This is the roll center, suspension pickup, and steering angle modification thread. - Page 6 - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Ghostdrifter · 01-01-2010, 06:50 PM

Kognition in which way did the JIC team modify the rear toe mount? Did they rotate it so the pick up point is lower?

95KA-Turbo · 01-01-2010, 07:09 PM

They made it so the toe arm is parallel to the LCA, how it is from the factory.

PoorMans180SX · 01-01-2010, 08:42 PM

Quote:

Originally Posted by Toadstool

That's a good idea. Moving the steering rack forward by moving that whole chunk of subframe forward.

Quote:

Originally Posted by Teknolust72

My friend was the race mechanic for the JIC S15 last year, and he mentioned they also raised their entire steering rack by drilling out new position holes for the steering rack brackets.

Ahhhh, so they moved the FLCA inner pivots up and the steering rack. Keeping the arcs the same.

Quote:

Originally Posted by Jonnie Fraz

Formula D Rules, etc, etc.

Well, looks like I won't ever be competing in Forumula D. Oh well, I never did like FD.

I can see the modification thing, but no strengthening? I think that's kinda stupid.

Made some changes to the OG post.

*Jonnie Fraz* · 01-01-2010, 09:39 PM

Quote:

Originally Posted by PoorMans180SX

Well, looks like I won't ever be competing in Forumula D. Oh well, I never did like FD.

I can see the modification thing, but no strengthening? I think that's kinda stupid.

Made some changes to the OG post.

I hear ya! I am really not following the re-enforcing the subframe rule.
Tons of people out there running modded subframes, as well as the S14 subframe in the S13 chassis or s15 subframe in the S14.
Now the rules do state that you can get an exception from Formula D, but the pick up points can not be moved more than an inch.

I also remember a quote from one of the crew cheifs I ran across saying..." It's our job to cheat and it is their job to catch us."

PoorMans180SX · 01-01-2010, 09:43 PM

Quote:

Originally Posted by Jonnie Fraz

I hear ya! I am really not following the re-enforcing the subframe rule.
Tons of people out there running modded subframes, as well as the S14 subframe in the S13 chassis or s15 subframe in the S14.
Now the rules do state that you can get an exception from Formula D, but the pick up points can not be moved more than an inch.

Hahaha, so how does that make sense? The pickup points can't be modified, but then they can?

Pretty dumb.

Clearly the front pickups were modified on the JIC S15. They must have got an exception.

*kognition* · 01-01-2010, 10:30 PM

Remember that the S15 left the states sometime late last year. Maybe Oct or Dec. I don't follow the Drifting rules in FD, as i am not a drifter. But maybe they did not have rules restricting it at the time? How much did the car drift? I only know it from time attack. But in any case, it's gone now. And i think that they only have the S14 now. Which has been at the fabricators forever.

Quote:

Originally Posted by PoorMans180SX

Hahaha, so how does that make sense? The pickup points can't be modified, but then they can?

Pretty dumb.

Clearly the front pickups were modified on the JIC S15. They must have got an exception.

udon! · 01-01-2010, 10:41 PM

Quote:

Originally Posted by PoorMans180SX

Yeah Udon, PSM's front knuckles are not roll center adjusting. They just adjust for bump steer (tie rods).

That's why everyone is in for the Driftworks. Look on the first post. See how the hubs are moved up in the front knuckles (towards the shock mounting bolt holes)?

GOT IT! so basically if youre car is fucking slammed with driftworks or psm knucklesyou may not have perfect roll center, but its going to be ALOT better than stock knuckles because on the driftworks/psm knuckles the part that hooks up to the links is much lower than stock.

is that right?

udon! · 01-01-2010, 10:48 PM

how does a tension rod work?
how does a traction rod work?

can you guys show me pics of these installed?

PoorMans180SX · 01-01-2010, 11:19 PM

Quote:

Originally Posted by udon!

GOT IT! so basically if youre car is fucking slammed with driftworks or psm knucklesyou may not have perfect roll center, but its going to be ALOT better than stock knuckles because on the driftworks/psm knuckles the part that hooks up to the links is much lower than stock.

is that right?

Exactly

Quote:

Originally Posted by udon!

how does a tension rod work?
how does a traction rod work?

can you guys show me pics of these installed?

Pretty newbish stuff man, although the traction rod is a little harder to understand.

