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

[Bink Industries]

Originally Posted by derass

I would think that with a 0 Ackerman setup, you should be trying to take advantage of the fact that the trailing wheel is not scrubbing at full lock and maximize it's contact patch. I've found that -4* camber is the sweet spot, flat contact patch on the leading tire without being excessive. Combine this with a factory caster setting (5* ?), as I've always found that level of caster to provide good self-steer/centering.

Mind you, I do have some ackerman with my knuckles, so I have not tried to dial out camber and caster, as doing so would increase the trailing tire contact patch and therfore scrub.

as u add caster u need to add camber or you will begin to use your side wall at or near full lock. this is why there is no for sure settings. taking tire temps and read the tires. the car will tell you what its asking for camber wise. caster is up to you and what you like.

In competition drifting we need our transitions to be as snappy as possible. some drivers like to throw the car around requiring less caster. some like the car to drive its self requiring more caster. specific case being the driver Im crew chief for Joon Maeng. He likes tons of self steer, just let go of the wheel and it transitions on its own. but our friendly competitor Ryan Kado prefers less caster as his driving style is more aggressive and he likes to throw the car around more. if you add SAI into the mix then you get into a whole new world of combos.

zero ackerman causes interesting problems with transition speed and steering feel but that can be fixed somewhat with scrub but the real fix is what wisefab did with adding caster trail. zero Ackerman is desirable for high speed courses. slow speed stuff or really tight stuff likes ackerman. So again there is no perfect all the time setting. for the most part a reduction in ackerman is good for most people.

so don't get to hung up on "settings". its a balance of what the car is asking for and what the driver wants as well.

hope this helps

[Matej]

What effects does the distance of the knuckle mounting points from the shock have on steering/geometry? I have been curious, since different coilovers place the knuckle at different distances.
In theory, would it not be ideal to mount the knuckle as close to the shock as possible, and tune the suspension from there? Or would it be best to have the axis of rotation of the shock aligned directly with the pivot point of the knuckle? Or is there nothing of significance to be gained/lost here?

[Bink Industries]

Originally Posted by Matej

What effects does the distance of the knuckle mounting points from the axis of rotation of the shock have on steering/geometry? I have been curious, since different coilovers place the knuckle at different distances.
In theory, would it not be ideal to mount the knuckle as close to the shock as possible, and tune the suspension from there? Or is there nothing to be gained/lost here?

that distance is called the "included angle"

it changes your roll centers and changes your camber curve. you cant just simply say it will be better or worse based off just the distance. you will need to plot your suspension geo and find out what effect it will have on YOUR car at its ride height wheels tires offset, sai, track width all come into play. I made custom ones for Joon maeng specificly where I wanted them for RC and cmaber curve.

[powahh]

Thanks, I definitely want the modern setup, the 2003 setups are obsolete now.
Thanks for the feedback.

What about ackerman? What are you guys running? Will the car self steer with enough caster alone and zero ackerman? 6-8 degrees? 10?
Sorry for noobish questions, I'm in the process of building my front suspension ATM, and i don't wanna do it multiple times,
I want lots of front end grip, want the car to self steer back to zero, enough for quick transitions and want to feel whats happening, after driving my buddies E36, I was mind blown by how little feel Schassis have, well maybe it was just mine.

[powahh]

Lol N8 of SEmpire just answered all of my questions

[Matej]

Originally Posted by N8 of S-Empire

that distance is called the "included angle"

Here is a more crude image.
Obviously the end behaviour will be a collective result of the entire setup, though I was just curious what would be the direct effects of either extreme if any (besides inner wheel clearance), if starting with a blank slate.

[Motary]

Originally Posted by N8 of S-Empire

that distance is called the "included angle"

it changes your roll centers and changes your camber curve. you cant just simply say it will be better or worse based off just the distance. you will need to plot your suspension geo and find out what effect it will have on YOUR car at its ride height wheels tires offset, sai, track width all come into play. I made custom ones for Joon maeng specificly where I wanted them for RC and cmaber curve.

Changing the angle of the coilover does not do anything to roll center. It still pivots around 3 in space.. not lines..

[MILAS131JZ]

Originally Posted by Motary

Changing the angle of the coilover does not do anything to roll center. It still pivots around 3 in space.. not lines..

Hi
Im looking for super steering angle for my S13,
I found a few options (Godspeed Knuckles, parts shop by max and wisefab)
which angle can I get with this parts Godspeed or max knuckles(degrees)
Why should I buy Max super steergin angle Knuckles instead of the wisefab?
My Car s13 Street/drift

[Irresistible]

How can I tell if my rack is over-centering on my S14 without actually driving the car? It currently doesn't run, but I'd like to know if it's over-centering or not so I can try to address that problem before I get it running again.

