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Author Topic: Roll center vs. bump
ozone
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Post Roll center vs. bump
on: December 16, 2015, 21:51
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As I raise one wheel the roll center is well behaved until suddenly it jumps laterally, then comes back to the expected value. Can I assume this is not a problem?

Thanks for the help and the awesome calculator.
racingaspi-
rations.co-
m
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Post Re: Roll center vs. bump
on: December 17, 2015, 10:13
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Some suspension designs will do this and can be taken as the limit of the suspension travel.

Can you post the link to your model?

Huw
ozone
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Post Re: Roll center vs. bump
on: December 18, 2015, 13:02
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Once again, I posted and it acts like I didn't. It's not my first forum.

Anyway, I hope this isn't the case because the roll center jumps away after only 1.875" of travel. Here is the design: //www.racingaspirations.com/mods/1ywwqdvi
racingaspi-
rations.co-
m
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Post Re: Roll center vs. bump
on: December 18, 2015, 13:27
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It looks to be caused by the instant centre moving from above to below ground level. As the point at which the tyres meet the ground is used in the roll centre calculation it does have quite an effect.

This may be an indication that your design needs some modification unless the point at which it happens is outside the working range.

Huw
ozone
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Post Re: Roll center vs. bump
on: December 21, 2015, 00:34
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I agree that it seems to happen when the roll center drops below ground level, but is this a problem in reality? Many designs either fall below the ground in bump or cross to above ground level in droop. I find it hard to believe this would cause a problem with a real suspension. Thoughts?
racingaspi-
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m
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Post Re: Roll center vs. bump
on: December 21, 2015, 17:14
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The roll centre calculation is based on a well know algorithm. It's not difficult - basically, the intersection of the instant centres and the point at which the tyres touch the ground. Lifting one wheel up will have a major impact on this but, it isn't wrong.

Maybe you can compare with some other suspension models on the site or research the effects that the roll centre moving like that will have?
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