a 700r4 from the factory, can I use the crossmember and driveshaft from an '82 in a '69? What about the shifter, would I need a shifter and cable from an '82 or do I grind another detent notch for the extra gear in the the '69 shifter? If I can modify the '69 shifter to work what exactly needs to be done to it? What about the trans lockout cable that goes from the trans to the steering column, does anyone make a cable bracket for a 700r4 so that I can keep the lockout cable? By the way, can a 700r4 handle a mildly modified 454 big block? I do know that the '88-'92 700r4's are the ones to look for because they have some stronger stuff inside them. The 700r4 I have is a '90 trans that I got for free from a friend (the price was definitely right, lol) so at least I don't have to go out and buy one. But I am worried about it's ability to handle a big block, especially if I decide to hop up the motor some more. Or would I be better off going with a Gear Vendor overdrive on the turbo 400 that's in the car right now? Speaking of which, what needs to be done to the car to put a Gear Vendor overdrive in it besides a shortened driveshaft? Does the floor need to be modified to make it fit? How much power can they handle? I want overdrive in the car but I don't want to go broke doing it which is why I haven't bothered to consider putting a 4L80E trans in it because they're expensive to buy and expensive to install. I don't want to have to spend a lot for a good 4L80E trans and then have to spend a bunch more money to make a 4L80E work in the car (getting an expensive aftermarket computer for it, getting a new tailshaft housing and the stuff required to connect a cable drive speedometer to it, etc) on top of needing a shifter, a crossmember, and a shortened driveshaft. I don't have money to burn, I don't want to blow thousands of dollars on the overdrive conversion. Any advice from those on here that have done an overdrive conversion? Should I do the 700r4 or the Gear Vendor conversion? Are there any other aftermarket overdrives available for a turbo 400 besides a Gear Vendor? Any advice/help/etc is greatly appreciated.
http://www.bowtieoverdrives.com/cata...m.php?ITEMID=9
I have the Level 2 behind my SBC and it is good to 400-450 torque. My SBC is approaching 350/390tq at this time so it is well within the Level 2 capability.