Some guys in my area talking I should switch my 350 trans to a 2004R. But only two have done it. One in a 67 GTO and the other in a Buick. Both said they had it done elsewhere, so they couldn't give me any details. OK so those of you who have done it let me know your thoughts, worth it, whats involved, drive shaft, speedo accuracy, kick down, mpg, rpm, benefits etc. I see there are quit a few sellers of them on line. Looking forward to what all of you have to say.

 

Philosophically, the benefits are if you have a numerically high rear end for reasonable cruise rpm. If you don't have one, there's no reason to do it. What is your rear end ratio?

Speedo can be accurate, you need a drive shaft, and the main issue is setting the TV cable right because you can damage the transmission without it. I believe there is minor tunnel fitment involved.

 

I did the conversion last year on my 75 supreme with a 350 in it with a th 350 transmission & 3:42 gears in it. I love it, I had the tranny beefed up,. I installed a tranny cooler, synthetic oil, stall converter 2400-2600 same driveshaft & yoke, moved the double hump crossmember back to where the th400 would sit, installed a larger aluminum pan with drain plug, bracket for the tv cable at the carb, modified the carb linkage for the tv cable attachment, console shifter cable and brackets & automatic torque converter lock up switch.
Makes a big difference on the highway cruising at 70 mph.

Jeff

 

I did a TH400 to 200-4R switch. Driveshaft is the same for the 400 (can’t speak to the 350) only a new yoke. No modification at all to the tunnel. Factory crossmember works (I think you have to move it for the 350, but holes are already there). Minor change to the transmission cooler lines. Speedo accuracy is set by matching speedo gears to your rear end & tire diameter - very easy. MPG bumped from 15 mpg to 20 with 3.08s. I had no drop in mpg when I bumped up to 3.73s. The 3.08s in overdrive were lugging the engine a bit on inclines, so the 3.73s bumped it just enough. RPM is an easy calculation...plenty of calculators out there (final drive on the 200-4R is 0.67). Be sure to get the TV cable adjusted properly; it’s critical. Plenty of brackets available for it. There are also shifter conversion kits that’ll give you the right detents and indicators.

I cannot recommend TCI. I rebuilt one with their shift kit and bought one of their street fighter versions. Both had unbearably harsh shifts. Took all of the fun out of driving at part throttle.

Car is a 68 with an Olds 350. Overall it is an incredibly simple swap and well worth the effort if you can get one that shifts like a normal automatic.

 

Hello, I swapped out a 350 for a 200r4 and the driveshaft required no modifications yoke is the same. Had to move crossmember
back which requires modifications to the parking brake cable. I bought a shorter cable but have not installed it yet. Besides the TV cable to the carb i had to get a kit from TCI which has a vacuum switch for the overdrive. I haven’t been able to take the car freeway speeds yet but seem to function perfectly at lower speeds. My car is a 65 cutlass with a 350 and 3:08 gears
Greg

 

Once again:

The 200-4R is the same length as a short tail TH350. The TH400 is several inches longer, meaning that the driveshaft for a TH400 is several inches too short. Using a TH400 driveshaft with a 200-4R (or TH350) risks having the yoke pull out of the trans, or at a minimum the yoke won't sufficiently engage the tailhousing bushing, causing excessive wear and possible vibration. Don't do it.

The 200-4R uses the same front driveshaft yoke as a TH350, Jetaway, or manual trans.

The 200-4R requires the crossmember to be located in the TH400 position. This is pre-drilled on all 1967-77 A-body frames. 64-66 will not have this provision since the TH400 wasn't used in those years. Moving the crossmember requires you to change the front and intermediate e-brake cables to those for the same-year TH400 car.

The reason to use a 200-4R even if you have a low numerical rear axle is the fact that first gear in the 200-4R is 2.74:1 vs 2.52 on a TH350, 2.48 on a TH400, and 1.74 on a Jetaway. Off the line acceleration will benefit no matter what rear axle you have.

 

I did it. Worked fine. Plenty of engagement, never pulled out, no vibrations.

I won’t speak to every iteration of the 400 (short tail 400 is less than 3/4” longer), nor every iteration of driveshaft (mine was cut for the 400 install). But I know for a fact I’ve swapped those transmissions back and forth with the exact same driveshaft and nary an issue.

