This is the roll center, suspension pickup, and steering angle modification thread. - Page 33 - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

*!Zar!* · 06-10-2010, 12:32 PM

Quote:

Originally Posted by nieko

http://i58.photobucket.com/albums/g2...G/100_2868.jpg

took me like 10 minutes to do the notching on both sides.

super easy, super straightfoward.

i also slanted them a LITTLE bit upwards hoping to correct a little bumpsteer.

was that a bad idea? lolol

Update since notching/install?

GSXRJJordan · 06-11-2010, 12:32 AM

He updated on his Socal-Drift build thread:

Quote:

should have bolted it up and taken a picture too but oh well lol its real snug and not going anywhere.

the drift works inner tie rod spacer they have machined on is like 2 mills smaller than my old tie rod spacer, i might figure out a way to rig somethign to get a little more angle lolol

tie rod end doesnt even slap my control arm anymore... how depressing hahahaha

The BOSS Build Thread. - Page 13 - Socal-Drift

Slidin' Sam · 06-12-2010, 05:33 AM

Ok, so I am not sure if this issue has been covered with the parts shop max steering knuckles or not.

They drop the tie rod end's down, which is good, but you cant adjust them back up to stock if need be. Also, they correct roll center issues with the tie rods, but what about the lower control arm. That still mounts in stock location, so when the wheel travels up and down the lca and the tie rods will not be working together how they were designed to in stock layout.

This was brought up to me by Shinji Minawa when I asked him if he would weld them together for me if I ordered their parts kit. He said they he, and many other people who started making knuckles 6 or 7 years ago tried this and failed. I want to know if I am missing something or not. I really wanted these knuckles but I am not sure if they are going to be worth it. I LOVE everything else that I have ever owned from PSM, just a little unsure now after talking to Shinji.

PoorMans180SX · 06-12-2010, 10:04 AM

Quote:

Originally Posted by Slidin' Sam

Ok, so I am not sure if this issue has been covered with the parts shop max steering knuckles or not.

They drop the tie rod end's down, which is good, but you cant adjust them back up to stock if need be. Also, they correct roll center issues with the tie rods, but what about the lower control arm. That still mounts in stock location, so when the wheel travels up and down the lca and the tie rods will not be working together how they were designed to in stock layout.

This was brought up to me by Shinji Minawa when I asked him if he would weld them together for me if I ordered their parts kit. He said they he, and many other people who started making knuckles 6 or 7 years ago tried this and failed. I want to know if I am missing something or not. I really wanted these knuckles but I am not sure if they are going to be worth it. I LOVE everything else that I have ever owned from PSM, just a little unsure now after talking to Shinji.

1. Why would you want your tie rods at the stock location if you're lowered?

2. PSM knuckles do nothing for roll center. Nothing at all.

3. As much as people freak out about the tie rod and LCA curves being the same, it's been widely proven that this is not as big of a deal as people make it out to be, and you can improve bump steer by spacing the tie rod ends.

4. Many people have used PSM knuckles. They have worked fine for what they are. In fact, Matt Powers has hit the wall a couple times, and the only thing that has survived are the knuckles. If you're really worried, just send your knuckles to PSM to have them weld them.

Slidin' Sam · 06-12-2010, 10:45 AM

I understand that you can improve bump steer by lowering the tie rod ends on a lowered car.

The parts shop max knuckles lower the tie rod ends, doesn't this affect the roll center in some way?

Do you have any actual proof, other than hear say, that the lca's and tie rods having different geometry from each other (the fact that they are no longer parallel to each other) has no negative effect on the car?

If there is a negative effect because of the LCA, what do you do to correct that?

Since their knuckles are so different, why hasn't anybody else taken this approach?

Pandapants · 06-12-2010, 11:02 AM

Roll center is calculated by the pivot points of the lower control arms, not the tie rods. Having tie rods some what parallel to lca helps eliminate bumpsteer, not roll center.

95KA-Turbo · 06-12-2010, 11:41 AM

When the tie rod is spaced down and the LCA is not then you help correct bump steer. Correcting bump steer and not correcting roll center isn't a negative thing, it just isn't perfect. You ideally want to correct them both, but there is no affordable piece you can just buy and fix it, you'll have to make something if you want it to be cost effective.

Def · 06-12-2010, 12:28 PM

You can't space the tie rods down much with the stock FLCA. From the little bit of data I collected on my car with stock FLCA, spacing the tie rods down about .5" was decent for bumpsteer. The PSM stuff spaces it down WAY more than this, and my data showed it to make the bumpsteer very bad.

That said, drifting doesn't really follow the traditional rules on setup, so you could possibly get a better response at high angle by using a bit of bumpsteer to help correct for ackermann etc.

PoorMans180SX · 06-12-2010, 01:30 PM

Quote:

Originally Posted by Slidin' Sam

Do you have any actual proof, other than hear say, that the lca's and tie rods having different geometry from each other (the fact that they are no longer parallel to each other) has no negative effect on the car?

Since their knuckles are so different, why hasn't anybody else taken this approach?

Well, let's see. I had SPL v4 tie rod ends spaced down one inch from stock. My car was just on top of the tread on 195/60/15s. Car had way less bumpsteer than stock, and I liked the way it felt more than spaced down .75 inch. Tie rods were parallel with the FLCAs.

Slidin' Sam · 06-12-2010, 08:20 PM

How far down to the max knuckles drop the tie rod ends...looks like about 2 inches...can you drop the ends down too low?

xs042lol · 06-12-2010, 11:47 PM

wtf guys, im so lost. any website i can read this in english? this confused the hell out of me

PoorMans180SX · 06-13-2010, 01:49 AM

The first prototype PSM knuckles!

These look to be somewhere between stock and driftworks (need a side by side), so they may just be perfect. Come with heim joints as well.

Man am I glad I waited this out. Front aluminum knuckles coming out, rear drop knuckles going to be available stateside, so excited!

mmdb · 06-13-2010, 03:47 AM

any idea how much they much alter the hub position?

Slidin' Sam · 06-13-2010, 04:22 AM

hub position should remain the same. it just changes all your pickup locations for suspension arms/coilovers.

GripTerror · 06-13-2010, 06:04 AM

eh i like driftworks cause i really wana go low and have maximum correction... shock travel aint so much a problem since ill be cutting the car up

PoorMans180SX · 06-13-2010, 12:07 PM

Quote:

Originally Posted by Slidin' Sam

hub position should remain the same. it just changes all your pickup locations for suspension arms/coilovers.

Which is the same as changing your hub position. Raising the hub or dropping the suspension pickup points. Same thing.

Quote:

Originally Posted by mmdb

any idea how much they much alter the hub position?

They were originally saying 3/4 of an inch, or 20mm. Don't know if that's what they stuck with or not.

Z33dori · 06-13-2010, 01:38 PM

PBM is gonna be doing aluminum knuckles?

awesome

atutt · 06-13-2010, 06:25 PM

Did they just move the pick up points up on the knuckle a little bit?

Slidin' Sam · 06-13-2010, 09:16 PM

PoorMan - Can you explain to me how the hub position is changed with the rear knuckles...I am having a hard time visualizing this right now. Thanks!

articdragon192 · 06-13-2010, 11:27 PM

If you move the pick up points on the knuckle, you technically move the hub up.

Slidin' Sam · 06-14-2010, 01:09 AM

The way I picture it is backwards. I see that that when you raise the pickups or extend them out the hub stay's in the same location. I just can't picture how the hub changes I guess. So is the idea to keep the hub as close to stock location as possible while modifying the pickup points?

mmdb · 06-14-2010, 01:24 AM

^ Imagine how your car sits now, and the hub position relative to the knuckle it's attached to and imagine keeping your knuckle, suspension arms, etc in the same location. Now mentally detach the and take the hub, which is connected to the wheel and move it upwards 90 degrees to any distance allowed by the wheel well. What happens as the wheel moves closer into the wheel well? The car sits lower correct? In lieu of lowering your car with your coilovers, use the imaginary knuckles to move your wheel closer into the wheel well resulting in a lowered ride, with the same suspension geometry as was before using the coilovers.

Another, crude way of thinking about it is say there's no such thing as coilovers but a fixed shock - you CANNOT adjust it. Now add the knuckles. Ta-da, a lower car with the same suspension geometry. Does it necessarily mean you change the pick up points? I wouldn't think so. For a multilink suspension, I'd be cautious to, but in my opinion I'd be at ease knowing they didn't change, otherwise there's a great benefit in having a unit that has adjustable pickup points (one of DEF's goals developing his front knuckles).

Slidin' Sam · 06-14-2010, 04:18 AM

ok, I see how the hub is being changed, so by using knuckles to help lower the car as well, you then correct roll center?

atutt · 06-14-2010, 05:52 AM

Quote:

Originally Posted by Slidin' Sam

ok, I see how the hub is being changed, so by using knuckles to help lower the car as well, you then correct roll center?

Only if the knuckles are made with roll centre correction built into them.

Pandapants · 06-14-2010, 06:50 AM

Actually, I interpreted it as "Yes". The knuckles lower you car so you don't have to lower it via coilovers, therefore keeping/fixing your roll center?

atutt · 06-14-2010, 07:09 AM

Quote:

Originally Posted by Pandapants

Actually, I interpreted it as "Yes". The knuckles lower you car so you don't have to lower it via coilovers, therefore keeping/fixing your roll center?

The knuckles don't lower it significantly. driftworks knuckles lower it 45-55mm... And the PSM are even less apparently.
I'm pretty sure the idea was to be able to lower it significantly, bot not entirely on the coilover. But it still needs roll centre correction. So it's built in to the knuckle.

However, if I am wrong, someone correct me.

Now.. lets use drop spindles and that extreme subframe mod!!

mmdb · 06-14-2010, 09:26 AM

Quote:

Originally Posted by Slidin' Sam

ok, I see how the hub is being changed, so by using knuckles to help lower the car as well, you then correct roll center?

You don't necessarily "correct" roll center as there's no defined/ideal height, but you minimize the CG (center of gravity) and RC (Roll Center) distance called the moment arm which determines the amount of roll you encounter during lateral acceleration.

More in depth explanation found HERE.

PoorMans180SX · 06-14-2010, 10:16 AM

Quote:

Originally Posted by atutt

The knuckles don't lower it significantly. driftworks knuckles lower it 45-55mm... And the PSM are even less apparently.

Now.. lets use drop spindles and that extreme subframe mod!!

It's said to be 45mm in the front, and 50mm in the rear. BTW, 50mm is nearly 2 inches. That's pretty significant.

Except for the fact that raising your subframe that much is a bad idea. You will have zero squat and zero traction.

Quote:

Originally Posted by mmdb

You don't necessarily "correct" roll center as there's no defined/ideal height, but you minimize the CG (center of gravity) and RC (Roll Center) distance called the moment arm which determines the amount of roll you encounter during lateral acceleration.

This is true.

Quote:

Originally Posted by Z33dori

PBM is gonna be doing aluminum knuckles?

awesome

Those, good sir, are steel.

Thought it was interesting how little of a difference there seems to be between the distances the hub bolts are from the camber arm pickup between the PSM and Driftworks knuckles:

Maybe I'm just bad at judging things visually? Maybe PSM dropped the knuckle more? Maybe Driftworks dropped the knuckle less?

And maybe this is just me too, but doesn't it look like the PSM knuckle is more "compact" vertically? There seem to be a lot of small differences between all three knuckles.

