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

[Wepeel]

Originally Posted by fatoni

how do stiffer springs create more weight transfer exactly? its not intuitive really as i would think a spring would be more of a resistance and the weight would be pushed elsewhere.

It's more weight transfer relative to the end that wasn't stiffened. So if you just stiffen the rear springs, like Andy said, it would increase the share of the lateral load that that "axle" takes, which means the front axle now has less weight transfer (since total load transfer remains the same).

In theory if you increase spring rates proportionately* at both ends this wouldn't affect lateral load transfer distribution or total load transfer (and understeer/oversteer balance wouldn't change), but there would be less suspension movement and it would settle faster.

*not just spring rates but spring rates -> wheel rates -> frequency

[leicaboss]

Originally Posted by wparsons

Camber should be set based on tire wear and temperatures (requires testing), and will be dependent on driving conditions and tire choice.

Stiffer tires, or less sticky tires will need less camber than a sticky or softer tire, and stiffer springs can increase the need for more static camber (less suspension travel in a corner means less camber gain).

That said, there are some pretty safe starting points. Are you planning on mostly street driving, or more track? What tires?

I'm planning on more street driving for sure, it seems like most folks run a -2 up front and perhaps -1 in the rear, though this is a very very rough generalization.

I do want the car to handle as it should, as I love taking her out for a drive in the twisties every so often, and the road conditions are not always the best (lumpy, banked, etc).

Currently, I am on stock tires, but I am planning to swap to 17x9 +35 RPF1's with 245/40/17 Hankook V12's...

[fatoni]

Originally Posted by Wepeel

It's more weight transfer relative to the end that wasn't stiffened. So if you just stiffen the rear springs, like Andy said, it would increase the share of the lateral load that that "axle" takes, which means the front axle now has less weight transfer (since total load transfer remains the same).

In theory if you increase spring rates proportionately* at both ends this wouldn't affect lateral load transfer distribution or total load transfer (and understeer/oversteer balance wouldn't change), but there would be less suspension movement and it would settle faster.

*not just spring rates but spring rates -> wheel rates -> frequency

i get all of that but what is in bold which makes things difficult since its talked about like its assumed. i dont understand how that works. well that and i also dont think the "weight" of the car is static so the total forces on the spring can add up to more than the weight of the car but i dont think it matters for the purposes of whats going on at this level of discussion

[7thgear]

Originally Posted by fatoni

well that and i also dont think the "weight" of the car is static so the total forces on the spring can add up to more than the weight of the car but i dont think it matters for the purposes of whats going on at this level of discussion

you cannot create weight


you can increase force by increasing speed, but you cannot increase (or decrease) the weight of the car

[fatoni]

Originally Posted by 7thgear

you cannot create weight


you can increase force by increasing speed, but you cannot increase (or decrease) the weight of the car

correct me if im wrong but the spring cant tell the difference

[jvincent]

Originally Posted by 7thgear

you cannot create weight


you can increase force by increasing speed, but you cannot increase (or decrease) the weight of the car

Physics nerd moment.

Weight is actually a force. You can't create MASS, but you can change weight.

Sorry for interrupting the good discussion.

[7thgear]

Originally Posted by jvincent

Physics nerd moment.

Weight is actually a force. You can't create MASS, but you can change weight.

Sorry for interrupting the good discussion.

but that force becomes lateral, does it not?

[wparsons]

Originally Posted by leicaboss

I'm planning on more street driving for sure, it seems like most folks run a -2 up front and perhaps -1 in the rear, though this is a very very rough generalization.

I do want the car to handle as it should, as I love taking her out for a drive in the twisties every so often, and the road conditions are not always the best (lumpy, banked, etc).

Currently, I am on stock tires, but I am planning to swap to 17x9 +35 RPF1's with 245/40/17 Hankook V12's...

Rear has about -1.5 stock, so you don't want to reduce it. I would bet that -1 up front and -2 out back would be pretty decent for you. Adding more camber won't give better handling or more grip unless you need it to maintain the contact patch. If you're wearing the shoulders of the tires, it's a good sign you need more camber. If tire wear is even, then I wouldn't change it. Or, if you have a pyrometer and are setting camber for a specific track event you'll want to set it to get even heat across the width of the tire.

Originally Posted by fatoni

correct me if im wrong but the spring cant tell the difference

Unless you're generating downforce, you can't increase the weight of the car on the springs. You can shift it around, but not increase it.

[leicaboss]

Originally Posted by wparsons

Rear has about -1.5 stock, so you don't want to reduce it. I would bet that -1 up front and -2 out back would be pretty decent for you. Adding more camber won't give better handling or more grip unless you need it to maintain the contact patch. If you're wearing the shoulders of the tires, it's a good sign you need more camber. If tire wear is even, then I wouldn't change it. Or, if you have a pyrometer and are setting camber for a specific track event you'll want to set it to get even heat across the width of the tire.

Righto - though after doing some homework on this issue, it seems many have complained about the alignment settings from factory. Clearly the wide range of "acceptable" alignment settings aren't exactly great - so even a simple alignment will do wonders for helping the car out.

Do you mean to say -2 front and -1 rear? It seems most opt for more camber up front on their FR-S, I wonder if I need to adapt this since the BRZ does have a tighter front?

[fatoni]

Originally Posted by wparsons

Rear has about -1.5 stock, so you don't want to reduce it. I would bet that -1 up front and -2 out back would be pretty decent for you. Adding more camber won't give better handling or more grip unless you need it to maintain the contact patch. If you're wearing the shoulders of the tires, it's a good sign you need more camber. If tire wear is even, then I wouldn't change it. Or, if you have a pyrometer and are setting camber for a specific track event you'll want to set it to get even heat across the width of the tire.



Unless you're generating downforce, you can't increase the weight of the car on the springs. You can shift it around, but not increase it.

i think were veering away from the point. there are ways to exert more force on the springs than the car weighs but it doesnt matter for this discussion. all i want to try and understand is how a higher spring increases weight transfer on that portion of the car.

[solidONE]

Question for Andy @Racecomp Engineering :

I noticed that RCE like to run squared spring rates, so effectively they are much stiffer out front. Does this not produce a very under steering prone set up? Was this the goal? What was the reasoning behind these rates?

[jvincent]

Originally Posted by 7thgear

but that force becomes lateral, does it not?

My guess is that the lateral component probably increases significantly more than the downward one.

Stating the obvious, but rounding a corner at any kind of significant speed is a pretty complex problem from a weight distribution point of view when you factor in braking forces, etc.

To address one of the earlier comments, I'd guess that in very few instances is the force on the spring perfectly along its axis of compression. Whether that affects its performance or not is a question for the suspension designers.

[FirestormFRS]

You said anything...
How do the RCE Yellows pair with Koni Sport inserts from a ride/handling trade off stand point?

[wparsons]

Originally Posted by fatoni

i think were veering away from the point. there are ways to exert more force on the springs than the car weighs but it doesnt matter for this discussion. all i want to try and understand is how a higher spring increases weight transfer on that portion of the car.

Higher spring rates at one end of the car tend to increase weight transfer at the other end of the car, so stiffer rear will give more front grip.

Originally Posted by solidONE

Question for Andy @Racecomp Engineering :

I noticed that RCE like to run squared spring rates, so effectively they are much stiffer out front. Does this not produce a very under steering prone set up? Was this the goal? What was the reasoning behind these rates?

Not an official response, but RCE seems to be more focused on auto x, which favours quick transitions and the higher front rate will definitely help that.