 

My car is a 350 engine and 350 trans. Current tires are 225/70R-14. Differential is 2:73 I think which was pretty much standard??? Reason I am inquiring is I am turning 2750 rpm at 75 mph. The guy with the GTO said his gas mileage went way up and rpm down afterward. I am getting about 12-14 mpg now, but the rpm is scary on an engine with 85,000 miles on it. What is the TV cable and what does it do? Would a transmission shop supposedly know all the stuff that needs to be done? I know dumb question

 

TV cable in part helps transmission to shift. Cable must be adjusted so it pulls out fully at WOT and it should have a slight amount of slack at idle.
Your mileage will go up to 20 or so I’m guessing because I haven’t run mine yet. Rpm should drop to about 500 revs in overdrive.

 

I installed a 200r4 in my car with 3:42 rear and 2200 stall. The TV cable adjustment is critical and there is a lot of info available on how to correctly get it right. It is the single best mod I have performed to my car to improve both drivability and performance. My car was originally a 350/350. No driveshaft mods needed. Moved the crossmember back to the Turbo 400 holes and everything bolted up. Had to change the e brake cable to the correct cable for a turbo 400.. As others have said, the speedo gear will depend on your axle/tire combo but this is easy to calibrate. Hope this helps.

 

If it were me, I wouldn’t bother with the swap. Your highway RPM will be well below 2,000 RPM in top gear (probably at or below 1800). You’ll be down shifting for every slight incline. Your engine is fine at 2700 RPM. Don’t get me wrong, it would still be a benefit, but in my personal opinion, not worth it unless you’re also planning a lower rear gear to match.

TV cable controls line pressure for the transmission. Set wrong, the transmission will not shift correctly and can burn up if not getting enough pressure. The consequences of a bad setup are very bad, but in reality, it isn’t hard to get the correct geometry and adjustment.

I would not bank on a shop knowing how to swap them. Some can, but most don’t do swaps - just repair/replace. Doesn’t hurt to ask if you are unable to do it yourself.

 

I installed a 200r4 in my car with 3:42 rear and 2200 stall. The TV cable adjustment is critical and there is a lot of info available on how to correctly get it right. It is the single best mod I have performed to my car to improve both drivability and performance. My car was originally a 350/350. No driveshaft mods needed. Moved the crossmember back to the Turbo 400 holes and everything bolted up. Had to change the e brake cable to the correct cable for a turbo 400.. As others have said, the speedo gear will depend on your axle/tire combo but this is easy to calibrate. Hope this helps.

 

Here is a link to Extreame Automatics. I bought my 200r4 from Lonnie and he was very helpful with info. There is a nice file here on how to set up the TV cable. http://www.extremeautomatics.com/***...on_Install.pdf. Hope this helps

 

Seriously???

I routinely turn 3500 RPM on the freeway with the 215 in my 62, and similar RPMs when towing with my truck that has 300,000 miles on an untouched BBC (though I did change the timing chain at 150,000 miles).

 

Your car, your risk. If the driveshafts could be the same for a TH350 and TH400, GM wouldn't have wasted the money on two different lengths.

 

Daily driving both for years, I’m quite comfortable with the “risk”

 

Great thread, already answered several questions I've had about same swap. Been contemplating for years... I believe in mods to a point but am also proud of how my car runs with its factory drivetrain. Equally proud to be able to say its original. At the same time I would love to have a more aggressive gear with limited slip. Quicker performance is my primary motivation as i am pleased with current mpg.

I have a KZF 200-4R in good working order available to me, but the bottom line is i am absolutely torn on pulling the trigger on this swap.

Best of luck whichever way you go.

 

The 2004r would be a good swap if the existing 350 is tired and needs replacing. Your tach is off, your speedo isn’t accurate, or your 350 trans isn’t shifting into high gear. With 2.73 gears, I would expect highway rpm to be around 2200-2500.

As Joe said, the swap is pretty easy. Move the crossmember to the position of the 400 trans, use the 350 driveshaft, and make sure the TV cable is correct. Close is not good enough!! The TV cable doesn’t “help” the trans shift, it’s the only input the trans has to know throttle position. If the cable isn’t right, the pressures may be too low for sufficient clutch or band apply, causing slipping. If it’s too tight, late hard shift will result, along with possible 2nd gear starts.

