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

[mikerbike]

I found out some interesting stuff this week.

Since I modified my knuckles, I stopped using MAX rack spacers, since my outer tie rod hit the control arm before the rack bottomed out. But, in the quest for a flatter contact patch, I was reducing caster via tension rod adjustment.

As the wheel moved back in the well, it gained angle as a trailing wheel. I liked that a lot, less ackerman without losing leading wheel angle. My 17x9 +9 was hitting the tension rod/sway bar hard.

But, as the leading wheel, the rack started bottoming out before the tie rod hit the control arm. I installed the MAX rack spacers again, and goofed around with it for a few hours to find a happy medium.


That's with the front of the wheel about 1/4" away from the sway bar.

[blingbling]

^ lovin it

[Pandapants]

Originally Posted by Razi

Yeah, I guess I'll have to buy SPL.
I don't mind coughing up an extra 100, but don't I also need to buy Z33 inner rods to make em work with the stock knuckles?
Is that because the threads on the S14 inner rods don't go deep enough? Or can I trim a bit off the S14 inner rods and make them work with the SPL?

The threads don't go far enough down the s14 rods for the spl ends to zero out the toe on stock knuckles. You can use z32 rods too, not just z33. and if you really want to save money, you can buy the rods from your local auto parts store.

[GSXRJJordan]

Mikerbike, your angle looks great... still have a little Ackerman, but definitely increased the angle of the trailing wheel (the only one that matters in drifting).

What's your camber/caster like? I'd imagine you're not running much caster at all, so you've got to dial in massive camber to get decent grip on the trailing wheel.

[Razi]

Originally Posted by Pandapants

The threads don't go far enough down the s14 rods for the spl ends to zero out the toe on stock knuckles. You can use z32 rods too, not just z33. and if you really want to save money, you can buy the rods from your local auto parts store.

Cool.
Thanks for the info!

[mikerbike]

Originally Posted by GSXRJJordan

Mikerbike, your angle looks great... still have a little Ackerman, but definitely increased the angle of the trailing wheel (the only one that matters in drifting).

What's your camber/caster like? I'd imagine you're not running much caster at all, so you've got to dial in massive camber to get decent grip on the trailing wheel.

Um.. My caster.. About that.. I turned turned the wheel full lock right, and adjusted the caster til the front inner edge of the wheel was about a quarter inch away from the sway bar/tension rod, then repeated with full lock left. Judge me. It's okay.

A few weeks ago, I posted in this thread that I was going to turn my camber plates so that max camber would reduce caster. I still might do that because my wheel is still far from flat at lock.

Camber.. I have a bunch of marks on the camber plates, as I assume most do. I used to run max negative but Now I have the dot on the pillow ball on the 3rd mark away from max negative camber. I feel like both my cars push more at max negative camber.

I'd like to pull more caster to get more angle out of the trailing wheel. I will either need to get a skinnier front wheel or space out the one I have. I'm in no hurry.

[PoorMans180SX]

Originally Posted by GSXRJJordan

Mikerbike, your angle looks great... still have a little Ackerman, but definitely increased the angle of the trailing wheel (the only one that matters in drifting).

What's your camber/caster like? I'd imagine you're not running much caster at all, so you've got to dial in massive camber to get decent grip on the trailing wheel.

Maybe I'm not understanding you right, but the leading or "outside" wheel provides the primary grip and steering in drift. Yes, having the trailing wheel at more of the same angle as the leading wheel will help (by not scrubbing speed), but it is not nearly as important as the leading wheel. If you look at older pictures of Forrest's S13.4, it completely lifts the trailing wheel at deep angles. Not that that is the best setup, but it makes my point.

Mikerbike; adjusting caster with the camber plates should give some good results. It doesn't change the effective length of the tie rods like using the tension rod does. Also, you can get your same results with tie rod offset spacers and not have to move the wheel around in the well so much.

[GSXRJJordan]

We're saying the same thing, just calling leading and trailing backwards lol. Turn the wheel left, drift left, the left wheel is 'leading' and can basically disappear.

