Best trans for 427
#1
01-01-2010, 12:43 PM
Best trans for 427
What's the best trans for a 427 BB ? And what trans did the 69' Yenko's have ?
#3
01-02-2010, 11:06 PM
Join Date: Aug 2008
Location: Portland, Or
Posts: 9,097
I totally agree! M22 or TH400, unless you want to spend some money and get a T56 5spd or 6spd. Or if you want to go racing and weight is an issue, then go with a well built TH350.
When I was racing my 71 with 427engine I went to my tranny guy to have a TH400 built and he stopped me dead in my tracks. He said I could gain a couple tenths in my 1/4 mile time by using a TH350, as they are lighter, and have less spun weight too.
After he talked me into building up a TH350 for my BBC I was still hesitant, until I got it in the car. It's seen 16 yrs. of 1/4 mile racing, and another 10 yrs of street driving, and today it's 30 yrs old on that same rebuild with nothing more than fluid and filter changes.
What he built was a full competition, manual shift auto, with Trango kit, Corvette clutch pack, high stall converter. I really don't know what he did inside, as I'm no tranny guy, but whatever it is it's great!
When I was racing my 71 with 427engine I went to my tranny guy to have a TH400 built and he stopped me dead in my tracks. He said I could gain a couple tenths in my 1/4 mile time by using a TH350, as they are lighter, and have less spun weight too.
After he talked me into building up a TH350 for my BBC I was still hesitant, until I got it in the car. It's seen 16 yrs. of 1/4 mile racing, and another 10 yrs of street driving, and today it's 30 yrs old on that same rebuild with nothing more than fluid and filter changes.
What he built was a full competition, manual shift auto, with Trango kit, Corvette clutch pack, high stall converter. I really don't know what he did inside, as I'm no tranny guy, but whatever it is it's great!
#4
01-09-2010, 03:16 PM
The key is the good set of gears and the manual shift. Automatics use governor pressure to "decide" when to shift and governor pressure relies on Line pressure for a starting point. This limits what you can can do to line pressure. Line pressure is what engages the clutchs, kind of like the pressure rating of a manual clutch. Adding more line pressure is like adding strong springs to a manual clutch.
A bone stock transmission can generate 300 PSI of line pressure. It does this when in reverse. But when in forward most are limited to 180 PSI due to shifting controls. But once you go to a manual valve body those limits go away. At that point there is just a few weak points to fix up and you have doubled the strenght of the tranny. Take it the next level by putting in thru hardernd gears and larger clutch pack and you have dam strong tranny.
The reason the TH400 is used in many High HP High torque is the center support and the case itself. Everything you can do to a 350 you can do to a 400 and end up with a stronger trans. But as stated above if you don't need the 400 the 350 will be faster. If we are talking a 450HP/500FT motor I do not think we are talking tenths, my guess would more like hundreds of a second in the 1/4.
How strong your tranny need to be is not just a function of your motor. Your cars weight and the rears and even the tires you have on will have effect on the tranny. If you take a stock 12 bolt with a set of 265 street tires a given tranny could last 100K same exact car and motor with a 4 link setup correctly for launch and a set of drag radials on it could blow out that same trans in the first pass. I have seen several transmission not make it thru the first pass after a rear end/tire upgrade.
I guess you could say you have the ability of the engine to make torque and the abilty of the car to use torque. Your transmission needs to be stronger then the weaker of those two. I know confussing. Sorry.
A bone stock transmission can generate 300 PSI of line pressure. It does this when in reverse. But when in forward most are limited to 180 PSI due to shifting controls. But once you go to a manual valve body those limits go away. At that point there is just a few weak points to fix up and you have doubled the strenght of the tranny. Take it the next level by putting in thru hardernd gears and larger clutch pack and you have dam strong tranny.
The reason the TH400 is used in many High HP High torque is the center support and the case itself. Everything you can do to a 350 you can do to a 400 and end up with a stronger trans. But as stated above if you don't need the 400 the 350 will be faster. If we are talking a 450HP/500FT motor I do not think we are talking tenths, my guess would more like hundreds of a second in the 1/4.
How strong your tranny need to be is not just a function of your motor. Your cars weight and the rears and even the tires you have on will have effect on the tranny. If you take a stock 12 bolt with a set of 265 street tires a given tranny could last 100K same exact car and motor with a 4 link setup correctly for launch and a set of drag radials on it could blow out that same trans in the first pass. I have seen several transmission not make it thru the first pass after a rear end/tire upgrade.
I guess you could say you have the ability of the engine to make torque and the abilty of the car to use torque. Your transmission needs to be stronger then the weaker of those two. I know confussing. Sorry.
Last edited by Gorn; 01-09-2010 at 09:50 PM.
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