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-   -   This is the roll center, suspension pickup, and steering angle modification thread. (#/f/showthread.php?t=296725)

racepar1 12-28-2009 03:11 PM

I have some concerns about adjusting the rear roll center by simply spacing the joint down. The balljoints are mounted at an angle. That means that if you simply space the joint down you end up with a longer lower control arm to put the upright in the same position. Since the rear is a multilink that could affect the camber and toe curves. The affect could, of course potentially be positive or negative, but negative is much more likely. IMO in the rear the way to go is to re-locate the subframe and modify the spindles.

PoorMans180SX 12-28-2009 04:00 PM

Quote:

Originally Posted by mmdb (Post 3206636)
The Driftworks option posted on page one looks like the best option, though I'd like to know if it can be used with a z32 brake setup.

http://i7.photobucket.com/albums/y25...c/IMG_0663.jpg


Man, it's too bad GP Sports stopped making those for the S-chassis.

Supposedly you can use the Driftworks knuckles with the Z32 rear brakes, but they require "modifications" to fit.



Quote:

Originally Posted by racepar1 (Post 3206700)
I have some concerns about adjusting the rear roll center by simply spacing the joint down. The balljoints are mounted at an angle. That means that if you simply space the joint down you end up with a longer lower control arm to put the upright in the same position. Since the rear is a multilink that could affect the camber and toe curves. The affect could, of course potentially be positive or negative, but negative is much more likely. IMO in the rear the way to go is to re-locate the subframe and modify the spindles.

Are you talking about using a longer ball joint/shank in the lower control arm? This would affect the suspension curves, but really the affect would not be large.

Most roll center adjusting control arms/ball joints only move the pivot point down by 15mm or so and that 15mm only increases control arm length probably 5mm effectively, which should be able to be offset by the adjustment of the inner heim joints if you have an adjustable arm. And if not, just adjust all your other arms 5mm longer.

95KA-Turbo 12-28-2009 04:52 PM

He's talking about the actual arcs that the arms go through being effected in a negative way. Which is why a modification to the rear toe arm mount on the knuckle is likely necessary to achieve proper suspension geometry out back (like the picture I posted of the S15 with Z32 uprights).



Danny, I do not believe there is enough material on the front spindle to just cut the bottom off and bolt something else on. You can see the GP Sports knuckles have a good 1/2 inch more material then the stock knuckles where the bottom part bolts on.



It IS a shame that GP Sports stopped making them....but at the same time it was an unmarketable product. Very few S-chassis owners can afford/are willing to throw a good 1000-1200 bucks for a set of knuckles here in the US. Especially when it can be corrected by just raising the car up (which is what people who care about performance usually do).

NiSilS14 12-28-2009 07:52 PM

Can we sticky this? This is very good.

PoorMans180SX 12-28-2009 09:40 PM

Quote:

Originally Posted by 95KA-Turbo (Post 3206843)
He's talking about the actual arcs that the arms go through being effected in a negative way. .

Using a longer shank doesn't affect the arc of the control arm at all. It merely moves it down in it's arc. It moves exactly the same way, think about it. The other control arms stay the same as well.

EDIT: The relationship between the arms does change slightly, but as stated below, the change is not really a performance-hurting one.

mmdb 12-28-2009 10:56 PM

Quote:

Originally Posted by PoorMans180SX (Post 3207263)
Using a longer shank doesn't affect the arc of the control arm at all. It merely moves it down in it's arc. It moves exactly the same way, think about it. The other control arms stay the same as well. Their relationship does not change. Just because the lower control arm is spaced down doesn't mean that the arms move any different than they used to.

wrong. For the front, being a macphearson strut design, has a 1:1 ratio in relation for the lca moving 1" and the shock compressing 1", so you could almost assume it does not affect other suspension components. The problem is more apparent in a multilink suspension such as the rear links on our car. It's difficult to conceptually visualize, but a few hardcore racing companies have developed new spindles in contrast to addig spacers under the lca to combat the negative affects of lowering a production based vehicle while preserving the initial suspension dynamics from the factory. In other words there more to adding spacers between the knuckle and lca.

