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

[Motary]

Those can only change camber, KPI is determined by the strut top joint and lower control arm balljoint, also there is no camber gain with macpherson strut suspension, only camber change/loss

KPI will change if you adjust your adjustable strut top mount to adjust camber, since you are moving the the joint.

[My$800S14]

What about scrub? It seems that having those brackets extended would effect it since the knuckle rotates on that, it also seems like it would help the trailing wheel get a little more clearance in regards to the tension rod, but may cause more issues with the leading wheel rubbing the inner fender well,
Also you gain positive camber at full lock and all through out the steering travel on the leading wheel, that is what i was referring too I could be thinking about this all wrong, I'm seriously considering this especially if all it would effect is my camber
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[SomeoneWhoIsntMe]

the SAI remains an imaginary line drawn between the pivot points of the pillowball in the camber plate and the lower balljoint, regardless of the shape of your coilover's bottom bracket. the spring being put a greater angle to the SAI will either make the effective spring rate lower or greater I forget which I think lower, and the increased side load will put more wear on the dampers but meh

[Croustibat]

Originally Posted by My$800S14

i was wondering what negative effects there are with those megan 25mm extended brackets?

seen here: Megan Front Extended Brackets - S14 240SX 95-98 - Enjuku Racing Parts, LLC

would these increase scrub radius? or simply place the coilover at an awkward angle. and posisbly cause bigger issues with caster, kpi, and or camber gain through the steering range?

i ask this because i am thinking about putting my s13 megan tracks on an s14 that i may be getting, and i also have 25mm extended lca's it would be really cool if this would simply just help bring down the negative camber some with the extended lca's, if this will work, i would rather buy these extended s14 brackets, than drill the wholes for the s13 out, and just in case someone feels the need to through there opinion in, i know megans are garbage, we dont need to go over this, and i have pbm's for le track car, these guys are for use on what i intend to be a daily drifter, and i pucked them up almost new for $500

Thanks for the link, these are exactly what i need ...

they are used with "weak offset" wheels, to prevent the tyre from rubbing on the spring. It does not affect anything but your camber adjustment range, because it offsets your coilover body toward the inner side of the car. I.E as you extend your lower arms, you end up with a camber adjustment range going more toward negative.

Also they are the perfect thing to use on an S13 with swapped S14 knucles, as the bolts on the S14 upright are 14mm instead of the 12mm for the S13. And it allows you to run camber bolts, which are better than changing camber on the hat (as this changes SAI at the same time).

I am going to get them, i wanted to mod mine to get the same result (i need wheel spacers right now to make it fit and i hate that) but for that kind of money i think i wont bother.

[PoorMans180SX]

Originally Posted by Croustibat

they are used with "weak offset" wheels, to prevent the tyre from rubbing on the spring. It does not affect anything but your camber adjustment range

And it allows you to run camber bolts, which are better than changing camber on the hat (as this changes SAI at the same time).

Actually, adjusting camber at the knuckle does affect your scrub radius. I am a firm believer that camber bolts should never be run on a car, they are weak and a piss-poor solution that is much better solved with the top hat. Where did you get this notion that adjusting camber at the top hat is "bad"? You change steering axis (or the wheels relation to the axis) either way, and the added negative camber of adjusting at the top mount far outweighs any "negative" side effects of a few degrees of steering axis change.

[Croustibat]

As said above, changing camber with the top hats changes SAI, as you are changing the top ball joint position of the strut assembly. And you dont want to change your SAI, you want to change your camber.

Changing camber with camber bolts does not change SAI though.

[PoorMans180SX]

Originally Posted by Croustibat

As said above, changing camber with the top hats changes SAI, as you are changing the top ball joint position of the strut assembly. And you dont want to change your SAI, you want to change your camber.

Changing camber with camber bolts does not change SAI though.

Moving your SAI in that direction positively effects roll center, and doesn't really change your scrub radius much. Lengthening the control arms changes your SAI the same way. There is nothing wrong with either.

Messing with the knuckle effects the wheel's relationship to the steering axis, which is a whole different ball of wax. Will it work? Yes. Should you test both ways? In my opinion, yes. There are a lot of different ways to optimize the McPherson front suspension depending on your goals, and there isn't really a "right" or "wrong" way to adjust camber, as long as you don't take things to extremes.