[PoorMans180SX]

Originally Posted by GSXRJJordan

We're saying the same thing, just calling leading and trailing backwards lol. Turn the wheel left, drift left, the left wheel is 'leading' and can basically disappear.

Haha, good deal.

[Patrick Bowering]

The Ultimate Handling Guide Part 8: Understanding Your Caster, King Pin Inclination and Scrub

[mikerbike]

Kay, so.. Queso, I did the same to my other car today. But, I couldn't push the wheel as far back in the well because I run a taller tire and it hit the rear pinch weld too soon. And I don't have rack spacers to install on this car. And I tried road racing and enjoyed it, so this car doesn't need any more angle mods. But I took a picture anyway.


Also, I did sumpin bad. I made adjustments based of points of the unibody. So one side probably has about 2* more caster than the other. Oh well. I flipped the camber plate (as can be seen in the above photo) and adjusted the tension rod until there was about 1/4" clearance from the corner of the tread to the pinch weld as the wheel swings past. Sooooo scientific.


I think I ended up with a little more static camber than when the camber plates were normal and set to the middle. I'm not worried about what I did to the black car. I already tested that (on a closed course, BRO), but I kinda wonder if I should have left more caster for grip driving on the white car. But, I did all this stuff with the tools I carry in my car, so I can change it at the track between sessions.

[nieko]

Brooo, you're supposed to cut a small slit at the bottom of that pinch weld and the top.

Then hammer that bitch as flat as you can! hahaha done!

[Csomme]

Why did you flip your camber plates to give you less caster? That shit feels horrible.

[ManoNegra]

Originally Posted by Csomme

Why did you flip your camber plates to give you less caster? That shit feels horrible.

to maintain tire contact area while doriftoring...?

[roboticnissan]

Someone is socal should hold like a seminar about alignments. That would be dope. It's.really hard for me to full understand what you guys are doing to.your cars. I guess it would just be nice to see it first hand and in person.

[GSXRJJordan]

Originally Posted by roboticnissan

Someone is socal should hold like a seminar about alignments. That would be dope. It's.really hard for me to full understand what you guys are doing to.your cars. I guess it would just be nice to see it first hand and in person.

Here you go, from the Suspension Whisperer himself.

The Ultimate Guide to Suspension & Handling

[mikerbike]

Originally Posted by ManoNegra

to maintain tire contact area while doriftoring...?

Yes. And just to try something. I'm not sure I like it yet, but I've only driven to work and back today.

[Def]

Zilvia, where the answer to everything is a MotoIQ link...

[GSXRJJordan]

Originally Posted by Def

Zilvia, where the answer to everything is a MotoIQ link...

I'm not one to blindly link a thread rather than writing something out. It's a little simplified at parts, but all the good engineering tech is there.

Mike Kojima is the single best source of knowledge for S-chassis suspension tech. Time Attack, road racing, and Formula D cred, plus he's got this idea that he should share his knowledge with everyone.

Pretty cool if you ask me.

[Def]

Originally Posted by GSXRJJordan

I'm not one to blindly link a thread rather than writing something out. It's a little simplified at parts, but all the good engineering tech is there.

Mike Kojima is the single best source of knowledge for S-chassis suspension tech. Time Attack, road racing, and Formula D cred, plus he's got this idea that he should share his knowledge with everyone.

Pretty cool if you ask me.

Not a dig against you personally, but I think there's QUITE A FEW MotoIQ articles linked in this thread. They're a good resource for some basic stuff, but it's pretty amusing just how often (some of the same) articles are linked here.

[codyace]

Originally Posted by GSXRJJordan

I'm not one to blindly link a thread rather than writing something out. It's a little simplified at parts, but all the good engineering tech is there.

Mike Kojima is the single best source of knowledge for S-chassis suspension tech. Time Attack, road racing, and Formula D cred, plus he's got this idea that he should share his knowledge with everyone.

Pretty cool if you ask me.

