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Author Topic:   any new info on front roll centers ????
JT54
Dirt Maniac

Total posts: 170
posted October 06, 2005 07:15 PM  
I have been playing around with my front roll center the last couple of times out ......I was running a high wedge set up on short three link and I had a pretty flat right upper control arm and allot of angle in my left ....no matter what I did with bar angles etc. in the rear I could not calm the car down (big wheelies)....I ran accross a post about front roll centers and the angle of the upper control arms...the way I understand it is the more angle in the left as apposed to the right will move roll center left and vise versa .....well I messed around and lowered my front end and played with ride hights untill I got the upper controll arms at the same angle ,re scaled and found I lost a lot of cross but the car calmed down a bunch......I am wondering if I lower the upper mounts on the right control arm about half an inch and gain some more angle if I can then add more cross to get back my killer drive off the left rear I had with the high wedge set up and still have the car calmed down like it is now????any one been playing this game ?....JT

Fastride 38
Dirt Maniac

Total posts: 125
posted October 06, 2005 07:36 PM  
Wow, and I thought I was confused about front to rear percentages...I personally haven't tried any of what you are doing but you have peaked my intrest. Please keep us posted on your findings. I personally am intrested on how you do and what you find out.

wfoondirt
Dirt Forum Champ
Total posts: 505
posted October 07, 2005 06:53 AM  
Your on the right track JT. But I would draw out on paper or use a computer program to find where your r/c is and where you want it to be before you just arbitrailly change a-arm angles.

JT54
Dirt Maniac

Total posts: 170
posted October 07, 2005 10:56 AM  
your right ,I should map the whole thing out...I have no idea how high or low my roll center is now I only know that it is alot closer to center than it was before ,also I am not sure where the optimom positioning is .....I think it is just a trial and error thing ,and I am used to that.....I feel if you are doing what all the others are doing than you are stuck inside the box...I prefer to venture outside the box and it has prooved to have mixed results....anyone ealse out there have any knowledge on this?......what are some good starting points on a small metric with stock lowers and pinto spindles .....it seems to me that with the short spindle I need to have the right side upper control arm heim joint almost touching the frame to get what I think I need.....JT

FlyNLoIMCA17
Dirt Forum Champ
Total posts: 753
posted October 07, 2005 05:56 PM  
I run the same setup as u JT, metric with pinto spindles. My front RC is 2.9" up and 3.5" left of center. Both my upper arm heim joints are down on the frame. The basic starting point you can shoot for is 2-4" above ground and 3-4" left of center. Then of course its like everything else, trial and error to find what you like. The problem your going to find thou is the same one I have. Static my R/C is ok, but the dynamic R/C lacks a little. Also by using the 3/8" longer lower ball joints from an impala I think (most all race suppliers sell them) it will raise the roll center up for you. If you can get away with running the mono-ball ball joints, I highly recommend you do so. They will save alot of time. But if you use the impala's you will have to ream out the pinto spindles. Over this winter I will be fixing my dynamic R/C. Last winter I done the static to see what results I'd get and I was very surprised, my car came to life!! But it stills lacks some, so getting the dynamics right should really help out!

Good Luck!! Tinkering with the R/C's is time very well spent!!

JT54
Dirt Maniac

Total posts: 170
posted October 08, 2005 12:14 PM  
Thanks for the reply....I think us racers get to cought up in the rear suspension and try to get the cars to dig ditches with the rear tires ,when we should realy be concentrating on the front....I got the digging ditches part down now if I can get the car to be a little smoother and stay a bit flatter with the same forward bite I will be happy .....well for a minute anyway.

Fastride 38
Dirt Maniac

Total posts: 125
posted October 08, 2005 01:45 PM  
LMAO JT....there's always something you/we can do to make it faster ain't there???

JT54
Dirt Maniac

Total posts: 170
posted October 09, 2005 01:07 AM  

the_one
Dirt Full Roller

Total posts: 49
posted October 11, 2005 10:11 AM  
i know this has been said before on here but what is a good program to find the front r/c and rear r/c

wfoondirt
Dirt Forum Champ
Total posts: 505
posted October 11, 2005 12:08 PM  
WinGeo 4.0

WRC
Dirt Roller

Total posts: 5
posted October 11, 2005 01:50 PM  
Also Auto-Ware as a good 3d front and rear geometry programs. www.auto-ware.com

FlyNLoIMCA17
Dirt Forum Champ
Total posts: 753
posted October 11, 2005 08:55 PM  
I use Performance Trends program. www.performancetrends.com

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