This is the roll center, suspension pickup, and steering angle modification thread. - Page 45 - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

DC Dan MAX USA · 07-27-2010, 02:31 PM

Quote:

Originally Posted by Z33dori

leading 58degress, trailing 52degress

Hows the over centering?

Z33dori · 07-27-2010, 03:32 PM

Quote:

Originally Posted by DC Dan MAX USA

Hows the over centering?

not sure, i'll try and get a word with Victor in Vegas, if he is there.

but this is interesting

But back to my main thing i wanted to know. how do you guys feel about lowering the caster after adding knuckles? Since most ppl add caster for faster wheel return, but most knuckles act as steering quickeners, right? So would it be better to run the caster down to keep the wheel more flat at full lock, I'm still not sure if its better to have a flat tire or a tire that is rolling positive at full lock.

95KA-Turbo · 07-27-2010, 04:11 PM

Quote:

Originally Posted by DC Dan MAX USA

Hows the over centering?

Is that little bit of angle on the right tie rod over centering? Would that small amount of angle be a big issue since the other arm is straight?

*!Zar!* · 07-27-2010, 05:58 PM

Would would the downside be if I were to just drill my front lower control arm higher on the crossmember? I haven't had a chance to go check for clearance, but I'm pretty sure I remember someone else doing that.

PoorMans180SX · 07-27-2010, 06:16 PM

Quote:

Originally Posted by Z33dori

But back to my main thing i wanted to know. how do you guys feel about lowering the caster after adding knuckles? Since most ppl add caster for faster wheel return, but most knuckles act as steering quickeners, right? So would it be better to run the caster down to keep the wheel more flat at full lock, I'm still not sure if its better to have a flat tire or a tire that is rolling positive at full lock.

You'll get more grip and steering ability with the tire as flat as possible. Most guys either put caster back to stock specs and/or alter the steering axis so they can have the outside tire as flat as possible.

Quote:

Originally Posted by !Zar!

Would would the downside be if I were to just drill my front lower control arm higher on the crossmember? I haven't had a chance to go check for clearance, but I'm pretty sure I remember someone else doing that.

This has been discussed. You will have big bumpsteer issues unless you move the rack up as well.

95KA-Turbo · 07-27-2010, 07:46 PM

^^ Not to mention the effects on the tension rods - I remember Def saying it would be bad.

At the same time people do it - like the JIC S15 time attack car. I am not sure what else they've done but they seem to have simply moved the inner pick up point up ~1". There is enough room to move it up a solid 1.5".

DC Dan MAX USA · 07-27-2010, 07:49 PM

Progress today...

About the caster, it needs to go. We have designed caster adjustable top plates for our pro version coilovers coming in a few months, and also the super adjustable tension rod/lca combo. With those two items tag teaming the caster, you will maintain wheel position in the arch and be able to steer flat at super angle. If you want to see a good example of this excess caster elimination proven in competition, just look at Forsbergs car.

About one tie rod locking, thats just the way it is when you turn all the way, and for sure its a big deal, its easy to loose control having to man handle the steering out of lock.

Z33dori · 07-27-2010, 08:36 PM

yea thats one of the things i've been watching alot at each round. Seems there is a bit more to it, or maybe it just not achievable on all car set ups?

Slidin' Sam · 07-27-2010, 08:58 PM

LCA looks good! You guy's keep coming out with tons of new parts! What's this about new coilovers now?

So with adjusting the caster so that the tires are flat, you want to pull the wheel closer to the front bumper correct?...or am I 180 degrees off on that one?

Carbomb · 07-27-2010, 09:21 PM

Quote:

Originally Posted by Slidin' Sam

LCA looks good! You guy's keep coming out with tons of new parts! What's this about new coilovers now?

So with adjusting the caster so that the tires are flat, you want to pull the wheel closer to the front bumper correct?...or am I 180 degrees off on that one?

more caster closer to front ,less closer to driver.

Slidin' Sam · 07-27-2010, 09:33 PM

Quote:

Originally Posted by Toadstool

more caster closer to front ,less closer to driver.

Right, so you want more caster to get the tires flat when countered like in the picture of Chris, correct?

jeffwiggins · 07-27-2010, 10:29 PM

great thread

DC Dan MAX USA · 07-27-2010, 11:47 PM

No. Caster is like a chopper motorcycle front shock and no caster is the shock totally vertical when viewed from the side. So imagine if the chopper has a ten inch wide car wheel on it with a 40 series tire, and then turn the handle bars 55 degrees to one side and you can visualize how just the edge of the tire is touching the ground.

mmdb · 07-27-2010, 11:54 PM

This is a good read. you'll be that much smarter after you do!

http://www.google.com/url?sa=t&sourc...qWhH3aXv70BY-w

Slidin' Sam · 07-28-2010, 01:27 AM

Quote:

Originally Posted by DC Dan MAX USA

No. Caster is like a chopper motorcycle front shock and no caster is the shock totally vertical when viewed from the side. So imagine if the chopper has a ten inch wide car wheel on it with a 40 series tire, and then turn the handle bars 55 degrees to one side and you can visualize how just the edge of the tire is touching the ground.

