This is the roll center, suspension pickup, and steering angle modification thread.

[95KA-Turbo]

You all should just do what did to my LCAs to correct your roll center until Def gets his proper shit made. From what I can tell they will adjust the roll center enough to be as low as you could ever want to go....and all of the parts by themselves adds up to like 200-300 bucks to do all four corners.

[articdragon192]

Originally Posted by 95KA-Turbo

You all should just do what did to my LCAs to correct your roll center until Def gets his proper shit made. From what I can tell they will adjust the roll center enough to be as low as you could ever want to go....and all of the parts by themselves adds up to like 200-300 bucks to do all four corners.

Which is exactly what I'm gonna do on my Z.

[Choku_Dorian]

thanks to the OP and other major contributors for making this an incredibly informative thread.

Originally Posted by 95KA-Turbo

You all should just do what did to my LCAs to correct your roll

im leaning heavily towards this for the front...

Question about raising the rear subframe:

I know it increases anti-squat, is loss of traction the only negative effect of raising the SF/increased anti-squat?

Would running a wider/stickier tire help to offset the increased anti-squat...

I mean obviously a better tire = more traction but is the amount of traction we are talking about losing through raising the subframe comparable with simply running a wider tire or am I comparing apples to oranges?

I am going from a 225 to a 275 is why I am inquiring...

Also it is a drift car. So I am guessing correcting roll center > a bit more squat, for my application...

Thanks for any help.

[Z33dori]

So can some one explain the true definition of anti squat. For some reason i've had the entire theory backwards.

I thought having anti squat would help plant the rear tires, w/o removing weight from the front tires. As this would mean the car was squatting less, which meant less camber change under accel = more traction.

but after re-re-re reading, and comparing what thought i knew, to what im reading. You do want the car to squat, yes this transfers the weight back, but it also lifts the weight from the front tires. Is that right? or wrong?

anyone care to shed a lil light on this some more for me.

[PoorMans180SX]

Originally Posted by Choku_Dorian

thanks to the OP...

Would running a wider/stickier tire help to offset the increased anti-squat...

You're welcome. I've learned a ton from this thread as well.

Are you talking about using subframe risers, or something more extreme? With the subframe risers, you'll be fine, with something more extreme good luck. Your back end will be all over the place regardless of tires. Weight transfer/anti-squat comes into play when going around corners too.

Originally Posted by Z33dori

So can some one explain the true definition of anti squat. For some reason i've had the entire theory backwards.

I thought having anti squat would help plant the rear tires, w/o removing weight from the front tires. As this would mean the car was squatting less, which meant less camber change under accel = more traction.

but after re-re-re reading, and comparing what thought i knew, to what im reading. You do want the car to squat, yes this transfers the weight back, but it also lifts the weight from the front tires. Is that right? or wrong?

anyone care to shed a lil light on this some more for me.

Yes, weight tranfers to the rear under squat, increasing traction. Less squat ( or more anti-squat geometry) means less weight transfer and thus less traction. Keep in mind this applies during weight transfer fore/aft in a corner.

This is a major reason race cars run way less anti-dive and anti-squat geometry than street cars. In a race car, body motion is controlled by the springs, so dive and squat are not effecting so much of the geometry while giving increased traction.

[atutt]

Originally Posted by PoorMans180SX

You're welcome. I've learned a ton from this thread as well.

Are you talking about using subframe risers, or something more extreme? With the subframe risers, you'll be fine, with something more extreme good luck. Your back end will be all over the place regardless of tires. Weight transfer/anti-squat comes into play when going around corners too.



Yes, weight tranfers to the rear under squat, increasing traction. Less squat ( or more anti-squat geometry) means less weight transfer and thus less traction. Keep in mind this applies during weight transfer fore/aft in a corner.

This is a major reason race cars run way less anti-dive and anti-squat geometry than street cars. In a race car, body motion is controlled by the springs, so dive and squat are not effecting so much of the geometry while giving increased traction.