[TheRealSy90]

Never saw these before, KTS Rear Cradle support bars.

[az_240]

Originally Posted by Irresistible

How can I tell if my rack is over-centering on my S14 without actually driving the car? It currently doesn't run, but I'd like to know if it's over-centering or not so I can try to address that problem before I get it running again.

Put car on the ground (preferably a smooth surface) and turn the wheel to full lock either way... It's pretty obvious when it's overcentering. The steering wheel will feel 'stuck' at full lock. You might be able to get away with just jacking the LCA up a bit while it's on jack stands and see if it over centers at full lock.

Originally Posted by TheRealSy90

Never saw these before, KTS Rear Cradle support bars.

Sunline Racing made something similar a while back

[Bink Industries]

Originally Posted by Motary

Changing the angle of the coilover does not do anything to roll center. It still pivots around 3 in space.. not lines..

I does not directly. if you have 3 degrees of camber with your upper camaber plates maxed out toward CL of the chassis and say 20 degrees of SAI. now you change the lower pivots out to ones with more included angle in them. now lets say you have the same 3 degrees of camber but now you camber plates are maxed out all the way outward with an SAI of lets say 10 degrees now. that will change your roll center. just like anything in suspension geo you change one thing it changes 10 others.

[S13alldayyo]

Sent from my iPhone using Tapatalk

[Motary]

Originally Posted by N8 of S-Empire

I does not directly. if you have 3 degrees of camber with your upper camaber plates maxed out toward CL of the chassis and say 20 degrees of SAI. now you change the lower pivots out to ones with more included angle in them. now lets say you have the same 3 degrees of camber but now you camber plates are maxed out all the way outward with an SAI of lets say 10 degrees now. that will change your roll center. just like anything in suspension geo you change one thing it changes 10 others.

Adjusting camber via camberplates does that yes, it raises roll center and decreases front view swing axle length and raises its height

[KA240SX808]

Originally Posted by az_240

Sunline Racing made something similar a while back

Thats actually the Nismo Braces, 1" Tubing.

[LuckyX2]

So what's the better way of getting camber up front? All the camber you can get where the knuckle meets the strut and then a little more from the camber plate? Or minimum camber where the knuckle meets the strut and then a lot more from the camber plate?

Bonus points if you can say why.

[az_240]

Originally Posted by KA240SX808

Thats actually the Nismo Braces, 1" Tubing.

Oh, have that pic saved as Sunline Racing for some reason but was thinking they might be Nismo.

[Matej]

Originally Posted by LuckyX2

So what's the better way of getting camber up front? All the camber you can get where the knuckle meets the strut and then a little more from the camber plate? Or minimum camber where the knuckle meets the strut and then a lot more from the camber plate?

Bonus points if you can say why.

A longer FLCA would generally be the best.
For me personally the main reason is that the wheels do not rub on the wheel wells when turning in as they would if I achieved the same wheel fitment through the use of a larger spacer. In fact, I have my camber plates set to the maximum positive setting, to move the pivot point as far away from the wheel well as possible.

Then again, my setup is to have a somewhat driveable over-lowered car. I am sure someone else can chime in on what is best strictly for drifting.

[LuckyX2]

Originally Posted by Matej

Extending the FLCA would generally be the best.
For me personally the main reason is that the wheels do not rub on the wheel wells when turning in as they would if I achieved the same wheel fitment through the use of a larger spacer. In fact, I have my camber plates set to the maximum positive setting, to move the pivot point as far away from the wheel well as possible.

Then again, most of my setup is to have a usable over-lowered car, I am sure someone else can chime on what is best strictly for drifting.

Thanks for the input. And actually, I don't drift. So I would be looking for the best method of getting camber for an autocross/road course car.

[Bink Industries]

Originally Posted by LuckyX2

So what's the better way of getting camber up front? All the camber you can get where the knuckle meets the strut and then a little more from the camber plate? Or minimum camber where the knuckle meets the strut and then a lot more from the camber plate?

