M-F 8-6pm
Sat 10-2pm
1-866-441-8699
1-812-379-1134

Contact us!

Ph: 866-441-8699 or 812-379-1134

Owned & Operated by

Columbus, IN

sales@5speedtransmissions.com


The Starting Line Ratio (SLR), also known as Launch Ratio, is very important to consider when selecting a transmission and/or a rear-end gear ratio.

Starting Line Ratio = 1st gear ratio * rear gear ratio

First Gear Ratio:

Rear End Gear Ratio:

SLR:

 

Note: If the SLR number is real big, like >12,  then your launch will resemble a dump truck; lots of noise but doesn't go anywhere. The reverse is true if you have a ratio in the < 8  range, the car will likely go 100 mph in first gear but the clutch may have shortened life spa due to the amount of slippage needed to get the car rolling.
A 9-10-11 range SLR is desireable.

Search this site

Cool Pages:
Gear Calculator
Build Quote
Tech Tips
 

Great for:
  Pro-Touring
  Hot Rods
  Street Rods
  Musclecars
  Pro-Street
  Drag Race
  Road Race
  Trucks
  and more!

However, the above calculation alone isn’t the whole story.  You must also consider your rear tire diameter.  For example, a 25” tire will result in a higher overall SLR compared to a 31” tire. Try out ‘distance travelled in 1st gear” calculator here.

Near future possible enhancements to this page:

  • a chart to show range of choices with pros/cons, and an indicator to show where on the chart the calculated value is at.  Colored with recommended range (green), red for areas not recommended.
  • add discussion about tire rollout also! 
  • Show # of feet travelled for first shift at given RPM
  • link back to calculator

 

 

13+  shift before leaving the garage!
12 - shift before the crosswalk
11 - shift comes quickly, but not un-usable
9-10  ideal
8 - pretty long in 1st, hard on clutch
<7  very hard on the clutch

talk about personal preference, tire spin, clutch slippage, etc.  estimated distance til first shift (on calc page)


 

 

Trans Gear Ratio:

Rear End Gear Ratio:

Tire Dia.

Engine RPMs to travel 100 feet

Scenario 1

Scenario 2

Scenario 3

Designed for

©  2014 Wedan Street & Performance  All rights reserved

This website is a comprehensive collection of information regarding the installation of TREMEC transmissions into various vehicles. Material contained in here may be reproduced for PERSONAL USE ONLY. No material may be redistributed in electronic or printed form without the written permission of Brad Wedan (owner). Owner believes to the best of his knowledge this information to be correct, however no warranty is made as to its accuracy. Owner also disclaims any liability for financial loss, property damage or injury in connection with use of this information. Not affiliated with, endorsed or compensated by TTC, or any sanctioning body mentioned within. Any trademarked names are property of their respective trademark holder and are used for identification purposes only. Portions of this website may be copyrighted by other individuals or organizations.

Designed for Internet Explorer 5.0+