TH400 rear end gear?????? - LS1TECH - Camaro and Firebird Forum Discussion

Automatic Transmission 4L60E | 4L80E | TH350 | TH400 | TH2004R | Powerglide | Converters | Shift Kits
Sponsored by:
Sponsored by:

TH400 rear end gear??????

Thread Tools Search this Thread
Old 07-20-2011, 01:35 AM   #1
Thread Starter
iTrader: (17)
Trev_SS's Avatar
Join Date: Jul 2004
Posts: 1,787
Default TH400 rear end gear??????

I am going to be switching rear end gears when I swap my m6 for a Th400. I am wandering what gears will be decent for the car. It is a H/C car with nitrous that will have a 28in tires if that makes a difference. I will be driving the car on the street and still want to take it to work on an occasion so it will see highway. I was really considering a 3.73 for the rear end or would a 3.42 be better. Let me know what you guess that have TH400's are thinking. Thanks Trevor
Trev_SS is offline   Reply With Quote
Old 07-20-2011, 07:12 AM   #2
TECH Addict
iTrader: (4)
forcd ind's Avatar
Join Date: Sep 2007
Location: woodbine, md
Posts: 2,974

a 400 is 1-1 in high gear-if your present trans (i dont know what an M6 is)
has a 1-1 gear, just drive around in that, its gonna be like a 400
3.73's, 28" tire, plus a stall converter, your gonna be reving up, a custom converter built to your specs. would help
there are some calc. out there to plug in your #'s, see what your RPM's would be, but they dont take into consideration to much converter slippage
having lived with these things for so many years w/o an OD trans, i can tell you i use nothing but a 4L80E anymore, lol
3.55's are a pretty good choice, but you really need the cam, converter, rear ratio to all be working together, not mismatched
ok, i have had too much coffee this morn, lol
forcd ind is offline   Reply With Quote
Old 07-20-2011, 09:07 PM   #3
TECH Addict
iTrader: (28)
Cam72aro's Avatar
Join Date: Feb 2006
Location: Sugar Land, Tx
Posts: 2,144

I have a 4.11 in my th400 car and hate it. Car tachs about 3500rpms on the freeway at 65. Its screaming. I am about to do a 4l80e swap. Drive your 6 speed in 4th for a little while. Thats 1:1 just like 3rd in a th400.
Cam72aro is offline   Reply With Quote
Old 10-15-2011, 10:46 AM   #4
9 Second Club
iTrader: (2)
midwestjunk's Avatar
Join Date: Feb 2006
Location: Addison, IL
Posts: 249

how is it in the 1/4 mile with the th400 and 4.11 gear? does it run thru the traps ok or do you run out of gear? what kind of HP you making? I have a 4.10 and doing a th400 swap. i'm worried i'll run out of gear with the 700hp motor.
midwestjunk is offline   Reply With Quote
Old 10-15-2011, 11:59 AM   #5
11 Second Club
iTrader: (16)
SuperSlow02's Avatar
Join Date: Feb 2006
Location: Cape Girardeau, MO
Posts: 1,865

depends on your rpms. I was turning 65-6800 going through the id say not a 1/4 set up. I did a calculation and it said top speed was 135, only about 30mph off LOL. I doubt converter slip could account for that... This is with a 4.11 gear/28in tire
SuperSlow02 is offline   Reply With Quote
Old 10-15-2011, 08:14 PM   #6
9 Second Club
iTrader: (34)
dnkynrbk's Avatar
Join Date: Mar 2005
Posts: 2,248

for 1/4 you need 3:73 or 3:90 depending on set up cam,nitrous or turbo
dnkynrbk is offline   Reply With Quote

Related Topics
Thread Thread Starter Forum Replies Last Post
Need specific gearing question answered. Norbit2 Manual Transmission 15 04-07-2017 11:14 AM
800-1100ish whp turbo guys! What Rear gear with a th400? trap speeds? Tires? Street? BlackSS4thgen Drag Racing Tech 2 03-08-2016 08:25 AM
2000 Firehawk... turbo with t56 or th400? Snap-On Forced Induction 8 12-28-2014 02:42 PM
th400 swap what's the drive shaft length? flarhoades Chevrolet Camaro 1967-2002 0 02-07-2014 10:08 PM
What gear should I use????? whitedevil Forced Induction 7 09-06-2008 01:39 AM

14, 373, 373s, 400, 500hp, end, gear, gears, max, mi, rear, speed, street, th400, transmission, whats

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

All times are GMT -5. The time now is 08:50 PM.

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to and affiliated sites.
  • Ask a Question
    Get answers from community experts
Question Title:
Your question will be posted in: