Thanks to martin we have gotten some nice translations of some useful Drift tengoku articles. Today's article will be about improving roll centers.
Drift Heaven. January 09, pg57~63.
"Lets find the way to achieve the lowness and speed in Drifting!"
everyone knows that low drift cars are cool. Lower the better. But when you search for higher level at drifting you will come across this problem. "when its too low, you loose a lot of suspension travel". If we take a look at the suspension and how it works one more time, we can try to achieve our goal, "low-drift car that can go fast!"
so we are going to talk about roll-center.
It's like this. lower the car-> center of gravity and roll-center goes down-> your car rolls more
Lower the car-> arm is angled up-> lose grip and more stress to the ball joints
it seems like when your car is lower you can corner faster, but reality is, the position of the roll center point determines the effect of your car. again, Low-center gravity and roll-center are two different things. Its definitely good to have the center of gravity low but you have to think about the importance of roll-center when you think about performance of your drift car.
"maybe stiffing up the springs would take care of that" we hear this a lot but this method works to a certain point, plus its compensated by uncomfortableness.
When you look at factory suspension set up, when the car is parked, the arm is angled slightly down and the balljoint sitting at the stress-free position. So what we need to do is to get our rides closer to this situation.
Take a look at F1 Cars.-> F1 cars are low(almost scrapping the ground). Its low-center gravity and roll-center are at the same point. This means that they can corner without the car having any roll. Another F1 fact is that adjusting the heights of these two points from front and rear can change from your car being under-steer to over-steer.
Since its impossible to get our rides to the most perfect scenario like F1 cars, job is to do our best. Lets look at products and techniques to help out this situation.
#1 products
MF-R Roll center adaptor. $90~240. This product help lowering your lower arms without changing its heights.
Ikeya-formula roll-center adjustable pillowball lower arms. $800~1200.
MF-R roll-center joint. $300~360. replaces stock lower arm ball joints .
G-reddy roll-center adjuster. $150~260. replaces stock lower arm ball joints
#2 Rigid mount subframe to change roll-center
This technique only works for the rear. You can drop your subframe and take out stock sub-frame bushings and replace it with steel plates. Since you can raise the sub-frame closer up to the actual body of the car, without raising the heights, you can bring the roll-center higher. It depends on the car but you can raise the roll-center anywhere from 10mm ~ 20 mm! This modification is time consuming but also gives you the extra rigidity to the frame, which is a great modification for your chassis duration and performance.
#3 Knockle mod to achieve better roll-center for the front.
G-master. hyper knuckle kit. $1300. Optional spacers to raise your roll-center by 10mm~20.$130,160.
V1 knuckle(17mm roll center adjust) $400~520)
MF-R bump adjust tie rod end. $270
Kazama. super tie rod end. $170
Last section is theories from the masters.
Miue from 3up.
"I drive ECR33 and don't have anything in particular for roll-center except the rear. I have my sub-frame rigid mounted and settled toe to be 0 at 1G. Since the subframe is mounted higher, the toe change seems less dramatic under load"
Nakamura from Team Burst.
"I don't really know anything about roll-center,I think if you have adjustable links, you can do a lot by changing your toe alignment. You can set up to have a lot of traction this way too. when I go to the mountains, I set my alignment 5mm toe in. at the circuit, 0mm toe. but I max my front camber at 5-degrees! this set up is so~good"
Hibino (D1 driver)
"yeah I have roll center adaptor on my AE86, I could tell a small difference but don't think you need it for drifting...."
Satou san from sato Auto
"I think if you have modified knuckles and more steering angle, you need to take care roll-center. Because you can not get the right amount of contact patch at full lock especially if your car is lowered."
Okachan from yashio factory.
"On my S15, first I rigid mounted the subframe and got 15mm of roll-center, and Gp knuckle +ikea formula"s lower arms which gave me 20mm of roll-center for the front. This combination works really well. I've heard that F1 cars back in the day had open diff but they were able to corner really hard because the car had no roll. I wanna make drift car that does the same thing. No roll and easy to start drift,and gets traction when I want."
Sazukawa from a-bo-mu-nn.
"I've been Shakotan for 10 years but still don't understand the concept of roll-center. What i worry is how my car sounds and how my aero comes off....."
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