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

[cdrazic93]

Originally Posted by Calum

That's correct.

UGH so complicated. So what is this ratio you speak of? The front is close to 1:1 which means compression:rebound? Or is that way off target? Lol

Anther question...why isn't this thread stickied?

[Racecomp Engineering]

Think of it as spring rate at the wheels. Its really spring travel vs. wheel travel...in the rear its not 1:1 since the spring is inboard.

Its also why you can't directly compare spring rates between different models of cars. My 1968 Datsun roadster has 14k springs and weighs under 2000 lbs but that doesn't mean anything unless you know the motion ratio.

- Andy

[FRS-HHH]

Just got my bilstein pss b14s in but ive never installed coil overs before just springs. Any diy videos or something to help me out since these dont have the camber plates. I know I need a spring compressor but is it hard to remove the oem ones and reinstall them? ?

[Dimman]

Originally Posted by Calum

Wont the dampers have a large effect on the wheel frequency? To my knowledge, the system of the spring and damper is used to achieve a desired frequency. But the spring alone is used to achieve the desired roll resistance and the damper is tuned to suit.

I think it works by starting with the natural frequency and damping it accordingly.

In the old shitty tire era of racing the target was grip through as soft as possible springs that don't bottom, damped properly with bars to manage roll. So there was kind of separation between pitch and roll.

This still sort of makes sense to me, but the modern trend seems more for stiff springs and ignoring bars.

The Euros seem to have a different philosophy as well, which is tune the springs to a target frequency based on comfort/track conditions (softer for crappy, rough surfaces), damp compression at ~60-70% of critical and rebound 2-3 times what compression is. The frequency is often rear biased by ~10%, and over/understeer balance is brought back with bars. This has to do with staying settled over bumps which also affects the perception of harshness/comfort over straight line bumps.



But I keep reading that these very fast, very grippy soft setups feel 'squirmy', and don't feel as fast, despite being objectively faster.

They also run contrary to the common forum 'knowledge' that moar harder is moar better.

Like @7thgear mentioned before, why aren't people emulating the rally setups that seem perfect for non perfect roads?

We need more Brits with hill climb experience in the suspension forums.



(Not that RCE and CSG Mike aren't doing a fantastic job, shining beacons against the darkness of ignorance that they are.)

[Wepeel]

Originally Posted by cdrazic93

UGH so complicated. So what is this ratio you speak of? The front is close to 1:1 which means compression:rebound? Or is that way off target? Lol

Anther question...why isn't this thread stickied?

The motion ratio is the the ratio of how much the spring moves per unit of wheel motion. This might help:
http://www.ft86club.com/forums/showp...&postcount=107

[cdrazic93]

Originally Posted by Wepeel

The motion ratio is the the ratio of how much the spring moves per unit of wheel motion.

Interesting. So is there any benefit to having a ratio lower than 1:1 in the rear?

[cdrazic93]

Originally Posted by Dimman

damp compression at ~60-70% of critical and rebound 2-3 times what compression is. The frequency is often rear biased by ~10%, and over/understeer balance is brought back with bars. This has to do with staying settled over bumps which also affects the perception of harshness/comfort over straight line bumps.

I have no idea what any of this means. oh dear

Originally Posted by Dimman

Like @7thgear mentioned before, why aren't people emulating the rally setups that seem perfect for non perfect roads?

From my perspective, the stroke of the damper would be far greater than any road car would like to have as a suspension setup, then again in this debate I am a man among giants...

Originally Posted by Dimman

(Not that RCE and CSG Mike aren't doing a fantastic job, shining beacons against the darkness of ignorance that they are.)

a little bit of ignorance and some innocence (in my case some eagerness to learn about this stuff) as well

[solidONE]

^ I believe he was referring to tarmac rally setups. 2013 Pikes Peak comes to mind. Read wepeel's post above about his post in another thread. Better yet, read that entire thread.

http://www.ft86club.com/forums/showt...23#post1188723

[solidONE]

Wouldn't it be awesome if every single 86 owner is or eventually becomes a suspension nerd to a certain level. Kinda like how many of Mazda MX-5/Roadster enthusiasts became. Achieve the Imposhiburu!

[cdrazic93]

Originally Posted by solidONE

^ I believe he was referring to tarmac rally setups. 2013 Pikes Peak comes to mind. Read wepeel's post above about his post in another thread. Better yet, read that entire thread.

http://www.ft86club.com/forums/showt...23#post1188723

Unfortunately that thread is now out of the mathmatical range I can think in. Oh well, atleast I saw pictures

In regards to tarmac setups in pikes peak and why they should be on everyday cars;

it could be that the suspension is tuned so specifically, or to the very limit that they would need a rebuild after each run and cost a bazillion moneys to make, making any ordinary coilover budget a laughable excuse for a setup...I'm shooting in the dark now, I should stop before I hurt myself lol

& yes I am trying to become a suspension nerd to a certain level, but gotta leave room for the important stuff, like school work...

