The Stovebolt Site Forums The Shop Area Engine Shop 250/200R4

I have a 66 1/2 ton with a 250/3 speed and I would like to know if anyone has put a 200R4 behind the 250 and what was involved in doing so. I tried a search and did not find any answers. Thanks for any help or advise you can provide.

MikeP

RUN, do not walk, away from that conversion! The 200 R4 is the "Terrible 200", plus an overdrive. I made a lot of money replacing Turbo 200's with Turbo 350's, and the 4-speed model has a couple of really oddball additions, like that variable-displacement vane pump that never worked right, and an overdrive to boot. I'd choose a 700R4 if you've just got to have an overdrive!
Jerry

Why do you say it's terrible? A stock 250 makes 150 gross HP, and these transmissions were built to live behind 180 NET hp buick GN and Olds H/O engines. It'll be more than strong enough. They're just as strong as the 700R4, and on top of that, you get a steeper OD gear (.67 vs .70). If you want to swap out the engine for something more powerful, you can always build them up. There are guys with buick GN's running 9's in the 1/4 mile on the same transmission for 2-3 years at a time.

If you want to do this swap, first make sure the bellhousings will bolt up. I believe that all 200R4's were built with the BOPC-Chevy bellhousing patterns, but I"m not sure, and I know there are transmission companies that make adapters for oddball applications. They are the same length as a TH350, so your crossmember will not need modified or moved. However, this is a lockup torque converter style transmission, you will need to devise a way to hook up the tranny. This means that you will have to either get a kit from B&M or something that will lock up the converter for you, or rig up a switch on the dash where you manually lock and unlock the converter.

IMO, it's a good swap, and if you find a healthy JY transmission, it'll live for years. However, a couple things to watch out for - if the computer in the car has been disconnected, or the torque converter has been unable to lock up, it may have overheated the transmission and/or converter, leading to premature failure. Also, the reverse gear has been known to go out on these trannies in big cars, so limit your search to the granny versions of cutlasses, monte carlos, etc. By granny versions, I mean the 2 door, V6 powered cars with no power and ones that people haven't beat on. The big cars were usually used to tow stuff with, and the fancier cars were hot rodded and beat on, so get a nice sedate grannymobile to get the transmission out of.

I will tell you though, that it is nice to have that OD and 2.73 gears. 80 mph is 1800 RPM's locked up and in OD. Cool as heck. Watch out though, because it'll lock up the tranny at 55 mph and you'll be stuck with an engine lugging at 800 RPM's and you won't be able to get anywhere like that.

I also know guys with 200R's in 10 sec. GN's and they never break. I have a 700R in my Syclone and my Typhoon. The Typhoon is stock,runs high 13's, and the tranny has never had a problem but the Syclone runs low 12's in the 1/4 and im on tranny #3. All i know is....

10 sec. GN + built 200R = No breakage..

12 sec. Syclone + built 700R = BOOM...there goes another tranny!

Thanks for the replies. I would like to keep the 250 somewhat stock for fuel milage and am just looking for options as it is time to replace the clutch.

MikeP

I will have to agree that the 2004R is tougher than you think. I have had several, with the latest in an 84 Cadillac boat, and it worked well.

I have rebuilt many more 700's than the 2004R in my area.

A search of this topic will show that it has been discused before. First, it should be understood that "T", "TH", and "THM" are all used to stand for "Turbo Hydra-Matic".
A T200 is not a 200R4.
[img]http://www.nastyz28.com/pictures/transpan.gif[/img]

The THM200 and the THM250 have pans shaped like a THM350, HOWEVER, the THM200 will have the words HYDRAMATIC DIV. and METRIC stamped into the pan.

The above and the following is from This Page

Automatic Transmission Description & Usage
THM200 - Light duty, "metric" 3 speed transmission.

THM250 - Used in small 4 cylinder cars (Vega, Sunbird, Monza) from 1973 to 1981 and some Nova/Camaro/Chevelle 6 cylinders in 1974 & 75. The 4 cylinder models have 4 large cooling holes near the torque converter, while on the "bigger cars" there are no cooling holes.