Dan from Parts Shop MAX mentioned that it looks like Driftworks drops the lower control arms more than the rest, and the fact that you can't raise the hub more than 25mm and not make the axle boot contact the camber arm.

Pandapants · 06-14-2010, 04:59 PM

Quote:

Originally Posted by atutt

The knuckles don't lower it significantly. driftworks knuckles lower it 45-55mm... And the PSM are even less apparently.
I'm pretty sure the idea was to be able to lower it significantly, bot not entirely on the coilover. But it still needs roll centre correction. So it's built in to the knuckle.

I didn't mean modified knuckles was the proper/only way to lower a vehicle, but rather they could lower your car without changing the roll couple. That's something coilovers cannot do.

I agree that the psm knuckles look alittle more "compact", but I think it's b/c they cut down on a lot of material and the welds make it look like there's a lot more going on than there really is.

I do like how big the pick up points are compared to the DW though.

atutt · 06-14-2010, 05:11 PM

Quote:

Originally Posted by PoorMans180SX

It's said to be 45mm in the front, and 50mm in the rear. BTW, 50mm is nearly 2 inches. That's pretty significant.

Except for the fact that raising your subframe that much is a bad idea. You will have zero squat and zero traction.

Thought it was interesting how little of a difference there seems to be between the distances the hub bolts are from the camber arm pickup between the PSM and Driftworks knuckles:

Maybe I'm just bad at judging things visually? Maybe PSM dropped the knuckle more? Maybe Driftworks dropped the knuckle less?

And maybe this is just me too, but doesn't it look like the PSM knuckle is more "compact" vertically? There seem to be a lot of small differences between all three knuckles.

Dan from Parts Shop MAX mentioned that it looks like Driftworks drops the lower control arms more than the rest, and the fact that you can't raise the hub more than 25mm and not make the axle boot contact the camber arm.

True.. 2'' is a lot. But, I guess it depends on one views. For me. I kinda wanna have my balls dragging on the floor low. And still have correct(ed) geometry. So to me. 2'' doesn't seem like much, lol

How is raising the subframe bad though? I thought raisng it was a good thing, as it would increase traction. Hence why companies sell the risers that put it up against the frames.
Or is it just that a SEVERE amount is bad?

Quote:

Originally Posted by Pandapants

I didn't mean modified knuckles was the proper/only way to lower a vehicle, but rather they could lower your car without changing the roll couple. That's something coilovers cannot do.

I agree that the psm knuckles look alittle more "compact", but I think it's b/c they cut down on a lot of material and the welds make it look like there's a lot more going on than there really is.

I do like how big the pick up points are compared to the DW though.

True. I must have misinterpreted what you said. My bad.

06-12-2010, 05:33 AM	#963
Slidin' Sam Zilvia Addict Join Date: Jul 2009 Location: Japan Posts: 729 Trader Rating: (9) Feedback Score: 9 reviews	Ok, so I am not sure if this issue has been covered with the parts shop max steering knuckles or not. They drop the tie rod end's down, which is good, but you cant adjust them back up to stock if need be. Also, they correct roll center issues with the tie rods, but what about the lower control arm. That still mounts in stock location, so when the wheel travels up and down the lca and the tie rods will not be working together how they were designed to in stock layout. This was brought up to me by Shinji Minawa when I asked him if he would weld them together for me if I ordered their parts kit. He said they he, and many other people who started making knuckles 6 or 7 years ago tried this and failed. I want to know if I am missing something or not. I really wanted these knuckles but I am not sure if they are going to be worth it. I LOVE everything else that I have ever owned from PSM, just a little unsure now after talking to Shinji. __________________

