CSG and RCE tag-team suspension Q&A thread! Ask us anything!

[ZDan]

Originally Posted by mike156

[COLOR=black][FONT=Verdana]For the purposes of this discussion, you have to consider five different centers of gravity. One for each unsprung mass and one for the sprung mass. When you change unsprung mass into sprung mass, you change the sprung masses center of gravity. True, the overall COG remains the same for the system, but it does "move" the sprung mass COG.

You don't have to worry about all that to determine when you get an inside tire lifting, and what happens to load distribution on the other three after that. The left/right and front/rear load distribution on the four contact patches is only a function of:
static weight and weight distribution
acceleration (lateral g's and longitudinal g's)
c.g. height
track
wheelbase
To further determine individual tire loads, you just need to know relative front/rear roll stiffness.

That's it. For simplicity, I talked about steady-state cornering (front/rear load distribution is same as static). You could just as easily calculate the individual wheel/tire loads for other points on the friction circle, like 0.71-g braking combined with 0.71-g cornering (trail-braking), and 0.5-g acceleration combined with .87-g cornering (lowish power/weight car accelerating out of low-speed corner).

Maybe wording was poor, but I’m not saying it adds additional weight to the inside rear with additional cornering load. It maintains a higher percentage of load on the inside for longer, the tire continues to loose load with additional cornering loads though.

Ah, I misunderstood what you were saying. Yes, if you tune the suspension with greater front roll stiffness for a rwd setup, the inside front will pick up sooner, but you will keep greater load on the inside rear for longer. And for a fwd setup, you dial in more rear roll stiffness, picking up the inside rear sooner, keeping more load on the inside front for longer.

Either way, once you do pick up an inside wheel, you increase the rate of loading the outside wheel and unloading the inside wheel at the opposite end of the car. It sounded to me like you were saying that when you picked up the inside front, you'd actually start to INCREASE load on the inside rear. Now I see you must have meant that if your *setup* is such that you lift the inside front first, that this keeps the inside rear loaded more. Agree!

It is of course still preferable to keep all four on the ground, but if you have enough grip you will start to pick up an inside wheel given a track width, c.g. height, and grip levels. On just about any halfway decently set up fwd car (even totally stock) you will pick up the inside rear on corner entry due to massive static front weight bias and near-1g braking combined with some cornering load.
On a rwd car with decent power/weight and weight distribution and setup, it is also possible to lift an inside front accelerating out of a low-speed corner (my 255hp 240Z did this).

Given limitations on c.g. location and track width, you sacrifice a bit of ultimate cornering grip to get better drive out of the corners. On a 60/40 - 70/30 FF car, you use rear roll stiffness to keep the inside front planted for corner exit. On a 50/50-60/40 FR car, you dial in a lot of front roll stiffness to keep the inside rear loaded.

[ZDan]

Regarding aftermarket control arms, I'm a *MUCH* bigger fan of offset bushings like those linked to by Calum above ( http://www.whiteline.com.au/product_..._number=KCA436 ) and keeping the stock arms, which are known to have been designed and tested for a lifetime of usage on the car by a small army of well-equipped design, analysis, and test engineers. Anything aftermarket, you're pretty much guaranteed that they don't have nearly the engineering development and testing behind them. I've seen some aluminum arms for the twins that have MINIMUM section properties at the point of MAXIMUM bending moment.

I ran offset aluminum/delrin bushings on the 240Z for many years, thousands of track miles, they *never* shifted and I had zero wear issues. I did lubricate them with Nevr-Sieze when I installed them, but no maintenence after that (some people install zerk fittings to periodically grease them).

If one of the bushings wears out, no problem, you'll hear it, and you won't be structurally compromised. I'm *much* more worried about replacing well-developed and -engineered PRIMARY VEHICLE STRUCTURE from the factory with aftermarket parts.

[7thgear]

properly installed anything is gonna last you a good amount of time

[ZDan]

Originally Posted by 7thgear

properly installed anything is gonna last you a good amount of time

Improperly designed but properly installed will FAIL prematurely. I knew people with "high-performance" lightweight suspension components from a well-respected supplier for a particular car that had multiple on-track failures where the factory components (which weighed only *ounces* more) are known to pretty well last forever. The parts looked great, were well-built, but the basic DESIGN just wasn't up to the loads applied for any reasonable number of cycles.

It pains me to see people so eagerly replace well engineered CRITICAL primary structures with aftermarket designs that may look great, but don't have the engineering development or testing behind them.

If you don't have the ability to do the analysis yourself, I say *stay away* from aftermarket STRUCTURAL components. There's very little to nothing to be gained there, and a lot to lose...