The driveshaft for a 400 is too short to be used with a 200r4 in my opinion. Unless the driveshaft was too long with the 400, I would expect some pretty sever vibration with the 200R4, and rapid bushing and seal wear. Unless the transmission yoke is longer than the typical car yoke, there is about an inch difference in overall length between the transmissions. An inch doesn’t sound like much (feel free to add your own juvenile humor to that comment!&#128514.

 

Not dumb at all, in my book probably the most important question you could ask.

Bingo !

yellowone I've been dealing with mechanics for over 30 years now. 1960s Olds even back then. In 1989 when i would show up at a shop all the mechanics marveled at how empty and basic our cars were. Needless to say most of them eagerly wanted to work on it. Today its the opposite. The manager sees me coming and is scrambling for the one mechanic he has that's comfortable working on our rides.

Not to state the obvious but our cars are now really OLD. Us being as hands on as possible will help enormously. I would only bring to a mechanic / shop that you feel very comfortable with. Not only ask if they can do the work but ask if they can really do the work. If its a headache for them it can be a nightmare on your pocket. Not to mention that i doubt you want somebody sorta learning to do something on the fly...

Thank you for this Joe. I highly value your knowledge, experience, and occasionally your opinion when it comes to Olds. Been enjoying Olds Faqs and your contributions to it for decades. As well as other sources of info where your name has popped up.

I am more at ease now with potentially going 3.42 or even 3.91 and leaving the trans alone...

 

2750 RPM (from the OP) x 0.67=1843 RPM, not counting the lockup with the torque converter.

I ran those RPMs with 3.73s and a 26” tall tire...

 

No 2750 rpm with no lock up at 75 mph will be close, he will drop 1000 rpm at 75 mph. The 250 to 300 rpm for the torque converter makes a noticeable difference alone. My 70 with shorter 235/60R14 tires, very similar 2.78 gears ran 1900 rpm at 70 mph. Very easy swap overall as said.

 

I have the 2004R behind a 455 with a 3.73 rear gear. It's an awesome upgrade to get the overdrive. I can cruise the highway at 70mph+ and the RPMs stay low (2200 rpm) and I get decent gas mileage. I hooked up the lockup converter on a toggle switch so when I hit OD, I lock the converter. This drops the RPM another 200-300 and the trans temps will drop 40 degrees within 1-2 minutes with the converter locked.

Will probably go to 4.10 gears as the 0.67 overdrive in the 2004R will allow for it. With no overdrive trans, you are stuck with 3.08 gears or never being able to do sustained 65mph+ highway runs without causing excessive wear & tear on engine and getting horrible MPG.

Overdrive transmissions are the best thing that happened to cars since FI. Now they have double and even triple overdrives in 8 speed auto transmissions. Old school 3 speed autos truly do belong with the dinosaurs. It's outdated tech. It was good for racing the 1/4 mile but otherwise for day-to-day, they did not do well for today's modern highway speeds of 65mph+

 

I'm not suggesting that the OD isn't a good upgrade. I am suggesting that 2700 RPM on the freeway with a motor with 85K miles is not worth losing sleep over. Will the car be smoother and quieter with the OD? Sure. Personally I prefer the OD swap to let me run steeper gears off the line.

 

The steeper gear in the back with OD is worth it alone. "Free" torque multiplication with a steeper gear gives the vehicle quicker acceleration (traction being key). Back then (60's 70's) they couldn't put the steeper gears in because the vehicle would overheat (especially AC cars) and would have a hard time running on the highway without buzzing the engine into oblivion and causing accelerated wear & tear. A 1:1 ratio meant 3.23 or lower gears for highway cruisers.

With OD, one can put 3.73 or higher gears in back and still have the engine run at 2,100 RPM while going down the highway at 70MPH.

I would definitely recommend getting the lockup converter with the 2004R and running it with a B&M controller or toggle switch. Locking the converter drops the engine RPM by another 300 RPM and keeps the trans running cool. Converter slippage is what causes heat build-up in the trans. Once locked, there is no slippage and the trans runs 40-50 degrees cooler.

