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

[varora]

Is RCE going to be doing new springs for the Sacks ZF dampers on the 2017 Performance Package?

[cwilson]

Originally Posted by renfield90

1/2 inch sag sounds like a lot. Have you checked if the spring perch is loose? It may have slowly been winding its way lower if it wasn't properly locked into position.

Checked out the possibility the spring perch was loose and no it wasn't. Shop that orig installed said they were locked and were still in the same location. Accordingly, to fix the spring sag they had to reset all the way to the top, so I no longer have any upward adjustment left. I guess this will be ok unless the springs sag even more, or unless it has changed the spring rate, etc.

Do you think the sag (1/2 inch) has affected the spring rate significantly? Is this something that warrants changing out the springs?

[DeaconRoc]

Originally Posted by Brayden_23

Is the preload on the stock ARB adjustable? I wasn't looking at upgrading those yet until I know how the car handles with the new suspension first.

It's the drop link length that sets the preload which is why as you lower it adjustable links can be useful.

[strat61caster]

Originally Posted by cwilson

Do you think the sag (1/2 inch) has affected the spring rate significantly? Is this something that warrants changing out the springs?

Depends on how serious you are about the performance, quality aftermarket springs from Eibach or Hyperco are ~$60-$70 each so about $250 for a set of four.

If I was in your position I absolutely would be ordering springs right now. I have no idea how much of a difference it would make but I would absolutely not trust those springs. Rates should be in the manual or some marketing material, iirc KW uses 60mm ID springs, likely 6" long.

Eibach catalog:
http://eibach.com/sites/devperforman...20_Catalog.pdf

Hyperco catalog:
http://www.hypercoils.com/hyperco-catalog

Find the spring part number you want, google it, order from the cheapest site, I've bought from Summit, Pro Parts, and Pit Stop USA without trouble.

[endless_pain]

@Racecomp Engineering, as you upgrade to spherical bushings, how much this should be taken into account when selecting alignment settings?
Is my understanding that in hard corners, as soft oem bushings flex, alignment changes more drastically than with spherical bushings, but is it a big difference?
So lets say I like 1/16 toe in at the rears. With oem bushings that is ok because on acceleration tires/wheels "open" up so the tires are not being dragged causing extreme wear, but with spherical, toe in should be reduced because with less flex, tire wear would increase more dramatically. Is this correct?

[renfield90]

Originally Posted by cwilson

Checked out the possibility the spring perch was loose and no it wasn't. Shop that orig installed said they were locked and were still in the same location. Accordingly, to fix the spring sag they had to reset all the way to the top, so I no longer have any upward adjustment left. I guess this will be ok unless the springs sag even more, or unless it has changed the spring rate, etc.

Do you think the sag (1/2 inch) has affected the spring rate significantly? Is this something that warrants changing out the springs?

Spring rate won't change. These are linear springs. What can happen is a spring loses some of its memory and doesn't fully return to its resting place.

The softer the spring, the farther it is compressed when the car is just standing still and thus the greater potential for memory loss. Think of the extreme case where you squeeze a spring all the way until the coils bind, and left it there for two years. You wouldn't be surprised if it ended up a little shorter when you finally released it.

If you're ok with your current ride height, AND you have enough shock travel while basically missing a half inch of spring (not riding on the bump stops), I wouldn't do anything. If you want to raise the car you're going to need new springs at the correct length.

[DeaconRoc]

Why is it that a lot of high end dampers (I'm thinking olhins TTX, JRZ, Moton, etc) are tuned more for low speed shaft velocities than high speed? Is it because at higher (track) speeds (and typically these sorts of dampers would be used more in race type situations) low speed shaft velocities are more important whereas for normal road use it's the high speed velocities that are more of an issue?

[cwilson]

Originally Posted by renfield90

Spring rate won't change. These are linear springs. What can happen is a spring loses some of its memory and doesn't fully return to its resting place.

The softer the spring, the farther it is compressed when the car is just standing still and thus the greater potential for memory loss. Think of the extreme case where you squeeze a spring all the way until the coils bind, and left it there for two years. You wouldn't be surprised if it ended up a little shorter when you finally released it.

If you're ok with your current ride height, AND you have enough shock travel while basically missing a half inch of spring (not riding on the bump stops), I wouldn't do anything. If you want to raise the car you're going to need new springs at the correct length.

After an AX yesterday where extreme manuevers caused the front end to feel like it bottomed out, in spite of the height adjustment, I'm wondering if maybe the coil overs are due for replacement? They have 30k miles and 3 yrs of fairly heavy AX usage. I typically run about 25 AX a year. I have no idea when CO should be rebuilt or what the specific signs are of failure, but this feels like it might be the time?

[Racecomp Engineering]

Originally Posted by varora

Is RCE going to be doing new springs for the Sacks ZF dampers on the 2017 Performance Package?

We're looking into it, but haven't been able to get our hands on the new dampers to see any differences.