Bonus points if you can say why.

max out your camber plate outward and run camber in the included angle on the lower coilover perch. if you have adjustable lower arms just make them as long as possible.

this may seem scary to a lot of people but the minimum amount of thread needed in your part is the OD of the rod end. if you have a 3/4 rod end you need a minimum of 3/4 thread in the bung on the part. then red loctite on the lock nut, again name brand if you can. if you bought a china/ebay arm go buy some real rod ends before you do this please. circuit sports seems to have a better grip on the quality of there product, they are ok.

anyways this gets your SAI at a much more reasonable setting which reduces jacking as you turn the wheel. and now you don't have to run 2" of spacers to get your scrub right It will give you a wider front track which gives you better turn in on initiation and overall grip do to less lateral load transfer. And as stated above it simply gives you more room for angle.

you may still have to cut your fenders depending on your set up and angle. I don't have that problem as all the cars I build the first thing I do is cut the whole front of the car off and tube everything. makes it easier to work on after and gives me clearance for a number of things. street cars this is not an option really, you could have fun with a hammer or tub it.

hope this helps

[MrChow]

Originally Posted by InsTanCeZ

Sneak peek: KPI / SAI / Camber 3 position lockout front lower mount set

Waiting..... Any more info anyone on this?

[TheRealSy90]

Seems pointless imo, the bolt would hold it on a slotted setup just fine.

[n2o_matt]

Originally Posted by N8 of S-Empire

that distance is called the "included angle"...

max out your camber plate outward and run camber in the included angle on the lower coilover perch. if you have adjustable lower arms just make them as long as possible.

Maybe I'm reading it wrong, but it sounds like you're calling the angle between the knuckle and strut the included angle - its not. The included angle is simply the SAI inclination + camber. However, leaving the top hat where it is changes the camber and included angle but not the SAI, so I guess the concept is the same, just found it a bit confusing the way you said it.

Originally Posted by N8 of S-Empire

anyways this gets your SAI at a much more reasonable setting which reduces jacking as you turn the wheel. and now you don't have to run 2" of spacers to get your scrub right

What is a reasonable setting? Not trying to be smart, I'm new to the S-chasis and don't know where it should be. Which brings me to:

Originally Posted by N8 of S-Empire

In competition drifting we need our transitions to be as snappy as possible. some drivers like to throw the car around requiring less caster. some like the car to drive its self requiring more caster... if you add SAI into the mix then you get into a whole new world of combos.

Can you elaborate on this a bit? SAI typically adds positive camber to the outside wheel (or trailing wheel while drifting), so i'm thinking you can use this to keep your trailing wheel camber in check, or maybe even add some negative camber to the leading wheel? But then this would mean higher SAI, which you were recommending to reduce. Does the jacking effect from SAI (due to the resulting scrub) cause more/less self steering?

Originally Posted by N8 of S-Empire

zero ackerman causes interesting problems with transition speed and steering feel but that can be fixed somewhat with scrub but the real fix is what wisefab did with adding caster trail. zero Ackerman is desirable for high speed courses. slow speed stuff or really tight stuff likes ackerman. So again there is no perfect all the time setting. for the most part a reduction in ackerman is good for most people.

This might be asking too much, but can you explain why ackerman has that effect and how scrub can be used to fix it? Also, what is caster trail?

Thanks! sorry for all the questions, pretty awesome to have a drift team's crew chief on here helping people out!

[n2o_matt]

Originally Posted by TheRealSy90

Seems pointless imo, the bolt would hold it on a slotted setup just fine.

good way to make sure they're at the same angle on both sides maybe?

[az_240]

Originally Posted by TheRealSy90

Seems pointless imo, the bolt would hold it on a slotted setup just fine.

It will hold fine but have you ever tried torquing these bolts down with the upper hole slotted? It's damn near impossible to keep the spindle from moving unless you put a jack on the hub and jack it up a little to keep it at full neg.

[Bink Industries]

Originally Posted by n2o_matt

Maybe I'm reading it wrong, but it sounds like you're calling the angle between the knuckle and strut the included angle - its not. The included angle is simply the SAI inclination + camber. However, leaving the top hat where it is changes the camber and included angle but not the SAI, so I guess the concept is the same, just found it a bit confusing the way you said it.

i apologize for the confusion i was not talking about THAT included angle. im talking about (word it different) "angle that is included" in the lower coilover perch. some coilovers like Meagan racing the holes for the mount are of equal distance from CL of the shock. where as a dg5 has a shorter distance on top than on bottom creating an angle that is included in the coilover giving you more camber. for instance we used dg5 coilovers a car set up 4.5 degrees of camber. same ride height on PSM and we only had 1.5 degrees. so you can see that lower coilover perch is actually a big deal in setting up your car properly

What is a reasonable setting? Not trying to be smart, I'm new to the S-chasis and don't know where it should be. Which brings me to:

if I told everyone exactly what im doing i would be out of my job. that being said i can point in general directions typical rule of thumb is to have at least if not more SAI than caster. going with way to much is bad to.