[solidONE]

Originally Posted by ZDan

Improperly designed but properly installed will FAIL prematurely. I knew people with "high-performance" lightweight suspension components from a well-respected supplier for a particular car that had multiple on-track failures where the factory components (which weighed only *ounces* more) are known to pretty well last forever. The parts looked great, were well-built, but the basic DESIGN just wasn't up to the loads applied for any reasonable number of cycles.

It pains me to see people so eagerly replace well engineered CRITICAL primary structures with aftermarket designs that may look great, but don't have the engineering development or testing behind them.

If you don't have the ability to do the analysis yourself, I say *stay away* from aftermarket STRUCTURAL components. There's very little to nothing to be gained there, and a lot to lose...

Well said! Unless of course the stock component you want to replace has a know weakness or issue. If you want "fancy" you can always paint it with some plastidip like all the cool kids are doing.

[7thgear]

Originally Posted by ZDan

Improperly designed but properly installed will FAIL prematurely. I knew people with "high-performance" lightweight suspension components from a well-respected supplier for a particular car that had multiple on-track failures where the factory components (which weighed only *ounces* more) are known to pretty well last forever. The parts looked great, were well-built, but the basic DESIGN just wasn't up to the loads applied for any reasonable number of cycles.

It pains me to see people so eagerly replace well engineered CRITICAL primary structures with aftermarket designs that may look great, but don't have the engineering development or testing behind them.

If you don't have the ability to do the analysis yourself, I say *stay away* from aftermarket STRUCTURAL components. There's very little to nothing to be gained there, and a lot to lose...

I don't disagree

I meant to say something else with my comment, I left it too open for interpretation.

[Calum]

Originally Posted by 7thgear

^
it's just an offset bushing

nothing fancy.. until it mis-aligns itself O.o

Yes and no. While it is very simple, and certainly doesn't warrant $110 (FML) I would much rather use this type of design over everything else I've seen. So, fancy, no. Eloquent, yes. Unfortunately Sam Strano doesn't sell a similar Powerflex product.

[FR-S Matt]

Installed SPC LCA's and I must says they are fantastic for bringing the back into spec after a decent lower. I didn't need to use the toe kit. They are very stock like and the joint is nicer.

[Turdinator]

Originally Posted by CSG Mike

Sounds like you're doing some hard driving. Were you on stock alignment before?

Put in the camber bolts, and add the maximum amount of negative camber that you can get with the bolts.

Alignment at present is dead stock. I may have made things sound worse than they are but after 13,000kms the fronts have a noticable wear on the outside and the tread has a bit of a saw tooth shape to it. The rears are wearing faster overall but in a flat uniform way.

Thank you for the input :happy0180:

[YDNA]

my friend has some leftover swift springs in 6" 10k/12k and said i could have them for free. if i were to swap them out onto my kwv3s, would i have to revalve them? i was thinking of going to a stiffer rate but i think that might be way too high.

[Racecomp Engineering]

10k/12k would be pushing it big time for KW V3.

- Andy

[Wepeel]

Real quick RCE - does the BRZ have the same rear tophats as the GR STI/WRX?

[OICU812]

Hmm something on topic but haven't really grasped this yet. I was wondering with top hats "front" that (ADD) a degree of castor such as Vorshlaggs, how does this affect things? Does a person have to somehow go about having less NEGATIVE camber setup up front due to forces of more castor while turning? Guess I'm trying to ask is with plates that add castor, should a user use less negative camber versus a plate that does not add castor?

[CSG Mike]

Originally Posted by ZDan

Regarding aftermarket control arms, I'm a *MUCH* bigger fan of offset bushings like those linked to by Calum above ( http://www.whiteline.com.au/product_..._number=KCA436 ) and keeping the stock arms, which are known to have been designed and tested for a lifetime of usage on the car by a small army of well-equipped design, analysis, and test engineers. Anything aftermarket, you're pretty much guaranteed that they don't have nearly the engineering development and testing behind them. I've seen some aluminum arms for the twins that have MINIMUM section properties at the point of MAXIMUM bending moment.

I ran offset aluminum/delrin bushings on the 240Z for many years, thousands of track miles, they *never* shifted and I had zero wear issues. I did lubricate them with Nevr-Sieze when I installed them, but no maintenence after that (some people install zerk fittings to periodically grease them).

If one of the bushings wears out, no problem, you'll hear it, and you won't be structurally compromised. I'm *much* more worried about replacing well-developed and -engineered PRIMARY VEHICLE STRUCTURE from the factory with aftermarket parts.

The SPL arms we recommend for those looking for a top quality product are WAY overbuilt for this specific reason. They're still lighter than stock, and offer very easy access to coilover adjustments (for those that have a bottom adjuster near the arm).

The @Hancha piece seems to be excellent as well.