This is the roll center, suspension pickup, and steering angle modification thread.

[Croustibat]

Hey guys, long time no see !

I thought it was time for a little visit. And as it happen, i was the first keisler kit user in France, so i can give a bit of feedback.

I use it on an S13, for grip driving. The car has been drifted too by someone i trust, too, but my main goal is to make a fast, easy, fun, and not uber expensive car, which i might have succeeded. I am not running monster tyres either, juste 235/40/17s on all corners.

The keisler kit has been on my car for at least 6 months now. What can i say ? it does the job. And it has a little bonus : there are 3 mounting points for the steering rod end, on the knucke, for faster response. And although the fastest is supposed to be used by drifters, i found it very interesting for racing ... as i do not ever need to let go of the wheel to turn. Ever dreamed of a karting steering wheel feeling ? Now i have it on an S13
I only need half a wheel turn to clear a hairpin. And the car still feel planted at high speed (like 130mph+ )

So far, not much to say against it. The ARB link is a bit high and that worried me.

Originally Posted by Lurch629

Appears to be fairly light as well.

That was actually my kit, not julian's
In my search for an easy car, i went the "light is right" way, too, and that is a place where the keisler kit shines. My current full front suspension, including wheels, tyres and brakes weight slighly less than the stock 257mm brake, 195mm tyres of the mk1 S13. While it runs 235/40/17 and def wilwood 300x32 2 piece brake kit. I am also running FA500 coilovers, and these are WAY lighter than the stock strut. And quite nice considering their price range too. I never thought a 12kg/10kg coilover system would be more comfortable than the previous megan racing coilovers with 5/4 springs i had. the car is also so much easier to feel and control when approaching its limits. I love it. I guess my next coilover upgrade, if it ever happens, will be for 3way dampers...

anyway i reallly love the "no inertia" feeling coming from the light wheels, tyres and brakes, and from the suspension parts. I don't know how to describe it. Before that i had heavy tyres and wheels, i also had 20lbs brake discs on each side, so i could feel the change every time i lightened these.

Originally Posted by ZacKisBacK_Fr

Those pics come from DG Motorsports in France, they use to work on my car and made my Z33 gearbox adapter plate for my SR20, they sell those keisler here. They made this comparison between the wisefab and the keisler for a customer that changed the wisefab to go with the keisler. [...]

I don't know if he did get the keisler, but he liked how it worked on my car. I also know the wisefab was bent and some welds were broken. The owner is a pro driver in the french drift championship. I'd say if he installed a keisler, we will know for sure if it can take the beating or not.

How is that rear knuckle from wisefab doing ? Is it worth getting when i already got a nicen low toe change from figuring out the right length of the traction rod for my setup ? if so i might give it a try later.

[kewilso3]

I'm not going to attempt to explain any of this, but on the topic of lower strut ears/mounts, here's a quote from Jason M over on NRR, speaking of his past modification regrets:

"Number two, I would not of experimented with my low SAI setup (12-14 deg's), as all that did was lower my roll center, and remove all camber gain, and in fact add positive camber gain during the second inch of suspension travel. In my ignorance, I neglected the fact that the Strut tube defines the slider axis, which defines the roll center & the camber curb of the mc strut suspension.

Number three, moving the strut inward with longer "strut ears", in order to fit wider wheels and tires, was also a huge mistake, as this changes the slider axis of the strut in a negative way."

[Bink Industries]

Originally Posted by kewilso3

I'm not going to attempt to explain any of this, but on the topic of lower strut ears/mounts, here's a quote from Jason M over on NRR, speaking of his past modification regrets:
I will try and clear things up

"Number two, I would not of experimented with my low SAI setup (12-14 deg's),
thoughs look like good numbers to me

as all that did was lower my roll center, and remove all camber gain, and in fact add positive camber gain during the second inch of suspension travel.
You don't want camber curve in drifting so this really only applies to road racing and even still than is a disadvantage to having McPherson strut is the lack of the ability to get proper camber cure. not saying you cant but its a lot harder.
In my ignorance, I neglected the fact that the Strut tube defines the slider axis, which defines the roll center & the camber curb of the mc strut suspension.
This is 100% incorrect. it only defines camber curve. I have actual suspension engineers from actual auto manufactures telling me this is incorrect. Im pretty sure they know what they are talking about. RC is drawn out 90 degrees from SAI not strut axis.

Number three, moving the strut inward with longer "strut ears", in order to fit wider wheels and tires, was also a huge mistake, as this changes the slider axis of the strut in a negative way."

again this has no effect other than changing camber curve. depending on what you want you may or may not want camber curve. road racing yes you want some drifting you want to eliminate it.

