Camber adjustment 300zx

[Z3_GoCar]

Got it. In that case, I'd agree that it's legal.

You have to understand that especially in the case of FWD it's very, very, very unusual to have struts like that. Most manufacturers, to improve production and decrease costs, will have separate strut and knuckle assemblies and the ball joints and and tie rods attach to the knuckles. The primary reason for this is that FWD knuckles also have to not only accommodate the strut, ball, joint, and tie rod attachments, but the drixe axle pass-through and wheel bearings assembly. Thus, it's much more cost-effective to build a separate casting (and it makes replacement struts very easy and cheap). In fact, with the noted exception of the Audi, I can't right off the top of my head think of another FWD car that does what's illustrated above...

Further note that if the tie rod and ball joint attach to the knuckle, changing the location of its attachment to the strut has zero effect on the suspension geometry; moving the strut up and down relative to the knuckle only affects the location of the piston rod and the position of its stroke within the bore. So, no geometry advantage.

I'd be all over redesigned front struts on the RX-7...and I even might go so far as to suggest it not get the strut subtractor... - GA

BMW's also use a forged knuckle, which bolts to the strut and a ball joint pressed in the control arm. The solution from James Clay is to replace the ball joint with a spherical bushing (sound familiar) and put spacers between the knuckle and the control arm to regain the correct angle. This neccetates a kit to correct for bump steer. I'd argue that it's perfetly legal under free bushing material.

As for Tristian, you can slot the holes in the rear, but not the front. That should get you a little more that ecentric bushings would.

 

[jimmyc]

So the way im reading the rules... for a typeical DWB

Bushing material, including that used to mount a suspension
subframe to the chassis, is unrestricted. This includes
the use of spherical bearings, so long as no suspension
component is modified to facilitate their installation. Retention
of spherical bearings by use of tack welds is allowed,
as long as the welds serve no other purpose.

Roll center adjusters are legal. And you might be able to make a case for bump steer adjustment being legal.

Ball joint = Suspension bushing

 

[JeffYoung]

A ball joint is a bushing?????

 

[TomL]

Okay, I guess we're mostly in agreement now.

Your original statement was.... "the downfall of true "struts" ain't camber curves, it's roll centers... the former you can fix, the latter is built in" (sorry I haven't figured out how to do the "quote" function) That's why I started this whole discussion in the first place.

And I still disagree about how much you can change roll centers. In a lowered RX7, the spacers mean the difference between having a roll center 2-3 inches underground versus something reasonable. And the spacers also mean the difference between having essentially zero camber gain and at least a little. So now I only have to run 5 degrees of static to make it work. If that qualifies as "virtually negat[ing] all geometry problems of the strut design", can we expect the GT1 guys to convert to struts in the near future?

Cheers

 

[jimmyc]

A ball joint is a bushing?????

what the heck else would it be? It allows controlled movement in the suspension. Kinda of a weirdly designed Spherical bearing.

 

[Z3_GoCar]

A ball joint is a bushing?????

Sure, BMW's use lots of ball joints for bushings. The inner pivot on the control arm is a ball joint, even the sway bar is connected in the stock form with mini ball joints.

 

[JeffYoung]

Tough one for me to swallow guys. GCR specifically defines ball joint and bushing separately:

Ball Joint [FONT=Univers,Univers]- A bearing coupling, generally in suspension or steering systems, consisting of two (2) mating surfaces, one (1) convex and one (1) concave, which permits a range of angular displacements of the two (2) attached shafts over a prescribed range. [/FONT]
[FONT=Univers,Univers][/FONT]
[FONT=Univers,Univers]Bushing/Bush [FONT=Univers,Univers]- A sleeve or tubular insert, whose purpose is to reduce the dimension(s) of an existing hole. A protective liner that cushions noise, friction, or movement such as a rod end or spherical bearing.
[/FONT][/FONT]

 

[Greg Amy]

I'd argue that it's perfetly legal under free bushing material.

No way, dude. Not even a gray area.

 

[jimmyc]

Tough one for me to swallow guys. GCR specifically defines ball joint and bushing separately:

Ball Joint [FONT=Univers,Univers]- A bearing coupling, generally in suspension or steering systems, consisting of two (2) mating surfaces, one (1) convex and one (1) concave, which permits a range of angular displacements of the two (2) attached shafts over a prescribed range. [/FONT]
[FONT=Univers,Univers][/FONT]
[FONT=Univers,Univers]Bushing/Bush [FONT=Univers,Univers]- A sleeve or tubular insert, whose purpose is to reduce the dimension(s) of an existing hole. A protective liner that cushions noise, friction, or movement such as a rod end or spherical bearing.
[/FONT][/FONT]

Sure it does because it is a specific kind of bushing. Just like a spherical bearing is a specific kind of bushing.

Just because they are defined differently does not mean that they aren't both suspension bushings.

 

[jimmyc]

No way, dude. Not even a gray area.

I disagree, this is perfectly legal.

Reasonable minds differ. But hey whats new, people have differing opinions on many things....

Just like i think that taking a non sun roofed chassis turning it into a model that was ONLY available with a sunroof and NOT adding the extra bracing that the sunroof equipped model has, is not legal. Not even close to being a gray area.

 

[Ron Earp]

I, and most of the people I race with, are WAY too conservative and concerned about being legal. Man these discussions are eye openers.

 

[Greg Amy]

And I still disagree about how much you can change roll centers. In a lowered RX7, the spacers mean the difference between having a roll center 2-3 inches underground versus something reasonable...

Dude, you're losing me here with confusing terms and mixing around all your cars and suspension designs. Some clarifications:

- First, the whole original point of this topic was about a 300ZX. You came into this discussion with an RX-7 as your base premise. Ergo, your initial posts became immediately confusing.