Raising the subframe really affects traction that much? Talking about a severe raise.

So if springs are controlling much of the body motion in a race car could you just simply run a stiffer coilover set up to combat the anti-squat?
That's the impression I'm getting.

P.S.
I think much confusion about anti-squat comes from the term itself.

I also think there may need to be a thread on anti-dive and anti-squat.
To clear the air once and for all.

[Pandapants]

my head hurts

[renegade_ewok]

You would run a SOFTER spring to combat anti-squat.

You have watched high HP V8s and supras, etc launch and the rear just DROPS. Thats a SOFT rear spring. If the rear geometry naturally supplies traction-based squat, then you can run stiffer suspension without sacrificing too much grip. It WILL still be effected though.

Squat by itself can be derived from ride height, spring softness, as well as suspension travel and geometry. If the rear end drops when launching through either a soft spring, long suspension travel due to suspension setup, or whatever, you have squat which will contribute to traction.

You can manipulate dive and squat through modifications in suspension travel length, geometry, and suspension components and how they act (e.g. stiffness, dampening bound/rebound). For example, if you can get a soft spring with low rebound and a car that has a LOT of power, you can get the car to squat for a longer time and maintain rear end traction.

[tryangle]

Originally Posted by 95KA-Turbo

You all should just do what did to my LCAs to correct your roll center until Def gets his proper shit made. From what I can tell they will adjust the roll center enough to be as low as you could ever want to go....and all of the parts by themselves adds up to like 200-300 bucks to do all four corners.

Parts list and numbers, to ease the search?

[PoorMans180SX]

Originally Posted by tryangle

Parts list and numbers, to ease the search?

It's in the first post.

Originally Posted by atutt

Raising the subframe really affects traction that much? Talking about a severe raise.

So if springs are controlling much of the body motion in a race car could you just simply run a stiffer coilover set up to combat the anti-squat?
That's the impression I'm getting.

P.S.
I think much confusion about anti-squat comes from the term itself.

I also think there may need to be a thread on anti-dive and anti-squat.
To clear the air once and for all.

Race cars run LESS anti-squat geometry, so that the car wants to squat MORE. But, you don't see as much squat because of the stiff spring rates. Your geometry has a lot to do with how weight transfers.

Originally Posted by renegade_ewok

You would run a SOFTER spring to combat anti-squat.

You have watched high HP V8s and supras, etc launch and the rear just DROPS. Thats a SOFT rear spring. If the rear geometry naturally supplies traction-based squat, then you can run stiffer suspension without sacrificing too much grip. It WILL still be effected though.
.

Yes. That is correct.

[atutt]

It's official.. I'm completely lost in this whole anti-squat, anti-dive stuff..

With each post it gets more and more confusing... lol

[drift freaq]

Now I do not think anyone would argue here that anti squat does not push the wheels down. Of course eliminating extreme squat can help the car to be more balanced.


Now the myth that adding squat increases traction is starting to be purported here.

Now Anti squat only offers the advantage of reducing vertical travel thus sometimes in some suspensions improving the geometry.

When the IRS is setup for Negative camber gain in bump or cornering under acceleration squat can cause camber change and track and contact patch change. If you are running wide flat tires this can lose traction.

Therefor if you are running a decent amount of negative camber in the rear having squat could put your suspension at a traction disadvantage.

While Nissan did change a few things with the S14 subframe I do not believe it made such a radical change in anti squat as to cause this issue.

But then one wonders if using the S14 subframe is in fact a such a great improvement over the S13 subframe? Quite possibly a lesson in unnecessary effort.

Perhaps one could get that improvement with changes to the suspension parts of the S13 i.e. through adjustability and spring rates.

There are actually people in the drift community that have gone both directions and come back saying indeed they can get the improvements with the S13 subframe. They also did not like what the S14 subframe did to how their car felt and handled. I for one am not a fan of S14's to begin with feel wise. LOL

Of course most people in the road race community will discount whatever the drifter says. As road racers quite often look down or frown upon the whole drift thing. I will also add in the that while what the drift community may do or say may not be correct nor are all things in the road race community always correct.

