R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Nitro On-Road

Thread Tools Search this Thread
Old 08-10-2007, 02:51 AM   #1
Tech Apprentice
johnypiston's Avatar
Join Date: Oct 2006
Posts: 62
Default Rollout mysteries

Of late I have been trying to study the finer aspects of tuning gas touring cars. After months of just getting confortable with the driving, I am now at a point where I can have the luxury of considering topics litle roll centers, ackerman and rollout calculations.

I am confused about rollout calculation and the pinion to spur ratio. The following questions come to mind:

1. I understand how to calculate the Pinion to Spur ratio but how can I arrive at a single number for both 1st and 2nd gear? Most articles address the use of 1 pinion and 1 spur ...as if we all had single speed cars. How does it work for 2 speed transmissions? Or do you arrive at two seperate ratios ...one for first gear and one for second gear?

2. Considering that most of us use foams, and are forced (if we do not get the appropriate optional parts to arrive at a 1:1 torque split) to have a 2mm tyre diameter split front to rear, how can you arrive at a single Rollout figure for the entire car? Can you calculate the front, then the rear, ADD the two together and then divide by 2? Would this be a valid Rollout number?

Any input would be appreciated. Thanks
johnypiston is offline   Reply With Quote
Old 08-10-2007, 04:39 AM   #2
Tech Adept
flack's Avatar
Join Date: Mar 2005
Posts: 240
Trader Rating: 1 (100%+)

My understanding is that most of the time you would want the FINAL ROLLOUT value. So you would use the second gear ratios for the calcuations.

I use the rear tires to calculate the rollout. In most cases, you are using a tire split that would create a 1:1 (or close to it) final drive ratio, because of the pulleys that make up the transmission. Also the rear tires are typically bigger and are what will be "driving" the car (more distance per rotation).

Below is a link to some good articles regarding transmission, rollout and overdrive calcuations.


flack is offline   Reply With Quote
Old 08-11-2007, 01:15 AM   #3
Tech Apprentice
johnypiston's Avatar
Join Date: Oct 2006
Posts: 62

Thanks Doug!! Very helpful info!!
johnypiston is offline   Reply With Quote

Similar Threads
Thread Thread Starter Forum Replies Last Post
Rollout Help treemagnet Electric On-Road 1 09-11-2008 05:33 AM
rollout 3808larry Electric On-Road 3 12-12-2006 06:28 PM
rollout pinggoy Electric On-Road 3 05-07-2006 09:27 PM
Rollout Freddybnj_2004 Rookie Zone 6 12-07-2004 02:34 PM
Rollout what is it for? Alvin Electric On-Road 11 01-17-2002 09:36 PM

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off

All times are GMT -7. It is currently 05:17 PM.

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net