[Motary]

The roll center improves very little with changing the SAI by a degree or two
If it were to improve in a linear manner it, which it doesnt then it would be an improvement of 6 mm per degree by this table I made a while ago


*RC height in mm!
Also keep in mind roll center height is not static and it is lowered when there is body roll

You see I added 12 degrees of SAI to get a better RC height, but having 15 degrees of SAI is silly and will cause huge tyre jacking with steering which you do not want in a drift car.
Camber bolts are not a poor solution if they are properly locked

[Motary]

My new setup:

[godrifttoday]

Omg.... Sell me one?

[Motary]

Only one?

I still have to make the top strut relocation bracket, there's so many ways to do it.. and sorry this will be a one-off setup. Save money and buy Wisefab kit, its very similar, but has more lock, I limited mine to 60 so the arms could be as short as possible

[240sxr]

ok,what specs are everyones alignment settings and why,i know is personal preference but i want to se what aligmnent does people use and why? i know 0 camber on the rear gives more traction while drifting,negative casmber on front gives more traction on full lock,but i want to know about caster,toe,etc thanks

[Guilty1s]

Originally Posted by 240sxr

ok,what specs are everyones alignment settings and why,i know is personal preference but i want to se what aligmnent does people use and why? i know 0 camber on the rear gives more traction while drifting,negative casmber on front gives more traction on full lock,but i want to know about caster,toe,etc thanks

My goal

Front
Camber - Around 5-6* of functional static camber. From extended LCA and to dial it in ill have adjustable +/-3 degrees with GKTechs knuckles. It definitely isn't necessary to run this much. Before angle mods, I ran 1.5* static and then maxed out my camber plates when I got to the track.
Caster - as much as I can run without rubbing anything. Will use my top camber plates for on the fly caster adjustment since I am adjust camber at the knuckle. Otherwise, they will be maxed out through the caster rods. More caster increase camber gain as steering increases, as long as your geometry is right. The complete opposite can occur if it isn't.
Toe - Some toe out helps with turn in. It also helps traction and kills tires. Too much is definitely bad. Ill have probably just 0.5 for giggles. With my setup I should have an amazing contact patch at full lock and all throughout my steering, I'm not going to worried too much about front grip. You gain toe as you input steering. This is the ackerman effect.

Rear
Camber - ZERO!!! To save the tires.
Toe- Just a tad bit of toe in. .05* in. Save the tires. Add a little bit of control in there. To much and that car will want to straighten up a lot if you don't keep your foot into it. Just a little will help with rear end control with the throttle pedal.

Take all this with a grain of salt. I haven't ran this setup before but it is more/less a collaboration of hours of research for planning my setup and experience I have had with other cars.

The amount of toe is the most about personal preference, natural car tendencies. Regardless, a bit on a drift car isn't a good thing.
I came from autocross and only on my first year of serious drifting. I put a little too much thinking into it but I definitely now how it is to have a minor alignment change make a world of difference. The ghetto alignment I did on the S14 made the difference of the car drifting and not drifting. Couldn't even keep a nut sideways with the toe I was running in the rear.

[Johnny_K]

Originally Posted by 240sxr

ok,what specs are everyones alignment settings and why,i know is personal preference but i want to se what aligmnent does people use and why? i know 0 camber on the rear gives more traction while drifting,negative casmber on front gives more traction on full lock,but i want to know about caster,toe,etc thanks

http://zilvia.net/f/motorsports-skil...ml#post4332542

[derass]

whats it going to take to clear the frame rail once i go with MA knuckles? running 17x9 +20 with 235/40R17 and it was touching with only rack spacers. i do not want to sacrifice grip or safety (stretch) by going to 215/40r17. so extended lca, 15-20mm spacers, or combination of both? lip has already been hammer flat obv.

also can i prevent over centering by limiting angle, eyeballed with bump stops on lca? i will not be relocating rack, so offset rack spacers are my other option.

[Motary]

Longer control arms and if you don't want to move the steering rack closer then your only option are the offset rack spacers.

[Guilty1s]

Bump stops would be effective

Another option is offset rack spacers or offset tie rod spacers.

[PoorMans180SX]

I thought this picture was pretty cool.

