Roll Center Adjusters for Daily Driver?
#1
01-09-2011 | 06:36 PM
Roll Center Adjusters for Daily Driver?
I'm looking at J's roll center adjusters for my GE as I have heard good things on how this changes the front handling. I was wondering if paying $222 + shipping + install would be worth it for a daily driver.
I already have Tein SuperCompact Coilovers and the Progress RSB and am loving my ride. Great daily comfort and very good handling. Are RCA overkill on my application?
Any thoughts/experiences welcome!
Cheers!
I already have Tein SuperCompact Coilovers and the Progress RSB and am loving my ride. Great daily comfort and very good handling. Are RCA overkill on my application?
Any thoughts/experiences welcome!
Cheers!
#2
01-09-2011 | 06:45 PM
since you already lowered the overall height of your fit i would absolutely recommend buying a set.
installing a set would help keep the steering response quick as if you were still at oem height.
btw if you want a set i could probably beat that price.
installing a set would help keep the steering response quick as if you were still at oem height.
btw if you want a set i could probably beat that price.
#5
01-24-2011 | 09:03 PM
Member
Joined: Apr 2010
Posts: 1,316
From: Minnesota
The easiest way to tell if you will benefit from RCAs is to look at your front lower control arms:
First, look at the top pic, that is looking at the stock suspension from the rear. You will notice the LCA is angled down from center of the car. The tie rod is angled up from the center of the car. The suspension design is greatly effected by ride hight . What does that mean? Well, look at the top pic again. As you lower the the suspension the LCA goes flat and then past one inch of drop it starts to angle up. This is very bad for the suspension when you look at side loads( cornering forces). If the LCA is angled up and the weight of the car pushing side ways while the tire is trying to stick to the road, this force will "tend" to push the LCA up more and cause the suspension to blow through its travel. If the LCA is flat or angled down, the cornering loads are directed down the LCA in to the sub frame.
Cliff notes: LCA angled up from the center of the car = you blow through your suspension travel and get lots of under steer. So do not lower the car more than one inch.
Here is some good info to illustrate the difference/benefit/cause/effect of lower your car, steering geometry etc etc...(originally posted by speedstar808 on clubrsx.com)
Due to the massive lowering, the angles of the suspension geometries are no longer optimum. Take a look at the below picture which shows the arms and tie-rods angled upwards. A Bumpsteer Kit (reverse tie rods) and a set of Roll Center Adjusters (RCA) should fix this problem.
What is Bumpsteer? A bit of an explanation: Bump steer on the front wheels is illustrated in the diagram below, and it can be seen that it is caused by unequal angles between the steering tie rod and the lower arm. Depending on the difference in the angles, the wheel will either exhibit toe in or toe out on bump.
Lowering a car changes the angles between the lower arm and the steering tie rod, this in turn increases the bumpsteer on the front wheels, hence the benefits of a lower mass center is not seen because of the bumpsteer.
Why use Roll Center Adjusters? Refer to the diagram below: At standard ride height, the roll center is set by the angle of the arms and the roll center is an imaginary point where their lines would intersect. Ride & Handling guru John Miles advises that roll center is set between 40mm - 60mm above the ground for stability, and from this baseline the handling geometries can be set.
When you lower a vehicle, the wheels "move up" into the body and the angle of the arms is no longer optimum, in some severe cases they push the roll center low down below ground level. This would result in more roll than standard therefore the benefits of lowering the vehicle would not be realized. This is why you may read in some magazines and documents why lowering a standard car too much without geometry change is actually dangerous and adversely affect handling.
Originally Posted by mustclime
First, look at the top pic, that is looking at the stock suspension from the rear. You will notice the LCA is angled down from center of the car. The tie rod is angled up from the center of the car. The suspension design is greatly effected by ride hight . What does that mean? Well, look at the top pic again. As you lower the the suspension the LCA goes flat and then past one inch of drop it starts to angle up. This is very bad for the suspension when you look at side loads( cornering forces). If the LCA is angled up and the weight of the car pushing side ways while the tire is trying to stick to the road, this force will "tend" to push the LCA up more and cause the suspension to blow through its travel. If the LCA is flat or angled down, the cornering loads are directed down the LCA in to the sub frame.
Cliff notes: LCA angled up from the center of the car = you blow through your suspension travel and get lots of under steer. So do not lower the car more than one inch.
