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That's the video that brought this subject up. My friend owns a 67 and wants to convert it to an automatic with as little work as possible to the body of the car. He saw this video and wanted to know if anyone on this forum had tried this setup.
Magic::::: Thank you. This is what he was looking for. I was posting at the same time that you submitted the article. I copied your address for the 200R4 article and sent it to him for him to peruse..
Has anyone on the forum installed a 200 R4 into a mid-year? If so, what kind of problems were incurred? Thanks for any help.
There's been a lot written about this swap mostly related to Chevelles, Camaros, and other GM cars that used the Powerglide transmission.
First of all, the correct name for this transmission is 200-4R. You had the last two characters reversed. No big deal, but this might affect the results you get when searching the internet.
The main advantages of the 200-4R are that it is dimensionally similar to the Powerglide. So, it'll fit without having to cut your driveshaft or modify the transmission tunnel. It has overdrive (.067 ratio) for lowered fuel consumption at cruise. You can elect to utilize its lockup torque converter feature for slightly improved fuel economy at cruise. Many disable that feature as it requires extra controls and the benefit in terms of mileage is negligible, especially in a C2 Corvette that won't get used that much. Having O/D also helps by allow you to run a lower rear end (e.g. 4.11's) without sacrificing driveability on the highway as engine rpm's are reduced at cruise. Most Powerglide cars came with 3:36 rear ends, which is a good compromise ratio. The 200-4R's greatest benefit, other that having a second gear and O/D, is it low first gear ratio of 2.74, which is a lot lower than the Powerglide's 1.76. This will give you a much harder launch from standstill and it'll feel like you just gained 100hp!
But, all this does come with some downside. The 200-4R is NOT a direct bolt-in. You must fabricate a new rear mount. This means cutting off the old Powerglide mount and fabricating a new mount for the 200-4R. Not so difficult for someone with basic welding skills, but certainly beyond what the average hobbyist can do. The 200-4R uses a TV cable setup to control shifting, unlike the Powerglide which uses a vacuum modulator (as do the THM-350 and 400). That TV cable needs adapting hardware at the carb, and is notoriously finicky to adjust. There is the risk of frying the transmission if the adjustment is not done correctly, a risk that does not exist with vacuum modulator transmissions.
The last downside is cost. Stock 200-4R's, except for the rare ones used in the '87 Buick GN and Chevy Monte Carlo SS, are weak. They were notorious for blowing up when used in taxi cabs, and have a well earned reputation among transmission builders as a profit center. No way a stock 200-4R will stand up behind a hot small block or any Big Block. The solution is to buy a beefed-up 200-4R from one of the specialty vendors such as Art Carr, or Bowtie. It'll cost you about $2,000, plus the torque converter, plus, plus. I'd say a conservative estimate for the whole job would be around $5,000 installed.
Another hassle will be adapting the Powerglide shifter to work with the 200-4R. The best solution is to buy a complete shifter assembly from Shiftworks. That'll set you back around $250. You can adapt the stock shifter, but it is finicky getting the shift detent set up so that the neutral safety swiich works properly and the back up lights come on when they should, etc. I know all about that...
Others have been successful in swapping the Powerglide for a 700-4R, or a THM-350. I went the latter route and am very happy with the results. The THM-350 (otherwise known as the Turbo 350) was introduced in 1969 as GM's replacement for the Powerglide, and its size and chassis mounting is almost the same. It was derived from the legendary THM-400 introduced in 1965 for GM's full-size and high performance vehicles. The Turbo 350 is a medium duty 3-speed transmission, excellently suited to intermediate sized cars. The THM-350 does not have O/D, nor lockup (except for the THM-350C which was used in 1980-81 - avoid that one). In my case, lockup is no loss, and O/D isn't critical either, as I drive my '67 coupe only about 1,200 miles a year. My car has a 3.08 rear, so cruising at 70mph has the motor turning at a relativly calm 2,700rpm. The THM-350 is much stronger in stock form that any 200-4R (except for the noted GN/SS versions) and can be built to HD specs by any competent builder in your town. They are proven, and reliable. Cores are dirt cheap.
So here's what I did. I bought a THM350 core for $150 on Craigslist, had it rebuilt with HD parts and a manual control shift kit for another $700. Installation did NOT require a custom rear transmission mount as the THM-350 bolts right up to the Powerglide rear mount. The trans cooler lines bolted right up. The installer was able to use the stock steel tube dipstick (the 200-4R must use a flex type dipstick which does not look stock). The engine of my car (a 327-300hp) did not need to be moved. The right head pipe did have to come out, but that wasn't any trouble. I re-used the THM-350 vacuum modulator steel line and hose from the core - easy! I needed a Lokar downshift bracket and cable kit (cheap). The exhaust did not need to be modified.