That is a VERY good way of explaining it...I love it when things get broken down Barney-style! Thank you!

DC Dan MAX USA · 07-28-2010, 01:37 AM

No prob! I try to use whatever I can relate to to visualize these things.

All the years of collective knowledge in grip racing is indeed very interesting, but it's application to drifting is not too relevant as soon as we steer the opposite direction around a corner.

95KA-Turbo · 07-28-2010, 06:54 AM

Ahhh, that makes more sense and explains why Def said using the tension rods to adjust caster is a bad idea.

Dan, just something I realized about your arm design. I have heard using a rod end for the outer ball joint is a bad idea because it puts the rod end 'in bending'. Have you guys thought about making an inclosed spherical bearing mount for the outside instead?

PoorMans180SX · 07-28-2010, 08:49 AM

Quote:

Originally Posted by 95KA-Turbo

Dan, just something I realized about your arm design. I have heard using a rod end for the outer ball joint is a bad idea because it puts the rod end 'in bending'. Have you guys thought about making an inclosed spherical bearing mount for the outside instead?

You're talking about the threaded part right? If there was anything that could handle it, I'm betting it's PSM's forged steel rod end.

They're a lot easier to replace that way as well.

Looks good Dan! Props for being so dedicated to the S-chassis community!

DC Dan MAX USA · 07-28-2010, 01:03 PM

Obviously it is stronger to have a fixed rod versus an adjustable one as suggested in this article
Formula Student Germany: Pat's Column - Rod Ends in Bending
The in bending refers to the shear forces on the thread but in reality every adjustable aftermarket part on the planet uses threaded rod ends, not just us.
The basic solution to this is to use a stronger rod end, our smallest threaded shaft is about one inch solid forged steel with about a 2 inch ring around the pillowball (and those two things are one piece) and the adjuster that encapsulates the threaded rod bumps up the thickness to a final OD of 1.5" all in steel.

Also the taper shaft cant help but be the skinniest thing in the mix because its OD is limited by the OEM taper OD and the pillowball ID which is about 7/10 of an inch.

Our rod ends are going to be sooooo much happier then these pieces of crap that sit on the edge of their range dinging the pillowball spacers all day long. Cant wait to get rid of these.

GripTerror · 07-28-2010, 05:03 PM

Keep it up power by max... now you got me interested, if you got stuff to show like this (meaning you're listening to people in this thread and potentially going to offer these products)...

95KA-Turbo · 07-30-2010, 11:13 PM

Quote:

Originally Posted by 95KA-Turbo

Front:

I just thought it was interesting that this control arm appears to be at nearly the same angle as mine:

So my front geometry should be the same if I raised my car up like 2.5 inches, lol.

nieko · 07-31-2010, 12:19 PM

I love all the trouble we go thru to have our car slammed.

hahahaha

PoorMans180SX · 07-31-2010, 03:00 PM

Real race cars are just as low. Just look at all the unlimited class time attack cars. You don't see them rocking the typical "I-race-on-the-roadcourse" s-chassis ride height. Their cars are slammed.

Def · 07-31-2010, 03:21 PM

Quote:

Originally Posted by PoorMans180SX

Real race cars are just as low. Just look at all the unlimited class time attack cars. You don't see them rocking the typical "I-race-on-the-roadcourse" s-chassis ride height. Their cars are slammed.

Most are about the same height as my car from what I've seen.

S chassis front fenders are very "short" - so if you're just comparing fender gaps it's misleading as most modern cars started lowering fender arches to make the car look "more aggressive."

My car has the framerails about 3" off the ground. Not sure how much lower you can realistically get and still be able to hop curbs and deal with undulations on track at speed.

My car IS higher than the average drift car though, where most seem to have <2" of framerail clearance(try curb hopping with that on a bumpy track... you'll need a new chassis soon enough).

So are you saying this from experience, or just looking at pics?

PoorMans180SX · 07-31-2010, 08:32 PM

Quote:

Originally Posted by Def

Most are about the same height as my car from what I've seen.

S chassis front fenders are very "short" - so if you're just comparing fender gaps it's misleading as most modern cars started lowering fender arches to make the car look "more aggressive."

