Thinking about swapping out my old transmission
Thread Starter
Instructor
Joined: May 2009
Posts: 240
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From: Norman Oklahoma
Thinking about swapping out my old transmission
I have a 79 Corvette with the stock 3-speed hydramatic transmission in it. Recently I rebuilt the engine and added a significant amount of horsepower. I don't know much about transmissions, but is it possible to create more torque or get a higher top end by upgrading to maybe a 700r4 tranny or even upgrading the diff? Tell me what you think, I want a lot of advice on this sort of thing.
Drifting
Joined: Sep 2007
Posts: 1,572
Likes: 51
From: Wichita Kansas
When my trans is ready I will go with a 700r4. I drive my car alot and would like the OD. I was just looking at some 700's on line and I found some reasonable modified 700's on ebay. One vender I have looked at is Mad Dog. There are others also who appear to know what they are doing and have great feed back.
Race Director
Joined: Jan 2000
Posts: 13,010
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From: Corsicana, Tx
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The 700R4 is a long way from an upgrade as far as strength. Not sure how much power you added...but they aren't that stout. They have O/D and that's about it....plus the funky TV cable system that has to be dead on the money to work right.
The 200R4 has done well behind some higher hp stuff if tweaked a little.
JIM
The 200R4 has done well behind some higher hp stuff if tweaked a little.
JIM
Burning Brakes
Joined: May 2008
Posts: 1,116
Likes: 5
From: Middleburg Florida
Either trans can be modified to handle higher HP engines. The 2004r is a better fit in that it's a bit smaller in physical size than the 700 and the drive shaft doesn't have to be cut. You'll have to modify your cross member for either trans. I like the 1st to 2nd gearing of the 200 better than the 700, (it's not as far a jump on the 200) but that's just me. The TV cable isn't difficult, there are lots of articles out there that will help you get that right. Depending on how your engine is set up (carb, intake) you might need a TV cable/bracket kit, but it's really not to difficult. I built my 200 and wired a switch to the console for the torque converter lock up. Again, just a couple of wires and a switch.
Either trans will fit and give you a fourth gear. If you have the lock up function operating, it'll drop an addition 500 or so RPM in fourth giving you a real overdrive.
Either trans will fit and give you a fourth gear. If you have the lock up function operating, it'll drop an addition 500 or so RPM in fourth giving you a real overdrive.
Safety Car
Joined: Aug 2001
Posts: 3,680
Likes: 199
From: Waterford Mi
I have a 200-4R in my 73. It was an easy conversion. I have a 3.55 rear gear which puts me at about 2200rpm's at 70mph. I get about 18mpg on a long road trip. The trans bolted right up to my crossmember, I had a TH400. I had to make my own TV cable cable bracket to fit to my Holley carb. I got almost everything form bowtieoverdrives.com
What I didn't get from them I made myself. One bracket I could not find anywhere was the bracket that holds the steering column lock cable to the trans. I made that one for several others on this site as well.
I later added a B&M controller to handle the lock-up convertor. (I didn't get it from here or pay near that much for it). It connected to the speedo cable and locks the convertor only after I hit 40mph. It unlocks anytime I slow down less then that so I don't have to worry about the engine chugging. It truly makes it hands free. I have been running this setup since 2003 without any issues.
What I didn't get from them I made myself. One bracket I could not find anywhere was the bracket that holds the steering column lock cable to the trans. I made that one for several others on this site as well.
I later added a B&M controller to handle the lock-up convertor. (I didn't get it from here or pay near that much for it). It connected to the speedo cable and locks the convertor only after I hit 40mph. It unlocks anytime I slow down less then that so I don't have to worry about the engine chugging. It truly makes it hands free. I have been running this setup since 2003 without any issues.
Last edited by redwingvette; Jan 4, 2010 at 08:32 PM.
