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Shakercars's 1972 Trans Am

2019 August
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There are many, many threads here regarding the subject of swapping an overdrive transmission for one of the stock 3 speeds. I thought that it might benefit some folks here to hear what I did, why, and how it turned out. Here goes nothing:

The car:

It started life as a 77 Esprit, had been cloned to resemble a Trans Am when I got it, and recently had the engine upgraded to a 469 with the following specs:

1970 cast 455 block, 40 over, 4.25 inch forged crank.
E-Heads via Kauffman (ported to 320)
Butler designed Comp Cam (Intake 294@.050 243, Lift w1.5 .540" exhaust 300@.050 248 .563 112 lobe seperation)...my rockers are 1.65.
Ported HSD Intake (thanks Steve C),
1.75 inch primary headers
10.1-1 compression ratio
3.42 gears

All of that went to a fairly strong but soft shifting TH350. I had recently run a 12.9 in the quarter at San Antonio Raceway, and spun in the first 2 gears.

So, I decided to do the hot-rod thing and take something that was working well as is, and spend a bunch of money to change it. After doing a ton of research, I decided on building a 200 4R. There is a ton of conventional wisdom out there that says the 200 4R isn't strong enough to handle big torque numbers, but there are plenty of others that have proven that false. The guy that "wrote the book" on performance 200 4Rs is Art Carr, and his current shop is CPT out in California. Several folks I have come to know and respect recommended him, and Butler Performance also sells his product (that's a solid endorsement).

I ultimately decided to have the transmission built at a local shop, and source all of the rebuild parts from CPT. The reason for this was warranty and location. CPT has a solid warranty, but if anything goes wrong you have to ship the transmission back to California. My local guy gave me a 1 year no-questions-asked warranty for parts and labor. That's pretty good, even with me telling him that I plan on beating on it.

The mechanical reasons for picking the 200 4R were:
Better low gear ratios than the TH350 and 700 4R
Able to build without any computer or electronics
Better overdrive ratio (.67) that the 700 or 4L (.70/.75)
Same length as the TH350, so no drive shaft modifications.

Some things that I learned along the way:
An additional transmission oil cooler was required. I got one from CPT and it went in easy.
The crossmember has to be changed and moved back from TH350. If you have a TH-400, you are good.
The shifter conversion kit is neat, but not necessary. Mine has positive stops in low, 2nd, drive, overdrive, neutral, & reverse and the only part from the kit that I used was the decal.
Research what speedometer gears you need prior to building the transmission. 200 4R gears are on the governor, and you have to drop the pan to get to them.

What I bought from Art Carr:
Super Rebuild Kit
Hi performance intermediate drum
10 vane hi performance rebuild kit w/rotor
heat treated stator support
hi-pro 2nd gear band
non-lockup valve body
.500 boost valve
rev boost valve
200 4R super servo
2nd gear anchor pin
10 inch HD/Super Torque 27 spline convertor (3000 stall)
Oil cooler
TV cable
Q Jet Brackets

In our ordering conversation, Mr. Carr asked about my rear gear and kinda groaned at my 3.42s and said that he thought it would work "a lot better" with 3.80 somethings. I figured that I would be improving my launch no matter what with the better low gears, and OD would be optional for highway use anyway. I was around $2100 in parts from CPT, and had $150 in my core from Craigslist.

My local shop here in Dripping Springs, TX did a great job with the build. I had one little hick-up with the governor, but my decision to have it built locally paid off and it was fixed under warranty with no issue.

I have had the car back for about a week, and I can say without a doubt that it is a huge upgrade from the TH350. It is quicker from the start, and the overdrive is fantastic on the highway. I'm running about 800 RPM lower at highway speed (may be off by a few, I'll know for sure once I get my speedo figured out). I'm burning a lot less gas, and my engine is staying a lot cooler. I haven't had it to the track for a solid test yet, but I'm looking forward to that once it cools off a bit. I don't have AC, so this car is only moving in the morning and early evenings (central Texas y'all).

