Hey guys, I'm swapping the 267 out of my '79 Malibu wagon for a 383, and I'm trying to decide on a trans. I've read that the 200r is weak (which is what I have now) and I would like to get something with overdrive, so I was thinking 200r4. Sounds like that needs a crossmember swap though? Does a TH350 drop in? I have one of those in the garage but that doesn't get me overdrive... What do you guys think?
Suggestions for a trans swap
- Thread starter 79MalibuWagon
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Are you ever planning on going real fast? I wish i would have went straight to a turbo 400. Turbo 350's are limited to about 600 hp or a little more.
As for an over drive a 200r4 is what i would choose if i couldn't afford a 4L80 or a turbo 400 with a GV unit.
brian
As for an over drive a 200r4 is what i would choose if i couldn't afford a 4L80 or a turbo 400 with a GV unit.
brian
Thanks for the reply, I'm not planning on exceeding 600 HP, probably looking at 400-450 with the 383 I'm building. I am feeling a little silly though, because I've been doing a little more research and I read that some wagons came with TH350s... and after a little pan identification, that's whats in my car #-o . I thought I had read previously that they all had the 200r. So, given that, is there a option for a bolt in overdrive trans or is my best bet to leave the TH350? Also, is there an RPO tag on these that lists what the axle ratio is? I know the Chevy trucks had them in the glove box, but I haven't found anything on the wagon. Thanks.
you probably have a turbo 250. It looks like a 350 but the output shaft is hollow and they have an externally adjustable band. To Check the gear ratio jack up the passenger side back tire, put the car in nuetral, mark the driveshaft then turn the wheel exactly 2 turns while counting the driveshaft revolutions. If it goes around 2.75 times thats 2.73 gears. If it goes around just over 2 times thats 2.19 or 2.29 etc...
Don't spend any money on that transmission if its a turbo 250
brian
Don't spend any money on that transmission if its a turbo 250
brian
Just swapped in a 200r4 in my malibu this spring. The car originally had a 250 that I got rid of long ago and had a 350 built for the current 383. With 3.73's out back it wasn't very "road trip" friendly. Because the 200r4 is weak knee'd in it's stock form, I had a good core built with hard parts, converter, etc from C/K Performance. It's supposed to handle 450ft lbs or better now. I built my 383 to 375hp with about 400ft lbs specs. Currently getting 18-19 mpg on the highway now but it cost me about $2300. That includes parts, labor and some local machining for partial rollerized internals. When I did the fameoff years ago I boxed the frame for multiple cross members. I gotta say, it's a much different car on the highway now. It's really a pleasure to drive at 65-70 at 2200 rpm. It was spendy but well worh it.
Steve
Steve
Hmmmm, another GM trans that it could be... I did a little net research and it sounds like the TH250 had an adjusting nut on the passenger side which mine does not. Soooo, it is (should be?) a TH350. Might keep that trans for now and save up for a swap. Nillabu, what all did you need to change to get the 200r4 in there? Anything other than the crossmember? I also checked the rear axle ratio, looks like it's a 2.73....
There are kits out there for extending the left side frame. Or fab it yourself. Either way it's not that difficult. Welding upside down can be a challenge though. I designed my own crossmember similiar to GForce's and drilled the frame to accept almost any trans length out there.
The TH350 downshift cable is not used, instead a "throttle valve" cable is used combined with specific geometry correction plates at the carb available thru Holley and others. Cable and adjustment are critical for correct line pressure for the 200r4.
The tube and dipstick are specific to the 200r4. I bought mine thru Art Carr. Fit perfect. The modulator vacuum isn't necessary anymore and slight adjustments had to be made to the cooler line bends. I believe the enter and exits are reversed also. The TH350 driveshaft and mount were reused. No adjustment were necessary.
The TH350 converter will not work with the 200r4. I'm using the "D5" medium stall single disk lockup convertor from C/K Performance. It's wired to lockup in overdrive only thru cruise/brake and manual dash switches. Alittle extra wiring was necessary.
Sometime, I plan to switch to 3.42's which may get me closer to 20-21mpg. I like the lighter weight, closer gear splits and the .67 overdrive ratio of the 200r4. Most of the expense was in installing good parts to make it capable of handling 450-500ftlbs of torque. my combo isn't nearly that aggressive so I should be okay. C/K Performance, among others, supply great experience/info and parts for these trannys. I finnally sold my TH350 and convertor so that brought my investment cost down to about $1800.
Hope this helps,
Steve
The TH350 downshift cable is not used, instead a "throttle valve" cable is used combined with specific geometry correction plates at the carb available thru Holley and others. Cable and adjustment are critical for correct line pressure for the 200r4.
The tube and dipstick are specific to the 200r4. I bought mine thru Art Carr. Fit perfect. The modulator vacuum isn't necessary anymore and slight adjustments had to be made to the cooler line bends. I believe the enter and exits are reversed also. The TH350 driveshaft and mount were reused. No adjustment were necessary.
The TH350 converter will not work with the 200r4. I'm using the "D5" medium stall single disk lockup convertor from C/K Performance. It's wired to lockup in overdrive only thru cruise/brake and manual dash switches. Alittle extra wiring was necessary.
Sometime, I plan to switch to 3.42's which may get me closer to 20-21mpg. I like the lighter weight, closer gear splits and the .67 overdrive ratio of the 200r4. Most of the expense was in installing good parts to make it capable of handling 450-500ftlbs of torque. my combo isn't nearly that aggressive so I should be okay. C/K Performance, among others, supply great experience/info and parts for these trannys. I finnally sold my TH350 and convertor so that brought my investment cost down to about $1800.
Hope this helps,
Steve
I know it's been awhile, but I appreciate all of your suggestions. I finished the 383 and swapped the engine, man a 383 is fun after that little 267! Even with the 2.73s I didn't like how it cruised on the highway though, so I bought a built 200r4 from Monster transmission (I'd pick a different company if I was doing it again but that's another story). I used a double hump crossmember for a 200r4 so I could bolt the transmission up and run a good true dual exhaust. While I was at it I also swapped to 3.73s at the same time. I love the combination, awesome power but still cruises on the highway very comfortably. I know its almost been 2 years but I wanted to let you guys know your suggestions really helped me out and were put to use. I tried to upload some photos but they're too big. I'll see if I can reduce them and try again. Thanks again guys!
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