Roll center heights
Instructor
Joined: Dec 2009
Posts: 162
Likes: 18
From: Newark ca
I would like to know as well. Sure hope the roll center is lower in the rear due to having the gas tank so high up on the chassis. I have been thinking of making a low CG gas tank that would be in place of the spare tire and jack. I figure you can easily drop 30-50 lbs. 6-8 inches lower behind the axle where it matters most.
Drifting
Joined: Oct 2008
Posts: 1,936
Likes: 92
From: Rochester Hills Michigan
Thread Starter
Racer
Joined: Apr 2002
Posts: 252
Likes: 30
From: San Diego Ca
Drifting
Joined: Oct 2008
Posts: 1,936
Likes: 92
From: Rochester Hills Michigan
Makes sense...They reduced camber change with wheel travel; I'm assuming this was due to the lower profile tire having greater camber thrust and steering the rear too much with rear suspension travel.
Because the upper link is the halfshaft and can't be changed, they dropped the lower link's inboard pivot to lengthen the effective swing arm, which also dropped the roll center...my guess, anyway. (That's what they did in 1968. The roll center went from 7.56 in '67 to 4.71 in 1968. They changed the bracket that mounts the inner pivots for the strut rods.)
Because the upper link is the halfshaft and can't be changed, they dropped the lower link's inboard pivot to lengthen the effective swing arm, which also dropped the roll center...my guess, anyway. (That's what they did in 1968. The roll center went from 7.56 in '67 to 4.71 in 1968. They changed the bracket that mounts the inner pivots for the strut rods.)
Racer
Joined: Dec 2013
Posts: 327
Likes: 17
I would like to know as well. Sure hope the roll center is lower in the rear due to having the gas tank so high up on the chassis. I have been thinking of making a low CG gas tank that would be in place of the spare tire and jack. I figure you can easily drop 30-50 lbs. 6-8 inches lower behind the axle where it matters most.
I suspect that you have an incomplete understanding of the interplay between roll centers and CG as they relate to a vehicle's tendency to roll. You see, the distance between a roll center and CG height forms a moment arm(lever, if you wish) that will be acted upon by cornering forces to cause the vehicle to roll. If that moment arm is long(rather than short), it will cause more roll. On the other hand, if the moment arm is short, because of a higher roll center and/or a lower CG, then roll will be less for a given cornering force.
So, your expressed preference for a LOW RC would indicate that you want more roll, not less. Not good in this case.
There are many good books/websites available that explain this stuff in detail. Good luck with your suspension studies !!!
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
Hello my friend,
I suspect that you have an incomplete understanding of the interplay between roll centers and CG as they relate to a vehicle's tendency to roll. You see, the distance between a roll center and CG height forms a moment arm(lever, if you wish) that will be acted upon by cornering forces to cause the vehicle to roll. If that moment arm is long(rather than short), it will cause more roll. On the other hand, if the moment arm is short, because of a higher roll center and/or a lower CG, then roll will be less for a given cornering force.
So, your expressed preference for a LOW RC would indicate that you want more roll, not less. Not good in this case.
There are many good books/websites available that explain this stuff in detail. Good luck with your suspension studies !!!
I suspect that you have an incomplete understanding of the interplay between roll centers and CG as they relate to a vehicle's tendency to roll. You see, the distance between a roll center and CG height forms a moment arm(lever, if you wish) that will be acted upon by cornering forces to cause the vehicle to roll. If that moment arm is long(rather than short), it will cause more roll. On the other hand, if the moment arm is short, because of a higher roll center and/or a lower CG, then roll will be less for a given cornering force.
So, your expressed preference for a LOW RC would indicate that you want more roll, not less. Not good in this case.
There are many good books/websites available that explain this stuff in detail. Good luck with your suspension studies !!!