Found this stuff on PDM Racing

PDM Racing - Battle Version Suspension Parts

Tension Rods:

Quote:

Originally Posted by PDM Racing

Adjustable TC Rods are crucial to increase positive caster on Nissans. Caster is a very good alignment quality to induce into your Nissan, as this allows you to reduce your static camber more, yet when the car turns in, negative camber will increase which generates higher cornering ability. Translation: less inner tire wear when the car is driving in a straight line which is over 85% of the time, yet when it comes time to corner, your car will have enough caster to create good negative camber to make your car feel like it’s cornering on rails. Also, having adjustable caster means you can equalize caster from left to right on your Nissan to maximize turning performance both left and right. (On our Hunter computerized alignment rack, we notice it’s common to see 240SX’s with left to right caster specs out by as much as 1.5 degrees. Some are from curbing accidents, others are off-balance straight from Nissan Japan!) By adding adjustable TC Rods, you ensure your car will corner equally fast turning left, or turning right.

The TC Rod is the ONLY arm that locates the bottom control arm on the 240SX. When a car is under severe braking from 100 mph, the force on that TC Rod is the most extreme force that any single suspension component will experience. So replacing the stock TC Rod bushings with a spherical bearing, will ensure under braking your front end will not shimmy or wander as caster and toe will change from the TC Rod bushing flexing back and forth. For example, many of our 300ZX customers complain of brake shimmy and thinking the rotor is the culprit, they have their rotors turned. Most often, the culprit is a worn OEM TC Rod bushing which is a viscous filled rubber membrane, which is good for comfort and compliance, but makes for a terrible locator for an arm that sees such severe duty. Over time, the stock outer membrane wears from repeated force, heat and oils. Quite often we see cars come into our shop with completely blown-open TC Rod bushings.

Traction Arms:

Quote:

Originally Posted by PDM Racing

The forward traction link arms locate the rear spindle assembly, and controls the forward and aft movement of the rear upper suspension assembly on independent rear suspension (IRS) cars as the suspension moves through its’ engineered movement. While the stock stamped steel arms works fine for most applications, it’s when you drastically lower the car for race or drift, that there needs to be arm adjustment for setting the rear bump steer.

Bump steer, in short, is the change in toe settings a suspension has as it moves through it’s compression and rebound cycles. Nissan Engineers designed toe in under compression which is safer than toe out, but for optimum settings, racers like to have control of bump steer to dial in the amount of toe change their race cars will encounter as it goes over bumps and dips on the course. Cars that are “nervous” or “twitchy” are often ones that have bad bump steer, so the car literally steers itself as the car goes into a bump. While not as critical as the rear toe links or upper rear control arms, Battle Version Rear Forward Traction Link Arms will complete your rear suspension by positively locating the rear spindle for very minimal rear suspension for and aft flex. For those that know how to plot your rear bump steer, this allows these racers to properly set up the rear suspension to their personal tastes.

udon! · 01-01-2010, 11:40 PM

yaya. thats pretty much the last n00b shiz i didnt really know about. kinda was embarrassed to ask...

PoorMans180SX · 01-01-2010, 11:44 PM

Quote:

Originally Posted by udon!

yaya. thats pretty much the last n00b shiz i didnt really know about. kinda was embarrassed to ask...

Hahaha, It's cool man. I know how that is.

PerilousActs · 01-01-2010, 11:47 PM

Does anyone have any books on suspension to recommend? This could be nice for us suspension noobs to learn from.

Maybe websites covering the basics?

ballinnmiami240sx · 01-02-2010, 06:51 AM

2010 formula D rules state that the subframe can be modded for the exception of one member. What does that mean? They leave it kind vauged for the teams. NASA and SCCA 2010 rule books also do this. Different folks will interprit the rules the way they want. In any type of motorsport "Teams WIll Find an advantage" if there is not a rule. Thats why every year the rules have to be updated. Now there are ofcourse exception to any of these rules. Grandfathered laws and hate to say this but money.

I would think people want to build a track car following the latest rule books. Just makes sense!!!!

Carbomb · 01-02-2010, 11:06 AM

Quote:

Originally Posted by PerilousActs

Does anyone have any books on suspension to recommend? This could be nice for us suspension noobs to learn from.

Maybe websites covering the basics?

How to make your car handle by fred puhn

Amazon.com: How to Make Your Car Handle (0075478000012): Fred Puhn: Books
I GOT THIS GIVING TO ME BY A FORMULA D TECH GUY.
GREAT BOOK

Home DECENT SITE ON ANGLE

*Jonnie Fraz* · 01-02-2010, 11:22 AM

Quote:

Originally Posted by PoorMans180SX

Hahaha, so how does that make sense? The pickup points can't be modified, but then they can?

