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

[RYU]

Going back to my dilemma... I love the stock suspension dynamics but I want to look cool and lower my car.

Evidently adjusting the lower shock mounting point like this can effectively lower the rear end 20mm at the shock and 25mm at the wheels. This will allow me to achieve my desired ride height while using the stock suspension system. Sounds rather brilliant. What am I missing?

How about the front? I hate mixing and matching but not sure how best to go about thinking thru a setup like this. Help Mike and Andrew!

(I'm thinking maybe... mild lowering springs in the front coupled with the stock shock to give me a spring rate of 250lb and a drop of 20mm out front... and a stock FRS spring rate in the rear on the stock shock to get to a close-enough balance as possible)

[solidONE]

Originally Posted by Dimman

It's essentially just the coil rate adjusted for the spring mounting angle.

If you look at a strut the spring and shock are basically locked to the top of the hub since there is no upper pivot. Wheel goes up, strut slides up the same amount.

Ah that's true, so in this case "C" and "D" is basically the same number on a mac strut front suspension. Although there should still be different values assigned to "B" and "A". Now when you change the the value for "B" (decreasing the wheel offset and increasing the track) more leverage is applied to the spring as a result.

Correct me if I wrong, cause I'm trying to understand how offset can have 0 effect on a strut suspension. If that were true then I can run +48 offset and still have the same rate to the tires as if I had -48mm offset.

[TouchMyHonda]

I like this thread.

[CSG Mike]

Originally Posted by RYU

Going back to my dilemma... I love the stock suspension dynamics but I want to look cool and lower my car.

Evidently adjusting the lower shock mounting point like this can effectively lower the rear end 20mm at the shock and 25mm at the wheels. This will allow me to achieve my desired ride height while using the stock suspension system. Sounds rather brilliant. What am I missing?

How about the front? I hate mixing and matching but not sure how best to go about thinking thru a setup like this. Help Mike and Andrew!

(I'm thinking maybe... mild lowering springs in the front coupled with the stock shock to give me a spring rate of 250lb and a drop of 20mm out front... and a stock FRS spring rate in the rear on the stock shock to get to a close-enough balance as possible)

If altering the mounts only increases damper stroke, then your springs will still be more compressed; you'll likely want slightly stiffer springs... exactly what you said. Keep the springs balanced relatively the same as stock, and the dynamic feel will be roughly the same.

You might want to look into roll-center correction as well, to compensate for the sluggishness you introduce into response by dropping the car without correcting it.

Disclaimer: The CSG BRZ doesn't have roll-center correction (yet). Our spring rates are high enough that the sluggishness is more than offset, but we do plan on eventually adding adjustble RCAs to maximize the effectiveness of our suspension.

[RYU]

Originally Posted by CSG Mike

If altering the mounts only increases damper stroke, then your springs will still be more compressed; you'll likely want slightly stiffer springs... exactly what you said. Keep the springs balanced relatively the same as stock, and the dynamic feel will be roughly the same.

You might want to look into roll-center correction as well, to compensate for the sluggishness you introduce into response by dropping the car without correcting it.

Disclaimer: The CSG BRZ doesn't have roll-center correction (yet). Our spring rates are high enough that the sluggishness is more than offset, but we do plan on eventually adding adjustble RCAs to maximize the effectiveness of our suspension.

Oops. i meant to include a picture of the lower control arms as well.

Using this type of setup and assuming the use of the stock shock, as long as there are no clearance issues (i.e. lower spring perch hits something) then I can't see why the spring would be any more compressed than normal?



Agree with the roll-center issue.

[CSG Mike]

Originally Posted by RYU

Oops. i meant to include a picture of the lower control arms as well.

Using this type of setup and assuming the use of the stock shock, as long as there are no clearance issues (i.e. lower spring perch hits something) then I can't see why the spring would be any more compressed than normal?



Agree with the roll-center issue.

Correct. It depends on HOW much it drops the mounting point, but any gain in stroke is good. I'm guessing 15-18mm eyeballing? IIRC, the shock and knuckle bolts are 17mm, and the sway is 14

[RYU]

Originally Posted by CSG Mike

Correct. It depends on HOW much it drops the mounting point, but any gain in stroke is good. I'm guessing 15-18mm eyeballing? IIRC, the shock and knuckle bolts are 17mm, and the sway is 14

Evidently, the shock point itself is lower 20mm which results in a 25mm total drop at the wheels.

So assuming using the stock FRS (I have a BRZ cuz it's the best! ) rear spring rate on the FRS rear damper... What do I do about lowering the front?

hmmmm..

[CSG Mike]

Originally Posted by RYU

Evidently, the shock point itself is lower 20mm which results in a 25mm total drop at the wheels.

