Hi, plan for this summer: replacing the 3.08 and TH350 with a TH200R4 and 3.73 gears. My question: does anybody know how much improvement can be expected on the 0-60 mph and the 1/4mile, I`m just curious? I can either go for the engine or the transmission and the gears, not enough money for everything, and I`m pretty sure the investment in the tranny with the higher gears is a good one. Any negative experiences with higher gear and TH200R4 on a standard `71 GS350 engine and 14" wheels? Thanks for your opinons.
The investment in a 2004R trans is definitely a good one, and I think your choice of a 3.73 is a good one as well. You have to consider that in overdrive your final drive ratio will be a 2.50, which is very likely lower(numerically) than what the car originally came with. The 1st gear ratio is 2.75 in the 2004R in comparison to the 2.52 that the TH350 has. The 2004R/3.73 combo would have the 1st gear equivalency of a TH350 with a 4.06 rear. It's a win/win every way you look at it :TU:
My car has a 200-4R trans and 3.73 rear gears. You'll only use the first three gears going through the quarter mile. First is steeper than in the th350 I believe. So you should get off the line quicker, especially stepping up to a 3.73 rearend. My car also had a 3.08 rear gear before I switched to the 3.73's. I went from 12.9's to 12.3's. So my guess, overall, is that you'd drop about a half second off of your quarter mile time.
Hey, looks like it`s the way to go. No disadvantages going with the new trans/rearend and the standard engine without mods (next step!)? Another thing going round in my head is where to purchase the trans. I had contact with Art Carr, sounds good, very good reputation, but pricey...on the other hand, this is a one-time-buy, so it`s ok if I get a good tranny. Bowtie overdrive is a lot less pricey, but you read different things about their way of doing business (no insult here, just the stories you read in the net). As this tranny will be shipped and installed in Europe, I NEED it to be bulletproof the first time! Any ideas ?
CK Performance is one of the best out of New Jersey. Chris is a great guy to deal with. And when you say Art Carr, you have to deal with California Performance Transmissions to get a real Art Carr trans. He sold off his company with his name years ago and the people that bought it are riding on his reputation and not as good any more. Here are some links: http://www.ckperformance.com/resources/GM2004RCATALOG.html http://www.cpttransmission.com/
I haven't bought a transmission from them but I have bought a lot of other items and have had nothing but great service and quality parts from www.bowtieoverdrives.com
you can try www.extremeautomatics.com century transmissions janis transmissions david husek transmissions pts extreme transmissions or ck as stated above they all can get you where you want to go - the v6 brethren at www.turbobuick.com would vouch for any of these guys :TU:
Janis Transmissions in Akron, OH is also a great builder of these transmissions. He gets his parts from CPT or CKPerformance. He built the trans in my car and I've been very happy with it. And he's only 20 minutes from my house.
Ok, so I get some pretty good advices here. I`ll check on each and everyone of them, promised, and as you guys have had good experiences, I`ll trust the builders. But back to the other question: no problems going the TH200R4-and-3.73-route with the standard, unmodified engine? Thanks a lot for your help
Going to a 200-4R trans is not a problem. But they were not designed to handle the torue of a 455. You will need to upgrade the internals to have it last.
if its a stock low comp (71) 350 should be no trouble but if you are getting one built make sure it can handle any future up grade. The transmisions i use are stock unmodified that came in cars with 307 olds engines and seem to work ok with the stock 68 350's i use :TU:
I`m the third owner of the car, as far as I can say there have been no mods on the engine whatsoever. But a good advice to built it for further upgrades, I already had this in mind (I`m on a 70` 455 block, have to figure out for myself if I want to stay on the "build your SB" road or want to go big!)