The whole swap cost less than $2,000 and it transformed the character of the car! It is now much more flexible for in-town and driving in hilly country, having a 2nd gear. Low gear is 2:52, which means I can fry the tires off the line if I want to get a bit frisky. All my needs are satisfied in a swap that was simpler (i.e. no rear mount fabrication, no finickly TV cable, no lockup electrics, no O/D control electrics) and cheaper when compared to using a 200-4R. Of course your needs may vary, so if O/D is a must for you, then the 200-4R would be the way to go.
Several forum members have successfully swapped out their Powerglides for 200-4R's. Search this forum for the terms "Powerglide swap", and "200-4R" or "Automatic". You'll learn a lot, and be better placed to make the right swap decision for your car and driving needs.
I have a 700 r4 in my 61 with a 3.73 rear gear behind a 370hp 350. I have no complaints and it was a fairly easy swap with the M21 and 283 that was in there originally. It may be a better option than the 200 4r.
There's been a lot written about this swap mostly related to Chevelles, Camaros, and other GM cars that used the Powerglide transmission.
First of all, the correct name for this transmission is 200-4R. You had the last two characters reversed. No big deal, but this might affect the results you get when searching the internet.
The main advantages of the 200-4R are that it is dimensionally similar to the Powerglide. So, it'll fit without having to cut your driveshaft or modify the transmission tunnel. It has overdrive (.067 ratio) for lowered fuel consumption at cruise. You can elect to utilize its lockup torque converter feature for slightly improved fuel economy at cruise. Many disable that feature as it requires extra controls and the benefit in terms of mileage is negligible, especially in a C2 Corvette that won't get used that much. Having O/D also helps by allow you to run a lower rear end (e.g. 4.11's) without sacrificing driveability on the highway as engine rpm's are reduced at cruise. Most Powerglide cars came with 3:36 rear ends, which is a good compromise ratio. The 200-4R's greatest benefit, other that having a second gear and O/D, is it low first gear ratio of 2.74, which is a lot lower than the Powerglide's 1.76. This will give you a much harder launch from standstill and it'll feel like you just gained 100hp!
But, all this does come with some downside. The 200-4R is NOT a direct bolt-in. You must fabricate a new rear mount. This means cutting off the old Powerglide mount and fabricating a new mount for the 200-4R. Not so difficult for someone with basic welding skills, but certainly beyond what the average hobbyist can do. The 200-4R uses a TV cable setup to control shifting, unlike the Powerglide which uses a vacuum modulator (as do the THM-350 and 400). That TV cable needs adapting hardware at the carb, and is notoriously finicky to adjust. There is the risk of frying the transmission if the adjustment is not done correctly, a risk that does not exist with vacuum modulator transmissions.
The last downside is cost. Stock 200-4R's, except for the rare ones used in the '87 Buick GN and Chevy Monte Carlo SS, are weak. They were notorious for blowing up when used in taxi cabs, and have a well earned reputation among transmission builders as a profit center. No way a stock 200-4R will stand up behind a hot small block or any Big Block. The solution is to buy a beefed-up 200-4R from one of the specialty vendors such as Art Carr, or Bowtie. It'll cost you about $2,000, plus the torque converter, plus, plus. I'd say a conservative estimate for the whole job would be around $5,000 installed.
Another hassle will be adapting the Powerglide shifter to work with the 200-4R. The best solution is to buy a complete shifter assembly from Shiftworks. That'll set you back around $250. You can adapt the stock shifter, but it is finicky getting the shift detent set up so that the neutral safety swiich works properly and the back up lights come on when they should, etc. I know all about that...
Others have been successful in swapping the Powerglide for a 700-4R, or a THM-350. I went the latter route and am very happy with the results. The THM-350 (otherwise known as the Turbo 350) was introduced in 1969 as GM's replacement for the Powerglide, and its size and chassis mounting is almost the same. It was derived from the legendary THM-400 introduced in 1965 for GM's full-size and high performance vehicles. The Turbo 350 is a medium duty 3-speed transmission, excellently suited to intermediate sized cars. The THM-350 does not have O/D, nor lockup (except for the THM-350C which was used in 1980-81 - avoid that one). In my case, lockup is no loss, and O/D isn't critical either, as I drive my '67 coupe only about 1,200 miles a year. My car has a 3.08 rear, so cruising at 70mph has the motor turning at a relativly calm 2,700rpm. The THM-350 is much stronger in stock form that any 200-4R (except for the noted GN/SS versions) and can be built to HD specs by any competent builder in your town. They are proven, and reliable. Cores are dirt cheap.
