I'm about to have a built TH350 thrown in my 71 and my TH400 with 160k miles taken out. Good idea? I've been told its much easier to turn... so its much more efficient. It really comes down to this, rebuild my 400 or get a new 350.... and its only gonna run my 600 for installation plus the tranny.... 750$. What do you guys think? Also, besides shortening the halfshafts, what else needs to be done.......... if it isn't too stupid a q'... what is a half shaft

Thnx,

Brandon

Keep the TH400. It is a much stronger transmission although the TH350 can be built to be as strong, the TH400 can be built to be that much stronger.

Reid '72 T-top

The TH350 is highly underated and will serve well depending on how many ponies you are trying to put through it. Given a choice however, I would opt for rebuilding the TH400, it's a lot stronger transmission. I would be surprised if the 400 would cost much more then the 350 you are describing. I had mine rebuilt with new torque converter for 700 and some change.

|UPDATED|5/1/2004 9:09:18 PM (AZT)|/UPDATED|

The 350 is one of the finest transmissions ever built by anyone. It will take a lot of punishment and abuse, and serve well. The 400 is better.

The 350 has about a 2.75:1 first gear ratio. The 400 has about a 2.5:1, so the 350 has a bit more power off the line in first gear. But as, stated, the 400 is stronger. When the torque converter is factored in, according to Chevrolet, the 400 first gear ratio is 5.2:1.

The 350 does require slightly less torque than the 400, but unless you are timing at hundreds of a second on the 1/4 mile, you won't be able to tell the difference from the torque requirement. It is less than trival.

The 1/2 shafts are the drive shafts from the diff to the wheels. They have nothing to do with the trans. But the drive shaft will need to be a bit different length for a 350.

If you are going to do a conversion, I would consider a 700R4. This gives you the lower gear ratio for first and the better mileage of an overdrive. Some folks do this with a 200R4, but the 700, again, is stronger. Depending on your engine, this may not make a difference to you. The 200 is the weakest of all of these choices.

I have a 400 and I am going to keep it.

|UPDATED|5/1/2004 9:20:13 PM (AZT)|/UPDATED|
kstyer38471.8292361111

i'm going to have to agree with everyone else on this, the turbo 400 is flawless, and since you already have it, i'd stick with it. If it's rebuilt properly it won't cause you any trouble.

I concur... keep the 400.. 350 has its uses. but ive torn up many a 350 and havent lost a 400 yet.

I do hear the 700R4 is a good swap though.

shouldnt involve the half shafts at all, just the drive shaft.

i like the elctric kickdown on the 400

wire up a manual override switch and it's a load of fun.

Hey...if you check my tailshaft post....

I have 7 BRAND NEW thm400's sitting on pallets!!! I mean brandy brand new, NOT rebuilt. These were sitting in a receiving wherehouse....and have never been turned by a vehicle!!!

I got them at a DRMO auction.....I could let you have one....make me an offer, (or come up with something interesting to trade) I was thinking $500.oo a piece...but I could be convinced to make you a deal..) Also, I live in California...so shipping might be a bit of a bear). drop me a line at dpanzerman@aol.com if you are interested.
EO1

[QUOTE=cthulhu]

i like the elctric kickdown on the 400

wire up a manual override switch and it's a load of fun.[/QUOTE]

This sounds cheap and interesting. How would I do it, and what parts do I need?

My 2 cents..... If you are doing a trans swap, go for the 700R4. I think it is the same length as the TH400. I have the TH 700R4 behind a 355 HP ZZ-4 with 3:55 gears. I turned 3500 RPM @ 75 MPH with the old TH350 and now turn 2300 @ 75 MPH with the 700R4 and lockup converter. Mileage is 14 city, 20 hwy.

Unless you are making BIG horsepower, the 700R4 will handle the load.

If the choice is only TH350 vs. TH400, stick with the TH400, more beef!!!

Dave

I would also spring for the extra money to do a 700r4 conversion, It was well worth it for me. A 3.55 with a 700r4 is a great combo for a vette that gets driven on the streets, great acceleration and good gas mileage and less cruising RPMs. Bowtie Overdrives is the company to look at for the conversion kit.