Pretty dumb.

Clearly the front pickups were modified on the JIC S15. They must have got an exception.

Like Mike said the rules last year were allowing modification of the pick up points. It was like 1.5" in all directions if I remember correctly.

The new exception rule states:
8.3.8 Provisions for vehicles with Vehicle Identification numbers 0-129
Competition vehicles with VID numbers 0-129 can opt for exemption from
sections 8.1.1.1, 8.3.1, 8.3.2, 8.3.3, and 8.3.4.
In such case the following is true:
• Previously approved modifications of the firewall, subframe and
transmission tunnel, as indicted in the vehicles technical record are
allowed.
• Suspension pick-up points may be moved to within 1” of the OEM
location
• Stock hubs must be used.
“Pre 130” vehicles wishing not to use the 8.3.8 exemption must request a
new VID.

As for the member modification...The way I am interpeting it is that the sub frame may be modified, but can not be compleatly cut in in half, as to retain stock dimentions side to side.
For instance this sub frame...

would be illegal since it had been cut compleatly into three parts and welded back together, but if you did not cut the front plane and just cut out the rack mounting and moved it, then it would be legal.
The only reason I can figure that they went with this is to keep competitors from widening the pick up points.

*ManoNegra* · 01-02-2010, 01:32 PM

Quote:

Originally Posted by PerilousActs

Does anyone have any books on suspension to recommend? This could be nice for us suspension noobs to learn from.

Maybe websites covering the basics?

Borrowed this one from a friend, plan on buying it eventually

Allan Staniforth's Competition Car Suspension: A Practical Handbook

Amazon.com: Competition Car Suspension: A practical handbook (9781844253289): Allan Staniforth: Books

PoorMans180SX · 01-02-2010, 01:43 PM

Quote:

Originally Posted by Jonnie Fraz

More Formula D rules

Well, that doesn't make it sound so bad.

Carbomb · 01-02-2010, 04:04 PM

Quote:

Originally Posted by Jonnie Fraz

Like Mike said the rules last year were allowing modification of the pick up points. It was like 1.5" in all directions if I remember correctly.

The new exception rule states:
8.3.8 Provisions for vehicles with Vehicle Identification numbers 0-129
Competition vehicles with VID numbers 0-129 can opt for exemption from
sections 8.1.1.1, 8.3.1, 8.3.2, 8.3.3, and 8.3.4.
In such case the following is true:
• Previously approved modifications of the firewall, subframe and
transmission tunnel, as indicted in the vehicles technical record are
allowed.
• Suspension pick-up points may be moved to within 1” of the OEM
location
• Stock hubs must be used.
“Pre 130” vehicles wishing not to use the 8.3.8 exemption must request a
new VID.

As for the member modification...The way I am interpeting it is that the sub frame may be modified, but can not be compleatly cut in in half, as to retain stock dimentions side to side.
For instance this sub frame...

would be illegal since it had been cut compleatly into three parts and welded back together, but if you did not cut the front plane and just cut out the rack mounting and moved it, then it would be legal.
The only reason I can figure that they went with this is to keep competitors from widening the pick up points.

This is 1 piece I cut the center out and moved it... so it would be "legal" as f last years rules... I think. its sectioned. not fully cut. FYI

ballinnmiami240sx · 01-02-2010, 05:15 PM

so you chopped it in 3 peices and welded it back? That would not pass tech in 2010. I dont want to turn this into a rulebook debate. More talk about suspension.

*Jonnie Fraz* · 01-03-2010, 12:07 AM

Quote:

Originally Posted by Toadstool

This is 1 piece I cut the center out and moved it... so it would be "legal" as f last years rules... I think. its sectioned. not fully cut. FYI

Not saying it is not great work, just by this years rules it is a no go.

Carbomb · 01-03-2010, 12:47 AM

2 pieces... you'll see if you do it...

*Jonnie Fraz* · 01-03-2010, 02:33 AM

If you cut into two as long as the front plane was not cut then you are good to go. In the pic it looks like it was cut into three pieces. Sweet job, and great idea. How did it work out?

I did some major mods on some Ae86 lower control arms today. Added Battle Version adjusters, moved the holes for the TC rods 25mm inboard, built new adjustable sway bar mount, and plated the crap out of them. Should have cost a forture, but he is my sponsored driver.
Now for some pics...