So here's what I did. I bought a THM350 core for $150 on Craigslist, had it rebuilt with HD parts and a manual control shift kit for another $700. Installation did NOT require a custom rear transmission mount as the THM-350 bolts right up to the Powerglide rear mount. The trans cooler lines bolted right up. The installer was able to use the stock steel tube dipstick (the 200-4R must use a flex type dipstick which does not look stock). The engine of my car (a 327-300hp) did not need to be moved. The right head pipe did have to come out, but that wasn't any trouble. I re-used the THM-350 vacuum modulator steel line and hose from the core - easy! I needed a Lokar downshift bracket and cable kit (cheap). The exhaust did not need to be modified.
The whole swap cost less than $2,000 and it transformed the character of the car! It is now much more flexible for in-town and driving in hilly country, having a 2nd gear. Low gear is 2:52, which means I can fry the tires off the line if I want to get a bit frisky. All my needs are satisfied in a swap that was simpler (i.e. no rear mount fabrication, no finickly TV cable, no lockup electrics, no O/D control electrics) and cheaper when compared to using a 200-4R. Of course your needs may vary, so if O/D is a must for you, then the 200-4R would be the way to go.
Several forum members have successfully swapped out their Powerglides for 200-4R's. Search this forum for the terms "Powerglide swap", and "200-4R" or "Automatic". You'll learn a lot, and be better placed to make the right swap decision for your car and driving needs.
Alex
Alex,
I sent a copy of your post to the guy who is asking the question about this. You are correct, it is 200-4R but everyone refers to it as the R4, not sure why. Thanks for your information. It will help him.
I have a 700 r4 in my 61 with a 3.73 rear gear behind a 370hp 350. I have no complaints and it was a fairly easy swap with the M21 and 283 that was in there originally. It may be a better option than the 200 4r.
I also sent him your information. Not sure how he will handle his change over. That is up to him. Any information will be helpful at this point. Thanks.
Alex, that was a fantastic dissertation on the 200-4R in general and specifically too and easily understood. I have a 4:11 and also a 4sp at this time, so unless I was to swap rear ratios the OD is a must.
Can anyone explain the difference between the 200-4R and the 700-R4? Is it a simpler unit to install (no TV cables etc and less finicky in use).
Factoid, what modifications did you have to make for this install. Modify tunnell? New tanny mount? New driveshaft? I've only heard about these transmission and have never owned any vehicles with them installed.
Butch
I found this link and it pretty much spells out the difference between the two and the authors preference for street application. So, I guess it boils down to installation and is there someone or a shop who can dial it in and keep it there.
With all the cost, modification, and work to be done on this swap, I decided to keep my powerglide. I don't do that much highway driving, and all that is not worth the trouble to me.
I have a 700 r4 in my 61 with a 3.73 rear gear behind a 370hp 350. I have no complaints and it was a fairly easy swap with the M21 and 283 that was in there originally. It may be a better option than the 200 4r.
Did you have to notch or cut your "X" crossmember to install this tranny? I'm told by a local source they don't fit the C1 without doing surgery on the "X" member.
Alex, that was a fantastic dissertation on the 200-4R in general and specifically too and easily understood. I have a 4:11 and also a 4sp at this time, so unless I was to swap rear ratios the OD is a must.
Can anyone explain the difference between the 200-4R and the 700-R4? Is it a simpler unit to install (no TV cables etc and less finicky in use).
Factoid, what modifications did you have to make for this install. Modify tunnell? New tanny mount? New driveshaft? I've only heard about these transmission and have never owned any vehicles with them installed.
Butch
I found this link and it pretty much spells out the difference between the two and the authors preference for street application. So, I guess it boils down to installation and is there someone or a shop who can dial it in and keep it there.
The short answer is that for a C2 Corvette, the 700R4 is a bolt-in swap with no modifications to the tunnel or the frame. The 2004R requires no modifications to the tunnel, but it does require modifications to the frame for the rear transmission mount. If you want the simplest swap for a C2 Corvette, use the 700R4.
The 700R4 requires a shortened drive shaft, but this is a pretty simple operation for a driveshaft shop. And, if you don't want to have it done yourself, you might be able to get one from Bowtie Overdrives.
Last edited by GearheadJoe; 07-19-2018 at 11:16 PM.