Even though Road racing is actually linked to drifting both here in the U.S.( Super Modifieds, quarter midgets etc) and in Japan.(drifting growing out of Japanese Road racing)

Sorry guys but I just had to point this stuff out. Its still not a clearly addressed issue in my book and I feel there are different schools. Possibly neither being wrong or right.




Now as far as roll center goes we are all in agreement.

[Choku_Dorian]

Originally Posted by PoorMans180SX

You're welcome. I've learned a ton from this thread as well.

Are you talking about using subframe risers, or something more extreme? With the subframe risers, you'll be fine, with something more extreme good luck.

just the risers, or washers/pipe. which Im almost certain raise it the same amount...

thanks, exactly what i needed to know.

Originally Posted by renegade_ewok

You would run a SOFTER spring to combat anti-squat.
.

yea exactly but wont that increase body roll as well?

Originally Posted by atutt

It's official.. I'm completely lost in this whole anti-squat, anti-dive stuff..

With each post it gets more and more confusing... lol

acceleration causes weight to be tranferred to the rear(why rwd faster than fwd), that is squat, giving you more traction on your rear tires. when you raise the subframe you increase anti-squat or 'lessen the amount of squat'. meaning less weight gets transferred to your rear tires, in turn, less traction with your rear tires.

Braking causes nose dive. anti dive setups would reduce the amount of nose dive you see under braking.

got it?

[95KA-Turbo]

It should be pretty straight forward right?

IF: squat = grip

THEN: anti-squat = anti-grip


You just have to take things into account like shocks, springs, and suspension geometry to name a few....right? (I am understanding this properly right?)


It appears a lowered S14 with 7K rear springs on Fortune coilovers allows for a decent amount of squat:

YouTube - Big Slide at the Koni Weekend

The rear was sinking down just past the wheel lip (it is a little blurry in the video but its happening).

Since I lowered the rear 1" from that and have 1/2" subframe risers I should only need a little more from my LCA modification to correct the geometry to the point of that video.

[drift freaq]

Originally Posted by Choku_Dorian

acceleration causes weight to be tranferred to the rear(why rwd faster than fwd), that is squat, giving you more traction on your rear tires. when you raise the subframe you increase anti-squat or 'lessen the amount of squat'. meaning less weight gets transferred to your rear tires, in turn, less traction with your rear tires.

Braking causes nose dive. anti dive setups would reduce the amount of nose dive you see under braking.

got it?

above is actually the purported myth I am talking about in my post. I am not sure you should purport what your saying as gospel.
As I have posted adding squat is not always advantageous. In fact Nissan had a problem with too much squat in the early Z's.

I think you guys are taking the anti squat vs squat debate and trying to make it to cut and dry. Its not and my post pointed it out.

[atutt]

Originally Posted by drift freaq

above is actually the purported myth I am talking about in my post. I am not sure you should purport what your saying as gospel.
As I have posted adding squat is not always advantageous. In fact Nissan had a problem with too much squat in the early Z's.

I think you guys are taking the anti squat vs squat debate and trying to make it to cut and dry. Its not and my post pointed it out.

I think this is why I've had such a hard time understanding it, lol...

I have a much better understanding now with the few posts above though.

For some reason this didn't want to sink in.

[Z33dori]

what about the 2nd half of my theory. If you have to little anti- squat, then would you be lessening you front grip ( in drifting form).

[drift freaq]

Originally Posted by Z33dori

what about the 2nd half of my theory. If you have to little anti- squat, then would you be lessening you front grip ( in drifting form).

well anti squat does not affect weight transfer, it controls the resultant angle the sprung mass will adopt due to weight transfer. Now anti squat will try to prevent the front end from rising, not effecting weight transfer at the front but it will affect camber curves.