I guess now that you say this, it makes sense. I never really thought about the fender height.

I'm mostly going from pictures, you're right. Things like the Tomei/Cusco Impreza:

and the M-speed Skyline:

Def · 07-31-2010, 10:13 PM

I agree, some cars can be made fast and run very low. In general it's tough to do even with a "tubbed" front wheel wells since you're really not that far from the hood when you start getting down to tucking tire on our cars.

Those cars also probably have near $100k in the build - so I'd say they're a bit outside of what most "real race cars" are. Unless you're talking pro only cars.

nieko · 08-03-2010, 12:34 AM

Kinda going back but...

CG is approximately your crank centerline in the front correct?

well what is it in the rear? im sure its the same thing, but like what point can we refference?

i know this is horribly not exact.... but i wanna get it close.

is the only real way of figuring out CG with scales?

articdragon192 · 08-03-2010, 12:44 AM

Say a car is doing double duty, both drifting and road racing. What's a good happy medium for Ackerman?

swiftmini · 08-03-2010, 03:21 AM

The cg at crankline height is just a guide for c of g height. Its not at the front or the rear its somewhere in between. Like 60/40 - 50/50.

If you know your weight split, front - rear, you can assume the height is around crankline and that the posistion along its the length of the vehicle is x% of wheelsbase.

If you know the weight split front to rear, the total weight and also the weight split with the rear of the car raised by a known amount (1/2M or 1M) then you can work it out accurately using some simple maths.

this is my understanding of c of g calculation or guesstimation, please correct me if iam wrong.

swiftmini · 08-03-2010, 03:39 AM

Hi peeps.

I have raised/flush mounted my rear subframe.

The lst couple weeks i have been working on a new front crossmember. I have moved my rack forward by 23mm (which i have done before with great results) and now iam considering modding it further so that it is raised 15-20mm higher (like the rear is).

This will raise the steering and lca mounts all together at same time. Yes it will raise the engine 15mm but i have room to go slightly lower by machining the solid mounts a fraction.

I also realise that i will need to raise the front tension rod bracket (or just mounting hole by 15mm).

I cannot think of any reason why not to do this! I dont have to worry about regulations ect ect!!

I have already ran with psm style knuckle mods that had 65mm drop for the tie rod end and 55mm extended bottom balljoint, the car handled and steered amazing. But i want to reduce the length of the extended balljoint for strength reasons and also for kpi reasons (break discs are in the way for stock kpi and 55mm drop).

I was thinking raised front crossmember by 15-20mm and rc correct the bottom balljoint taper on the front knuckle by 40mm.

Seems. Legit too me

07-27-2010, 05:58 PM	#1324
!Zar! Premium Member Join Date: Nov 2004 Location: North Korea Posts: 14,576 Trader Rating: (27) Feedback Score: 27 reviews	Would would the downside be if I were to just drill my front lower control arm higher on the crossmember? I haven't had a chance to go check for clearance, but I'm pretty sure I remember someone else doing that. __________________

07-27-2010, 07:46 PM	#1326
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 the effects on the tension rods - I remember Def saying it would be bad. At the same time people do it - like the JIC S15 time attack car. I am not sure what else they've done but they seem to have simply moved the inner pick up point up ~1". There is enough room to move it up a solid 1.5". __________________ Instagram - SJKnoop

07-27-2010, 07:49 PM	#1327
DC Dan MAX USA Zilvia.net Advertiser Join Date: Aug 2005 Location: San Diego Posts: 2,478 Trader Rating: (79) Feedback Score: 79 reviews	Progress today... About the caster, it needs to go. We have designed caster adjustable top plates for our pro version coilovers coming in a few months, and also the super adjustable tension rod/lca combo. With those two items tag teaming the caster, you will maintain wheel position in the arch and be able to steer flat at super angle. If you want to see a good example of this excess caster elimination proven in competition, just look at Forsbergs car. About one tie rod locking, thats just the way it is when you turn all the way, and for sure its a big deal, its easy to loose control having to man handle the steering out of lock. __________________ How To order: You can order directly from our zilvia advertiser threads. When you add to cart, you get an instant shipping estimate, & the cart will remember all of your items as you move between forum threads and our website www.poweredbymax.net until you remove them or check out. I can also calculate estimates manually for you but the cart's estimates are way faster and more accurate. Order Inquiry: IM me your real name and paypal address. Thanks for your business!