Reason: add info
Alex, that was a fantastic dissertation on the 200-4R in general and specifically too and easily understood. I have a 4:11 and also a 4sp at this time, so unless I was to swap rear ratios the OD is a must.
Can anyone explain the difference between the 200-4R and the 700-R4? Is it a simpler unit to install (no TV cables etc and less finicky in use).
Factoid, what modifications did you have to make for this install. Modify tunnell? New tanny mount? New driveshaft? I've only heard about these transmission and have never owned any vehicles with them installed.
Butch
I found this link and it pretty much spells out the difference between the two and the authors preference for street application. So, I guess it boils down to installation and is there someone or a shop who can dial it in and keep it there.
I researched all the options before deciding to go with the Turbo 350 to replace the Powerglide in my '67 Coupe. The overdrive automatic options are the 200-4R and the 700R4, and the non-overdrive options are the Turbo 350 and Turbo 400. The pros and cons of the 200-4R have been covered here before. I dismissed the 700R4 as an option because:
The 700R4 was intoduced in 1982 as a replacement for the TH350. Early versions weren't reliable, so you should get one made after 1987. Note that it's a bulkier and heavier than the 200-4R. This means minor mods are required to get it to fit in the C2 tunnel. Its larger bulk means it sits closer to the floor of the car so more heat is transmitted to the passenger compartment.
One purported advantage of the 700-R4 is that it has a lower 1st gear (3.06) than any of the other transmissions. The 200-4R has a 2.74 first gear, the TH350 is 2.52, and the TH400 is 2.48. A lower first gear is helpful for increasing torque multiplication from a standing start. However, in a relatively light car like a C2, with a torquey engine, this really isn't necessary. Another disadvantage to some of the 700-R4 is the drop in gear ratio between first (3.06) and second gear (1.62).
The 700-R4 uses a TV cable, just like the 200-4R. Finicky to adjust, but once set up properly should work fine.
The bottom line is that installing a 700-R4 is no easier than swapping in a 200-4R. The 700 was used in heavier duty applications, so is presumed to be a stronger unit. But that depends on a lot of variables. Opinion seems to be split on which is a better transmission. They'll both work fine, but the 700 is larger and heavier, needs the driveshaft to be cut, relies on that fussy TV cable, and is larger so you'll probably have to move the engine and modify the undercar exhaust to get it to fit.
I researched all the options before deciding to go with the Turbo 350 to replace the Powerglide in my '67 Coupe. The overdrive automatic options are the 200-4R and the 700R4, and the non-overdrive options are the Turbo 350 and Turbo 400. The pros and cons of the 200-4R have been covered here before. I dismissed the 700R4 as an option because:
The 700R4 was intoduced in 1982 as a replacement for the TH350. Early versions weren't reliable, so you should get one made after 1987. Note that it's a bulkier and heavier than the 200-4R. This means minor mods are required to get it to fit in the C2 tunnel. Its larger bulk means it sits closer to the floor of the car so more heat is transmitted to the passenger compartment.
One purported advantage of the 700-R4 is that it has a lower 1st gear (3.06) than any of the other transmissions. The 200-4R has a 2.74 first gear, the TH350 is 2.52, and the TH400 is 2.48. A lower first gear is helpful for increasing torque multiplication from a standing start. However, in a relatively light car like a C2, with a torquey engine, this really isn't necessary. Another disadvantage to some of the 700-R4 is the drop in gear ratio between first (3.06) and second gear (1.62).
The 700-R4 uses a TV cable, just like the 200-4R. Finicky to adjust, but once set up properly should work fine.
The bottom line is that installing a 700-R4 is no easier than swapping in a 200-4R. The 700 was used in heavier duty applications, so is presumed to be a stronger unit. But that depends on a lot of variables. Opinion seems to be split on which is a better transmission. They'll both work fine, but the 700 is larger and heavier, needs the driveshaft to be cut, relies on that fussy TV cable, and is larger so you'll probably have to move the engine and modify the undercar exhaust to get it to fit.
Hope this helps.
Alex
Hi Alex:
I understand your preference for the TH350 and I think that is a fine transmission for someone who is not interested in an overdrive top gear for highway driving. Just having the three gears of a TH350 instead of two gears of the Powerglide improves the around-town driving experience considerably. However, it makes no improvement in the highway driving experience. I think this pretty much sums up how the driving experience of the two transmissions compares.
I don't quite agree with your description of the evolution of the 700R4. In the 1970s GM used the TH350 in light-duty cars and the TH400 in heavy-duty applications such as muscle cars. To my knowledge, the 700R4 was developed as a replacement for the TH400. At some point GM developed the 2004R for use in light-duty applications. I'm not sure, though, how that development was timed with the use of the TH350.