Can you elaborate on this a bit? SAI typically adds positive camber to the outside wheel (or trailing wheel while drifting), so i'm thinking you can use this to keep your trailing wheel camber in check, or maybe even add some negative camber to the leading wheel? But then this would mean higher SAI, which you were recommending to reduce. Does the jacking effect from SAI (due to the resulting scrub) cause more/less self steering?

Your trailing wheel has a small effect on front grip. its your leading wheel that's pointing you around the track So trying to set up your geo for more contact patch on the trailing tire would be counter productive. you want to dial in your lead wheel.

SAI is a source of self steer. but having too much of it causes geometry problems and makes it hard to get all of your other things like RC and scrub in check. and SAI does not cause scrub it causes jacking just like caster. it rasies the car so naturally the car wants to go to its lowest point and that's what returns the steering.


This might be asking too much, but can you explain why ackerman has that effect and how scrub can be used to fix it? Also, what is caster trail?

ackerman helps with selfsteer because your trailing wheel is scrubing trying to pull the wheel back to center. the more scrub radius you have the bigger the lever arm to pull it back. don't get hung up and think you need tons of scrub because you aren't getting self steer. you probably have a problem somewhere else in your geo set up.

Having to much ackerman in a car will react like you just put on on the front brakes. the wheels toe out as you add steering angle. a small amount is good for self steer but not too much so you don't slow the car down to much. I make a knuckle i make that gets 55 degrees of ACTUAL angle 5 degrees of ackerman at full lock and no over centering using NO offset spacer. it works great i have had pro and proam drivers rave about them.


this is caster trail/ mechanical trail. what wise fab has done is added steering axis offset which increses your caster trail. so a car with 9 degrees of caster stock knuckle has lets say 5 inchs of caster trail. if you offset the hub more you can now run 3 degrees of caster and have the same 5 inches of caster trail. make sense? that's how they get selfsteer with almost no SAI and caster. this reduces jacking and keeps the contact patch more flat through angle. unfortunately the self steer is now speed sensitive with this set up so the hair pin at longbeach requires hand over hand to steer the car but at higher speeds it steers its self on transistions.





Thanks! sorry for all the questions, pretty awesome to have a drift team's crew chief on here helping people out!

No problem don't worry about it. Im here to help. call me out if you guys need any questions answered. I will do my best to point you guys in the right direction

[n2o_matt]

Thanks! Wish this forum had rep/karma/etc to give.


Your trailing wheel has a small effect on front grip. its your leading wheel that's pointing you around the track So trying to set up your geo for more contact patch on the trailing tire would be counter productive. you want to dial in your lead wheel.
SAI is a source of self steer. but having too much of it causes geometry problems and makes it hard to get all of your other things like RC and scrub in check. and SAI does not cause scrub it causes jacking just like caster. it rasies the car so naturally the car wants to go to its lowest point and that's what returns the steering.
Interesting suggestion to have a bit more SAI than castor. For track I've seen many people say you need at least half as much castor as SAI to fight the positive camber gain of the (normally) outside wheel. This is why I was thinking it might be beneficial even for the leading tire, since I'm assuming it would add dynamic negative camber, or at lest lessen the positive camber gain from castor on the leading wheel.

SAI, doesn't cause scrub but it does effect it doesn't it? Scrub is like the trail of SAI in a front view right?


Thanks for the help on ackerman, just realized it was answered on the previous page. This thread is quite something to get your head around, wish it had its own section rather than a single, endless thread.

this is caster trail/ mechanical trail. what wise fab has done is added steering axis offset which increses your caster trail. so a car with 9 degrees of caster stock knuckle has lets say 5 inchs of caster trail. if you offset the hub more you can now run 3 degrees of caster and have the same 5 inches of caster trail. make sense? that's how they get selfsteer with almost no SAI and caster. this reduces jacking and keeps the contact patch more flat through angle. unfortunately the self steer is now speed sensitive with this set up so the hair pin at longbeach requires hand over hand to steer the car but at higher speeds it steers its self on transistions.
Ah, that's what i've always heard it as, "mechanical trail." Makes sense, been a while since i've looked this deep into suspension geometry.

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...