06-12-2010, 10:45 AM	#965
Slidin' Sam Zilvia Addict Join Date: Jul 2009 Location: Japan Posts: 729 Trader Rating: (9) Feedback Score: 9 reviews	I understand that you can improve bump steer by lowering the tie rod ends on a lowered car. The parts shop max knuckles lower the tie rod ends, doesn't this affect the roll center in some way? Do you have any actual proof, other than hear say, that the lca's and tie rods having different geometry from each other (the fact that they are no longer parallel to each other) has no negative effect on the car? If there is a negative effect because of the LCA, what do you do to correct that? Since their knuckles are so different, why hasn't anybody else taken this approach? __________________

06-12-2010, 11:41 AM	#967
95KA-Turbo Post Whore! Join Date: Jul 2005 Location: LA Age: 36 Posts: 3,402 Trader Rating: (19) Feedback Score: 19 reviews	When the tie rod is spaced down and the LCA is not then you help correct bump steer. Correcting bump steer and not correcting roll center isn't a negative thing, it just isn't perfect. You ideally want to correct them both, but there is no affordable piece you can just buy and fix it, you'll have to make something if you want it to be cost effective. __________________ Instagram - SJKnoop

06-12-2010, 12:28 PM	#968
Def Post Whore! Join Date: Apr 2004 Location: Houston, TX Posts: 2,701 Trader Rating: (16) Feedback Score: 16 reviews	You can't space the tie rods down much with the stock FLCA. From the little bit of data I collected on my car with stock FLCA, spacing the tie rods down about .5" was decent for bumpsteer. The PSM stuff spaces it down WAY more than this, and my data showed it to make the bumpsteer very bad. That said, drifting doesn't really follow the traditional rules on setup, so you could possibly get a better response at high angle by using a bit of bumpsteer to help correct for ackermann etc. __________________ S13 Hatch - Goes around tracks quickly DEFSPORT

06-12-2010, 08:20 PM	#970
Slidin' Sam Zilvia Addict Join Date: Jul 2009 Location: Japan Posts: 729 Trader Rating: (9) Feedback Score: 9 reviews	How far down to the max knuckles drop the tie rod ends...looks like about 2 inches...can you drop the ends down too low? __________________

06-12-2010, 11:02 AM	#966
Pandapants Zilvia Junkie Join Date: Mar 2008 Location: SoFla Age: 32 Posts: 302 Trader Rating: (4) Feedback Score: 4 reviews	Roll center is calculated by the pivot points of the lower control arms, not the tie rods. Having tie rods some what parallel to lca helps eliminate bumpsteer, not roll center.

06-12-2010, 11:47 PM	#971
xs042lol BANNED Join Date: Jun 2010 Location: shitcago Age: 31 Posts: 46 Trader Rating: (0) Feedback Score: 0 reviews	wtf guys, im so lost. any website i can read this in english? this confused the hell out of me

06-13-2010, 01:49 AM	#972
PoorMans180SX Zilvia.net Advertiser Join Date: Nov 2005 Location: Michigan Age: 33 Posts: 5,431 Trader Rating: (16) Rides Gallery: PoorMans180SX Feedback Score: 16 reviews	The first prototype PSM knuckles! These look to be somewhere between stock and driftworks (need a side by side), so they may just be perfect. Come with heim joints as well. Man am I glad I waited this out. Front aluminum knuckles coming out, rear drop knuckles going to be available stateside, so excited! __________________ Build: http://zilvia.net/f/showthread.php?t=643065 Friends don't let friends buy knock-offs.

06-13-2010, 03:47 AM	#973
mmdb Zilvia FREAK! Join Date: Apr 2003 Location: 240sx Posts: 1,558 Trader Rating: (20) Feedback Score: 20 reviews	any idea how much they much alter the hub position? __________________ .25 till 3

06-13-2010, 04:22 AM	#974
Slidin' Sam Zilvia Addict Join Date: Jul 2009 Location: Japan Posts: 729 Trader Rating: (9) Feedback Score: 9 reviews	hub position should remain the same. it just changes all your pickup locations for suspension arms/coilovers. __________________