VIPDRFT · 01-03-2010, 03:20 AM

How would you adjust the rear roll center on a car that has a RUCA but no RLCA like this?

Would you have to modify the knuckle and/or raise the subframe? Thanks.

Steve Lloyd · 01-03-2010, 09:03 AM

Couldn't you just alter the mounting point on the struts (custom housings) to raise the spindle. There's already a guy that makes custom housings, but I was thinking you could alter the mounting location to put the spindle wherever you wanted it, and use more minor adjustments on the LCA.

Just a thought...........

240sxScores · 01-03-2010, 09:07 AM

^^ I would say raise the subframe.

The upper control arm has a ball joint. So it would be the same as a car with RLCA just flipped upside down.

95KA-Turbo · 01-03-2010, 11:19 AM

What kind of car is that?

You can do this for your lower arms (you'll have to weld in some flat metal on the one with a hole in it):

It looks like there's another arm on top of the spindle? You would need to correct that as well.

Changing the strut length will just raise the car up higher, which would correct the geometry - but defeat the purpose.

Def · 01-03-2010, 12:13 PM

That's similar to an E36/E46 rear suspension(BMW) - most of those guys just raise up the subframe as much as possible and call it good in the rear.

In our cars, the roll center doesn't drop as quickly in the rear as the front, so a huge amount of correction is not needed back there like the front.

*slider2828* · 01-03-2010, 12:22 PM

Awesome thread guys... THose books could be found on google books. Here's a link to one.

How to make your car handle - Google Books

ballinnmiami240sx · 01-03-2010, 01:04 PM

nice find. Ill have to read that later.

95KA-Turbo · 01-03-2010, 02:04 PM

Quote:

Originally Posted by Def

That's similar to an E36/E46 rear suspension(BMW) - most of those guys just raise up the subframe as much as possible and call it good in the rear.

In our cars, the roll center doesn't drop as quickly in the rear as the front, so a huge amount of correction is not needed back there like the front.

So having it flat in the front and nearly flat in the back is ideal?

01-01-2010, 06:50 PM	#151
Ghostdrifter Zilvia Member Join Date: Sep 2005 Location: New Orleans, LA Age: 34 Posts: 213 Trader Rating: (2) Feedback Score: 2 reviews	Kognition in which way did the JIC team modify the rear toe mount? Did they rotate it so the pick up point is lower? __________________

01-01-2010, 07:09 PM	#152
95KA-Turbo Post Whore! Join Date: Jul 2005 Location: LA Age: 36 Posts: 3,402 Trader Rating: (19) Feedback Score: 19 reviews	They made it so the toe arm is parallel to the LCA, how it is from the factory. __________________ Instagram - SJKnoop

01-02-2010, 06:51 AM	#163
ballinnmiami240sx Zilvia Junkie Join Date: Jan 2005 Location: gloucester, VA Age: 42 Posts: 517 Trader Rating: (6) Feedback Score: 6 reviews	2010 formula D rules state that the subframe can be modded for the exception of one member. What does that mean? They leave it kind vauged for the teams. NASA and SCCA 2010 rule books also do this. Different folks will interprit the rules the way they want. In any type of motorsport "Teams WIll Find an advantage" if there is not a rule. Thats why every year the rules have to be updated. Now there are ofcourse exception to any of these rules. Grandfathered laws and hate to say this but money. I would think people want to build a track car following the latest rule books. Just makes sense!!!! __________________ 1994 FD3S Drift // 945garage // sumospeed.com

01-02-2010, 05:15 PM	#169
ballinnmiami240sx Zilvia Junkie Join Date: Jan 2005 Location: gloucester, VA Age: 42 Posts: 517 Trader Rating: (6) Feedback Score: 6 reviews	so you chopped it in 3 peices and welded it back? That would not pass tech in 2010. I dont want to turn this into a rulebook debate. More talk about suspension. __________________ 1994 FD3S Drift // 945garage // sumospeed.com

01-03-2010, 02:33 AM	#172
Jonnie Fraz Premium Member Join Date: Jan 2005 Location: Cali Age: 53 Posts: 1,371 Trader Rating: (29) Rides Gallery: Jonnie Fraz Feedback Score: 29 reviews	If you cut into two as long as the front plane was not cut then you are good to go. In the pic it looks like it was cut into three pieces. Sweet job, and great idea. How did it work out? I did some major mods on some Ae86 lower control arms today. Added Battle Version adjusters, moved the holes for the TC rods 25mm inboard, built new adjustable sway bar mount, and plated the crap out of them. Should have cost a forture, but he is my sponsored driver. Now for some pics... __________________ Stealth-Custom-Fab.com

01-01-2010, 10:48 PM	#158
udon! Nissanaholic! Join Date: Mar 2009 Location: So-Cal Posts: 2,025 Trader Rating: (5) Feedback Score: 5 reviews	how does a tension rod work? how does a traction rod work? can you guys show me pics of these installed?

