th400 with 373 gears vs 342 gears

87GN_Bart

Active Member
Joined
Jul 12, 2016
I am wondering what the rpm difference would be in the 1/4 mile and the mph difference. Please let me know as i am considering making the change, is it worth it.
 
8.8% difference
at 6000 rpm thats 528 rpm more through traps than with the 3.42
i went 3.23s, with mt pro 275s 28.3" ptc 9.5 trapping over 140 at under 5800 rpm ... if i had 3.73's (15.4% difference) i would need nearly 6700rpm for that mph
 
do you have the 400 installed already? If not I would consider going with a 4l80e . If you do street driving then the OD really helps . I'm running a 400 with stock gears and if I can do it over I definitely would go 4l80 . I love my 400 though knowing it won't break like the 4 200 I've broken lol
 
i have been running the th400 for 2 yrs and love it with 373's however i believe 342 which i have would be a better fit to keep the rpms down in the 1/4.
 
Pacecarta you are on the money the car ran 9.44 @ 146 at 6600 rpm that was with 3.73 gears, precision 6870 turbo and 28lbs of boost. I guess the new Richmond ring and pinion 342 will help. Thanks for the info.
 
PTC 9.5" loose 3000 works great for street and track, call Dusty he can spec the right one for you.
 
It depends where the engine makes peak power. My car ran the same from 3.73 to 3.31. Power doesnt fall off, shifting at 7000, the car runs the same as 6500.
 
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