TheLion
Well-Known Member
I'm learning as I go, but roll center is more or less a lever arm. The lower the roll center (closer to the ground), the greater the lever arm, so it works against the spring rates. Can compensate to some degree with stiffer springs, but it also affects steering geometry and how toe angles change as the suspension compresses.
Roll centers are pretty carefully setup in high performance variants like the GT350R. But may be adjusted for a higher ride height on the common run of the mill variants like the PP GT's. I'm looking to achieve handling that is fairly close to the GT350R as I can get for under $2k and I'm in the process of deciding what's really beneficial and what is not.
Here's the thing, the Steeda Roll Center and Bump Steer kit can benefit the car with the current springs and struts. The SP080's have slightly decreased corner entry steering and increased throttle steering over stock. So the car under steers a little more right now going into a corner which I DON'T like and steers even more with throttle mid corner and on exit which I also DON'T like as it's too much throttle steering for my comfort.
The car also tramlines quite a bit with my RTR Tech 7 wheels due to the combination of bump steer and increased scrub radius. With the stock PP wheels currently on the car it's not bad, tram-lining is still fairly mild as the scrub has not been increased. Both toe angle and scrub affect steering inputs. But I'd rather deal with increased leverage from scrub than bump steer doe to toe angle changes.
So the steeda extended ball stud lateral links will re-balance the under steer / throttle steer issue and the steeda bump steer toe rod end links will help reduce the tram-lining with the RTR +33 mm offset wheels and make it nearly non-existent with the stock PP wheels. No, I have not yet had and alignment, so that will affect the handling, but I don't think an alignment is going to be enough to fully re-balance the car. I do like the lower CG, I love the looks, but I don't like the increased tram-lining, reduced entry steering and slightly excessive throttle steering. I'm sure the huge mid-range torque increase of 45 ft-lbs at 4k and 5k rpms isn't helping the throttle steering either with my Power Pack 2. I'm due for an alignment soon, but trying to hold off til I'm ready for new tires late fall so it can all be done at once.
I'm leaning towards a -1.75 front camber with BMR's 7.21 caster angle, 0 front toe, 0.20 total rear toe and -1.5 rear camber. A slightly more aggressive variation of @BMR Tech recommended alignment settings for SP080's.
Roll centers are pretty carefully setup in high performance variants like the GT350R. But may be adjusted for a higher ride height on the common run of the mill variants like the PP GT's. I'm looking to achieve handling that is fairly close to the GT350R as I can get for under $2k and I'm in the process of deciding what's really beneficial and what is not.
Here's the thing, the Steeda Roll Center and Bump Steer kit can benefit the car with the current springs and struts. The SP080's have slightly decreased corner entry steering and increased throttle steering over stock. So the car under steers a little more right now going into a corner which I DON'T like and steers even more with throttle mid corner and on exit which I also DON'T like as it's too much throttle steering for my comfort.
The car also tramlines quite a bit with my RTR Tech 7 wheels due to the combination of bump steer and increased scrub radius. With the stock PP wheels currently on the car it's not bad, tram-lining is still fairly mild as the scrub has not been increased. Both toe angle and scrub affect steering inputs. But I'd rather deal with increased leverage from scrub than bump steer doe to toe angle changes.
So the steeda extended ball stud lateral links will re-balance the under steer / throttle steer issue and the steeda bump steer toe rod end links will help reduce the tram-lining with the RTR +33 mm offset wheels and make it nearly non-existent with the stock PP wheels. No, I have not yet had and alignment, so that will affect the handling, but I don't think an alignment is going to be enough to fully re-balance the car. I do like the lower CG, I love the looks, but I don't like the increased tram-lining, reduced entry steering and slightly excessive throttle steering. I'm sure the huge mid-range torque increase of 45 ft-lbs at 4k and 5k rpms isn't helping the throttle steering either with my Power Pack 2. I'm due for an alignment soon, but trying to hold off til I'm ready for new tires late fall so it can all be done at once.
I'm leaning towards a -1.75 front camber with BMR's 7.21 caster angle, 0 front toe, 0.20 total rear toe and -1.5 rear camber. A slightly more aggressive variation of @BMR Tech recommended alignment settings for SP080's.
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