01-01-2010, 11:40 PM	#160
udon! Nissanaholic! Join Date: Mar 2009 Location: So-Cal Posts: 2,025 Trader Rating: (5) Feedback Score: 5 reviews	yaya. thats pretty much the last n00b shiz i didnt really know about. kinda was embarrassed to ask...

01-01-2010, 11:47 PM	#162
PerilousActs Zilvia Junkie Join Date: Feb 2009 Location: Walton, Kentucky Age: 30 Posts: 545 Trader Rating: (6) Feedback Score: 6 reviews	Does anyone have any books on suspension to recommend? This could be nice for us suspension noobs to learn from. Maybe websites covering the basics?

01-03-2010, 12:47 AM	#171
Carbomb Zilvia Junkie Join Date: Apr 2009 Location: USA Age: 33 Posts: 318 Trader Rating: (6) Feedback Score: 6 reviews	2 pieces... you'll see if you do it...

01-03-2010, 03:20 AM	#173
VIPDRFT Zilvia Junkie Join Date: Dec 2007 Location: Osan, South Korea Age: 35 Posts: 338 Trader Rating: (2) Feedback Score: 2 reviews	How would you adjust the rear roll center on a car that has a RUCA but no RLCA like this? Would you have to modify the knuckle and/or raise the subframe? Thanks. __________________ Holding it and...WHEEL POPS OFF! O^O^O

01-03-2010, 09:03 AM	#174
Steve Lloyd Zilvia Member Join Date: Dec 2005 Location: florida Posts: 182 Trader Rating: (0) Feedback Score: 0 reviews	Couldn't you just alter the mounting point on the struts (custom housings) to raise the spindle. There's already a guy that makes custom housings, but I was thinking you could alter the mounting location to put the spindle wherever you wanted it, and use more minor adjustments on the LCA. Just a thought...........

01-03-2010, 09:07 AM	#175
240sxScores Zilvia Junkie Join Date: May 2005 Location: Pocono's PA Age: 34 Posts: 304 Trader Rating: (2) Feedback Score: 2 reviews	^^ I would say raise the subframe. The upper control arm has a ball joint. So it would be the same as a car with RLCA just flipped upside down.

01-03-2010, 11:19 AM	#176
95KA-Turbo Post Whore! Join Date: Jul 2005 Location: LA Age: 36 Posts: 3,402 Trader Rating: (19) Feedback Score: 19 reviews	What kind of car is that? You can do this for your lower arms (you'll have to weld in some flat metal on the one with a hole in it): It looks like there's another arm on top of the spindle? You would need to correct that as well. Changing the strut length will just raise the car up higher, which would correct the geometry - but defeat the purpose. __________________ Instagram - SJKnoop

01-03-2010, 12:13 PM	#177
Def Post Whore! Join Date: Apr 2004 Location: Houston, TX Posts: 2,701 Trader Rating: (16) Feedback Score: 16 reviews	That's similar to an E36/E46 rear suspension(BMW) - most of those guys just raise up the subframe as much as possible and call it good in the rear. In our cars, the roll center doesn't drop as quickly in the rear as the front, so a huge amount of correction is not needed back there like the front. __________________ S13 Hatch - Goes around tracks quickly DEFSPORT

01-03-2010, 12:22 PM	#178
slider2828 Premium Member Join Date: Oct 2004 Location: San Francisco, CA Posts: 5,824 Trader Rating: (13) Feedback Score: 13 reviews	Awesome thread guys... THose books could be found on google books. Here's a link to one. How to make your car handle - Google Books __________________ Turn and Burn!

01-03-2010, 01:04 PM	#179
ballinnmiami240sx Zilvia Junkie Join Date: Jan 2005 Location: gloucester, VA Age: 42 Posts: 517 Trader Rating: (6) Feedback Score: 6 reviews	nice find. Ill have to read that later. __________________ 1994 FD3S Drift // 945garage // sumospeed.com

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