Help me understand gear ratio's and Torque Convertors
Thread Starter
Launching!
Joined: Nov 2001
Posts: 219
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From: Westminster, CO
Help me understand gear ratio's and Torque Convertors I'm getting ready to order a new tranny and rearend. What I need to figure out is exactly what I'm going to order.
First off how exactly do you figure out final ratio? I know it involves the gear ratio in the tranny, in the rear and the tire height, but I don't understand what to do from there.
Next I sort of recall someone mentioning that with the final ratio you can figure out what speed you will be at based off of engine RPMs?
Finally can someone explain Torque convertors to me? Hopefully the explaination will allow me to answer my last question and that is, just what is the highest stall speed and STR you can go with for a stock rev limiter on a LS1?
Now to put this all together, my goal is to build a tranny and rearend combo that kicks *** at the track. I'm willing to limit my top speed by quiet a bit and plan to get a TH350 or maybe a TH400. Currently my car dyno's at ~340HP and ~350TQ, but since I'm in Denver that has a 1.23 CF. Also my best 1/4 was 13.8@104, which is very good for Bandimere.
First off how exactly do you figure out final ratio? I know it involves the gear ratio in the tranny, in the rear and the tire height, but I don't understand what to do from there.
Next I sort of recall someone mentioning that with the final ratio you can figure out what speed you will be at based off of engine RPMs?
Finally can someone explain Torque convertors to me? Hopefully the explaination will allow me to answer my last question and that is, just what is the highest stall speed and STR you can go with for a stock rev limiter on a LS1?
Now to put this all together, my goal is to build a tranny and rearend combo that kicks *** at the track. I'm willing to limit my top speed by quiet a bit and plan to get a TH350 or maybe a TH400. Currently my car dyno's at ~340HP and ~350TQ, but since I'm in Denver that has a 1.23 CF. Also my best 1/4 was 13.8@104, which is very good for Bandimere.
On The Tree
Joined: Nov 2001
Posts: 153
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From: Joliet
Re: Help me understand gear ratio's and Torque Convertors Drive divided by driven = gear ratio. count the teeth on your drive gear and divide it by the number of teeth on your pinion gear.
Torque converters? wow i think I can explain them sort of but then I'd confuse you lol. <img src="images/icons/tongue.gif" border="0">
Torque converters? wow i think I can explain them sort of but then I'd confuse you lol. <img src="images/icons/tongue.gif" border="0">
Re: Help me understand gear ratio's and Torque Convertors Check out Yank's site for soem info on converters; look at their race converters and read the FAQs. www.converter.cc
I assume if you're going TH 400 that drivability is not a big issue, but the highest performing converters have some drivability issues around town. They feel "loose" which means your car has no pep at low rpms; <img src="images/icons/frown.gif" border="0"> but spin the motor up and hang on! <img src="images/icons/grin.gif" border="0">
I assume if you're going TH 400 that drivability is not a big issue, but the highest performing converters have some drivability issues around town. They feel "loose" which means your car has no pep at low rpms; <img src="images/icons/frown.gif" border="0"> but spin the motor up and hang on! <img src="images/icons/grin.gif" border="0">
Thread Starter
Launching!
Joined: Nov 2001
Posts: 219
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From: Westminster, CO
Re: Help me understand gear ratio's and Torque Convertors [quote]Originally posted by SuperCamaroSS:
<strong>Drive divided by driven = gear ratio. count the teeth on your drive gear and divide it by the number of teeth on your pinion gear.
</strong><hr></blockquote>
Actually this in not what I was referring to. Late me try again. Let's say I have a 1st gear of 3.06 in the tranny, 4.57 gears in a 9" and 28" tall slicks. How do I figure out where 1st gear hits 6200rpm's and do the math so I could plug in 2nd and 3rd gear ratios and get the top speed, and an RPM estimate for crossing the traps.
<strong>Drive divided by driven = gear ratio. count the teeth on your drive gear and divide it by the number of teeth on your pinion gear.
</strong><hr></blockquote>
Actually this in not what I was referring to. Late me try again. Let's say I have a 1st gear of 3.06 in the tranny, 4.57 gears in a 9" and 28" tall slicks. How do I figure out where 1st gear hits 6200rpm's and do the math so I could plug in 2nd and 3rd gear ratios and get the top speed, and an RPM estimate for crossing the traps.
TECH Senior Member
Joined: Nov 2001
Posts: 9,246
Likes: 3
From: Troy, AL
Re: Help me understand gear ratio's and Torque Convertors Getting the final drive is easy. That's just tranny gear times rearend ratio. 3.06 x 4.56 = 13.9536
Figuring in the tires so that you can get your MPH at a given rpm is easiest to do with a calculator such as this one... http://www.richmondgear.com/streetcalculators.html
Just put the tranny ratio where it says "Overdrive Ratio."
Figuring in the tires so that you can get your MPH at a given rpm is easiest to do with a calculator such as this one... http://www.richmondgear.com/streetcalculators.html
Just put the tranny ratio where it says "Overdrive Ratio."