THM200-R4 - Used in GM rear wheel drive cars with the 3.8 V6, 305 & 350 Olds and 301 pontiac from 1981 to 1989. This is a 4 speed, overdrive unit.

THM350 - Medium duty 3 speed trans used from 1969 to 1989, Used in Buick, Olds, Pontiac and Chevrolet cars and Chevy & GMC light trucks until 1987. Generally used in straight and V6 and small block engines. Generally able to handle up to 400 foot pounds of torque.

THM375B - This trans is identical to the THM350, but is considered a heavier duty transmission.

THM375 - This transmission is a derivative of the THM400 sharing the external appearance of the 400. It'll be marked 375-THM on the bottom of the tailshaft housing. It's a light duty version of the THM400, has ABSOLUTELY NO RELATION to the THM375B, and was found in 1972 to 1976 full-size cars. The Turbo 375 was modified to accept the Turbo 350 driveshaft yoke.

THM400 - The THM400 was GM's Heavy-duty 3 speed transmission used from 1964 to 1990. Used on large displacement, high torque engines and engines with towing packages. Generally found in Chevy & GM trucks, cadilacs and large displacement engined, full size GM rear wheel drive cars.

THM700-R4 - 4 Speed transmission used in GM cars and light trucks with the 2.8, 3.1, 4.3, V6, Chevrolet built 305, 350 and 454 engines from 1982 to 1992.

4L60 - Early 1990's saw the 700R4 renamed to the 4L60, and "electronic" models were named 4L60E. 4L60 means 4 forward speeds, L = longitudily mounted (rear wheel drive). 60 is the strength rating (less than the 4L80).

3L80 - The 3L80 is a renamed THM400, used in the early 1990's. The 3L80HD would be the THM475 (heavy duty unit).

4L80 - An overdrive model of the THM400. The 4L80E would be the "electronic" model.

When GM says "E" such as on 4L60E, they mean computer. The 4L60 still has a electrical hookup and these two web pages give two different ideas of what to do with it.
Chevyasylum
Bowtie Overdrives

They also use 4T60 designation to stand for transverse mounted on front wheel drive.

I drove GM intermediates with 200 &2004r,s
for many years. It seemed like about 75-100
k miles is what I got out of them. The 7004r
is a better choice. I had a63 1/2 ton with
one & it was agreat driver. I will put one
in the 70 I,m driveing now soon. It is an easy
swap & there are ways of dealing with converter
lock up.

It really depends on the upgrades done to either 2004R or the 700R4 and how they are driven as to how long the last. The 2004R should be more than enough to handle a 250 six cylinder. Just be sure to check on the condition of any trans you put behind any engine.

In my stock 83 delta 88 with a 307, the original transmission got 175,000 HARD miles before the reverse took a dump. The one I have now I am ruthless with. It's a completely new transmission that is built to H/O/GN specs. This thing has been down the dragstrip numerous times at WOT, idles around town and runs at 95+ mph on the highway, not to mention burnouts, powerslides, light neutral drops, and everything else I can think of to blow up my 307. After 4,500 miles of driving like this, it still shifts hard enough to snap your head back, and when the TC locks up in 3rd gear, it'll shove you back in your seat. I'm expecting this transmission to outlast the engine.

Buddy of mine has an 81 delta 88 (3800 lbs) with 3.73's and a mild (350 HP) Olds 455. Runs 14.3's at the track and is using a stock 200R4. No slipping or anything, and this is with slicks and burnouts at the dragstrip. It's his daily driver and he gets about 4,000 miles a year on it.

Like I said though, get it out of a granny car, not out of a high performance or fullsize car.

BTW, if you want real info about these trannies from people that put serious power in front of them and how they'll hold up, go to a GN board, or www.realoldspower.com . The Olds board is a great place for anyone with any Oldsmobile related questions anyway, as we've got the fastest people in the Oldsmobile planet there, as well as some straight up resto freaks.