Torque Question
Thread Starter
Intermediate
Joined: Apr 2008
Posts: 36
Likes: 0
From: Glendale AZ
Torque Question
I have a couple questions about torque and torque ratings. Is torque multiplied when it’s transferred through a set of gears? For example, engine makes 400 ft lbs of torque, transmission is in a 1:1 gear and the rearend has a 3.90 gear. Is the 400 ft lbs multiplied by 3.90 so you are putting effectively 1560 ft lbs to the ground?
If a transmission has a certain torque rating, does that rating vary as the first gear ratio changes?
If a transmission has a certain torque rating, does that rating vary as the first gear ratio changes?
Racer
Joined: Aug 2005
Posts: 340
Likes: 0
From: Rural Crete Nebraska
That is incorrect. You actually lose a large fraction of your power through the trans and then on through the rear end too. That's why horsepower and torque ratings are less at the rear wheels than they are at the flywheel. Your rear end gears determine how many revolutions of the driveshaft make one revolution of the wheels. So a 3.90 would take 3.9 revolutions of the driveshaft for the half shafts (thus the rear wheels) to rotate once. With a higher numerical gear, the engine would be at a higher rpm at a given MPH, so probably making more power at a lower vehicle speed. Basically the gearing just determines engine rpm versus vehicle speed.
Burning Brakes
Joined: Dec 2003
Posts: 1,004
Likes: 7
From: Adelaide South Australia
There is a lot of misunderstanding with rear wheel torque.
especially with data from dynos....
I read a recent post from our Australian LS1 forum, with a very good technical explanation on how dyno systems operate to provide the data displayed and provided to the customer.
Worth a read. rear wheel torque is very dependant on gear ratio, diff ratio, tyre size AND dyno roller radius.
http://www.ls1.com.au/forum/showthre...53#post1194753
especially with data from dynos....
I read a recent post from our Australian LS1 forum, with a very good technical explanation on how dyno systems operate to provide the data displayed and provided to the customer.
Worth a read. rear wheel torque is very dependant on gear ratio, diff ratio, tyre size AND dyno roller radius.
http://www.ls1.com.au/forum/showthre...53#post1194753
Drifting
Joined: Sep 2007
Posts: 1,442
Likes: 1
Yep, that is the whole purpose of a gear reduction system. Torque multiplication.
