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

[!Zar!]

Too many people bitch about bumpsteer.

FACT

If something is helping remove bumpsteer, cool.

But if it doesn't do it perfectly, whatever; imo.

Not to mention most cars are designed with bumpsteer into them.

[codyace]

Originally Posted by !Zar!

Too many people bitch about bumpsteer.

FACT

If something is helping remove bumpsteer, cool.

But if it doesn't do it perfectly, whatever; imo.

Not to mention most cars are designed with bumpsteer into them.

Dare I say this may be a 'drifter' comment, as there is nothing more annoying (to me as a grip based owner) that dealing with crappy bumpsteer on a uneven/poor surfaced track (which 90% of the NorthEast has, or at least bad pavement juntions mid turn). Not saying you are wrong though, but for a normal car, within normal 'angle' it can be frustrating to say the least

Sure I understand it may not go away 100%, but to say corrected roll control arms, and proper alignment, and rie rods pointing to the north star is 'ok' is not good in my book. I hope the SPL outers help fix most of this issue.

[cazman]

Originally Posted by Def

Are you talking about the actual vertical orientation of the tie rod stud?

That doesn't matter one bit as long as you aren't binding the tie rod stud while steering.

Bumpsteer occurs due to different arcs of the FLCA and tie rod(for a strut car like ours) during suspension travel. Once both pivots are in line with each other, they follow the same arc, and you don't have toe changes with suspension travel.

What do you think bumpsteer is, because that doesn't sound like what you're referencing.

i understand bumpsteer.

If you plot the points it makes more sense.
As the tie rod end is on such an angle your ackerman is at a different state from left to right lock, and different at wheels straight ahead.

You have to offset your inner mounts to match the ackerman you have reduced when adding knuckles.
If your steering arms arent the same length as your control arms you will have bumpsteer to begin with.
This kit states it has no rack spacers.

The next issue is the angle of the tie rod. Look at the wheels from lock to lock. This doesnt add bumpsteer no, but the steeriong ratio alters I should say. I don't think it would be a huge isse when these cars arent chasing full grip or accurate ackerman at such angles. What I was trying to say is, measure angle of each tyre like KPR do. But plot it every 10 degrees and youll see it changes at different rate to any other knuckle design.

As stated, these are still the best option I have found for drift cars.

Do all Americans get this angry on forums? Ive only used NNR and never seen such hate.

[PoorMans180SX]

I still have no idea what you're talking about.

Yes, the tie rod end will change vertical as well as horizontal position when swinging through the steering arc, but that is due to the steering axis on our cars. Is that what you're getting at?

This does mess with bumpsteer and whatnot, but like I said, there's only so much you can do. Make the pivot points parallel at the center of the steering, and you'll have eliminated all of the bumpsteer that you can.

Not trying to hate man, just trying to make sure everyone has accurate info here.

[SoSideways]

Originally Posted by cazman

i understand bumpsteer.

If you plot the points it makes more sense.
As the tie rod end is on such an angle your ackerman is at a different state from left to right lock, and different at wheels straight ahead.

You have to offset your inner mounts to match the ackerman you have reduced when adding knuckles.
If your steering arms arent the same length as your control arms you will have bumpsteer to begin with.
This kit states it has no rack spacers.

The next issue is the angle of the tie rod. Look at the wheels from lock to lock. This doesnt add bumpsteer no, but the steeriong ratio alters I should say. I don't think it would be a huge isse when these cars arent chasing full grip or accurate ackerman at such angles. What I was trying to say is, measure angle of each tyre like KPR do. But plot it every 10 degrees and youll see it changes at different rate to any other knuckle design.

As stated, these are still the best option I have found for drift cars.

Do all Americans get this angry on forums? Ive only used NNR and never seen such hate.

So, where are the charts with those plots on them?

Since you've done SO MUCH research, you should have at least a chart with all the data on them for comparison's sake?

Come on mate, out with it then.

[longfellow]

Originally Posted by codyace

I hope the SPL outers help fix most of this issue.

They did on my car. Night and day difference in how the car steers. I cant wait to test it out more in the mountains.

[codyace]

Originally Posted by cazman

Do all Americans get this angry on forums? Ive only used NNR and never seen such hate.

I don't think the issue is 'hate', it's that you came in here with a 'been there, done that' attitude (which congratulations if you have; in the same regard you are not going to win over any new fans by stating it or not), claiming that another company has 'no information' and yet you don't have any yourself.