So assuming using the stock FRS (I have a BRZ cuz it's the best! ) rear spring rate on the FRS rear damper... What do I do about lowering the front?

hmmmm..

Ground control top mounts?

[RYU]

Originally Posted by CSG Mike

Ground control top mounts?

just took a quick peek at those. thanks for the suggestion. it seems they do not raise the spring height; just raises/increases the stroke. I might still end up with a spring problem.

thinking out of the box a little.. what if I use a stock BRZ front shock. use a conservative lower spring like the RCE yellow. This will get me the 20-25mm drop out front with the stock damper rate. (I never really had a problem with the front dampers. It's the rears that are just so short.) With this combo maybe I can tune the understeer with a stiffer rear sway bar.

Oh man... What a pain. I really need to ride on your latest Tein SRCs.

[CSG Mike]

Originally Posted by RYU

just took a quick peek at those. thanks for the suggestion. it seems they do not raise the spring height; just raises/increases the stroke. I might still end up with a spring problem.

thinking out of the box a little.. what if I use a stock BRZ front shock. use a conservative lower spring like the RCE yellow. This will get me the 20-25mm drop out front with the stock damper rate. (I never really had a problem with the front dampers. It's the rears that are just so short.) With this combo maybe I can tune the understeer with a stiffer rear sway bar.

Oh man... What a pain. I really need to ride on your latest Tein SRCs.

Only problem is, the rears will be better damped than the fronts with your proposed setup, and there's no real way to alter where the spring sits without major work in the front

OT: waiting for adapters to arrive... (grr). You'll get a ride soon enough. Coming to the track 9/14-15 or 9/28-29?

[Dimman]

Originally Posted by solidONE

Ah that's true, so in this case "C" and "D" is basically the same number on a mac strut front suspension. Although there should still be different values assigned to "B" and "A". Now when you change the the value for "B" (decreasing the wheel offset and increasing the track) more leverage is applied to the spring as a result.

Correct me if I wrong, cause I'm trying to understand how offset can have 0 effect on a strut suspension. If that were true then I can run +48 offset and still have the same rate to the tires as if I had -48mm offset.

Does it help to think of the tire as fixed and the force being applied to the control arm? No matter where the tire is the distance from the hub pivot and strut to the chassis pivot doesn't change.

Offset affects track width and roll resistance, I believe.

[solidONE]

Originally Posted by Dimman

Does it help to think of the tire as fixed and the force being applied to the control arm? No matter where the tire is the distance from the hub pivot and strut to the chassis pivot doesn't change.

Offset affects track width and roll resistance, I believe.

So making the contact patch of the tires sit further outboard does not change the amount of leverage it has on the spring? Im just talking about how this effect the springs and the amount of force it puts against the spring, nothing else. I think an actual formula for calculating wheel rate would help me better wrap my mind around that.

I'm picturing a longer lever on the spring as a result of positive offset vs. negative offset, therefore requiring less force (but longer distance of travel) to compress the spring which stays in the same position relative to the inner pivot.

Edit: I'm just going to leave this link here for @Dimman , @Wepeel and @ZDan. According to this guy that created the PDF file linked, motion ratio on a mac stut system is dependent on the centerline location of the wheel, thus wheel offset. [backs away slowly]

[RYU]

Originally Posted by CSG Mike

Only problem is, the rears will be better damped than the fronts with your proposed setup, and there's no real way to alter where the spring sits without major work in the front

OT: waiting for adapters to arrive... (grr). You'll get a ride soon enough. Coming to the track 9/14-15 or 9/28-29?

Strangely enough having the rears better damped might just be the ticket. All setups i've been on so far seems to fall short on the rear damping based on my inaccurate butt dyno.

OT Reply: awesome! I'm waiting to receive my final version for the NSX. As soon as I get it i'll join you out there on whichever day.

[Calum]

Originally Posted by RYU

just took a quick peek at those. thanks for the suggestion. it seems they do not raise the spring height; just raises/increases the stroke. I might still end up with a spring problem.

thinking out of the box a little.. what if I use a stock BRZ front shock. use a conservative lower spring like the RCE yellow. This will get me the 20-25mm drop out front with the stock damper rate. (I never really had a problem with the front dampers. It's the rears that are just so short.) With this combo maybe I can tune the understeer with a stiffer rear sway bar.

Oh man... What a pain. I really need to ride on your latest Tein SRCs.

The RCE yellows are pretty close to the rate of the frs rears. There certainly is a difference, but it might be less the you're thinking. (I don't know how much you've looked into it.).

Also you might want to look into the robispec rear mounts.

And finally Koni's might be worth looking into.