Kojima is a smart dude/cool dude no doubt; a true import engineer. With that said, I'd trust him with a B/P chassis before S chassis any day of the week. Not that it's 'that' much different, but Mike has been playing with the FWD cars forever (hell almost as long as I've been able to drive/buy super street)...not that he won't understand our cars (or others, he does have a badass Z), but he's by far not the S chassis guru. He's undoubtedly smarter than 97% of this forum, but that's from a generic aspect, not S chassis specific.

[Tearlessj]

Well I raised my car a little. From my understanding, it seems that being so low is one of the main causes steering issues. Car felt great, I was just wondering what would be the next steps to increase my handling performance? or any alignment advise?

Before:
Toe:-.01
Caster: 9.2
Camber: -2.5


After
Toe: 0
Caster: 7.3
Camber: 3.1

[GSXRJJordan]

Why do you care about the inside wheel when you're drifting? All that caster is to get the outside wheel (the one carrying all the weight) to have the correct geometry.

Are any of you guys checking inner/center/outer tire temps after a run? That and overall wear characteristics will tell you a lot about whether you're running too much camber/caster.

[GSXRJJordan]

Originally Posted by codyace

Kojima is a smart dude/cool dude no doubt; a true import engineer. With that said, I'd trust him with a B/P chassis before S chassis any day of the week. Not that it's 'that' much different, but Mike has been playing with the FWD cars forever (hell almost as long as I've been able to drive/buy super street)...not that he won't understand our cars (or others, he does have a badass Z), but he's by far not the S chassis guru. He's undoubtedly smarter than 97% of this forum, but that's from a generic aspect, not S chassis specific.

He's the chassis engineer behind Dai's S13, among others, and EVERYONE else in Formula D running a S-chassis listens to him. KW listens to him. I don't know anyone with more S-chassis racing experience at that level.

[mmdb]

Buy a damn book instead! Ya damn illiterate crowd! Like a jillion pages and no one has any data on how how low you want your roll axis angle, how much static camber you want based on your camber gain during x.x amount of g forces etc? Dayam. Get cracking!

With that said someone buy my knuckles 'n arms.

[mmdb]

Originally Posted by s14unimog

I think there is actually a spacer that supposed to go between the LCA and the snap ring retention feature. Either the case it seems even the stock ones don't actually contact the LCA; I just took mine out for powder coating. I think its just a safety measure. The ball joints in my Cherokee don't have snap rings at all; but I've actually seen someone rip them out on the trail.

That's one good looking glove-on-hand! Wow!

[codyace]

Originally Posted by GSXRJJordan

He's the chassis engineer behind Dai's S13, among others, and EVERYONE else in Formula D running a S-chassis listens to him. KW listens to him. I don't know anyone with more S-chassis racing experience at that level.

I guess to that degree true, being that I'm not into drifting I don't follow much besides some MotoIQ stuff. I guess i'm to much of a FWD MK fanboy to admit otherwise Dog-Cars for life!

[SicBastard]

Originally Posted by mmdb

Buy a damn book instead! Ya damn illiterate crowd! Like a jillion pages and no one has any data on how how low you want your roll axis angle, how much static camber you want based on your camber gain during x.x amount of g forces etc? Dayam. Get cracking!

With that said someone buy my knuckles 'n arms.

It really isn't a matter of how low you want your roll axis, I think it's more a matter of how high you're physically able to get the front roll center before the ball joint hits your inner wheel shell. Finally an excuse to run 19s!

[Def]

Originally Posted by Tearlessj

Well I raised my car a little. From my understanding, it seems that being so low is one of the main causes steering issues. Car felt great, I was just wondering what would be the next steps to increase my handling performance? or any alignment advise?

Before:
Toe:-.01
Caster: 9.2
Camber: -2.5


After
Toe: 0
Caster: 7.3
Camber: 3.1

Run less negative camber up front, and you need to correct your roll center if you're going to run the front of the car that low.

[Tearlessj]

Originally Posted by Def

Run less negative camber up front, and you need to correct your roll center if you're going to run the front of the car that low.

I already raised the car a ton, not sure if I would want to go much higher. Might just to redo the suspension.