06-13-2010, 06:04 AM	#975
GripTerror Zilvia Addict Join Date: Nov 2009 Location: Canada Age: 36 Posts: 685 Trader Rating: (0) Feedback Score: 0 reviews	eh i like driftworks cause i really wana go low and have maximum correction... shock travel aint so much a problem since ill be cutting the car up

06-13-2010, 01:38 PM	#977
Z33dori Post Whore! Join Date: Dec 2006 Location: Riverview, FL Age: 32 Posts: 5,557 Trader Rating: (12) Feedback Score: 12 reviews	PBM is gonna be doing aluminum knuckles? awesome __________________

06-13-2010, 06:25 PM	#978
atutt Zilvia Addict Join Date: Oct 2006 Location: barrie, ontario, canada Age: 35 Posts: 997 Trader Rating: (0) Feedback Score: 0 reviews	Did they just move the pick up points up on the knuckle a little bit?

06-13-2010, 09:16 PM	#979
Slidin' Sam Zilvia Addict Join Date: Jul 2009 Location: Japan Posts: 729 Trader Rating: (9) Feedback Score: 9 reviews	PoorMan - Can you explain to me how the hub position is changed with the rear knuckles...I am having a hard time visualizing this right now. Thanks! __________________

06-13-2010, 11:27 PM	#980
articdragon192 Post Whore! Join Date: Jan 2005 Location: West covina/ Irvine Age: 35 Posts: 6,789 Trader Rating: (9) Feedback Score: 9 reviews	If you move the pick up points on the knuckle, you technically move the hub up. __________________ Need help? Click here Still stumped? Try this Can't find what you're looking for? Here you go.

06-14-2010, 01:09 AM	#981
Slidin' Sam Zilvia Addict Join Date: Jul 2009 Location: Japan Posts: 729 Trader Rating: (9) Feedback Score: 9 reviews	The way I picture it is backwards. I see that that when you raise the pickups or extend them out the hub stay's in the same location. I just can't picture how the hub changes I guess. So is the idea to keep the hub as close to stock location as possible while modifying the pickup points? __________________

06-14-2010, 01:24 AM	#982
mmdb Zilvia FREAK! Join Date: Apr 2003 Location: 240sx Posts: 1,558 Trader Rating: (20) Feedback Score: 20 reviews	^ Imagine how your car sits now, and the hub position relative to the knuckle it's attached to and imagine keeping your knuckle, suspension arms, etc in the same location. Now mentally detach the and take the hub, which is connected to the wheel and move it upwards 90 degrees to any distance allowed by the wheel well. What happens as the wheel moves closer into the wheel well? The car sits lower correct? In lieu of lowering your car with your coilovers, use the imaginary knuckles to move your wheel closer into the wheel well resulting in a lowered ride, with the same suspension geometry as was before using the coilovers. Another, crude way of thinking about it is say there's no such thing as coilovers but a fixed shock - you CANNOT adjust it. Now add the knuckles. Ta-da, a lower car with the same suspension geometry. Does it necessarily mean you change the pick up points? I wouldn't think so. For a multilink suspension, I'd be cautious to, but in my opinion I'd be at ease knowing they didn't change, otherwise there's a great benefit in having a unit that has adjustable pickup points (one of DEF's goals developing his front knuckles). __________________ .25 till 3

06-14-2010, 04:18 AM	#983
Slidin' Sam Zilvia Addict Join Date: Jul 2009 Location: Japan Posts: 729 Trader Rating: (9) Feedback Score: 9 reviews	ok, I see how the hub is being changed, so by using knuckles to help lower the car as well, you then correct roll center? __________________

06-14-2010, 06:50 AM	#985
Pandapants Zilvia Junkie Join Date: Mar 2008 Location: SoFla Age: 32 Posts: 302 Trader Rating: (4) Feedback Score: 4 reviews	Actually, I interpreted it as "Yes". The knuckles lower you car so you don't have to lower it via coilovers, therefore keeping/fixing your roll center?

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode