This is the roll center, suspension pickup, and steering angle modification thread. - Page 53 - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Csomme · 08-27-2010, 07:11 PM

How? like details on how?

I'm sitting here with my girlfriend getting ready to go to a movie and just yelled out, "What the fuck!? How!?"

So, pwease do tell<3

Ordering soon Dan.

*!Zar!* · 08-29-2010, 03:19 PM

I'm still interested in how much the average person is cutting off of their knuckles. Everyone says that it depends on the wheel combo, but I'd imagine the average would be something like a x9 or a x9.5 +0 up front?

So would something like 2.5" shorter be a ball park or what?

Aside from that, everyone seems to be up in arms about their front roll center and and trying to achieve great roll center or whatever, but then most are rocking the rear stock/stockish. To me it seems like it would be best to leave both alone, and then try to change all of it at once, because changing only the front will disrupt front to rear balance.

Def · 08-29-2010, 03:56 PM

Quote:

Originally Posted by !Zar!

I'm still interested in how much the average person is cutting off of their knuckles. Everyone says that it depends on the wheel combo, but I'd imagine the average would be something like a x9 or a x9.5 +0 up front?

So would something like 2.5" shorter be a ball park or what?

Aside from that, everyone seems to be up in arms about their front roll center and and trying to achieve great roll center or whatever, but then most are rocking the rear stock/stockish. To me it seems like it would be best to leave both alone, and then try to change all of it at once, because changing only the front will disrupt front to rear balance.

The front roll center drops much further with lowering than the rear due to the geometry. So the front needs correction more than the rear. Of course, going crazy on the front with zero adjustment in the rear is not smart.

I spaced my front lower balljoints down ~1.625"(probably about 1.25" more than stock), and raised the rear subframe up to the framerails with SPL bushings. Feels great to me, but the front could probably use a bit more correction.

codyace · 08-29-2010, 06:01 PM

Quote:

Originally Posted by Def

The front roll center drops much further with lowering than the rear due to the geometry. So the front needs correction more than the rear. Of course, going crazy on the front with zero adjustment in the rear is not smart.

I spaced my front lower balljoints down ~1.625"(probably about 1.25" more than stock), and raised the rear subframe up to the framerails with SPL bushings. Feels great to me, but the front could probably use a bit more correction.

This is exactly what I have done as well - the car rides better than it ever has...all I'm awaiting now are the SPL outer tie rod ends to make some of the bumpsteer go away and we're set.

zorak · 08-29-2010, 10:16 PM

comparison:

DC Dan MAX USA · 08-30-2010, 01:34 AM

Quote:

Originally Posted by Csomme

How? like details on how?

To summarize what's spread out in my posts in this thread, I use the MAX Super Angle Kit installed like this:
MAX SAK Tommy Roberts Spec
That in combo with the prototype long tie rods and long lower control arms produces that angle without letting the knuckles steering arm line up with the tie rod.
A wheel spacer eliminates hitting the wheel on the frame and tie rod. There are no aftermarket steering rack parts and the rack has not been moved.

95KA-Turbo · 08-30-2010, 06:52 AM

So if that black thing (looks like a massive zip tie?) was in line with the tie rod as well, that would be over centering?

thefro526 · 08-30-2010, 07:12 AM

Quote:

Originally Posted by DC Dan MAX USA

Angle is 55 degrees (center to lock while on the lift) but the most unique thing is that we are achieving this angle without overcentering.

heres proof

Wow, that's pretty rad.

It's impressive that you did all of that without over centering... Shoot, I was getting ready to move my rack forward and stuff too.

Btw, do you have an ETA for the Tie Rods? I figure the LCA's are probably a few months out still?

PoorMans180SX · 08-30-2010, 10:27 AM

Quote:

Originally Posted by 95KA-Turbo

So if that black thing (looks like a massive zip tie?) was in line with the tie rod as well, that would be over centering?

Yup. I think it's a metal straightedge though? Hahahah.

DC Dan MAX USA · 08-30-2010, 01:09 PM

Quote:

Originally Posted by 95KA-Turbo

So if that black thing (looks like a massive zip tie?) was in line with the tie rod as well, that would be over centering?

The metal ruler is the effective new knuckle steering arm angle determined by the mounting position of the MAX SAK. Exactly, if that was in line with the tie rod they would be centered, or mechanically locked due to the rack having no leverage angle to turn the knuckle.

PoorMans180SX · 08-30-2010, 01:43 PM

How many degrees of caster are you running on the S15 Dan?

*!Zar!* · 08-30-2010, 01:48 PM

How much caster is in that pic?

Edit: PoorMan said it before I noticed his post. hahaha

Tearlessj · 08-30-2010, 02:00 PM

Quote:

Originally Posted by DC Dan MAX USA

To summarize what's spread out in my posts in this thread, I use the MAX Super Angle Kit installed like this:
MAX SAK Tommy Roberts Spec
That in combo with the prototype long tie rods and long lower control arms produces that angle without letting the knuckles steering arm line up with the tie rod.
A wheel spacer eliminates hitting the wheel on the frame and tie rod. There are no aftermarket steering rack parts and the rack has not been moved.

Dan,

In the above photo with the new FLCA, are you running the normal SAK or the T.R. SAK's? I have the normal SAK, don't know whether I should wait to get the FLCA or send my knuckles in.

PoorMans180SX · 08-30-2010, 02:17 PM

He's running the Tommy-spec ones. He says it in the quote. Less ackerman, roll center corrected 25mm.

cazman · 08-31-2010, 07:15 AM

Quote:

Originally Posted by DC Dan MAX USA

Angle is 55 degrees (center to lock while on the lift) but the most unique thing is that we are achieving this angle without overcentering.

heres proof

Sure do prevent over centering. I had worked out how to do this over a year ago in Aus. I wonder how long it will take people to actually see whats different though.

The only downers are the ADD bumpsteer, as steering length changes with more lock. The distance between centers of the rack end and tie rod end.
This isnt so bad as stock does this, but this is reversed now.
It adds dead ahead bumpsteer too, Ie when your driving straight ahead.

Your ackeman is now dynamic too, changing with amounts of lock. Can you post up a picture that shows both wheels at full lock ?(underneath, midslide, hard parked etc)
once again not a huge problem, but if its not spot on you will get anti ackerman quickly.

But IMO it still fixes many of the problems that we face when drifting, and the good outways the bad IMO. And reps for just working out the binding knuckle secret.

PoorMans180SX · 08-31-2010, 07:36 AM

Quote:

Originally Posted by cazman

Sure do prevent over centering...

You, good sir, should read through the last several pages of this thread. The PSM knuckles are very well developed, and correct for bumpsteer and roll center. They also have less ackerman, but nowhere near anti-ackerman.

95KA-Turbo · 08-31-2010, 07:42 AM

Not to mention, if there is some super secret you should be talking about it, not talking from a pedestal. This thread isn't to show off what you know, its to share what you know with others so people who know more then you can assist with your ideas and make them better.

cazman · 08-31-2010, 07:44 AM

Quote:

Originally Posted by PoorMans180SX

You, good sir, should read through the last several pages of this thread. The PSM knuckles are very well developed, and correct for bumpsteer and roll center. They also have less ackerman, but nowhere near anti-ackerman.

I am slowly going back through the pages, Im still yet to see rpoof of the removed bumpsteer, and not some "seat of the pants" dyno proof either.

A genuine plot on an aligner.

I can see the ackerman a few pages back now, but as stated in my post, please measure ackerman at all steering wheel positions, not just MAX lock.
Lock to lock ackerman will be identical, and if the car is aligned it will have 0 at center too, but measure the dynamic, I suspect it will grow and shrink on the each side independently.

95KA-Turbo · 08-31-2010, 07:57 AM

I am not sure about the total removal of bumpsteer, but they have bumpsteer correction built into their knuckles. You can see it in this picture:

cazman · 08-31-2010, 07:58 AM

Quote:

Originally Posted by 95KA-Turbo

Not to mention, if there is some super secret you should be talking about it, not talking from a pedestal. This thread isn't to show off what you know, its to share what you know with others so people who know more then you can assist with your ideas and make them better.

Just look at the pictures, and the one camera angle that is missing from every image... I figured it would only be a matter of time till some one jigged or copied the idea anyway.

Im not trying to start a pissing fight, sorry. Just the province of bumpsteer removal without figures doesnt sit well.

I have a suspension tuning business in Aus, been playing with these for a while now. I have never really cared about the cash in it, don't worry about that :P

Here is a WIY FCA kit, most of the components came from the US anyway, hahaha

PoorMans180SX · 08-31-2010, 08:15 AM

Quote:

Originally Posted by cazman

I am slowly going back through the pages, Im still yet to see rpoof of the removed bumpsteer, and not some "seat of the pants" dyno proof either.

A genuine plot on an aligner.

I can see the ackerman a few pages back now, but as stated in my post, please measure ackerman at all steering wheel positions, not just MAX lock.
Lock to lock ackerman will be identical, and if the car is aligned it will have 0 at center too, but measure the dynamic, I suspect it will grow and shrink on the each side independently.

Ha, sometimes it's not all about the graph man. If you have both ends of the tie rod parallel with both ends of the FLCA, there will be as little bumpsteer as possible. Obviously bumpsteer changes with steering lock, but there really isn't any way around this.

I'm pretty sure you're confusing ackerman with toe and dynamic toe? There will never be any ackerman at center, on any car, ever. And of course changing ackerman will change dynamic toe, they're basically interchangable. It's a pretty simple curve of the tie rod end, nothing crazy.

So the above is a kit to make FLCA's like the PSM ones I take it? Except with modified stock arms and bearing cups for the ball joint ends, yeah?

Just to let you know, Ikeya Formula was the first to design arms like that.

SoSideways · 08-31-2010, 08:49 AM

How about we all take the ego out of this thread and just talk about what matters?

THE GODAMNED SUSPENSION.

Not who the fuck came up with who first.

Nissan obviously came up with this shit first, as they made the fucking car. I just don't think they gave a shit with drifting and how the car's suspension would be in a lowered car, or else their knuckles wouldn't be the way they are.

cazman · 08-31-2010, 09:03 AM

Im not trying to emphasise who came up with it first, just that more research has been done than in this thread, and there are reasons that it is bad practice.
Im not confusing the 2 don't worry.
Due to the new tie rod end angle, when your wheel is centered your tie rod ends now angle inwards (the angle is level to the ground stock)
As you turn wheels your tie rod/ rack length alters.

You can see here, the tie rod end no longer points to the ground at straight ahead.

Now you can imagine/see what happens at full lock either way. Instead of being equal angle both sides, it is now different lock to lock.
It makes the car feel a bit odd, and WONT remove bumpsteer. Nissan spent alot of time getting this stuff dead perfect, to alter a few points and angles really upsets things.

As far as the FLCA, it was the dentsport items that I based them off, I never said they were new. Just easily rebuilt once made.
No use of the stock arm, and they use a 3/4 bolt not a small taper bolt. Ive seen too many fail when the taper was incorrect, or the finish on the material was too coarse.
Def hasn't had issues with the 3/4s so far, and its a similar kit, but witha 7/8 bearing, and youll see the Roll center cones sit in the bearing, removing (reducing significantly) lateral load on the bolt.

PoorMans180SX · 08-31-2010, 09:34 AM

The whole point of the Parts Shop MAX knuckle is to make the tie rods level to the ground when the car is on the ground.

Then you can use the other parts to bring the FLCA pivot points parallel with the tie rod pivot points.

Thus, eliminating bumpsteer.

Csomme · 08-31-2010, 09:58 AM

Quote:

Originally Posted by cazman

You can see here, the tie rod end no longer points to the ground at straight ahead.

That wheel is turned brah.

Why don't you ask questions and THEN give your input instead of assuming?

I also think you have a misconstrued way of how bumpsteer works? or maybe you're not explaining yourself properly?

Def · 08-31-2010, 10:16 AM

Quote:

Originally Posted by cazman

Im not trying to emphasise who came up with it first, just that more research has been done than in this thread, and there are reasons that it is bad practice.
Im not confusing the 2 don't worry.
Due to the new tie rod end angle, when your wheel is centered your tie rod ends now angle inwards (the angle is level to the ground stock)
As you turn wheels your tie rod/ rack length alters.

You can see here, the tie rod end no longer points to the ground at straight ahead.

Now you can imagine/see what happens at full lock either way. Instead of being equal angle both sides, it is now different lock to lock.
It makes the car feel a bit odd, and WONT remove bumpsteer. Nissan spent alot of time getting this stuff dead perfect, to alter a few points and angles really upsets things.

As far as the FLCA, it was the dentsport items that I based them off, I never said they were new. Just easily rebuilt once made.
No use of the stock arm, and they use a 3/4 bolt not a small taper bolt. Ive seen too many fail when the taper was incorrect, or the finish on the material was too coarse.
Def hasn't had issues with the 3/4s so far, and its a similar kit, but witha 7/8 bearing, and youll see the Roll center cones sit in the bearing, removing (reducing significantly) lateral load on the bolt.

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.

SoSideways · 08-31-2010, 10:32 AM

Quote:

Originally Posted by cazman

Im not trying to emphasise who came up with it first, just that more research has been done than in this thread, and there are reasons that it is bad practice.
Im not confusing the 2 don't worry.

Well, so far, you haven't given a single input, other than sit there criticizing other people's work, and showing a picture of one of your kits in a non-assembled state.

I can go out and take a bunch of pictures of random bearings and bolts and shit and call it my kit too.

Honestly, you come in here on your high horse, calling everyone out, but your high horse is just a little donkey.

Get real or get out.

GripTerror · 08-31-2010, 10:45 AM

Guys shut up and stop fighting, don't ruin this beautiful thread.

conrad_s13.5 · 08-31-2010, 03:07 PM

^ aint fighting,..just hittin people with knowledge.
some idea's and inventions are created off debates!

im nothin' special but i for one cant wait for these to go public........the science and rigorous testing and Q&A that seems to go into these and all other PBM parts sold me long ago

DC Dan MAX USA · 08-31-2010, 04:35 PM

Quote:

Originally Posted by Tearlessj

Dan,

In the above photo with the new FLCA, are you running the normal SAK or the T.R. SAK's? I have the normal SAK, don't know whether I should wait to get the FLCA or send my knuckles in.

The way you say that may lead people to think there is more than one SAK.
Just to clarify, there is only one SAK and the difference is how much towards the outside you rotate it before its welded in. The more you rotate it out the less ackerman you get. So when I say Tommy Roberts Spec, I say that because its the first one we rotated to that extreme (still not zero, it still has 10 degrees of difference between innner and outer tire angles) And the front roll center is a separate mod, no kit for that just custom labor $150+return shipping.

Tommy does not have the new LCA, and I do so thats an independant mod too, compromise being you will loose negative camber ability without a longer LCA while having the roll center adjusted knuckle.

Quote:

Originally Posted by cazman

Sure do prevent over centering. The only downers are the ADD bumpsteer

Can you post up a picture that shows both wheels at full lock ?(underneath, midslide, hard parked etc)

But IMO it still fixes many of the problems that we face when drifting, and the good outways the bad IMO. And reps for just working out the binding knuckle secret.

Not sure if we are on the same page but the toe change under suspension compression is less than one degree with the current setup.

There was some pictures clearly showing both wheels on previous pages.
Next event is at the end of next month so maybe we'll get some cool action shots.

Thanks!

08-29-2010, 03:19 PM	#1562
!Zar! Premium Member Join Date: Nov 2004 Location: North Korea Posts: 14,576 Trader Rating: (27) Feedback Score: 27 reviews	I'm still interested in how much the average person is cutting off of their knuckles. Everyone says that it depends on the wheel combo, but I'd imagine the average would be something like a x9 or a x9.5 +0 up front? So would something like 2.5" shorter be a ball park or what? Aside from that, everyone seems to be up in arms about their front roll center and and trying to achieve great roll center or whatever, but then most are rocking the rear stock/stockish. To me it seems like it would be best to leave both alone, and then try to change all of it at once, because changing only the front will disrupt front to rear balance. __________________

08-30-2010, 06:52 AM	#1567
95KA-Turbo Post Whore! Join Date: Jul 2005 Location: LA Age: 36 Posts: 3,402 Trader Rating: (19) Feedback Score: 19 reviews	So if that black thing (looks like a massive zip tie?) was in line with the tie rod as well, that would be over centering? __________________ Instagram - SJKnoop

08-30-2010, 01:43 PM	#1571
PoorMans180SX Zilvia.net Advertiser Join Date: Nov 2005 Location: Michigan Age: 33 Posts: 5,430 Trader Rating: (16) Rides Gallery: PoorMans180SX Feedback Score: 16 reviews	How many degrees of caster are you running on the S15 Dan? __________________ Build: http://zilvia.net/f/showthread.php?t=643065 Friends don't let friends buy knock-offs.

08-30-2010, 01:48 PM	#1572
!Zar! Premium Member Join Date: Nov 2004 Location: North Korea Posts: 14,576 Trader Rating: (27) Feedback Score: 27 reviews	How much caster is in that pic? Edit: PoorMan said it before I noticed his post. hahaha __________________

08-30-2010, 02:17 PM	#1574
PoorMans180SX Zilvia.net Advertiser Join Date: Nov 2005 Location: Michigan Age: 33 Posts: 5,430 Trader Rating: (16) Rides Gallery: PoorMans180SX Feedback Score: 16 reviews	He's running the Tommy-spec ones. He says it in the quote. Less ackerman, roll center corrected 25mm. __________________ Build: http://zilvia.net/f/showthread.php?t=643065 Friends don't let friends buy knock-offs.

08-27-2010, 07:11 PM	#1561
Csomme Zilvia FREAK! Join Date: Feb 2009 Location: north carolinazzz Age: 30 Posts: 1,009 Trader Rating: (4) Feedback Score: 4 reviews	How? like details on how? I'm sitting here with my girlfriend getting ready to go to a movie and just yelled out, "What the fuck!? How!?" So, pwease do tell<3 Ordering soon Dan.

08-29-2010, 10:16 PM	#1565
zorak Zilvia Member Join Date: Oct 2008 Location: South Age: 31 Posts: 287 Trader Rating: (4) Rides Gallery: zorak Feedback Score: 4 reviews	comparison:

08-31-2010, 07:42 AM	#1577
95KA-Turbo Post Whore! Join Date: Jul 2005 Location: LA Age: 36 Posts: 3,402 Trader Rating: (19) Feedback Score: 19 reviews	Not to mention, if there is some super secret you should be talking about it, not talking from a pedestal. This thread isn't to show off what you know, its to share what you know with others so people who know more then you can assist with your ideas and make them better. __________________ Instagram - SJKnoop

08-31-2010, 07:57 AM	#1579
95KA-Turbo Post Whore! Join Date: Jul 2005 Location: LA Age: 36 Posts: 3,402 Trader Rating: (19) Feedback Score: 19 reviews	I am not sure about the total removal of bumpsteer, but they have bumpsteer correction built into their knuckles. You can see it in this picture: __________________ Instagram - SJKnoop

08-31-2010, 08:49 AM	#1582
SoSideways Post Whore! Join Date: Apr 2003 Location: 你老母 Posts: 4,371 Trader Rating: (4) Feedback Score: 4 reviews	How about we all take the ego out of this thread and just talk about what matters? THE GODAMNED SUSPENSION. Not who the fuck came up with who first. Nissan obviously came up with this shit first, as they made the fucking car. I just don't think they gave a shit with drifting and how the car's suspension would be in a lowered car, or else their knuckles wouldn't be the way they are. __________________ SoSideway's iTrader Rating!! *SoSideways' Review Thread!!* http://sosideways.wordpress.com/

08-31-2010, 09:03 AM	#1583
cazman Join Date: Aug 2008 Location: SA Age: 35 Posts: 22 Trader Rating: (0) Feedback Score: 0 reviews	Im not trying to emphasise who came up with it first, just that more research has been done than in this thread, and there are reasons that it is bad practice. Im not confusing the 2 don't worry. Due to the new tie rod end angle, when your wheel is centered your tie rod ends now angle inwards (the angle is level to the ground stock) As you turn wheels your tie rod/ rack length alters. You can see here, the tie rod end no longer points to the ground at straight ahead. Now you can imagine/see what happens at full lock either way. Instead of being equal angle both sides, it is now different lock to lock. It makes the car feel a bit odd, and WONT remove bumpsteer. Nissan spent alot of time getting this stuff dead perfect, to alter a few points and angles really upsets things. As far as the FLCA, it was the dentsport items that I based them off, I never said they were new. Just easily rebuilt once made. No use of the stock arm, and they use a 3/4 bolt not a small taper bolt. Ive seen too many fail when the taper was incorrect, or the finish on the material was too coarse. Def hasn't had issues with the 3/4s so far, and its a similar kit, but witha 7/8 bearing, and youll see the Roll center cones sit in the bearing, removing (reducing significantly) lateral load on the bolt.

08-31-2010, 09:34 AM	#1584
PoorMans180SX Zilvia.net Advertiser Join Date: Nov 2005 Location: Michigan Age: 33 Posts: 5,430 Trader Rating: (16) Rides Gallery: PoorMans180SX Feedback Score: 16 reviews	The whole point of the Parts Shop MAX knuckle is to make the tie rods level to the ground when the car is on the ground. Then you can use the other parts to bring the FLCA pivot points parallel with the tie rod pivot points. Thus, eliminating bumpsteer. __________________ Build: http://zilvia.net/f/showthread.php?t=643065 Friends don't let friends buy knock-offs.

08-31-2010, 10:45 AM	#1588
GripTerror Zilvia Addict Join Date: Nov 2009 Location: Canada Age: 36 Posts: 685 Trader Rating: (0) Feedback Score: 0 reviews	Guys shut up and stop fighting, don't ruin this beautiful thread.

08-31-2010, 03:07 PM	#1589
conrad_s13.5 Zilvia FREAK! Join Date: Jan 2009 Location: STL Age: 33 Posts: 1,533 Trader Rating: (6) Feedback Score: 6 reviews	^ aint fighting,..just hittin people with knowledge. some idea's and inventions are created off debates! im nothin' special but i for one cant wait for these to go public........the science and rigorous testing and Q&A that seems to go into these and all other PBM parts sold me long ago __________________ cONtRol FReAkS

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