Def 12-28-2009 11:51 PM

Quote:

Originally Posted by mmdb (Post 3207378)
wrong. For the front, being a macphearson strut design, has a 1:1 ratio in relation for the lca moving 1" and the shock compressing 1", so you could almost assume it does not affect other suspension components. The problem is more apparent in a multilink suspension such as the rear links on our car. It's difficult to conceptually visualize, but a few hardcore racing companies have developed new spindles in contrast to addig spacers under the lca to combat the negative affects of lowering a production based vehicle while preserving the initial suspension dynamics from the factory. In other words there more to adding spacers between the knuckle and lca.

Not really sure what you're getting at, but all you would change(besides the roll center) would be the camber and possibly toe curves(I'm imagining this might stay the same). If anything, you'll probably increase your camber gain in the rear, even though that's not really a problem when lowered.

As for the GP Sports knuckles - if you're fine with two bolts in bending, why not just drill out the stock spindle and use a 3/4" bolt in bending in place of the balljoint?

mmdb 12-29-2009 12:06 AM

Just making the point that it requires more attention to correctly raise the roll center given a multi-link suspension. Unless I misread.

PoorMans180SX 12-29-2009 12:26 AM

Quote:

Originally Posted by mmdb (Post 3207470)
Just making the point that it requires more attention to correctly raise the roll center given a multi-link suspension. Unless I misread.

Do you realize I started this thread? Hahaha, I know more than you think, though I think Def knows more than all of us.

Quote:

Originally Posted by mmdb (Post 3207378)
It's difficult to conceptually visualize, but a few hardcore racing companies have developed new spindles in contrast to addig spacers under the lca to combat the negative affects of lowering a production based vehicle while preserving the initial suspension dynamics from the factory. In other words there more to adding spacers between the knuckle and lca.

Did you read through the first post? There are a couple that I posted up.

Anyway, I was responding to racepar1's post.

You have a point, but as I stated in my post, the only real difference is LCA length. Which is really quite slight, as the angle of the ball joints makes the additional length of the ball joint/shank not the length the control arm is extended. Here's my crude Paint example:

http://i24.photobucket.com/albums/c25/Turbo711/LCA2.jpg

And as Def stated, the camber and toe curves change very little with this.

I think you guys are making it out to be a bigger deal than it actually is.

RastaS13 12-29-2009 01:07 AM

Geder done andy!!!!!

ballinnmiami240sx 12-29-2009 06:28 AM

This is the reason we went ahead with making our set up. Alot of assumptions, I think's, and what if's. Until we get this 95katurbo's car on an alingment rack and take it to the track we will not know the results. Kinda ol'skool engineering I call it. Build it and take it to the track and beat the piss out of it. If it works everyone will want to have his set up. If it breaks into a billion pieces then we will get "the i told you so". As I look at the set up on the ground with the new GM ball joint set up we will be spacing the LCA about 20mm down. The spherical bearing that I intalled works with the up and down movement of the LCA. Essentially affecting nothing at this point. Under lateral G's we will have to wait and see. As far as I can tell I see nothing but positives from our set up. It beats the crap out of an old worn out rubber set up.

scottie 12-29-2009 08:07 AM

Where did you find the pic of Powered Max fabbing some new hubs?

PoorMans180SX 12-29-2009 09:26 AM

Quote:

Originally Posted by scottie (Post 3207764)
Where did you find the pic of Powered By Max fabbing some new hubs?

BTW, it's Parts Shop MAX. Powered By MAX is the website name.

POWERED BY MAX: Forums フォーラム/ 作ってもらいたã �„パーツ Wish List / Rear knuckle

lazysk8er2 12-29-2009 09:40 AM

good info subscribed

mmdb 12-29-2009 11:18 AM

Found these on Driftworks' website here.

http://media.driftworks.com/assorted/NewUprights1.jpg

http://media.driftworks.com/assorted/NewUprights2.jpg

PoorMans180SX 12-29-2009 12:07 PM

Solid! I've just found out they also make tie rod offset spacers (found them in that link). These space the tie rods farther forward to correct for "over centering" of the steering rack with all that increased angle. Sick!

Check them out:

http://i24.photobucket.com/albums/c2...RackSpacer.jpg

http://i24.photobucket.com/albums/c2...ckSpacers3.jpg

http://i24.photobucket.com/albums/c2...ckSpacers7.jpg

Original post edited!