07-27-2010, 08:36 PM	#1328
Z33dori Post Whore! Join Date: Dec 2006 Location: Riverview, FL Age: 32 Posts: 5,557 Trader Rating: (12) Feedback Score: 12 reviews	yea thats one of the things i've been watching alot at each round. Seems there is a bit more to it, or maybe it just not achievable on all car set ups? __________________

07-27-2010, 08:58 PM	#1329
Slidin' Sam Zilvia Addict Join Date: Jul 2009 Location: Japan Posts: 729 Trader Rating: (9) Feedback Score: 9 reviews	LCA looks good! You guy's keep coming out with tons of new parts! What's this about new coilovers now? So with adjusting the caster so that the tires are flat, you want to pull the wheel closer to the front bumper correct?...or am I 180 degrees off on that one? __________________

07-27-2010, 10:29 PM	#1332
jeffwiggins Zilvia Junkie Join Date: Jan 2008 Location: mira loma, ca Age: 32 Posts: 558 Trader Rating: (5) Feedback Score: 5 reviews	great thread

07-27-2010, 11:47 PM	#1333
DC Dan MAX USA Zilvia.net Advertiser Join Date: Aug 2005 Location: San Diego Posts: 2,478 Trader Rating: (79) Feedback Score: 79 reviews	No. Caster is like a chopper motorcycle front shock and no caster is the shock totally vertical when viewed from the side. So imagine if the chopper has a ten inch wide car wheel on it with a 40 series tire, and then turn the handle bars 55 degrees to one side and you can visualize how just the edge of the tire is touching the ground. __________________ How To order: You can order directly from our zilvia advertiser threads. When you add to cart, you get an instant shipping estimate, & the cart will remember all of your items as you move between forum threads and our website www.poweredbymax.net until you remove them or check out. I can also calculate estimates manually for you but the cart's estimates are way faster and more accurate. Order Inquiry: IM me your real name and paypal address. Thanks for your business!

07-27-2010, 11:54 PM	#1334
mmdb Zilvia FREAK! Join Date: Apr 2003 Location: 240sx Posts: 1,558 Trader Rating: (20) Feedback Score: 20 reviews	This is a good read. you'll be that much smarter after you do! http://www.google.com/url?sa=t&sourc...qWhH3aXv70BY-w __________________ .25 till 3

07-28-2010, 01:37 AM	#1336
DC Dan MAX USA Zilvia.net Advertiser Join Date: Aug 2005 Location: San Diego Posts: 2,478 Trader Rating: (79) Feedback Score: 79 reviews	No prob! I try to use whatever I can relate to to visualize these things. All the years of collective knowledge in grip racing is indeed very interesting, but it's application to drifting is not too relevant as soon as we steer the opposite direction around a corner. __________________ How To order: You can order directly from our zilvia advertiser threads. When you add to cart, you get an instant shipping estimate, & the cart will remember all of your items as you move between forum threads and our website www.poweredbymax.net until you remove them or check out. I can also calculate estimates manually for you but the cart's estimates are way faster and more accurate. Order Inquiry: IM me your real name and paypal address. Thanks for your business!

07-28-2010, 06:54 AM	#1337
95KA-Turbo Post Whore! Join Date: Jul 2005 Location: LA Age: 36 Posts: 3,402 Trader Rating: (19) Feedback Score: 19 reviews	Ahhh, that makes more sense and explains why Def said using the tension rods to adjust caster is a bad idea. Dan, just something I realized about your arm design. I have heard using a rod end for the outer ball joint is a bad idea because it puts the rod end 'in bending'. Have you guys thought about making an inclosed spherical bearing mount for the outside instead? __________________ Instagram - SJKnoop

07-28-2010, 01:03 PM	#1339
DC Dan MAX USA Zilvia.net Advertiser Join Date: Aug 2005 Location: San Diego Posts: 2,478 Trader Rating: (79) Feedback Score: 79 reviews	Obviously it is stronger to have a fixed rod versus an adjustable one as suggested in this article Formula Student Germany: Pat's Column - Rod Ends in Bending The in bending refers to the shear forces on the thread but in reality every adjustable aftermarket part on the planet uses threaded rod ends, not just us. The basic solution to this is to use a stronger rod end, our smallest threaded shaft is about one inch solid forged steel with about a 2 inch ring around the pillowball (and those two things are one piece) and the adjuster that encapsulates the threaded rod bumps up the thickness to a final OD of 1.5" all in steel. Also the taper shaft cant help but be the skinniest thing in the mix because its OD is limited by the OEM taper OD and the pillowball ID which is about 7/10 of an inch. Our rod ends are going to be sooooo much happier then these pieces of crap that sit on the edge of their range dinging the pillowball spacers all day long. Cant wait to get rid of these. __________________ How To order: You can order directly from our zilvia advertiser threads. When you add to cart, you get an instant shipping estimate, & the cart will remember all of your items as you move between forum threads and our website www.poweredbymax.net until you remove them or check out. I can also calculate estimates manually for you but the cart's estimates are way faster and more accurate. Order Inquiry: IM me your real name and paypal address. Thanks for your business!