[n2o_matt]

Originally Posted by N8 of S-Empire

So is the GK Tech knuckle loosing steering axis offset? Maybe to allow road racers to gain more (-) camber through more castor with out the disadvantage of increased steering effort...


no that looks the same as stock. 5/16 offset forward like a bicycle, not backward like a shopping cart. (if my memory correct)

Does seem to be about stock now that I look at some more pictures. It appears the offset of the lower ball joint looks to be to the rear while the upper mount is to the front - or maybe this is an optical illusion. This would make the angle in the knuckle itself leaning top forward a bit, but I don't think the angle matters since the knuckle will pivot to the castor angle its set at. What would matter is if the line connecting the lower ball joint to the top hat passes in front of, behind, or through the wheel center or to give the steering axis ofset right? This is all very hard to visualize (for me anyway) off the car.

Originally Posted by TheRealSy90

I'm not well versed in all this but, I don't see how anything changes (other than camber) when slotting the lower coilover mount, because the upper top hat has a pillowball, and isn't going to stay perfectly perpendicular to the coilover as shown in that picture. It's just going to pivot at the tophat pillowball no?

It will pivot, but what is important for SAI, caster, trail, etc is the axis through the top hat and lower ball joint not necessarily the angle of the coilover makes with the chassis. However, that "slider axis" stuff kewilso3 is quoting is a new (to me) dynamic where the struct orientation does matter.

Croustibat - what are your alignment settings? I have the same kit (he's local to me here in knoxville) but mine is not feeling right. Is your steering smooth lock to lock while sitting still with the engine running? Ever have any issues with returning to center? I also noticed the high sway bar endlink, mine is maxed out as short as possible and its still higher than stock. I would guess this may cause some stiction in bump do to the sway bar being out of its normal operating range??

Originally Posted by kewilso3

"Number two, I would not of experimented with my low SAI setup (12-14 deg's), as all that did was lower my roll center, and remove all camber gain, and in fact add positive camber gain during the second inch of suspension travel. In my ignorance, I neglected the fact that the Strut tube defines the slider axis, which defines the roll center & the camber curb of the mc strut suspension."

Shouldn't having less SAI raise the RC? Or maybe that's the effect of the strut axis? I've always thought of them as being co-linear, but I guess they don't have to be.

[n2o_matt]

Guess I took too long to type ha

Originally Posted by N8 of S-Empire

again this has no effect other than changing camber curve. depending on what you want you may or may not want camber curve. road racing yes you want some drifting you want to eliminate it.

In a drift the car is still rolling toward the leading wheel, so wouldn't you want some (-) camber gain on that wheel to fight the (+) camber effects of caster?

[Bink Industries]

Originally Posted by n2o_matt

Guess I took too long to type ha



In a drift the car is still rolling toward the leading wheel, so wouldn't you want some (-) camber gain on that wheel to fight the (+) camber effects of caster?

In road racing as you take a corner you turn the wheel the car tries to go straight but the tires win and make the car take the corner.as this happens you get a later load transfer to the outside wheel the tire will try and roll under the car and create an un even contact patch.

as you corner harder the more the tire will want to roll under its self at the same time the car with also roll over to the outside. to take advantage of the roll and use of suspension you ad camber. this will even out as you corner harder you camber in more keeping that flat contact patch.

make sense?

in drifting your not doing almost any of this. so the theory is different and the importance to get it bang on is not as important as your thinking. your camber is changing so much based on steering angle. it is (to me) almost impossible to have perfect contact patch ALL of or even most of the time unless u do what wise fab did and even he eliminated camber gain in the front as well.

camber gain in the rear is a huge no no but that's a whole nother story.

all this said with a traditional set up (cut knuckle, long flca) we don't have front grip issues. this is my opinion.

[TheRealSy90]

This thread makes my head hurt.

[PoorMans180SX]

Camber change with suspension compression is extremely small in a McPherson setup. To the point where it's not worth worrying about. Caster /caster trail and camber at lock is much more important. Also, roll center is very important and the most overlooked thing in drifting outside of a professional series.

[az_240]

Originally Posted by TheRealSy90

Yeah I have and i've never had a problem. You tighten the bottom bolt (not slotted) first and it doesn't move.

If the bolts are facing the same way on both sides it will still move because of the way the torque is being applied... If you flip the bolt around on one side so you're tightening the bolt towards the car instead of away it'll work though. Not sure why I didn't think of that before.

[TheRealSy90]

Or you could just hold it with your hand so that it doesn't move...