As built by GM, the 20004R and the TH350 were considered to be far weaker than the 700R4. However, today the aftermarket builders have identified the weak spots in the 2004R and the TH350 and developed stronger replacement parts that can be used for rebuilding them. As a result, it is now possible to get a 2004R, TH350, or 700R4 that is rated to handle 500 HP.
Regarding your comments on fitment, my view is that if two different transmissions can each be bolted in without modifications to the tunnel or frame, it makes no difference whether one transmission has more tunnel clearance than the other. Regarding installation, I do not think the engine has to be moved to install any of these transmissions.
The shorter driveshaft required by the 700R4 is a simple matter. A local driveshaft shop can either shorten the driveshaft you have, or build you a new one to replace the one you have. There are also companies that will build you a drive shaft to order and ship it to you.
In the end, the difference between a TH350 and a 700R4 comes down to the overdrive top gear. The driving characteristics of the 700R4 are almost identical to the TH350 if you never use 4th gear in the 700R4. So, in terms of the driving characteristics, the key question is what value is placed on the overdrive 4th gear in the 700R4. That's a personal decision and needs to be considered carefully.
Compared to a Powerglide, the TH350 is a big step up for in-town driving due to the lower first gear, but there will be no change in the driving experience at highway speeds. Most people who have installed an overdrive transmission absolutely love the overdrive top gear because it greatly reduces engine noise at highway speeds.
Several years ago I was all set to replace the Powerglide in my '67 with a 700R4, and I did a lot of research on this topic. In the end, I changed course and installed a 5-speed TKO-600 manual transmission instead. However, in terms of gear ratios, the comparison with the TH350 and the 700R4 is still valid.
I absolutely love the deep first gear for launch from a standing start, and I absolutely love the overdrive top gear for the reduced engine noise at highway speeds.
Did you have to notch or cut your "X" crossmember to install this tranny? I'm told by a local source they don't fit the C1 without doing surgery on the "X" member.
BH
Sorry team, I’ve been absent from this thread. I may not be the best resource as I have a C1 and it has had many changes made (Jim Meyer front frame stub, power R&P steering, PB, A/C, side engine mounts welded in (eliminating the front mount and allowing a serpentine accessory set up), to answer your question, Butch, the only modification was to the tranny mount. The engine stayed in its original position.
I just came back from a long drive in 102 degree temps to check the A/C and general comfort level my wife will feel tomorrow when we make the two hour drive north to COTA in Austin for the Corvette Invasion. She will be fine. The A/C kept the temp perfect and the engine never went above 180. I have a pretty hot 350 in front of the 700R4 with 3.73 gears in the rear. In my opinion, it is just about perfect and I LOVE driving this beast! The TV set up is simple there are several aftermarket brackets and cables (Lokar, etc.) to make it even easier. People get nervous about the TV cable when they read all the warnings about line pressure and burned up transmissions. I’ve had several over the years and never had a problem. Just make sure it is installed in the right position (geometry), pull it all the way out at wot and you are good to go! If I don’t pay attention, I find myself creeping up above 80 on the highway with the engine barely turning. I give it three snaps in a Z pattern!
I copied this picture from a previous discussion a while back. This was how someone did the 200R4 transmission mount on the stock C2 crossmember. maybe they'll jump in here.
I put a 700R4 behind a Blueprint 383 a couple years ago in my 1962 Corvette. It was a powerglide car so it had the 3.36 rear end gear that seemed to be perfect. 1950 RPM at 65 miles per hour in overdrive. What I didn't like about it was the steep difference between low gear and second. If you were on the throttle any amount at all it would jerk very hard when it shifts 1-2. The 2004R has a closer spread with a 2.75 gear compared to the 700R4 with a 3.06.
I copied this picture from a previous discussion a while back. This was how someone did the 200R4 transmission mount on the stock C2 crossmember. maybe they'll jump in here.
I put a 700R4 behind a Blueprint 383 a couple years ago in my 1962 Corvette. It was a powerglide car so it had the 3.36 rear end gear that seemed to be perfect. 1950 RPM at 65 miles per hour in overdrive. What I didn't like about it was the steep difference between low gear and second. If you were on the throttle any amount at all it would jerk very hard when it shifts 1-2. The 2004R has a closer spread with a 2.75 gear compared to the 700R4 with a 3.06.
Here's the ratios:
it's interesting that the 700r4 and the 4l60e are the same ratios; I wonder if the newer one is better?
Bill
07-10-2018, 03:05 PM
200 r4