07-28-2010, 05:03 PM	#1340
GripTerror Zilvia Addict Join Date: Nov 2009 Location: Canada Age: 36 Posts: 685 Trader Rating: (0) Feedback Score: 0 reviews	Keep it up power by max... now you got me interested, if you got stuff to show like this (meaning you're listening to people in this thread and potentially going to offer these products)...

07-31-2010, 12:19 PM	#1342
nieko Post Whore! Join Date: Sep 2007 Location: Westminster Age: 30 Posts: 2,694 Trader Rating: (14) Feedback Score: 14 reviews	I love all the trouble we go thru to have our car slammed. hahahaha __________________

07-31-2010, 03:00 PM	#1343
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	Real race cars are just as low. Just look at all the unlimited class time attack cars. You don't see them rocking the typical "I-race-on-the-roadcourse" s-chassis ride height. Their cars are slammed. __________________ Build: http://zilvia.net/f/showthread.php?t=643065 Friends don't let friends buy knock-offs.

07-31-2010, 10:13 PM	#1346
Def Post Whore! Join Date: Apr 2004 Location: Houston, TX Posts: 2,701 Trader Rating: (16) Feedback Score: 16 reviews	I agree, some cars can be made fast and run very low. In general it's tough to do even with a "tubbed" front wheel wells since you're really not that far from the hood when you start getting down to tucking tire on our cars. Those cars also probably have near $100k in the build - so I'd say they're a bit outside of what most "real race cars" are. Unless you're talking pro only cars. __________________ S13 Hatch - Goes around tracks quickly DEFSPORT

08-03-2010, 12:34 AM	#1347
nieko Post Whore! Join Date: Sep 2007 Location: Westminster Age: 30 Posts: 2,694 Trader Rating: (14) Feedback Score: 14 reviews	Kinda going back but... CG is approximately your crank centerline in the front correct? well what is it in the rear? im sure its the same thing, but like what point can we refference? i know this is horribly not exact.... but i wanna get it close. is the only real way of figuring out CG with scales? __________________

08-03-2010, 12:44 AM	#1348
articdragon192 Post Whore! Join Date: Jan 2005 Location: West covina/ Irvine Age: 35 Posts: 6,789 Trader Rating: (9) Feedback Score: 9 reviews	Say a car is doing double duty, both drifting and road racing. What's a good happy medium for Ackerman? __________________ Need help? Click here Still stumped? Try this Can't find what you're looking for? Here you go.

08-03-2010, 03:21 AM	#1349
swiftmini Zilvia Member Join Date: Jan 2010 Location: uk Age: 38 Posts: 227 Trader Rating: (0) Feedback Score: 0 reviews	The cg at crankline height is just a guide for c of g height. Its not at the front or the rear its somewhere in between. Like 60/40 - 50/50. If you know your weight split, front - rear, you can assume the height is around crankline and that the posistion along its the length of the vehicle is x% of wheelsbase. If you know the weight split front to rear, the total weight and also the weight split with the rear of the car raised by a known amount (1/2M or 1M) then you can work it out accurately using some simple maths. this is my understanding of c of g calculation or guesstimation, please correct me if iam wrong.

08-03-2010, 03:39 AM	#1350
swiftmini Zilvia Member Join Date: Jan 2010 Location: uk Age: 38 Posts: 227 Trader Rating: (0) Feedback Score: 0 reviews	Hi peeps. I have raised/flush mounted my rear subframe. The lst couple weeks i have been working on a new front crossmember. I have moved my rack forward by 23mm (which i have done before with great results) and now iam considering modding it further so that it is raised 15-20mm higher (like the rear is). This will raise the steering and lca mounts all together at same time. Yes it will raise the engine 15mm but i have room to go slightly lower by machining the solid mounts a fraction. I also realise that i will need to raise the front tension rod bracket (or just mounting hole by 15mm). I cannot think of any reason why not to do this! I dont have to worry about regulations ect ect!! I have already ran with psm style knuckle mods that had 65mm drop for the tie rod end and 55mm extended bottom balljoint, the car handled and steered amazing. But i want to reduce the length of the extended balljoint for strength reasons and also for kpi reasons (break discs are in the way for stock kpi and 55mm drop). I was thinking raised front crossmember by 15-20mm and rc correct the bottom balljoint taper on the front knuckle by 40mm. Seems. Legit too me

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