[marks14]

Originally Posted by Bink Industries

In my ignorance, I neglected the fact that the Strut tube defines the slider axis, which defines the roll center & the camber curb of the mc strut suspension.
This is 100% incorrect. it only defines camber curve. I have actual suspension engineers from actual auto manufactures telling me this is incorrect. Im pretty sure they know what they are talking about. RC is drawn out 90 degrees from SAI not strut axis.

I'm not trying to say you are wrong in any way, I'm just trying to get some clarification.

When looking at the front view swing arm geometry the instant center is defined where a projected line from the LCA intersects an imaginary line drawn 90 degrees from the strut axis. This effects the camber curve like you said. To find the roll center you project lines from the ICs to the middle of the contact patch of each of the tires. Where those two lines intersect is the roll center.

So I was under the impression that changing the slider axis -> changes IC -> changes RC

Do you have a written source that defines the RC as 90 degrees from the SAI? Or am I interpreting my suspension kinematics books incorrectly?

[Bink Industries]

Originally Posted by marks14

I'm not trying to say you are wrong in any way, I'm just trying to get some clarification.

When looking at the front view swing arm geometry the instant center is defined where a projected line from the LCA intersects an imaginary line drawn 90 degrees from the strut axis. This effects the camber curve like you said. To find the roll center you project lines from the ICs to the middle of the contact patch of each of the tires. Where those two lines intersect is the roll center.

So I was under the impression that changing the slider axis -> changes IC -> changes RC

Do you have a written source that defines the RC as 90 degrees from the SAI? Or am I interpreting my suspension kinematics books incorrectly?

I dont. just phone conversaions and shared drawings with suspension engineers from Hyundai and other people I will not name drop that are some of the most respected and experianced set up guys in Formula D. they ALL told me throw strut axis out the door and plot based off SAI. Instant centers roll on this axis not strut axis.

when the rules of roll center where written for McPherson the struts where mounted like such.


actual car with suspension like this is the 86 corolla. the strut axis is the SAI. but now we have offset from strut axis to SAI. so you still go off of SAI where your pivots are.

[az_240]

Originally Posted by TheRealSy90

Or you could just hold it with your hand so that it doesn't move...

Tried... it moves.

[marks14]

Originally Posted by Bink Industries

I dont. just phone conversaions and shared drawings with suspension engineers from Hyundai and other people I will not name drop that are some of the most respected and experianced set up guys in Formula D. they ALL told me throw strut axis out the door and plot based off SAI. Instant centers roll on this axis not strut axis.

when the rules of roll center where written for McPherson the struts where mounted like such.

actual car with suspension like this is the 86 corolla. the strut axis is the SAI. but now we have offset from strut axis to SAI. so you still go off of SAI where your pivots are.

I guess it's just a case of real world practice being a little bit different than the text.
I was treating the strut as an A-Arm of infinite length then looking at it like SLA suspension. I wonder if the strut axis and the SAI are close enough to just make the small angle assumptions? Maybe that's why you go off of SAI in the real world. Interesting.
Thanks for sharing your knowledge especially since you've worked with some of the top people.

[Croustibat]

Originally Posted by n2o_matt

Croustibat - what are your alignment settings? I have the same kit (he's local to me here in knoxville) but mine is not feeling right. Is your steering smooth lock to lock while sitting still with the engine running? Ever have any issues with returning to center? I also noticed the high sway bar endlink, mine is maxed out as short as possible and its still higher than stock. I would guess this may cause some stiction in bump do to the sway bar being out of its normal operating range??

I am using a fairly neutral alignment setting, front 1°50 camber, 7°30 caster, 5mm total toe out front, 1°30 camber, 0 toe rear.

At something like halfway point, the steering gets harder, then softer again. Looking from the outside, the front gets lifted at that moment. I think it also has to do with car height. I do have wheels and tyres with a total diameter identical to oem, so even with a somewhat low car, the suspension arms are not that inclined. When watching from under it looks like the steering arm to kuckle point is too low for me.

Mind you, i dont drift mine so cant really say it bothers me that much. I can confirm julian has installed the keisler too on his drift car. Interestingly enough, he is running with very low caster to get a flat contact patch at full lock.

[Motary]

I had a look into susprog and as odd as it seems, upper line for macpherson strut is indeed perpendicular to the strut, not SAI



oh and these are done:

[Bink Industries]

I have used other programs that use SAI as well. I've seen both. But I will continue to trust what I have been told by the people I respect. i also talked to two chassis guys that have built baja winning class one and trophy trucks in the days passed and they both said the same thing SAI not strut axis. To many industry professionals saying the same thing.