Due to the massive lowering, the angles of the suspension geometries are no longer optimum. Take a look at the below picture which shows the arms and tie-rods angled upwards. A Bumpsteer Kit (reverse tie rods) and a set of Roll Center Adjusters (RCA) should fix this problem.
What is Bumpsteer? A bit of an explanation: Bump steer on the front wheels is illustrated in the diagram below, and it can be seen that it is caused by unequal angles between the steering tie rod and the lower arm. Depending on the difference in the angles, the wheel will either exhibit toe in or toe out on bump.
Lowering a car changes the angles between the lower arm and the steering tie rod, this in turn increases the bumpsteer on the front wheels, hence the benefits of a lower mass center is not seen because of the bumpsteer.
Why use Roll Center Adjusters? Refer to the diagram below: At standard ride height, the roll center is set by the angle of the arms and the roll center is an imaginary point where their lines would intersect. Ride & Handling guru John Miles advises that roll center is set between 40mm - 60mm above the ground for stability, and from this baseline the handling geometries can be set.
When you lower a vehicle, the wheels "move up" into the body and the angle of the arms is no longer optimum, in some severe cases they push the roll center low down below ground level. This would result in more roll than standard therefore the benefits of lowering the vehicle would not be realized. This is why you may read in some magazines and documents why lowering a standard car too much without geometry change is actually dangerous and adversely affect handling.
#6
01-24-2011 | 09:07 PM
Member
Joined: Apr 2010
Posts: 1,316
From: Minnesota
Basically, if the front lower control arms (LCAs) angle upwards from the center of the car you have actually made your car handle worse that stock. RCAs will help move the LCAs closer to the flat position...but this is only a band-aid for doo-doo handling. The best thing is not to lower the car beyond 1".
#7
01-24-2011 | 09:19 PM
But then the car will not look good in the fashion show parking lot gatherings!!! It needs to be hellaphucked or go home.
Mmmmmm sarcasm tastes good. haha
I still have the full lower arm replacements collecting dust as I will not install them until I actually go with a sussy that lowers more than 25mm (what the Honda Access sussy lowers to).
Mmmmmm sarcasm tastes good. haha
I still have the full lower arm replacements collecting dust as I will not install them until I actually go with a sussy that lowers more than 25mm (what the Honda Access sussy lowers to).
#8
01-24-2011 | 09:31 PM
Member
Joined: Apr 2010
Posts: 1,316
From: Minnesota
I'm sure you are well aware of the flaws of the McPherson struts being a previous DC5-R owner.
BTW, you need to check in on the progress of my k24 swap in the link in my sig. I picked up BNIB OEM A-spec shocks (believed to be the same as DC5-R).
#9
01-24-2011 | 09:35 PM
I purchased way back when I purchased all the other J's bits the full lower arm replacments instead of just the RCAs. Just easier to install then having to pop out the stock part and then install the J's RC in the stock arm. Basically it is just a stock Fit arm with the J's RCA already installed. Another reason I have yet to install, still trying to find out about the CR-Z's aluminum lower arm and its compatibility with the GE. I would much rather have the strenght and lightness of that coupled with a J's RCA versus just the stamped steel arm of the GE.
I'll give a gander to your Civic here shortly.
I'll give a gander to your Civic here shortly.
#11
01-24-2011 | 09:54 PM
The shocks nobody ever really confirmed if they are the same or not as the stock R sussy. Obviously can't tell by looks as even the stock Type S shocks look similar. 
Looking good so far. Really going to go blue? NH-0 would be prime for it.
Looking good so far. Really going to go blue? NH-0 would be prime for it.
#12
01-25-2011 | 01:11 AM
Member
Joined: Apr 2010
Posts: 1,316
From: Minnesota
NH-0...is that Nighthawk black? Too plain!
#14
01-25-2011 | 11:18 AM
I think the Fit's McPherson design is quite different from the DC5. The reason I say this is, I've read all the info or help links on honda tech about how to correct your DC5 and blah blah theory. Its almost like the worst design made. I've never driven a DC5 but from what I read, they make it sound like the damn car just wont rotate and if it does, its only for a brief turn in then it corrects the camber and toe and BOOM understeer.
Ill be honest, Like i said ive never driven a DC5, but does the fit do the same BS? I really think it handles damn good. I think when they created the new si, they corrected the issue along with the fit.