In effect roll center can come into play here as well. If roll center drops rapidly due to c.g. then anti squat would help the situation. ( extreme rare cases)

did I digress a bit? LOL in Motorcycles squat does indeed cause the bike to steer wide. So one would theorize that the same dynamics are going on in cars as well as it is physics.

When I drove 240Z's I experienced lighter feeling front ends when the rear would squat hard, especially in corners which would tend to cause an understeer situation. The answer( for me at the time , hehehhehe) was to apply throttle on oversteer to correct the situation. i.e. in my opinion anything over 70 in a corner with a 240Z was a driving sideways situation if you did not want to understeer. Of course this was running sways and shocks and springs.

I should also qualify this, as I was not driving a factory effort road racing 240Z which tended to be somewhat of a different animal.



Of course the Z has had the disadvantage of that 6 cylinder engine hanging out way in front of the strut towers. Which by all means did not help either.

510's were not as bad of course 510's had semi trailing arms vs the Z's A arms. Both the suspensions had their down sides though they were pretty good for they day considering the cost of the cars.

Of course 510's on the track and Z's tended to be sprung pretty damn stiff to eliminate body roll as well. Hence 510's going through corners flat as board while the Alfa GTV would lift its inside front wheel. Even the BMW could not corner as smoothly and had more body roll.

There I go again. LOL

So your theory is sound.

[Slidin' Sam]

How about this...if you lower your car 2" and then raise the subframe 2", your suspension armes should travel as if in the stock height location, which seems to be what people are after, right?

[Pandapants]

How do you even measure squat?

[UNITEDMASTER]

This thread has so much bogus/bad info its unreal. I would suggest for those that want to study/learn about suspension and suspension geometry to invest in a few key books that I think have been mentioned in this thread. These books have been written by people with first hand knowledge. That doesnt meen they are 100% either BUT you will have a better understanding of the basics. Then you can apply that to your particular situation.

[longfellow]

On the subject of Anti-squat/subframe rasing, here is my set up:

-Subframe flush with chassis
-4.5kgmm rear springs (KTS coil-overs)
-Spherical everything
-Stock rear sway bar with bushing kit
-255-40-17 NT05s
-S15 helical diff
-no roll center correction

I cant do more than chirp 2nd at 14-15psi which is around 260-270ft/tq

The car is planted and it squats pretty damn well, enough that when I launch it will tuck the rear rim (and tire) about an 1" into my fender. I have the coil-over set to full soft in the rear for DD reasons, but it seems to work very well when ever I toss it around on the back roads and stuff. I think its a good compromise.

I'm going to a DE this weekend so I'll play around with some settings and see what I like.

[PoorMans180SX]

Originally Posted by drift freaq

I think you guys are taking the anti squat vs squat debate and trying to make it to cut and dry. Its not and my post pointed it out.

You are correct in what you say. The only thing I was trying to point out is that too much anti-squat is bad, and raising your subframe more than 1/2" increases your anti-squat too much considering that S13's already have a lot of it.

Originally Posted by drift freaq

Now the myth that adding squat increases traction is starting to be purported here.

Originally Posted by drift freaq

well anti squat does not affect weight transfer, it controls the resultant angle the sprung mass will adopt due to weight transfer.

I think some of us are talking about different things. Some people are talking about geometry, and others are talking about the actual movement of the chassis.

Drag racers would not want their cars to squat if it did not increase traction at the rear wheels.

Front wheel drive drag racers use tons of anti-squat geometry in the rear to help keep the FRONT wheels planted during acceleration.

Originally Posted by Slidin' Sam

How about this...if you lower your car 2" and then raise the subframe 2", your suspension armes should travel as if in the stock height location, which seems to be what people are after, right?

See above.

[Choku_Dorian]

Originally Posted by drift freaq

above is actually the purported myth I am talking about in my post. I am not sure you should purport what your saying as gospel.
As I have posted adding squat is not always advantageous. In fact Nissan had a problem with too much squat in the early Z's.

