TH400 power robber?

[graphicjunki]

I've read this in many threads. But I haven't see WHY?

So what is it about the 400 that makes it such a power hog? and how MUCH does it rob?

What needs to be done to a TH350 to make it stout like the 400 and circling back, why doesn't that make IT the same hog?

Thanks.

[72SBVet]

I've heard around 50 hp but not sure accurate that is as it varies from person/site to person/site. How true my next statement is I'm not sure, but from what I can gather on my own opinion is that the internals are heavier duty and take more heat, but take more energy to rotate/apply. If I'm wrong please correct me as I would like to know myself.

[Texdentist]

This shows what B&M does to beef up the TH350

http://bmracing.com/?wpsc-product=st...mission-113001

[TimAT]

I've heard the 400 takes 20-25% more power just to turn it.
I KNOW it's a heck of a lot heavier than a 350. I can pick up a 350 in my bench fixture and mount it on the bench. Tried it once with a 400. Never again.

It's possible to build a 350 and make it plenty tough. I built one for a 67 GTO with 455 and 4.11 gears. Weekend drag racer, with slicks. Never did kill the trans. I used the red ALTO clutches, set all the clutch pack clearances to the low end of the specs, used the 34 element sprag and drum, and a Trans-Go Stage 3 kit. He ran it for about 8 years before he got tired of the car and sold it. Still out there as far as I know. I think part of his secret was he changed the fluid and filter in the trans once a month during the racing season. He said he never did see any real trash in the pan.

[blckslvr79]

A TH350 can be built stout. Heat is the killer though. Run a designated exterior trans cooler to help it last. Especially if you run a performance stall.

[graphicjunki]

One of my buddies keeps swearing to me that I need to dump the 400 and get a 700R4. He says that the first gear is way better, and it has the over drive. I started reading on line and there is so much back and forth...Not sure if it would be a good choice or not. The gear ratios are a no brainer...Although not sure if I would want that tall of an OD with 3:08's....

[TimAT]

The 700 is a good trans- it has a few problem spots, but there are mods to overcome them. And not killer expensive either.
THe 200 is a little lighter, has a little better gear ratio for the Vettes and is way less hassle to install. Crossmember is real close to right and no driveshaft mod.

First gear in a 700 is 3.06. Add the convertor to that it comes out about 6.12. Stock, the 700 shifts out of 1st about 10-12 MPH- way to early for most peoples' taste. It's possible to move that to a higher speed, but when you do, you get a rough 1-2 shift.