corvette forum members:

I am thinking of swapping the tranny from my 80 which has the TH350C for a 200R4. A local salvage yard has a tranny that they called a "2004R" from a Grand National. Is this the same thing as a 200R4? They are selling it for $200 with the converter.

Can anyone elighten me? By the way, I am familar with 200r4.com already but i wanted to keep the costs down.

Any assistance would be greatly appreciated.

Chris
aka migraine99

 

To the best of my knowledge it is the same thing. I have seen it listed as "R4" and "4R" several times. The 200"4R" is correct I think as is the 700"R4" correct. The 2004R did come in the Buick Grand National.

 

Id do it for $200,will they guarantee it that its ok and replace it.

 

I'm not sure. I'll have to call and ask.

I've been doing some further research and I guess 2004R and 200R4 are used interchangeably but 2004R is the correct number.

If I had looked closer at the web address, I would've seen it was 2004r.com not 200r4.com DOH!

Do I also recall that the 2004r is 3" longer than the TH350c?

Anyone? Bueller?

 

i think the 2004r is the same length as the TH350 so you don't need to shorten the driveshaft and the 700r4 is 3 Inches longer...

 

I just went through this on my 80 and here is what I learned. The tranny you buy either has to have 10 mounting hole which makes it a universal or it has to have six holes with a peak in the center of the housing on the top otherwise it won't bolt up.
Also you will need to either do some fabrication on your crossmember or get one from Bowtie $179. I think you also will need the wiring to hook up the lockup torque converter. And the 200r4 is the same length as your 350. Best mod I have ever done.

Kona

 

....well i can't decide if the OD tranny (700r4), the new 350/350 engine, or the steeroids is the best mod i made but i can tell you cruising at 70+ at like 1700-1800 rpm is definitely pretty cool

 

The 200-4R was made with different cases. Not sure if it was three or two. But one fits BOP (Buick/Olds/Pontiac), another for Chevy...and perhaps a universal, too.

 

doesn't ponitac and olds distributors run opposite to SBC? does that mean the engines rotate diffeently also?

 

The salvage yard told me it was from a Grand National. So, I'm assuming BOP mounting?

What other vehicles had this tranny?

Also, I have a crossmember from a 79 so I could run true dual exhaust. Will I absolutely need a new one?

 

I'm pretty sure that a 79 crossmember will work. I think they changed over in 80. Not sure if the mounting holes on the frame will be correct.


kona

 

I went with the BTO 700R4 in my '80 L48. I agree that cruising the highway, taching 1800+/-rpm at 70mph is a very good feeling

You will also need to address the TVS cable/mounting brackets on your carb. Not sure, but I suspect you will also need to set the line pressure on the 2004R in similar manner to the 700R4 (On the 700R4, I adjusted the TVS cable where it mounts to brackets on the intake at the carb). BTO provided a hydraulic pressure gauge/hose that attached to a fitting on the left side of the trans case. I followed their directions to correctly set the line pressure; critical for durability of the transmission as well as positioning of the shift points. Also, Bow-Tie provided a custom carb linkage adapter that made tuning of the shift points much easier. I used the '1904 Q-jet' adapter on my '80 L48 Q-jet. Bow-Tie Overdrives website and others may offer similar detailed info on the 2004R installation/setup. Need to cover all of the installation bases if you don't go with a kit. My kit provided all of this good detail for setup. I'd bet others that went the 2004R route can provide this FREE to you.

 

you are correct sir! In 80, they went with a single "humped" x-member instead of the dual holes from the earlier years. That way, they could run the 2-1-2 exhaust! yay!

 

I would recommend getting a turn-key kit from Bowtie rather than going the junkyard route. Along with rebuilding the tranny -- and strengthening its weak points -- they install a solenoid kit inside the tranny that's used to lockup the torque converter.

 

One of the best upgrades I have done.

 

No the distrubitor does not run opposite the SBC...but I guess U could say that maybe. What is happening is the placement of the distrubitor gear in relation to the cam gear. The Chevy distrubitor gear is located on one side of the cam & the BOC distrubitor is located on the opposite side. Hence the difference in rotation. The cranks in all of these engines rotate the same way. This is one reason the starters are located on opposite sides of the engine.

 

make sense....but you have to wonder why they changed it to begin with

 

If it's a true GN 2004R, those things are, or at least were, considered gold. You will pay a hefty amount for one if people know what it is.

The tag on the side should be BR or BRF if it's a true GN 2004R. 2004R in general has a better OD ratio than the 700R4, and better 1-2 gear spacing than it too. Be careful, there are many variations of the 2004R, and the weaker ones use plastic thrust washers instead of needle bearings, etc. The 2004R was used in just about everything except trucks, so very common. Monte Carlo, Regal, Cutlass, Caprice, Cadillac, and so on. Anything that had either the Olds diesel engines or the 307 Olds (which lasted until 1990) could have had a 2004R. (and Chev too, but there was the 700R4 in some cases there, 700 never used with BOP) You won't see them very common in the "lower end" cars, as a 3 speed was standard. The "lesser" 2004R's were made to shift for grandma and grandpa, not designed for high RPM positive shifting.

In GM's scheme of transmission labeling, the middle (if three) or last (if two) letter on that tag on the side of the transmission denotes the relative strength. A "CA" would be a sloppy shifting internally weak Chevy 2004R, while a "CQ" or "CZ" would be a higher/harsher shifting, internally stronger transmission, as for instances. CQ and CZ were the codes/transmissions used in the Monte Carlo SS's. OA would be a weak Oldsmobile, etc.

You will probably NEVER see a 2004R that isn't dual engine bolt pattern. They are *extremely* rare in Chev only pattern. I've never seen one. ALL BOP cases are universal and will work with a Chev motor.

As to the Pontiac and Olds motors comment, they aren't Chevy motors, and aren't based on them, so thats just how they were designed. They weren't "changed".

 

thank you for all the responses! as usual, you guys are a fountain of information.