I think you guys are taking the anti squat vs squat debate and trying to make it to cut and dry. Its not and my post pointed it out.

Yes I agree 100%.

I was just trying to keep it cut and dry and simple to understand how squat/anti-squat works, in theory. It's much easier for straight line racing.

Like u said a lot of squat will decrease your contact patch in the rear, could also affect your traction up front. That is just a lot for someone who is confused as to exactly what anti-squat is to begin with to understand.

But very good points to bring to light for sure.

[SoSideways]

The anti-squat on the S13 subframe can be tuned via those urethane "pineapple" bushings that go above/below the subframe mounting points by tilting the subframe, or straight up lowering it in the chassis.

Basically, what causes the S13's subframe to have more anti-squat than the S14/S15 subframes, is essentially the lower control arms' inner pick up points. On the S13 they are a bit more tilted/angled, versus the S14/S15 ones that are a bit more flat.

[nieko]

so you could also move the rear pickup point on the LCAs up and make them level and that would dial in just a little more squat?

[drift freaq]

Originally Posted by PoorMans180SX

You are correct in what you say. The only thing I was trying to point out is that too much anti-squat is bad, and raising your subframe more than 1/2" increases your anti-squat too much considering that S13's already have a lot of it.

I will agree that to much anti squat will cause wheel hop in the rear etc and is not a good thing.

Which seems to be why the road racers are so hung up on it. Though there are other factors at play though that can lead to wheel hop as well.

Originally Posted by PoorMans180SX

I think some of us are talking about different things. Some people are talking about geometry, and others are talking about the actual movement of the chassis.

Drag racers would not want their cars to squat if it did not increase traction at the rear wheels.

Front wheel drive drag racers use tons of anti-squat geometry in the rear to help keep the FRONT wheels planted during acceleration.

.

well there is indeed a debate about whether squat actually does add traction I am not so sure it does and I think its a myth. IMO

Originally Posted by SoSideways

The anti-squat on the S13 subframe can be tuned via those urethane "pineapple" bushings that go above/below the subframe mounting points by tilting the subframe, or straight up lowering it in the chassis.

Basically, what causes the S13's subframe to have more anti-squat than the S14/S15 subframes, is essentially the lower control arms' inner pick up points. On the S13 they are a bit more tilted/angled, versus the S14/S15 ones that are a bit more flat.

which brings me right back to my theory that using a S14 subframe in a S13 is perhaps not as critical or needed as some have indicated. Basically what you have described above is a way to tune out some of the anti squat behavior of the S13 subframe. Through bushings and or adjustable lower control arms.
If you feel its causing you problems or would like that.

One would suggest that there is more than one way to skin this cat.

[SoSideways]

Originally Posted by nieko

so you could also move the rear pickup point on the LCAs up and make them level and that would dial in just a little more squat?

Originally Posted by drift freaq

which brings me right back to my theory that using a S14 subframe in a S13 is perhaps not as critical or needed as some have indicated. Basically what you have described above is a way to tune out some the anti squat behavior of the S13 subframe. Through bushings and or adjustable lower control arms.
If you feel its causing you problems or would like that.

One would suggest that there is more than one way to skin this cat.

Quite right.

However, please make sure that if you are racing within a set of rules that you are allowed to use those urethane bushings to tilt the subframe, or change the inner pick up points of the lower control arms.

If those are not feasible options, then the S14/S15 subframe might be the only other thing that you can do, if you can convince the stewards that you're not really breaking any rules by switching to that subframe or something.

[Z33dori]

How about this :
s13 w/s14 SF
adj the subframe bushing the same as you would before to reduce the anti squat, and run a softer spring.

that way you now get:
wider track width
corrected roll center
and still reducing anti squat, hopefully to where it was before, maybe lower

[S14DB]

My understanding from the SCCA Tech was as long as the Studs in the Frame was in the same location you are not moving the mounting point.