 

Yellowone:
I highly recommend the OD swap, but the trans needs to be built properly to last behind anything over 250-300HP/TQ. There are some key upgrades required to make it live behind more HP/TQ: specifically, upgrade the pump, use roller bearings in place of the plastic thrust washers, drill out the drain back hole from the pump to prevent blowing out the front seal, and machine the OD piston to allow the installation of 1 additional friction in OD for more holding strength. I also recommend installing a pressure switch to automatically lock-up the converter in 4th (OD) gear. You can provide a little extra finesse by installing a vacuum switch inline with the 4th gear pressure switch to unlock the converter when vacuum drops, such as under part-throttle acceleration. The 300-400 rpm boost from unlocking the converter helps with drivability. If you really step into the gas pedal, the TV cable will down-shift the trans into 3rd (converter unlocked) for a passing gear.

Phil:
That KZF trans was installed from the factory in Olds HO cars with 3.73 gears. If you upgrade your rear gears to 3.73 your speedo should be correct, assuming your wheel & tire combo hasn't changed substantially from the factory set-up.

Rodney

 

To show the power advantage of OD transmissions. The new C8 Corvette comes with an 8 speed auto with 5 overdrive ratios. Now here it the kicker. The gear ratio is 5.12 in the new Corvette (4.90 in the non Z51). That's insane.

Having a 5.12 gear ratio is "free" torque multiplication. This allows the new C8 to run 11.30s in the 1/4 mile. The 500HP engine of course is vital but the 5.12 gear ratio gets the vehicle moving and multiplies the torque. The 8 speed overdrive has a final overdrive ratio of 0.32 which drops the 5.12 gear to a final ratio of 1.63 for cruising on the highway. The OD trans allows the best of both worlds. Awesome acceleration and great highway cruising.

Like I said, putting in an OD in a older muscle car makes for a huge performance advantage of the dinosaur antiquated 3 speed autos.

To take advantage of the 0.67 OD ratio in the 2004R. Best to run a 3.73 or 4.10 gear.

 

I installed a 3:08 posi in my blue 1979 Calais back in 2002 and that greatly assisted in blowing up my metric 200 trans on the way to the 2003 Nationals. I was running 3,100 rpms at 65 mph and for a 16 hour drive it was too much for the rest of the drive train. Since the "power curve" in my Olds 260 motor is zero to 1200 RPM, installing such a high ratio rear (orig was 2:29) was a recipe for disaster. Rather than get another garbage M200, I instead opted for a rebuilt 200R4. It entailed moving the crossmember slightly and getting a different drive shaft (which I still need to get balanced). This turned out to be a winning combo. Around town I keep it in 3rd, but as soon as I get onto the hwy I put it in 4th and I get back my 1850 rpm's at 65 mph, and my 22 mpg back that I originally had.

I'm experiencing a fine vibration at 65 to 75 mph which I attribute to the need to get that drive shaft re-balanced.

 

People should note, while dissing GM about rear end ratios and non overdrives, that those are the reasons why you have the big engines in the first place. Too many enthusiasts are all "If they'd done overdrive, they coulda hada TORRRQUEUEUE MONSTARRRRRRR" without realizing that said thing is their goal, not GM's. Had they done overdrive and steeper rear ends, a la cars of the 80s, you would have gotten the same engines from the cars of the 80s. The 442 was sold as a factory muscle car, not as a 12 second quarter mile car. Different priorities. The 84 Hurst has something like a 3.90 in it, an overdrive trans, and an engine that is not exciting.

 

Isn't the TH200 the same length as the 2004R and TH350? I have actually done the swap working in a garage. I remember my boss telling me to grab the driveshaft just in case, can't remember if I actually used it or the one in the car.

 

To the best of my knowledge, the highest gear GM used with a overdrive trans is a 3.08. You could probably get away with a 2.73 gear if you run the short factory tires. Anything lower would probably lug the engine at anything less than interstate speeds, kinda defeats the purpose of having overdrive in the first place

The turbo Buick cars used a 3.42, the Olds performance cats got the 3.73s. The small engine S-10 trucks got 4.10 gears. In my opinion, if you have no plans to step up the gears to 3.23 or better, it’s hard to justify the money, time, and effort to swap out a 350 trans for overdrive.