It's just an issue of accountibility -- If you have knowledge, why not share it? If not, don't act in such a way that you place yourself on some sort of pedestal, as that isn't a way to banter up support for your cause.

Remember, this thread is to help progress the inherent geometry issues our cars share once lowered == not a pissing match of who has done the most work, or research, or both.

[SoSideways]

Originally Posted by codyace

I don't think the issue is 'hate', it's that you came in here with a 'been there, done that' attitude (which congratulations if you have; in the same regard you are not going to win over any new fans by stating it or not), claiming that another company has 'no information' and yet you don't have any yourself.

It's just an issue of accountibility -- If you have knowledge, why not share it? If not, don't act in such a way that you place yourself on some sort of pedestal, as that isn't a way to banter up support for your cause.

Remember, this thread is to help progress the inherent geometry issues our cars share once lowered == not a pissing match of who has done the most work, or research, or both.

You said the same thing I said one page back, but in a super nice way lol

Glad to see you and I noticed the exact same thing haha

[Pandapants]

Since we're talking about bump steer, I have a question:
If we're adding correction to the tie rod ends when we lower the car, does that mean stock ends, on a stock car, with stock ride height has bump steer? And how exactly do you know when you have enough/not enough/too much correction? Are the end joints just supposed to be adjacent with the flca ball joints? If so, wouldn't that mean the PSM SAK have too mush adjustment? SPL, if you purchase their outers for bump steer adjustment for a stock flca, would that mean your bump steer correction is negated if you use the outers with their adjustable flca?

[DC Dan MAX USA]

Without going full on double nerd explanation, if your tie rod angle lines up with the lower control arm angle you wont have any preceivable bumpsteer. If those two angles are horizontal, the cars performance will feel great, and if those arm/rod ends are pointed up and at separate angles your car probably handles like shit. The SAK has bumpsteer without a roll center mod. Use it together with a repositioned LCA joint for best results. It's well worth the extra $150 to do the roll center mod.

[nieko]

^^^ this is truee!

car felt AMAZING last week!

soo much more grip! i also did s14 subframe and lsd though....

but i was having to have the gas wayyy more pinned than before, it was rad.

lot more foward grip


and the knuckles felt great tooo i can do a lot more than i used to be able too haha

and im pretty sure it is impossible to spin... unless you are completely retarted LOL


+1 for PBM thanks guys

[PoorMans180SX]

Def, I was wondering if your FLCA's are going to include a tension rod?

I was about to buy tension rods yesterday, but then I thought about this, and it would obviously be pointless for me to buy aftermarket ones if your FLCA's come with them.

[Def]

Originally Posted by PoorMans180SX

Def, I was wondering if your FLCA's are going to include a tension rod?

I was about to buy tension rods yesterday, but then I thought about this, and it would obviously be pointless for me to buy aftermarket ones if your FLCA's come with them.

I was going to make them work with stock tension rods. No point in reinventing the wheel when it's not necessary.

Is there still interest for those uprights/FLCA/tie rods? The only person that really showed much interest was mmdb, and he's selling his car, so I stopped finishing up the design work on everything.

It's pretty close to being done, just a few little details to add, and some FEA runs. If the interest is still there(I need at least 2 people to even come close to breaking even on machine setup costs), I'll finish them up. I can even tell you what your roll center height will be for a given ride height and its lateral migration with roll.

[!Zar!]

Prospective prices for this flca/knuckle/tierod thing? And will you be shortening the knuckle?

[NiSilS14]

I'm curious on what you might bring to the table. My interest is there but I would like to see kinda product I might purchase in the near future.

[Def]

Originally Posted by !Zar!

Prospective prices for this flca/knuckle/tierod thing? And will you be shortening the knuckle?

Right now the aim is $1500ish for knuckle, FLCA, tierod - all bolt on. Z33 hubs would be the only thing needed.

The uprights are modular, in that you can swap out steering arms for different levels of ackerman/and steering ratio. SAI is also adjustable via the upper strut hole mount.

It would offer a large amount of roll center correction("perfect" amount for someone with ~3.25" to their framerails), and has adjustable shanks for more, so if you feel the need to push your FLCA into your wheel, you can do that.

The brake bracket is also modular, so you can go from Z32 calipers on Z33 rotors, to Wilwood FSL-4 calipers on 12.2" rotors, or Z33 rotors all with just a bracket change on the upright.

Tie rod setup is adjustable for bumpsteer.

The FLCA are also designed around rod end adjustable sway bar endlinks, since the stock ones are utterly horrible.

