ok im a dumbass please explain: "Final Drive"
06-30-2007, 01:59 AM
#1
1.5 BAR
Thread Starter
Join Date: Apr 2004
Posts: 728
ok im a dumbass please explain: "Final Drive"
ive looked on websites over and over and cannot find out what a ------- final drive is, like what part it is and what it exactly does in the trans. bone i know you know.. hook it up.
06-30-2007, 02:28 AM
#2
3.0 BAR
Join Date: Feb 2006
Posts: 3,906
Re: ok im a dumbass please explain: "Final Drive"
your final driv is the ratio of 1 revolution of the imput shaft through all gear drives and to the final drive
IE
your engine turns the imput shaft at 1 revolution
your tranys 5th gear turns 4 times to the 1 turn of the imput shaft, that is put to the wheels
your final drive would be 4:1
and if its rear wheel drive u have to add the gears in the rear end into the exuation
to figour it out you have to do this
driven gear
---------------- X(next gear)
drive gear
IE
your engine turns the imput shaft at 1 revolution
your tranys 5th gear turns 4 times to the 1 turn of the imput shaft, that is put to the wheels
your final drive would be 4:1
and if its rear wheel drive u have to add the gears in the rear end into the exuation
to figour it out you have to do this
driven gear
---------------- X(next gear)
drive gear
06-30-2007, 03:14 AM
#3
0.0 BAR
Join Date: Jan 2005
Posts: 0
Re: ok im a dumbass please explain: "Final Drive"
"final drive" is the LAST gear reduction to occur in the transaxle.
Same thing as the "rear gear" in a RWD V8 powered car.
5.0 goes from 2.73 to 3.73 like we can go from 3.89 to 4.9
Also, tire size plays a factor.
Most V8 RWD try to stay at 26.0 stickys, 28.0 need 4.11 or 4.56's.
I run 20x8x14's for a reason.
Makes a stock 4.25 FD with 23" tall streets feel like a 4.89 FD
If you consider tire diameter as a gear reduction, and you should, you have three reductions to figure thru.
Now, figure out how I'm hooking 2500+ lb/ft of torque at launch.
Same thing as the "rear gear" in a RWD V8 powered car.
5.0 goes from 2.73 to 3.73 like we can go from 3.89 to 4.9
Also, tire size plays a factor.
Most V8 RWD try to stay at 26.0 stickys, 28.0 need 4.11 or 4.56's.
I run 20x8x14's for a reason.
Makes a stock 4.25 FD with 23" tall streets feel like a 4.89 FD
If you consider tire diameter as a gear reduction, and you should, you have three reductions to figure thru.
Now, figure out how I'm hooking 2500+ lb/ft of torque at launch.
06-30-2007, 03:21 AM
#5
0.0 BAR
Join Date: Jan 2005
Posts: 0
Re: ok im a dumbass please explain: "Final Drive"
Originally Posted by jagojon3
Wouldn't final drive in a RWD incorporate the tranny ratio? i.e. 3.73 rear end != 3.73 FD?
in RWD, the tranny is seperate from the rear end. With a transaxle (not limited to FWD) the final internal gear reductionis called the final drive.
07-02-2007, 01:55 AM
#10
0.0 BAR
Join Date: Jan 2005
Posts: 0
Re: ok im a dumbass please explain: "Final Drive"
why I'm good at gearing 
"Gene" in Detroit went from 7.2x to 6.8x with my suggested gear change. By going from 4.11 to 3.73 it soften the launch, alowed the chassis to "set" and plant the slicks before hitting the second stage and grabbing second gear. WIth car being stable he was able to use the THIRD stage finally in high gear when the clutches FINALLY lock up.
300/300/400 shot.
I'm not talking no little 1/8 mile bullshit either. Full 1320 T
his was on "lil Henry motor, 632 CID.
"BIG Henry" (740 CID) makes to much power for the chassis.....just too brutal. The chassis is a 1990 Pro Stock chassis, was only meant for mid 7's, now running high 6's in Top Sportsman.
"Gene" in Detroit went from 7.2x to 6.8x with my suggested gear change. By going from 4.11 to 3.73 it soften the launch, alowed the chassis to "set" and plant the slicks before hitting the second stage and grabbing second gear. WIth car being stable he was able to use the THIRD stage finally in high gear when the clutches FINALLY lock up.
300/300/400 shot.
I'm not talking no little 1/8 mile bullshit either. Full 1320 T
his was on "lil Henry motor, 632 CID.
"BIG Henry" (740 CID) makes to much power for the chassis.....just too brutal. The chassis is a 1990 Pro Stock chassis, was only meant for mid 7's, now running high 6's in Top Sportsman.