[solidONE]

Originally Posted by cdrazic93

Unfortunately that thread is now out of the mathmatical range I can think in. Oh well, atleast I saw pictures

In regards to tarmac setups in pikes peak and why they should be on everyday cars;

it could be that the suspension is tuned so specifically, or to the very limit that they would need a rebuild after each run and cost a bazillion moneys to make, making any ordinary coilover budget a laughable excuse for a setup...I'm shooting in the dark now, I should stop before I hurt myself lol

& yes I am trying to become a suspension nerd to a certain level, but gotta leave room for the important stuff, like school work...

Digest what you can. I'm sure you'll be on your way to suspension nerdom.

Reference to pikes peak was just an example of what tarmac rally is like, although it is much smoother in the spectrum of what's considered tarmac rally on account of it being freshly paved. I figure everyone has heard of pikes peak so I mentioned it. Also, there are certainly lower budget and classes for that race and not every car that races there is purpose built all out racing machines. Much of tarmac rallying takes place on surfaces that resemble public roads, if not on actual roads that people commute on. There are many production based classes, and modeling your suspension upgrades to what those guys run will certainly yield a very well handling road going car.

[Calum]

Originally Posted by Dimman

I think it works by starting with the natural frequency and damping it accordingly.

In the old shitty tire era of racing the target was grip through as soft as possible springs that don't bottom, damped properly with bars to manage roll. So there was kind of separation between pitch and roll.

This still sort of makes sense to me, but the modern trend seems more for stiff springs and ignoring bars.

The Euros seem to have a different philosophy as well, which is tune the springs to a target frequency based on comfort/track conditions (softer for crappy, rough surfaces), damp compression at ~60-70% of critical and rebound 2-3 times what compression is. The frequency is often rear biased by ~10%, and over/understeer balance is brought back with bars. This has to do with staying settled over bumps which also affects the perception of harshness/comfort over straight line bumps.



But I keep reading that these very fast, very grippy soft setups feel 'squirmy', and don't feel as fast, despite being objectively faster.

They also run contrary to the common forum 'knowledge' that moar harder is moar better.

Like @7thgear mentioned before, why aren't people emulating the rally setups that seem perfect for non perfect roads?

We need more Brits with hill climb experience in the suspension forums.



(Not that RCE and CSG Mike aren't doing a fantastic job, shining beacons against the darkness of ignorance that they are.)

Anti roll bars prevent the suspension from articulating independently, so the more they can move away from bars, the better the suspension will be able to conform to the road surface. The Mclaren MP4-12C come with no sway bars for this reason, didn't it? But the Mclaren has other ways to manage roll resistance and still maintain decent ride comfort and keep the tire in contact with pavement.

The subject of roll resistance keeps coming up, and guys like me keep getting told in some form or another that it doesn't matter, only conforming to the road surface matters. If that were true rock climbers would make the best tarmac race cars ever, with their 20 odd inchs of wheel travel and rolling like an old Corvette in a storm. Maybe I'm too old, or have read too many 'yo dogz my car iz stiff as nuts dog, coiloverrrzzzz!!' on the forums, but I can't get away from the idea that roll stiffness is still a large factor here. We need to prevent the weight from transferring around too much so the outside tires don't get overloaded and so the car can react to direction changes quickly. What am I missing?

[Calum]

Originally Posted by cdrazic93

I have no idea what any of this means. oh dear

Have you studied control systems at all? That's all this really is, in a very basic form. Natural frequency, impulse response, dampers, settling time... If you haven't studied controls yet, than this is going to be a great crash course. Just remember your instructor knows 'best'.

[FR-S Matt]

Originally Posted by FRS-HHH

Just got my bilstein pss b14s in but ive never installed coil overs before just springs. Any diy videos or something to help me out since these dont have the camber plates. I know I need a spring compressor but is it hard to remove the oem ones and reinstall them? ?

You need an open socket set in order to get the hex key through the socket to remove the top hats while they're compressed by the spring compressors. That's the hardest part. It helps if you have a friend to put the nut on the top hat of the new coilover while you are pushing down on the coils. Everything else is just a direct swap and connect back/torque. Also make sure you torque your lower control arm bolts when the car is actually on the ground and not raised.

Follow the DIY guide in the DIY section for a coilover/spring install. It will help drastically if this is your first time, and give yourself a good amount of time to do this as well.