[Axel18]

Question & problem:

-MA motorsport knuckles s13
-Oem flca extended 25mm & notched
-tein rods and several rack spacers
-rack moved forward

So ive adquired a lot of angle. but i havent centered the rack to split the same angle both sides.

My problem is that while uncentered. I have a feasty angle on the driver side but the other side is far from getting the same angle. If i center it ill have the same on both but i will lose a lot from one side to split it. i could have more if the rack travel would let me.

Is there a way to get more rack travel? Or another rack that can be used that may have more travel? Or am i missing something?

Sent from my GT-I9300 using Tapatalk

[Bink Industries]

Originally Posted by Axel18

Question & problem:

-MA motorsport knuckles s13
-Oem flca extended 25mm & notched
-tein rods and several rack spacers
-rack moved forward

So ive adquired a lot of angle. but i havent centered the rack to split the same angle both sides.

My problem is that while uncentered. I have a feasty angle on the driver side but the other side is far from getting the same angle. If i center it ill have the same on both but i will lose a lot from one side to split it. i could have more if the rack travel would let me.

Is there a way to get more rack travel? Or another rack that can be used that may have more travel? Or am i missing something?

Sent from my GT-I9300 using Tapatalk

MA sports knuckle out the box the way they make it is 44 degrees lead wheel 40 trailing wheel at 9 degrees caster. caster plates rotated for camber at the same 9 degress caster 1 degree reverse ackerman. if you want more angle get new knuckles. s14 arms and my kuckles yield 55 degrees lead wheel 48 trail under stock fenders which has worked well so far. so to me it sounds like you need a more modern knuckle.

[Axel18]

It was hard enough to get these knuckles lol. Im in the dominican republic and my budget is limited. Its definitely an improvement over stock. But since i see space for more angle, im trying to find our what else can i do.

Sent from my GT-I9300 using Tapatalk

[yomisiu]

Originally Posted by Motary

oh and these are done:

[IMG[/IMG]

where can i get those?

...nevermind

"If you're keen on having your name down for the second batch send an email through to Greg at [email protected] "

[PoorMans180SX]

You'll notice that TDP increased the caster trail quite a lot as well.

[Jifter]

First let me say this thread is the sh!t. I have read every page, started reading a year ago.. some pages more then once lol

I made this reply to get some advice on my setup and welding the knuckles for my goals.

My goal is to have zero ackerman, or as little as possible. And obviously as much angle as possible.

I looked closely at pics of the GKtech knuckles with the zero ackerman arms on. Im trying to angle and weld my arms as close to the same position as them. I have searched for pics of zero ackerman welded knuckles but I didnt find many good pics.

Here are a few pics of where im at and how im thinking of welding them. I know there are many people that have attempted to weld their knuckles for zero ackerman so I would like to hear from them.

Also, what is a good length for the knuckle arm? Im thinking around 3.5" eye to eye?

PS, the first and 2nd pic have the arm slightly angled differently. What angle would be better for zero ackerman? First pic has the arms straight edge lined up flush and the 2nd pic has the edge of the hole lined up with the edge.

Any tips would be awesome!

[Jifter]

This is what im getting with rack spacers and removed stoppers.

Its an s13.32 btw lol

[Slenis]

im mounting a steering angle kit on my s14 right now!

Welded knuckles, about 4" ackerman and 50´steering angle..
Will be running extended LCA (30MM) and motary castor arms...

But now to my problem, clearance in the wheelhouse/wheelarch!

I was planning on running 18" 9" wide.. But it will probably scrape as hell. RIGHT?

So i´m thinking about using my old track rims in front

17x7 with 235/45 tires?

Anyone in here using some angle with OEM wheelarch/wheelhouse ?

Perhaps build an own adjustable steering stop?


SRY for my bad english!

[Jifter]

Have any of you tried the new VooDoo13 tension rods?

http://voodoo13usa.com/shop/1989-199...san-s13-240sx/

[TheRealSy90]

Yes, they are awesome. Highest amount of clearance available other than a one piece tension rod/flca unit. And made right here in AZ.

[Akop]

Have any of you tried these? They're a decent price too

http://www.gktech.com/index.php/adju...trol-arms.html

[PoorMans180SX]

Originally Posted by Akop

Have any of you tried these? They're a decent price too

http://www.gktech.com/index.php/adju...trol-arms.html

GKtech makes some of the highest quality stuff on the market. Anything you get from them is going to be good.

[az_240]

Anyone know if the GKtech rear knuckles are still happening? Would be nice to go back to Z brakes in the rear.