hes not worried about that

 

You're on a budget, use the 355's & drive the car. When you're ready and have more cash you can always go to an OD or other gears. How many miles are you going to put on it anyway? A properly built 350 and TH350 will go 100k miles easy.

 

Thanks Gary. I am going to just buy the 3.55 ring/pinion from VanSteel and use my original TH350.

 

If your rebuilding the TH350, one upgrade that isn't too expensive is to buy a heavy duty sprag outer race. It's one of the most common things to break in at TH350, and if it goes say good bye tranny (it kinda of explodes and wipes out most of the internals). I ran a rather stock TH350 with a TCI outer race and some good clutch packs behind a big block for years without any problem. Its just good insurance to beef up the sprag (TCI's is $55).

 

I'll definitely be beefing up the TH350...no doubt about it. I have upgraded this entire car. I haven't skimped on parts either - I bought all quality stuff through VanSteel and a few other vendors, but mostly VanSteel. The last thing I would want to do is skimp on the engine and transmission parts - those are very important. Thanks for all the help guys.

 

Before overdrives came into the picture, people were happy to get 50,000 - 70,000 miles on their engine with out having to rebuild their engine. Saying that it should go 100k miles easy is a very optimistic if you ask me. However, if he goes with the 2004r in 10 - 20k miles from now, then I would agree that it should go 100k miles easy.

Sorry, if I seem to be a little too persistent on the OD tranny. IMO rebuilding the TH350 with a chance that you might swap it out later would be a waste of money and time. Its a lot easier to install the tranny now, then go back later and take a chance of damaging your hard work for something you should have gone with in the first place.
If I didn't feel so strongly that an OD was the best choice, I wouldn't be wasting my time typing right now after everyone has told you to go with your TH350 because of a budget. If you need to spend a little more time saving up, I think you should. Before you rule out the OD tranny, create a thread inviting all members who have gone with the 200 4r and ask how they feel about their tranny. I hope you understand that I am not trying to tell you how to build your car, I just don't want you to regret going with the TH350 later on down the road..

 

I agree. I yanked a 2004R out of a junkyard Monte Carlo (paid $50 for it at Pull-A-Part, and what fluid was left in it looked good. I probably could have run it as-is, but it was going in my parents' '63 Impala convertible and I wanted to be sure it would be reliable for them. I had it rebuilt, including a new convertor, for about $500. The car had a Turbo350 (non-original, it came with a Powerglide) and 3.36 gears, and while I had the driveshaft out I swapped in a 3.70 center section and WOW, its like a whole new car!!! Acceleration is much improved, even in a boat like that, and while I can't give you RPMS at speed (no tach) it is turning much lower rpms than it used to be at highway speed. Overall, the best mod we have done to the car. 3.55s would be great, too. Keep in mind most performance cars (Grand National, 442, Monte SS) that used this trans came with either 3.42 or 3.73 gears, and none of them are top speed limited by the transmission.

 

Now I am unsure of what to do. I really can't decide which tranny I want to go with right now...all I can decide is what gear ratio I will be putting in the diff (I am rebuilding it at the moment). I have decided to go with a 3.55 gear ratio in the diff - if I end up swapping over to a 200r4 or 700r4 when the time comes to make a decision on the tranny, is this a good gear ratio for these two models (200r4/700r4)?

 

I vote for an OD transmission. Once you have a high HP motor AND the gears you need for a good top speed you'll wonder why you ever drive your car with only three gears.

 

I have decided to go with a 3.55 gear ratio in the diff - if I end up swapping over to a 200r4 or 700r4 when the time comes to make a decision on the tranny, is this a good gear ratio for these two models (200r4/700r4)...anyone here have an answer for this?

 

I think I've changed my decision on which transmission I will be using. I think I'll be going with the automatic 200r-4 with the overdrive...I'll just have to save up enough money to purchase one and rebuild it. Since I want this thing to accelerate real fast, and still be in a respectable RPM range when cruising on the highway (only sometimes), will a 3.55 gear ratio in the differential suffice? The overdrive I assume will lower the extra RPMS on the engine which would have appeared if I went with the TH350. I don't want to kill the engine on this car after the rebuild, which is why I have decided to change my mind on the tranny.

 

As long as the 200r4 is a direct bolt in for the TH350, without the need of modifying the frame for a new crossmember (having to shift it back an inch...my frame is at powdercoat), I will probably go with the 200r4. Any mods on the frame (mine is a 1976 stingray)? I don't mind if I have to mod the crossmember, but the frame is a big problem.

 

You won't have to modify the frame at all...not even close. Just have a plate fabbed up to mate the stock mount to the tail shaft of the transmission.

I got my TH200R4 from a local salvage yard for $150. I will probably rebuild it myself for a total investment of a few hundred dollars.

 

What about the diff? Should I go with a 3.73 gear ratio in the rear because I will be able to lower the RPMS with the overdrive tranny? Should I go with a 3.55 ratio? I want this thing to pin me in the seat when I press the gas, but not run at crazy rpms when I'm on the highway.

 

bump

 

For what you describe you want...I suggest 3.60 or 3.73.

 

IMO the 3.55 and 3.70 are very similar.

At 70 MPH
3.70 = 2100 - 2200 RPM
3.55 = 2000 - 2100 RPM

 

...so you suggest I stick with the 3.55 gear ratio, or go higher?

 

bump

 

The higher you go the weaker your launches will be. I think what he was saying is that with the 3.73 you have almost the same high speed but it's a lower ratio so you have better takeoff.