 

If by "highest gear" you mean low numerical, then you're not even close. With the exception of handful of performance models in the 1980s, nearly all of the 200-4R transmissions were installed in front of 2-something axles. I have owned five 1980s 307 powered cars with 2.73 axles, and some even came with a 2.41. I still fail to understand the myth that a low numerical axle behind an OD trans will somehow cause "lugging". My 307s with their pavement-ripping 140 HP (on a good day) in a heavy Custom Cruiser have no problem with that 2.73 axle. If the car needs it, the trans downshifts. That's how automatics work. And the 2.74 first gear is still better than the 2.52 first in the TH350.

 

The 200 4R has the rear mount in same position as TH400 but the overall length and the driveshaft length is the same as TH350.

 

GM installs 5.12 gear ratios in the new C8 Corvette and with the 8 speed OD trans with a 0.32 deep overdrive ratio, the final gear ratio is a 1.63
There is NO lugging the engine even with a 1.63 final ratio.

Lugging only occurs mainly with old school carburetors that are not properly tuned but with FI, there is no such thing as "lugging" as the ECM will compensate and either reduce air/fuel ratios or downshift if needed.

 

Lugging occurs with any internal combustion engine that is in too tall of a gear for the load - fuel injection won't stop that.

And yes, an automatic that is paired with an extremely tall gear will downshift and downshift often. For every slight incline it will happily go in and out and in and out and in and out of overdrive to try to climb the hill. I mean, I know central Missouri is well known for its massive mountains and steep grades, but I really prefer a vehicle that is geared well enough to handle them in overdrive...

 

I guess lugging isnt the word I should have used. I suppose you could run a highway gear with overdrive, but the engine would be barely above idle at highway speed. Having the transmission downshift with the slightest headwind or hill would get annoying.

Ill say again, unless your willing to gear the car to be able to effectively use a overdrive trans, what’s the point? What’s the point in having a 4 speed trans if your only using 3 of them 90% of the time?

My my wife had a Chrysler 200 with the 9 speed trans. It wouldn’t shift into 9th gear until about 70mph. It also shifted about 3 times crossing an intersection. Obviously, there was absolutely nothing wrong with the car or the way it drove, it was just a big adjustment from my 69, and my 06 Ram diesel with its “primitive” 4 speed trans.

Im including a snapshot of a gear ratio/speed calculator. Note the 2.29 gear ratio, a 700 rpm engine speed (typical hot idle speed) common 27 inch diameter tires, and .70 high gear of a 4L60, or 2004R. With those parameters, idling at 35 mph isn’t practical.

 

You are correct. Lugging is simply being below the powerband at any given time while needing that power. If you're in the powerband, and need more power, you just don't have enough engine

Modern Corvette design practices are fairly irrelevant for discussing 50 year old muscle cars. A properly set up transmission will allow you to accelerate from interstate speed, go around someone, and return to that speed while staying in top gear. It will also allow climbing hills at interstate speed. Passing on a two lane road in an enthusiastic manner will require downshifting. A 350 cu in V8 from 1970 with a th350 with 2.73 should get 20mpg on the open road and do all that. No need for overdrive. 3.08, same thing.

 

I don't understand why people are so adverse to downshifting. In any case, the OD vs. non-OD is irrelevant. What matters is effective final drive ratio, which includes trans, rear axle, and tire diameter. The advantage to having more gears is that you have a wider ratio from first to high, which helps with low-end acceleration. And obviously all this needs to be matched to the power band of the engine. Modern engines are tuned for high efficiency and maximum output within a narrow RPM band, thus the need for 8, 9, and 10-speed transmissions. An internal combustion engine can be made very efficient over a narrow RPM band. Small engines are efficient but peaky. Approximating a CVT improves performance while maintaining efficiency.

 

First time I drove a CVT car I thought I was gonna blow the engine.

 

Good evening all,

I realize that this is an old thread, but I am in the process of swapping out my Jetaway for a 200-4R from a 1986 Monte Carlo SS into my 1969 Cutlass Convertible. I had the internals changed in the Diff from a 2.56 to a 3.43 Posi, and wondering if the Driveshaft is the same length? I moved the crossmember back to the TH400 position, and everything has fit perfectly so far.

Also, has anyone used the Bowler Tru-Shift System to adjust and maintain the TV Cable?

My apologies in advance if this is in the wrong place but thank you all for your guidance!

 

I’m pretty sure the Jetaway and TH350 are the same overall length, if so the driveshaft should work.

I have no experience with the bowler tv cable setup, put a line pressure gauge on it to be sure line pressure reacts the way it should with throttle opening.