So that's about it, not trying to go overly commercial with this post, as it's basically a still-born project at this point. Snce it'd be a one time run more than likely, it's more a "this is what it could be" post. People talk about their interest, but no one is really willing to pony up the cash from what I've seen.

I realize it's a lot of money to drop on suspension, but if you piecemeal things you're not too far away and you're probably running on modded stock spindles that may or may not be setup for what is good for your car.

I'll make a deal with the 240SX community, if two people come forward with REAL interest and this goes through, if they agree to it I'll post up my fully moveable roll center analysis for the front of an S13 to give people an idea of what is actually happening with their car and the forces acting on it as the suspension moves. Who knows... might happen.

[PoorMans180SX]

Originally Posted by Def

I'll make a deal with the 240SX community, if two people come forward with REAL interest and this goes through, if they agree to it I'll post up my fully moveable roll center analysis for the front of an S13 to give people an idea of what is actually happening with their car and the forces acting on it as the suspension moves. Who knows... might happen.

I am saving the money currently. I have $200 in my bank account right now with your name on it, and I'm taking money out of every check so I can purchase your setup.

I am very serious.

[GripTerror]

I'm in on Def's setup

[singlecamslam]

Someone give me some info real quick please. I just did the roll center on the front of my s13, raised it by 1'' since i'm not that low. But for the rear i did nothing because school just started and i plan on keeping it that way untill i have some free time.

How messed up will my car feel? if it will actually make a differece. To give you an idea how low i am, i have 17'' tires with 45 sidewall, and i have 1'' from tire to fender. Thank you.

[articdragon192]

Car might understeer a biit. Go for a drive though. Best way to know if there's a change.

You know what, I might have that wrong. Read up on mmdb's post from when he did only the front knuckles. His experience will explain the difference best.

[singlecamslam]

Not gonna be able to test it out since the next track day. Where can i find mmdb's post? I'm quite curious as what to expect since the front is more whack when you lower it compared to the back, so hopefully someone can tell me.

[articdragon192]

Earlier in this thread. Search his posts within this thread.

[SoSideways]

With only 1" of spacing up front, not correcting the roll center in the rear probably wouldn't be detrimental to your handling, as the rear suspension's roll center doesn't drop as fast as the front's.

mmdb had a bad handling problem when he only did the front knuckles because he added like almost 2" of spacing up front and like a quarter of an inch of adjustment on the rear.

I'm going to be going with about an inch in the rear and 2 inches in the front, will tell you how it feels this week, hopefully.

[GripTerror]

^Excited to hear the results

[swiftmini]

Iam running 40mm upfront and 15-20mm at the rear and iam very happy with the balance of the car. Also has an rb25 in the front and no anti roll bars

[3AM]

i went through alot of this thread and couldn't find what i was after so ill post it up.

how do people without max arms get good clearance on their rear upper arms?

mine are damn close to the chassis rail. theyre gonna get smashed if i go over any bumps.

[95KA-Turbo]

Are you talking about the RUCA? I had to notch my chassis because I am running the PBM subframe risers.

[3AM]

yeah RUCAs. I was thinking about notching the chassis rail actually. have you got any pictures of how you did it? i guess just welding a thick piece of tube or plate in would be sufficient to keep it strong?

[SoSideways]

I dunno, I have the Peak Performance arms, and I'm able to pretty much tuck quite a bit of rim and still not hit anything.

Then again, I don't have the subframe risers.


Here's something interesting I found last night while tightening everything down on the passenger side rear.

I noticed that after putting the GS arm on, and setting the adjustment pieces to the shortest as possible (everything stacked against each other, cannot be adjusted any further), that it made my wheel fitment go to crap.

It seemed like with it at the completely shortest adjustment, that the arm itself is shorter than stock.

I ended up lengthening it a bit, and eventually got the wheel fitment the way I wanted, but the camber gain wasn't the same; there were less camber gain as the wheel went up from full droop to where I wanted the ride height to be.

Toe out as the wheel went out was also not as pronounced.

I also noticed that, I lost a bunch of droop travel on my coilover, despite not even touching it for ride height or anything.

I wonder if the inch or so of roll center correction on these GS arms actually took some of the droop travel out of my coilover?

In any case, I have to take the wheel off again tonight to make some more adjustments before I'm 100% happy with this side. I had to quit for the night because my arms got too tired to lift my wheel up to the car/take it back off the car.

[95KA-Turbo]

I just cut it out with a grinder, hahahaha. Its pretty thick back there, I don't think the little bit that was cut out will matter too much.