I'm in the process of making the fit retarded tail happy. Its working so far.
staggered helps out so much and alignment.
PS: You guys following my Racing thread? Look at my recent post. My fit, as we speak, is getting a custom 8 point roll cage installed. sorry to go off topic but I know you guys would find this interesting just incase you missed my thread. <3 u
Ill be honest, Like i said ive never driven a DC5, but does the fit do the same BS? I really think it handles damn good. I think when they created the new si, they corrected the issue along with the fit.
I'm in the process of making the fit retarded tail happy. Its working so far.
staggered helps out so much and alignment.
PS: You guys following my Racing thread? Look at my recent post. My fit, as we speak, is getting a custom 8 point roll cage installed.
sorry to go off topic but I know you guys would find this interesting just incase you missed my thread. <3 u
Last edited by JCrimson; 01-25-2011 at 11:20 AM.
#15
01-25-2011 | 12:14 PM
Just ask kelsodeez about RCA's, they do improve handling when you put them on a lowered car... actually j's recommends them for cars lowered more than 20mm or 3/4 inch
the problem is that LCA's are weak, and if they're not installed correctly you could bend one...
on GD's i know you can't keep 14" wheels, as they won't clear the RCA, but since GE's have bigger stock wheels, that might not be an issue for you...
the problem is that LCA's are weak, and if they're not installed correctly you could bend one...
on GD's i know you can't keep 14" wheels, as they won't clear the RCA, but since GE's have bigger stock wheels, that might not be an issue for you...
#16
01-25-2011 | 01:07 PM
Member
Joined: Apr 2010
Posts: 1,316
From: Minnesota
@cr4zy3lgato
I don't know the exact drop necessary to justify RCA (I also don't know how to do the calculations...haven't really studied this)...sorry if I didn't make that clear. And, unless kelsodeez has done the calculations to figure out the roll center, there's no point in soliciting his opinion. We need objective data (i.e. calculations and lap times). A poor man's estimate is to look at the front LCAs...hopefully you at least looked at all the info I posted above.
On other Honda platforms utilizing the McPherson struts (i.e. RSX, EP3, EM2/ES1) the calculations suggest 3/4" to 1" max drop...before negatively affecting handling. It would be helpful if some of the sussy gurus here could do the math/sketches and help us all out.
The most important point to realize, is that if you've lowered your car to the point that you need RCAs then you've probably gone too far. Again, RCAs are just a band-aid...not a solution.
I don't know the exact drop necessary to justify RCA (I also don't know how to do the calculations...haven't really studied this)...sorry if I didn't make that clear. And, unless kelsodeez has done the calculations to figure out the roll center, there's no point in soliciting his opinion. We need objective data (i.e. calculations and lap times). A poor man's estimate is to look at the front LCAs...hopefully you at least looked at all the info I posted above.
On other Honda platforms utilizing the McPherson struts (i.e. RSX, EP3, EM2/ES1) the calculations suggest 3/4" to 1" max drop...before negatively affecting handling. It would be helpful if some of the sussy gurus here could do the math/sketches and help us all out.
The most important point to realize, is that if you've lowered your car to the point that you need RCAs then you've probably gone too far. Again, RCAs are just a band-aid...not a solution.
#17
01-25-2011 | 01:36 PM
Member
Joined: May 2006
Posts: 1,899
From: tx
I wanted to add to this that camber changes as the McPherson design compresses are not a linear rate of change. If you start your geometry at a point where not only is the roll center screwed, but from which, the rate of change will ramp up faster than if it had been traveling from the stock location, you are creating a drastic camber change with every bump and turn.
Basically, for every inch from the stock height that the suspension compresses, let's say theoretically, there is a .5 degree change; then if you start from that point, where there is already a .5 degree change (after lowering), and compress one more inch while driving, it will not go up by .5, like the last time, but rather, something like 1.5, thereby giving you 2 degree's at the same level of compression from static height, in the same scenario, instead of just .5. This isn't good for handling. Stiffening the springs helps, but they have to combat the new amount of force being exerted on the roll properties by changing the roll center to be way below the ground. This can be a huge strain on the spring rate, which combined with the newfound drastic camber changes, results in loosing grip quickly.
Then combine that with bumpsteer, and it becomes clear just how important how adjustments are needed for increasing performance over just looks, and "handling feel."
Depending on the design, in order to correct the drastic geometry changes, new LCAs will need to be put in.
