alright guys, i have a serious question that i've asked several people and nobody can give me a straight answer.

my question is this...does the gearing affect torque on a dyno?

what i mean by this is, i just put a transmission in my car with 4.785 final drive vs 4.40 final drive. obviously my car accelerates better and pulls harder through the gears because the motor has a better advantage.

now it seems like this would also increase the overall torque output of my car. i liken torque to twisting power, hypothetically speaking, if you could put a car on jackstands and hold the wheels from turning, the car with the shorter final drive would be able to twist and turn better which is torque, isn't it?

anyway, just wanted to see what you guys had to say, as i know a lot of you have installed 410 gears into your mustangs and have probably put your car ona dyno before and after this...

if anyone could explain this to me, i'd appreciate it...and if i'm wrong, please correct me.

thanks, chet.

 

so in essence, lower gearing just affects acceleration...which we all know is true...

see i would agree with this completely, but the example i was using before with holding the wheel seems to support an increase in torque.

 

alright, does this sound correct also: the car doesn't make more torque, its just able to make better use of the torque it already has?

like a 200lb person sitting on a seesaw, the further out the person sits, the more mechanical advantage, or leverage, but the weight remains the same.

this would mean then that the stress on the driveline is increased with longer final drive...and acceleration would also decrease.

 

Hehe...your all wrong. During acceleration it will decrease HP and TQ slightly measured at the wheels with a dynojet depending on the drop in ratio. Fbody guys have disussed this for years since the drop was significant due to wide gearing changes. They would always see from 5-7 rwhp and Tq loss accross the board when going from stock 3.42s to 4.10s. The reason is due to the more rapid rate of engine spin up. It takes less time to spin up all the rotating mass in the driveline and engine so therefore more energy is being consumed to acclerate the engines own rotating mass and not transmitted to the wheels though gearing. I have to do a search but I wrote a lil something about this a while back. It was archived on an Fbody tech page. Its a lenghty explanation so im going to find it and copy and paste it here.

*edit*
damn...wouldnt let me copy of the website. So heres a link. Disregard the reply under mine half way down the page...the guy didnt quite get what I was attempting to explain.

http://www.ls1info.com/article.php?sid=167

 

Dynojet program is correct and reflects a real world situation. If you looked at total work done at the wheels you would see its actually less with a higher numerical gear. This is also true at the drag strip. Many times...if traction is not an issue, guys will drop a mph or two when going to 4.10s from 3.42s. Of course the ET is better due to a better launch. Thats the real benifit of the mechanical advantage gained by going with a higher numerical gear ratio. Everything is a trade off.