Go Back  R/C Tech Forums > General Forums > Electric On-Road
Roll Center Program? > Roll Center Program?

Roll Center Program?

Reply

Old 04-03-2007, 10:26 PM
  #1  
Tech Master
Thread Starter
 
Speedie's Avatar
 
Join Date: Feb 2003
Location: Wisconsin
Posts: 1,844
Default Roll Center Program?

Hi I am looking for a free roll center calculator for regular or rc cars. If you know of any please let me know thanks.
Speedie is offline  
Reply With Quote
Old 04-03-2007, 11:06 PM
  #2  
Tech Elite
iTrader: (10)
 
Brian McGreevy's Avatar
 
Join Date: Jan 2003
Location: Illinois
Posts: 4,081
Trader Rating: 10 (100%+)
Default

That'd be a rather hard thing to come by. Roll center depends on a minimum of 4 separate variables (inner and outer camber link and arm pin heights), and realistically as many as 6. Not only that, you'd have to know those heights before you plugged them into the said calculator.
Brian McGreevy is offline  
Reply With Quote
Old 04-03-2007, 11:21 PM
  #3  
Tech Addict
iTrader: (4)
 
DrOlds's Avatar
 
Join Date: Oct 2003
Location: Kansas City
Posts: 644
Trader Rating: 4 (100%+)
Default

They're out there-full size dirt oval racers use them all the time.Don't know if you're going to find one for free though.
DrOlds is offline  
Reply With Quote
Old 04-04-2007, 01:13 AM
  #4  
Tech Elite
 
sosidge's Avatar
 
Join Date: Dec 2001
Location: Bristol, UK
Posts: 3,886
Default

I did once find one that had been done in a spreadsheet for RC cars. However as I recall one of the calculations was wrong so it needed a little correcting. Unfortunately I have now forgotten where I found it - but it may still be out there.
sosidge is offline  
Reply With Quote
Old 04-04-2007, 04:28 AM
  #5  
Tech Adept
 
Join Date: Dec 2003
Posts: 160
Default

Didn't john Stanahan make that spreadsheet ?
elvo is offline  
Reply With Quote
Old 04-04-2007, 09:04 AM
  #6  
Tech Fanatic
iTrader: (21)
 
Join Date: Apr 2005
Location: north-west Indiana
Posts: 831
Trader Rating: 21 (100%+)
Default

I googled roll center calculator and came up with this.
roll center calculator
There are a lot of measurements you need for it though, I hope it works.
trilerian is offline  
Reply With Quote
Old 04-04-2007, 11:19 AM
  #7  
Tech Fanatic
iTrader: (38)
 
Join Date: Jun 2006
Posts: 876
Trader Rating: 38 (100%+)
Default

That one isn't free though :/ Are you just looking for a spreadsheet that shows you height or looking to get the thing actually plotted? I think I can get access to all the proper formulas to calculate it.
mattnin is offline  
Reply With Quote
Old 04-04-2007, 03:03 PM
  #8  
Tech Elite
iTrader: (27)
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Default

Here is a link to a free roll center spreadsheet calculator that I wrote. You need Microsoft excel for it to work. The link goes to a post on the Pantoura Thread. Down lower in the post is a link to the free download. The post has an example of its use and a sample output. I had the wrong units on one of the outputs in the very first draft. This has long since been corrected.

http://www.rctech.net/forum/showthread.php?p=2981627&highlight=roll+center+cal culator#post2981627

John
John Stranahan is offline  
Reply With Quote
Old 04-05-2007, 01:01 AM
  #9  
Tech Master
Thread Starter
 
Speedie's Avatar
 
Join Date: Feb 2003
Location: Wisconsin
Posts: 1,844
Default

Thanks John Ill give that a try. At one time I had found a nice calculator that was free but I cannot find it or remember where I got it from. I can figure it out manually but just looking to save some time as I use roll centers alot racing dirt late models.
Speedie is offline  
Reply With Quote
Old 04-05-2007, 01:48 AM
  #10  
Tech Elite
iTrader: (22)
 
rcfoolz's Avatar
 
Join Date: Sep 2003
Posts: 3,327
Trader Rating: 22 (100%+)
Default

up till now, i didn't understand the reason behind the inner pivot point on the front of the car. now I understand why when I raise it up, steering goes away.
rcfoolz is offline  
Reply With Quote
Old 04-05-2007, 01:26 PM
  #11  
Tech Elite
iTrader: (27)
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Default

Here are some adjustments and their effect on roll center.

Inner upper pivot up - roll center down
Outer upper pivot up - roll center up
inner lower pivot down - roll center down

When using a standard front ball diff on an electric 4 wheel drive touring car I have found that lowering the roll center will give more traction to that end of the car.

When using a locked front diff on an electric 4-wheel drive touring car. Torque steer seems to be the predominant force driving the steering. In this case lowering the roll center in front will give less torque steer and as a result less steering traction. This assumes you are cornering with good power applied mid corner.

John
John Stranahan is offline  
Reply With Quote

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


Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Terms of Service