If I had a magic wand and could change something.... I'd have the transmission hold each gear a little longer under less than WOT. As it is, under moderate acceleration the car is in 3rd by 20mph and 4th by 30. The thing is, the motor makes so much torque that it doesn't matter. Even with the aggressive shift kit, acceleration under WOT is incredibly smooth and the convertor totally absorbs the shifts. I can give it half throttle and it will leave pretty hard and not feel a shift all the way up to 70MPH and not go much above 2200 rpm. Things don't go well if you hammer it at 30 after it already in 4th gear. It's about like you would expect if you jumped on the throttle of a standard transmission in OD. It will kick-down, but it isn't like a brand new car with EFI and a computer controlled transmission.

I have also found that if I am going to accelerate hard out of a 90 degree turn, it's best to just go ahead and pull it down into second. It also shifts harder and and at better points under WOT if I do it manually. Essentially, it drives like a Cadillac in D or OD...but if I want to beat on it, I've got to do some of the shifting myself. I'm guessing that I'm not the first person to experience this kind of thing, which is why Hurst and B&M etc exist. I'll probably invest in one of their products at some point, but am just gonna drive it for a while.

Overall, I am very happy with the upgrade, and would recommend Art Carr (CPT) to anyone nationwide and DC Transmissions here in Dripping Springs, TX to anyone in the area.

Feel free to ask questions and poke fun at my expen$e. I'll do my best to answer them.

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Bravo Navy Horn. This is an excellent piece. Thank you for sharing.

You forgot one more advantage of the 200 4R over the 700 R4 that is sometimes overlooked. It has the BOP (Buick-Old-Pontiac) bellhousing bolt pattern while the 700 R4 is the Chevy bolt pattern and requires an adaptor kit of some sort. If the 200 4R was good enough for the Grand Nationals and GNXs, it's good enough for me!.

I think it would be a good idea to post a link to Art Carr/CPT's website and any other vendors you used in your swap so others can duplicate your results.

How much did the whole thing cost - all in with everything?

Did you have to change your shifter cable?

Were you able to re-use the stock transmission cross over or did you have to get a new piece - since I've heard the 200 4R transmission mount is 2 inches further back than the TH350?

This has an electronic kickdown correct?

What is the stall speed of the torque convertor for your setup?

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The 200 series benefited greatly with the aftermarket cryo treated parts, both the 200C and the 200-4R. The superlight 200 3sp is highly prized for drag racing once it's been 'built'. GM left a lot of meat on those bones, and the aftermarket is still chewing. One of those 'bigger isn't always better' moments.

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I MIRRORED that 200R4 install in my GTO last year, having a local trans shop do the install.  Many probs most of which were shoddy work from the trans guy and many return visit's.  Never worked everything out, then the shop went out of business. I did add a His/Hers Hurst shifter to the new package,before taking it in.  Totally agree on the shifter yourself went ya wanna stand on it. Trans guy did not like the original shifter cable (said it was fraying) and replaced with the most cobbled up mess using a B&M cable, lost the adapter kit I had bought. I bought another kit and correct new cable and with the help of a friend got it back together correctly and installed a new kickdown and adjusted properly. (had a hip replaced last summer, so working under the car was a challenge at best) Still have a small leak somewhere.  I did not add an extra trans cooler, but it doesn't seem to be a problem with heat issues.  Also did not use Art Carr parts to rebuild the trans.  Shop owner seemed to know what upgrades were needed, but who knows what he installed.  End result, it drives well, sucks less gas, but have to live with a LIL drip.  He went to work for a National trans shop and will honor my 1yr warranty.   

Edited by JUSTA6
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This is the link to CPT:


I was just under $4K total for the project.

$200 for the core off of Craigslist
$200 to break it down and ensure it was suitable for rebuild
$1000 for the rebuild, $500 for install and setup.
$2000 in parts

Mr. Carr said the convertor is "2800-3000".  It flashes to about 3500.  I'm very happy with the convertor.  It doesn't "chug" at highway speeds with low RPM, and it soaks up the shifts in low gears.  It drives like a Cadillac when cruising, and a track car when manually shifting. 


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