- Andrew

[Racecomp Engineering]

Originally Posted by endless_pain

@Racecomp Engineering, as you upgrade to spherical bushings, how much this should be taken into account when selecting alignment settings?
Is my understanding that in hard corners, as soft oem bushings flex, alignment changes more drastically than with spherical bushings, but is it a big difference?
So lets say I like 1/16 toe in at the rears. With oem bushings that is ok because on acceleration tires/wheels "open" up so the tires are not being dragged causing extreme wear, but with spherical, toe in should be reduced because with less flex, tire wear would increase more dramatically. Is this correct?

The short version is that the car is more "sensitive" to its static alignment when you have spherical bushings. Like you said the OEM bushings have some flex designed in to alter alignment under load, mostly for stability's sake. Alignment does still change under cornering with spherical bearings due to suspension geometry, but you do need to be extra sure about how you set your alignment with the rubber gone. If you have an aggressive toe setting you better be okay with it.

Up front with the lower control arms is where you'll see more of the "designed in" bushing flex. In general, I keep the front toe at 0 either way and with sphericals I enjoy the sharper response and more consistent behavior. I'd be more likely to alter it from that on a stock bushing car BUT then you'd be sacrificing tire wear when you daily drive. Either way it is worth some driving and testing for each car/driver.

Hope that helps. It's a tough question.

- Andrew

[Racecomp Engineering]

Originally Posted by DeaconRoc

Why is it that a lot of high end dampers (I'm thinking olhins TTX, JRZ, Moton, etc) are tuned more for low speed shaft velocities than high speed? Is it because at higher (track) speeds (and typically these sorts of dampers would be used more in race type situations) low speed shaft velocities are more important whereas for normal road use it's the high speed velocities that are more of an issue?

On the street the average driver feels the higher velocities. Driving through my crap streets I notice the bumps, potholes, ruts, etc. Those stand out more than the handful of onramps and corners I get to go after. Getting the bumps right, even at the expense of low piston speed damping, is the priority and it's less expensive (which is also a priority for an OEM or street shock) to just get one part of the curve right.

Higher end dampers should have attention paid to the full range of piston velocities when they're being tuned, but the low speed becomes very important because that's where the handling happens and you get to control the rate of weight transfer through a corner. Bumps are of course still a thing on the track and a good high end damper will handle them well too.

Many high end motorsports shocks will ride awesome over big bumps. I've also been on some that ride well over big bumps, but actually ride poorly over what you thought were smooth roads simply because they have so much gas pressure and low speed damping. They're still great on the track and will eat up big mid-corner bumps, kerbing, and train tracks...but you'll feel your man boobs or female boobs jiggle on nice pavement. Always a lot of compromises to be made.

- Andrew

[DeaconRoc]

Originally Posted by Racecomp Engineering

On the street the average driver feels the higher velocities. Driving through my crap streets I notice the bumps, potholes, ruts, etc. Those stand out more than the handful of onramps and corners I get to go after. Getting the bumps right, even at the expense of low piston speed damping, is the priority and it's less expensive (which is also a priority for an OEM or street shock) to just get one part of the curve right.

Higher end dampers should have attention paid to the full range of piston velocities when they're being tuned, but the low speed becomes very important because that's where the handling happens and you get to control the rate of weight transfer through a corner. Bumps are of course still a thing on the track and a good high end damper will handle them well too.

Many high end motorsports shocks will ride awesome over big bumps. I've also been on some that ride well over big bumps, but actually ride poorly over what you thought were smooth roads simply because they have so much gas pressure and low speed damping. They're still great on the track and will eat up big mid-corner bumps, kerbing, and train tracks...but you'll feel your man boobs or female boobs jiggle on nice pavement. Always a lot of compromises to be made.

- Andrew

Thank you, that's a really useful answer and pretty much reflects exactly what I'm finding with the Motons I'm running (especially the man boob part! :-))

We did a few back to back tests on a really rough and bumpy road of the Motons against some Tein monosports. At low road speed the Motons were pretty jiggly and the teins not too bad (these monosports have had the spring rates lowered to 6/7kg from the usual 8/9kg). However when we upped the speeds the Motons really came into their own. For instance, one part of the road has a fairly large ridge - at 45mph in the tein equipped car you felt the wheels lose traction with the road whereas in the Moton equipped car you could be going a good 10mph quicker and still maintain full traction with the road over the ridge.

As you said compromises!

[nisti]

What is the opinion of @Racecomp Engineering on a size of rear sway bar upgrade for my setup:

RCE Yellows on stock struts
17x9 +35 RPF1
245/40-17 Conti ECDW

Trying to reduce understeer, but not sure if a 16 mm solid bar would be enough to help, or need to go bigger.
If anyone has experience here, let me know!
Here is my current alignment specs:

[OkieSnuffBox]

^Knowing your alignment numbers would be helpful as well.