- B, in the last couple of posts, when you said "spacers" I thought you meant wheel spacers. That's what my last response to you, wher eI said spacers would have insignificant effect on roll centers, was in reference to.

- Trois, yes I agree your "turn in spacers" or "correctors" or whatever as used on the front suspension of the Mazda RX-7 will significantly correct roll centers. That's why I made all those posts about how much I liked that and the Audi's front suspension.

- Quattro: BUT, since MOST CARS cannot use those ball joint/tie rod spacers legally (please read ALL my posts above) then the fact remains that the VAST MAJORITY OF CARS CANNOT correct roll centers. This is what my original premise of the lack of roll center correctability was based on.

Capiche?

GA

 

[Greg Amy]

I disagree, this is perfectly legal.

Reasonable minds differ. But hey whats new, people have differing opinions on many things...

Excellent. Let me know when we'll be at the track together and for $25 I can get the stewards' reasonable opinions.



GA

(P.S., No personal offense intended. But, you're wrong. And I have a very low tolerance for rules intorturation and/or outright cheating.)

 

[jimmyc]

Excellent. Let me know when we'll be at the track together and for $25 I can get the stewards' reasonable opinions.



GA

(P.S., No personal offense intended. But, you're wrong. And I have a very low tolerance for rules intorturation and/or outright cheating.)

But you are doing it with the non sunroof car, and turning it into a sunroof car without adding in he extra bracing. (out right cheating)

No personal offense taken.

PS i don't currently race IT.

 

[Z3_GoCar]

No way, dude. Not even a gray area.

So because mini ball joints are used on the sway bar, we can't change to spherical bearings for the sway bar link? If suspension bushings are allowed to be swaped out with sperical bearings, all of them, then why not any ball joint like bushings? IISYCTYBWC Doesn't the 240sx use ball joints to locate the rear? I seem to remember it had a roll steer system built in. It's not like I purchased this kit, but I thought given the spherical bearing debate it was legal.

 

[Greg Amy]

But you are doing it with the non sunroof car, and turning it into a sunroof car. (out right cheating)

Not that it's relevant, but "even if" I were cheating, that doesn't make "your" cheating legal or acceptable, nor does it make my premise that you're cheating incorrect or out of line.

And, you too have the ability - nay, the responsibility - to protest me if you truly believe the above (assuming you were racing in IT, and since you're not I hardly understand why you're stepping into this discussion other than just to argue...though you're certainly entitled to your misguided opinion.)

And finally, despite its irrelevance, you have zero clue about what I'm actually doing.

GA

 

[Greg Amy]

So because mini ball joints are used on the sway bar, we can't change to spherical bearings for the sway bar link?

Swaybars are free. Ball joints are not.

...then why not any ball joint like bushings?

Because ball joints are not suspension bushings.

Doesn't the 240sx use ball joints to locate the rear?

Yes, sphericals are used in place of suspension bushings, explicitly allowed as per ITCS.

Sorry, man...

GA

 

[Z3_GoCar]

Swaybars are free. Ball joints are not.

Because ball joints are not suspension bushings.

Yes, sphericals are used in place of suspension bushings, explicitly allowed as per ITCS.

Sorry, man...

GA

Sorry, maybe I'm confused... first you say ball joints are not suspension bushings, then you say they are??

 

[Greg Amy]

Sorry, maybe I'm confused... first you say ball joints are not suspension bushings, then you say they are??

Where did I say that ball joints are suspension bushings?

On edit:
James, just to make sure we're not cross-posting on terminology, look at your graphic above. #6 is not a ball joint, as you stated; it's a suspension bushing which may, depending on its design, incorporate a bearing. It is legal to replace #6 with a spherical bearing.

Your #3 is interesting, in that it is a suspension attach point that incorporates a ball joint, but it's not a suspension bushing. This one is open to reasonable interpretation, and could possibly be a gray area in regards to ITCS allowance. But, by the same token, since it's not a suspension bushing, one can also argue it is not eligible for "alternate material" consideration.

Your #s 16 and 17 are swaybar end links, which use a type of ball joint, but are not considered THE ball joint. And, under the ITCS allowances for swaybars, are free in design.

Your #4 is "the suspension ball joint", which is not a suspension bushing, and thus not legal to replace with alternate material under the suspension bushings ITCS allowance.

This #4 part is the one in question when we're talking about "the suspension ball joint". If you're trying to say someone is claiming that your #4 is considered a suspension bushing, and thus can be replaced with a spherical bushing/bearing and spaced out to correct roll center, they are incorrect. That part must remain equivalent to stock.

This is not to be confused with Tom's discussion above in regards to the Mazda RX-7 design. In that case, since the strut incorporates all the attach points for the tie rods and ball joints, then those attach points can be moved around to correct geometry under the "open strut" rule; however, the stock-equivalent ball joint must still be used. - GA

 

[jimmyc]

Not that it's relevant, but "even if" I were cheating, that doesn't make "your" cheating legal or acceptable, nor does it make my premise that you're cheating incorrect or out of line.

And, you too have the ability - nay, the responsibility - to protest me if you truly believe the above (assuming you were racing in IT, and since you're not I hardly understand why you're stepping into this discussion other than just to argue...though you're certainly entitled to your misguided opinion.)

And finally, despite its irrelevance, you have zero clue about what I'm actually doing.

GA

No but it does make you seem a bit hypocritical. Here you are calling me out for for something that i see as perfectly legal, and you spent i don't know how many pages arguing that you didn't need to have a structural part of the car on the car.

No i don't have any clue about what you are actually doing, but, again, you spent many of post in that thread saying how it was legal, and so on and so on.

You see my opinion as misguided and i see your as the same.

It is the internet, people have different opinions and life goes on.