[My$800S14]

Originally Posted by PoorMans180SX

Aasbo's TC uses S-chassis knuckles, and his angle kit is done like that.

i dont understand, how is this FD legal, nothing is in stock location for that vehicle? also the rear wheel drive factor, this always puzzled me BIG TIME


otherwise, on to a more important question which im pretty sure was covered so im really sorry if im beeing redundant, i saw something on page 102 or something that breifley covered this subject a little but didnt talk about the negative effects, what are the negative effects of flattening out the ball joint pick up point? i believe it sits at about 62* in relation to the face of the knuckle what would be the negative effect of making it sit at an even 90* and while we are at it why not talk about the possible benefits, i understand that it may possibly reduce ackerman, but would it cause some awkward lack of leverage for the tie rod, possibly making the rack work harder? and what if you were to flatten that out and then also bring the tie rod pick up point in line with it, to a zero ackerman state? sorry dudes, but this is something that has been floating around in my head for a good while now, and i keep forgetting to bring it up, me and my partner are working on a new knuckle design, and this was one of the big questions that i kept forgetting to bring up for discussion as of right now our design is at the factory angle in relation to the face of the knuckleand so is the angle of the tie rod pick up point in relation to the face of the knuckle. Really eager to understand how these angles play a role on the rest of the steering/suspension also wouldnt flattening the ball joint pick up point alter kpi in a potentially very negative way? sometimes is really easy to grasp one or two parts of the puzzle, but getting the whole big picture thats a big difference haha

thanks in advance

[PoorMans180SX]

Originally Posted by My$800S14

i dont understand, how is this FD legal, nothing is in stock location for that vehicle? also the rear wheel drive factor, this always puzzled me BIG TIME


otherwise, on to a more important question which im pretty sure was covered so im really sorry if im beeing redundant, i saw something on page 102 or something that breifley covered this subject a little but didnt talk about the negative effects, what are the negative effects of flattening out the ball joint pick up point? i believe it sits at about 62* in relation to the face of the knuckle what would be the negative effect of making it sit at an even 90* and while we are at it why not talk about the possible benefits, i understand that it may possibly reduce ackerman, but would it cause some awkward lack of leverage for the tie rod, possibly making the rack work harder? and what if you were to flatten that out and then also bring the tie rod pick up point in line with it, to a zero ackerman state? sorry dudes, but this is something that has been floating around in my head for a good while now, and i keep forgetting to bring it up, me and my partner are working on a new knuckle design, and this was one of the big questions that i kept forgetting to bring up for discussion as of right now our design is at the factory angle in relation to the face of the knuckleand so is the angle of the tie rod pick up point in relation to the face of the knuckle. Really eager to understand how these angles play a role on the rest of the steering/suspension also wouldnt flattening the ball joint pick up point alter kpi in a potentially very negative way? sometimes is really easy to grasp one or two parts of the puzzle, but getting the whole big picture thats a big difference haha

thanks in advance

Scion pretty much paid for the 2011 Formula D series, so they were allowed to bend the rules.

Did you look at the picture in the post above you? That is for the s-chassis. There is nothing wrong with making the ball joint 90*, Both TDP and wisefab do it, but it just means you need to redesign the lower control arm and change the angle the coilover attaches to the knuckle. You can still mess around with ackerman, KPI and all that just as you would with the stock knuckle. You have to remember that all of these are determined by lines drawn through two pivot points, so as long as there is no binding, you should be just fine. You'll just have to measure everything to make sure it's where you want it.

[thefro526]

Originally Posted by derass

whats it going to take to clear the frame rail once i go with MA knuckles? running 17x9 +20 with 235/40R17 and it was touching with only rack spacers. i do not want to sacrifice grip or safety (stretch) by going to 215/40r17. so extended lca, 15-20mm spacers, or combination of both? lip has already been hammer flat obv.

also can i prevent over centering by limiting angle, eyeballed with bump stops on lca? i will not be relocating rack, so offset rack spacers are my other option.

It sounds almost like you're unwilling to make some of the compromises required when one is in search of 'big' angle on an S-Chassis. In any case, improving your inner frame rail clearance is pretty straightforward.