Basically, for every inch from the stock height that the suspension compresses, let's say theoretically, there is a .5 degree change; then if you start from that point, where there is already a .5 degree change (after lowering), and compress one more inch while driving, it will not go up by .5, like the last time, but rather, something like 1.5, thereby giving you 2 degree's at the same level of compression from static height, in the same scenario, instead of just .5. This isn't good for handling. Stiffening the springs helps, but they have to combat the new amount of force being exerted on the roll properties by changing the roll center to be way below the ground. This can be a huge strain on the spring rate, which combined with the newfound drastic camber changes, results in loosing grip quickly.
Then combine that with bumpsteer, and it becomes clear just how important how adjustments are needed for increasing performance over just looks, and "handling feel."
Depending on the design, in order to correct the drastic geometry changes, new LCAs will need to be put in.
#18
01-25-2011 | 01:38 PM
Member
Joined: Apr 2010
Posts: 1,316
From: Minnesota
I think the Fit's McPherson design is quite different from the DC5. The reason I say this is, I've read all the info or help links on honda tech about how to correct your DC5 and blah blah theory. Its almost like the worst design made. I've never driven a DC5 but from what I read, they make it sound like the damn car just wont rotate and if it does, its only for a brief turn in then it corrects the camber and toe and BOOM understeer.
Ill be honest, Like i said ive never driven a DC5, but does the fit do the same BS? I really think it handles damn good. I think when they created the new si, they corrected the issue along with the fit.
Ill be honest, Like i said ive never driven a DC5, but does the fit do the same BS? I really think it handles damn good. I think when they created the new si, they corrected the issue along with the fit.
The DC5-R bests the DC2-R around the track...no question. This likely reflects the improvements of the Kseries over the Bseries...cause we all know that the DC2-R had the better sussy.
YouTube - INTEGRA Type R MEGA TEST & BATTLE - Best Motoring International
#19
01-25-2011 | 01:41 PM
Member
Joined: Apr 2010
Posts: 1,316
From: Minnesota
. Everything else is just a band-aid for sh!t handling.
#20
01-25-2011 | 02:07 PM
I didn't calculate it either (altough i will certainly check that when i swap my suspension) but this is from j's racing site
J's Racing The X'tream Honada Ride
J's Racing The X'tream Honada Ride
as refering to kelsodeez, i was talking about this thread: https://www.fitfreak.net/forums/fit-...adjusters.html
EDIT: Tanabe seem to think that ideal lowering is 1.2" (talking about the GF210) so basically best bet is to pick springs that lower the car the least (about an inch) and stick with that... i would only put RCA's if i tracked the car (which i do, but most people don't) honestly for the PITA factor i think you should save for coilovers instead... btw you guys don't have the clearance problem with the wheels: https://www.fitfreak.net/forums/aj-r...-adjuster.html
as for myself, i will set my coilovers at about 1" and i plan on corner balancing the car... so regardless of RCA's i think handling should be f***ing amazing!
The roll center adjuster corrects the roll center geometry and achieves the perfect setting you desire. The lower arm angle on a low-built car tends to be far from ideal and the roll center point can move to a far lower position. The deviation of the roll center from the center of gravity results in a deteriorated cornering force due to the increased body roll. The roll center adjuster rectifies the situation and produces the ideal suspension geometry.
[Results] Reduced roll, increased stability of the tires, sharper steering response, and faster corning!
This product is to be used for Fit whose height is reduced more than 20mm.
[Results] Reduced roll, increased stability of the tires, sharper steering response, and faster corning!
This product is to be used for Fit whose height is reduced more than 20mm.
J's Racing The X'tream Honada Ride
as refering to kelsodeez, i was talking about this thread: https://www.fitfreak.net/forums/fit-...adjusters.html
EDIT: Tanabe seem to think that ideal lowering is 1.2" (talking about the GF210) so basically best bet is to pick springs that lower the car the least (about an inch) and stick with that... i would only put RCA's if i tracked the car (which i do, but most people don't) honestly for the PITA factor i think you should save for coilovers instead... btw you guys don't have the clearance problem with the wheels: https://www.fitfreak.net/forums/aj-r...-adjuster.html
as for myself, i will set my coilovers at about 1" and i plan on corner balancing the car... so regardless of RCA's i think handling should be f***ing amazing!
Last edited by cr4zy3lgato; 01-25-2011 at 02:24 PM.