GSXRJJordan 12-29-2009 01:20 PM

^^^ Driftwerks = killer stuff. I'm happy to see innovation still being done in the S-chassis community!

I might have to get some measurements and CNC a spindle... I wonder how long it would take and how many pieces I'd screw up before I got it right lol...

93nismo 12-29-2009 02:02 PM

i love learning things about my car. this is the most ive learned in probably the 3 weeks ive been on break. awsome.

nathanong87 12-29-2009 02:25 PM

Quote:

Originally Posted by PoorMans180SX (Post 3208115)
Solid! I've just found out they also make tie rod offset spacers (found them in that link). These space the tie rods farther forward to correct for "over centering" of the steering rack with all that increased angle. Sick!

Original post edited!

i believe nigel from AUS also has these CNC'd :fruit:

!Zar! 12-29-2009 03:30 PM

I'd like to try out those offset tierod spacers. Are they up for sale yet?

PoorMans180SX 12-29-2009 05:22 PM

Quote:

Originally Posted by !Zar! (Post 3208491)
I'd like to try out those offset tierod spacers. Are they up for sale yet?

Negative. Not on their website at least.

It would be kinda nice if some people in the US made some of this stuff. Not that I don't want to support Drift Works, but I can't imagine it being very affordable to ship stuff from England.

Oh well.

ManoNegra 12-29-2009 05:41 PM

Quote:

Originally Posted by PoorMans180SX (Post 3208669)
Negative. Not on their website at least.

It would be kinda nice if some people in the US made some of this stuff. Not that I don't want to support Drift Works, but I can't imagine it being very affordable to ship stuff from England.

Oh well.

I'm oblivious, are those only for drifter knuckles with stupid crazy steering angle?
looks kinda sketchy to me.

PoorMans180SX 12-29-2009 05:54 PM

Quote:

Originally Posted by ManoNegra (Post 3208713)
I'm oblivious, are those only for drifter knuckles with stupid crazy steering angle?
looks kinda sketchy to me.

Yeah, they keep the tie rods from moving ahead of the knuckle at extreme steering angles.

That's a Chromoly bolt, CNC'd billet aluminum, and a tie rod. How is that sketchy?

nieko 12-30-2009 03:41 AM

wow... driftwerks if amazing... so genius.

when i end up getting knucles and fun, im buying those.

ballinnmiami240sx 12-30-2009 07:18 AM

those have been around for about 2 years now. The first time I saw them was on the C's garage yellow coupe.

ManoNegra 12-30-2009 07:46 AM

Quote:

Originally Posted by PoorMans180SX (Post 3208737)
Yeah, they keep the tie rods from moving ahead of the knuckle at extreme steering angles.

That's a Chromoly bolt, CNC'd billet aluminum, and a tie rod. How is that sketchy?

just wondering how a car would drive under normal conditions, daily for example, with those
or are they a drift only, trailered back and forth to track car deal?

ballinnmiami240sx 12-30-2009 08:35 AM

I dont see how it could effect anything. All you are doing is correcting geometry when the car is lowered or has extreme angle. I daily drove my car with modded knuckles and super low ride height. Did it suck? Yes, but I knew that was going to happen. Now did it perform on track. Hells yeah!!!! I dont drive my track car on the street anymore. The coilovers will rattle your teeth lose and the road noise is loud. hahaha.....I just realized I sounded OLD.

mmdb 12-30-2009 09:44 AM

I read a post on driftworks concerning those offset spacers. They were originally developed and used in japan, but during usage they either broke or caused heavy wear on the steering rack causing it to deform. I'll try to find the post.

PoorMans180SX 12-30-2009 10:43 AM

They were talking about the URAS ones, which are a different design and less quality.

Driftworks designed theirs to be better.

I'll quote:

Quote:

Originally Posted by James (from Driftworks)
Now that is a good call

If we were to do it, they wouldn't be the same design as the URAS ones. We're hearing reports from Japan of those ones either coming loose or snapping, but we have something else up our sleeves


Jonnie Fraz 12-30-2009 10:56 AM

Quote:

Originally Posted by mmdb (Post 3208002)

Now that is a JIG...Holy crap!


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