YellowFvr1

Looking into doing a fairly high HP nitrous/396 LTx build within the next year.....current tranmisson is a rebuilt a4 (4L60E)....and I'd like to stay with an auto transmission. From what I hear, the 700r is the way to go for high hp auto applications (i've also heard good things about the 4L80E)......I'd love to be further educated about the ins and outs of these tranny's....also a couple specific questions:

How much power can they take?
Is it a direct swap?
Are the gearing ratios the same as a stock 4L60E? (3.06 in first, 1.62 second, etc...)
Is it possible to modify the 700r or 4L80E (to perhaps make 4th more of a close gear ratio, so it will pull a bit harder at 150+)?

Morley

The 4L60E is an electronic 700R4. The 4L80E is a TH400 with an overdrive like the 700R4, also electronic.

Pete K

700 is a non electronic version of the 4l60e. The electronic trans shares most of the same pieces. Planetaries and other hard parts changed little throughout the years. For comparison reasons, the 2 transmissions should take equal power before the break. The electronic trans "should" last longer under normal driving conditions. The solenoids actuate the hydraulic systems quicker and more precisely than the 700 would.
Overall, your questions are too broad for accurate answers.
A 700 or 4l60e will take plenty of abuse when built right.
They seldom are built right though.
The 4l80e is basically an electronic th400 with an overdrive.
Stock they are tough. The torque converters (oem gm) are a weak link.

YellowFvr1

ok, to be less "broad".....which would you use if you were going to be making 650+ rwhp on the juice......streetability is fairly important. Which trans shops build some of the best?

Is it possible to close the ratio on 4th gear (for example, cobra guys often modify the T-56 and give it a viper 5th gear ratio) to make it pull slightly harder for high speed runs?

Pete K

Gear ratio's for the 4l60e are only available in the stock ratios.
4l80e conversions will likey cost 5k plus dollars, so I have been told.
If it were my car, I would install the following parts in your 4l60e:
Hardened input shaft
Beast reaction shell
Cryo'd planetary and sun gears
Carbon band on a new drum.
Red clutch in the 3-4 pack (6 clutch plate pack)
Tan clutches elsewhere
29 element foward sprag
I would keep end play down to .018-.022
3/4 clutch endplay at .050-.055
lo reverse stack up to 1.200- 1.215
Fowards at .045-.055
Stock specks for reverse input

YellowFvr1

thanks for the details! Can you explain to me about:
"I would keep end play down to .018-.022
3/4 clutch endplay at .050-.055
lo reverse stack up to 1.200- 1.215
Fowards at .045-.055"

I'm lost and a bit unknowledgeable

any idea of a cost for your recommendations?

Pete K

End play is input shaft end play. Tight is good, but too tight is bad. .015 is as low as you could go on end play. End play is needed so that the trans does not bind after it has warmed up.
Other specs relate to individual clutch packs clearances.
Input drum contains over run, foward and 3-4 clutch packs.
Revers input drum contains 1 clutck pack
low reverse stack is in the rear of the case
Band clamps the reverse input drum. Be sure the reverse input drum measures at least 7.022 inches. 7.026 is the size when new.

Pete K

Most trans builders would get $2,000- $2,500 for this type of build. Converter would be extra. Budget builds tend to range from $800-$1200, with minimal or no hard part upgrades.

YellowFvr1

thanks for taking the time to explain