Also, do you have any insite on the accuracy of laser alignment racks once SAI and such has changed? My recent firestone alignment showed my SAI at 14.0 and castor of 6.5 yet my wheel is very far forward in the wheel well. I'm running keisler knuckles (zero ackerman) and PBM rack spacers. My steerign is smooth but after about 30deg of angle it gets very difficult to steer, but it doesn't completely stop. Almost feels like its binding, but it steers smoothly when off the ground. If I'm going slow and turn the wheel hard it wants to keep on turning and not self steer, but it does seem to get better with speed. I haven't really tried it while drifting though...

Thanks agian!

[PoorMans180SX]

Originally Posted by n2o_matt

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...

Nope that's how the factory knuckle is setup.

[Bink Industries]

[QUOTE=n2o_matt;5640384]Thanks! Wish this forum had rep/karma/etc to give.


Your trailing wheel has a small effect on front grip. its your leading wheel that's pointing you around the track So trying to set up your geo for more contact patch on the trailing tire would be counter productive. you want to dial in your lead wheel.
SAI is a source of self steer. but having too much of it causes geometry problems and makes it hard to get all of your other things like RC and scrub in check. and SAI does not cause scrub it causes jacking just like caster. it rasies the car so naturally the car wants to go to its lowest point and that's what returns the steering.
Interesting suggestion to have a bit more SAI than castor. For track I've seen many people say you need at least half as much castor as SAI to fight the positive camber gain of the (normally) outside wheel. This is why I was thinking it might be beneficial even for the leading tire, since I'm assuming it would add dynamic negative camber, or at lest lessen the positive camber gain from castor on the leading wheel.

drifting is a new motorsport being only 11 years old professionally in the states. I am finding that this sport is vastly different than road racing. road racing for the most part you can buy a book (carrol smith series etc) follow whats in print and have a pretty successful race car IMO. You cant apply these things to drifting as the cars are doing something else and there for asking for something else. driver feedback is so important because we are still finding and learning what set up is required for drifting. what you set up for drifting WILL be different than a road racing car period. example being what your saying about SAI vs caster settings. driver feedback has told me otherwise for drifting.



SAI, doesn't cause scrub but it does effect it doesn't it? Scrub is like the trail of SAI in a front view right?

it can effect it, yes, based on the fact that you can have different contact patches at or near lock on your trailing tire that is scrubbing (on cars with ackerman) giving the scrubing more or less effect.


this is scrub. if your talking about scrub from Ackerman that is simply the difference in angle from your leading and trailing tire. more angle difference more scrub, simple. I could get into pneumatic trail and stuff and it effects but I will just tell you to go buy a book haha


Thanks for the help on ackerman, just realized it was answered on the previous page. This thread is quite something to get your head around, wish it had its own section rather than a single, endless thread.

this is caster trail/ mechanical trail. what wise fab has done is added steering axis offset which increses your caster trail. so a car with 9 degrees of caster stock knuckle has lets say 5 inchs of caster trail. if you offset the hub more you can now run 3 degrees of caster and have the same 5 inches of caster trail. make sense? that's how they get selfsteer with almost no SAI and caster. this reduces jacking and keeps the contact patch more flat through angle. unfortunately the self steer is now speed sensitive with this set up so the hair pin at longbeach requires hand over hand to steer the car but at higher speeds it steers its self on transistions.
Ah, that's what i've always heard it as, "mechanical trail." Makes sense, been a while since i've looked this deep into suspension geometry.

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)

Also, do you have any insite on the accuracy of laser alignment racks once SAI and such has changed? My recent firestone alignment showed my SAI at 14.0 and castor of 6.5 yet my wheel is very far forward in the wheel well. I'm running keisler knuckles (zero ackerman) and PBM rack spacers. My steerign is smooth but after about 30deg of angle it gets very difficult to steer, but it doesn't completely stop. Almost feels like its binding, but it steers smoothly when off the ground. If I'm going slow and turn the wheel hard it wants to keep on turning and not self steer, but it does seem to get better with speed. I haven't really tried it while drifting though...

I can not comment on laser alignment after SAI change as I don't use one. I have been using tape measures and bubble type camber gauges for 6 years. they have there quirks and there is better but that's just what ive been using. works great ive set up winning time attack cars using this method down to my street car. works great. if you have moddiffed knuckle you will lose mechanical advantage of your pivot so yes it will be hard to turn car off. if its doing that with the car on I have no comment as I don't know.

hope this helps
N8

[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?

Originally Posted by az_240

It will hold fine but have you ever tried torquing these bolts down with the upper hole slotted? It's damn near impossible to keep the spindle from moving unless you put a jack on the hub and jack it up a little to keep it at full neg.

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