Depending on your wheel to firewall clearance (move the wheels through the steering arc at various levels of suspension compression and measure the closest point between the wheel and firewall) you may be able to use a spacer to gain a small amount of clearance between the inner rail and your wheel, although since the spacer is moving the wheel away from the rail at an angle (and towards the fire wall) you won't get much clearance out of this method.

The best solution, as Motary suggested above is to lengthen the lower control arm by some amount (probably 20-25mm) to move the steering axis out which will effectively move the radius defined by the outer most point of the wheel away from anything that it could come in contact with in the insides of the wheel well. This might also neccesitate a longer tie rod and more than your desired amount of camber, so you'll need to look at your entire setup and see what this could interfere with.

As far as steering over centering, you could get offset rack spacers if you wanted, or offset steering rack bushings, or use both. it's kind of up to you. If you don't want to do some sort of insane cross-member mods then a combination of offset rack spacers and bushings is the way to go.

You should also look at your wheel tire combination in itself. Depending on what tire you're running, you may be able to get a 'better' tire that's actually narrower...

Originally Posted by My$800S14

i dont understand, how is this FD legal, nothing is in stock location for that vehicle? also the rear wheel drive factor, this always puzzled me BIG TIME

The way the FD rules are written, or at least last time I read them, anything outside of the chassis/unibody pickup points may be modified. In this case, struts, suspension arms, knuckles are essentially an 'unlimited' class as long as they connect to the stock mounting location.

As far as the RWD TC business, there was/is some clause in the FD rules that allow for an 'AWD Chassis' to be converted to RWD for competition use. In the case of the TC, Scion argued that it shared the same chassis as the Toyota Avensis, which came in AWD, thus allowing for an 'AWD TC' to be converted to RWD.

[Motary]

Well since this is steering angle posing thread





60 degrees of steering angle, I have two settings for ackerman, near 100% and negative ackermann. When I finally get my car running properly, I'll let you guys know it performs.

Wheel is 17x8,5j +20 with 225/45/17, I will probably be downsizing them to 7,5j and +38mm and 205/40 tyre

[INeedNewTires]

Originally Posted by Motary

The roll center improves very little with changing the SAI by a degree or two
If it were to improve in a linear manner it, which it doesnt then it would be an improvement of 6 mm per degree by this table I made a while ago


*RC height in mm!
Also keep in mind roll center height is not static and it is lowered when there is body roll

You see I added 12 degrees of SAI to get a better RC height, but having 15 degrees of SAI is silly and will cause huge tyre jacking with steering which you do not want in a drift car.
Camber bolts are not a poor solution if they are properly locked

dude that is a great chart and useful tool to save us time! you didnt happen to do anything like this for the rear did you?

[Motary]

I could make it based on stuff thats on the market like subframe raising solid bushes and new uprights, but for my car's ride height the rear roll center was fine at 87mm

[INeedNewTires]

i ask because after i calculate my rear corrected RC (i have driftworks rear hubs) i'm going to be plotting camber/caster/tow change on compression and droop to find out the best overall alignment. thinking about making my rear anti-squat adjustable as well. If you already had a baseline it would save (me) time

[My$800S14]

Soo I'm not seeing the disadvantages of increased scrub radius(except for braking sensitivity) nor do I se the disadvantages of an sai angle sitting more inward toward the chassis

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[GripTerror]

Originally Posted by PoorMans180SX

I thought this picture was pretty cool.

GKTech? .

[PoorMans180SX]

Originally Posted by GripTerror

GKTech? .

Track Day Performance. www.tdp.ie

[Motary]

Originally Posted by My$800S14

Soo I'm not seeing the disadvantages of increased scrub radius(except for braking sensitivity) nor do I se the disadvantages of an sai angle sitting more inward toward the chassis

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Disadvantage of big KPI/SAI is jacking:

Stock position and 20mm longer lower control arm:





Disadvantages of large scrub radius:

Lots of steering effort
Torque steer in front wheel drive configurations
Steering sensitivity to road imperfections under braking

[My$800S14]

Depends on the size of the scrub radius, once it gets to an extreme some steering situations offer easier steering effort, and I forgot about the jacking, but do you really think that adverse effect outweighs the disadvantages of excessive caster? Because my hopes were to use some inward sai to compensate for the lower caster that I was intending to run.

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