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Author Topic:   quick roll center question
dluna
Dirt Full Roller

Total posts: 42
posted August 09, 2002 04:58 PM
We are going to run a panhard bar behind the rear-end, mounted to the right side of the frame, and left side of the rear-end. When you lower the frame side, will this raise or lower the roll center? I think it will lower, just not completely sure. I read the tech document from the tool box and didn't quite understand what would happen if you do this.

Thanks!

P.S. I am still wondering what you want on dry-slick. Why do we add more lr bite, want more chassis roll, and go from a 3 to 4 offest on the RR? We just do it because it "works," but it would be great to understand why it is actually helping on a dry-slick track.

millerlt3
Dirt Forum Racer

Total posts: 95
posted August 09, 2002 09:53 PM
It will lower the rear roll center. But I have one question, if you are running dirt why are you mounting the panhard bar right side chassis and left side rear end, thats normally an asphalt set up? A bar thats right side chassis mounted will create a rising roll center as the chassis rolls and a left side chassis mounted bar creates a rear roll center which will decrease as the chassis rolls which on dirt is what you need to get side bite. Remember this is just a question I'm not saying your wrong or write mounting the bar right side chassis, but all the cars ive seen that run dirt are left side chassis and right side rear end mounted.

dluna
Dirt Full Roller

Total posts: 42
posted August 11, 2002 12:37 PM
We have just been trying all kinds of set-ups this year. At the last big show, 3 of the top 5 guys were running their panhard bar like this. The track was VERY dry-slick. So that is why the concept of asphalt seems to work I think.

I am still trying to learn about this roll center business. If you are mounted on L side of rear-end and R side of chassis, I figure as long as you are angled downhill to the right...shouldn't this lower the roll center as the chassis rolls? The lower you move the R side down, the lower the roll center??? I understand what you are saying if you are running at and angle uphill to the right, but I don't understand why it would be that way if the bar is running downhill.

Where would the roll center be with this kind of mount? Will it lie somewhere close the the middle part of the bar?

Thanks.

millerlt3
Dirt Forum Racer

Total posts: 95
posted August 12, 2002 12:08 AM
Regaurdless of uphill or downhill, the rear roll center is located at the center line of the panhard bar, both laterally and vertically. And to the other question at hand, If the bar is mounted downhill to the right side of the chassis, does the roll center lower as the chassis rolls. This is a very good question. But all the chassis tech that ive seen says when the bar is attached to the frame on the left the roll center decreases during body roll and when its attached to the chassis on the right, the roll center rises during body roll. So im going to assume that regaudless of uphill or downhill when mounted on the right side of the chassis, during body roll the roll center is still going to rise. But I may be wrong. maybe some of the other guys can verify this question. Let me know how the car reacts to the new set up, tacky and dry slick condition. Good luck

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