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

[EAGLE5]

Lots of people ruin their cars with bad suspension decisions. You can too! Compliance works in many ways. Stock components are designed with bushings in mind.

If you want more feel, start with a race seat. Start with actually receiving all the signals the car is already sending.

[ForeverCar]

Originally Posted by EAGLE5

Lots of people ruin their cars with bad suspension decisions. You can too! Compliance works in many ways. Stock components are designed with bushings in mind.

If you want more feel, start with a race seat. Start with actually receiving all the signals the car is already sending.

Good point about the seat. My “constraints” have inherent tensions so it’ll be a compromise in the end. I’m also optimizing for ease of use so race seat might be out. Going down the race seat slippery slope can easily end up with full harness, helmet, and Hans.

I can see how it’ll be ruined for sure. Looking to learn more details. Other components not able to take the added stress?

Dimensions of “ruined” (trade offs that I’m okay with and expect),
- significant increase of NVH
- overall system longevity
- suboptimal cost performance equation
- higher maintenance
- way less optimized for “commuting” type of driving

There are likely original system design parameters that will bite me too.

Maybe another way to ask this is, has anyone tried this setup? I suspect not exactly since most are after performance and value.

[churchx]

"ease of use"? taking out each and every compliant bushing strikes that out. NVH will deteriorate so much, that it would be too unpleasant to daily drive for meaningful distances. Acceptable for some for track-only car, certainly not so for dual-use one.
One thing is to replace some of bushings to less compliant ones, where trade-off might be worth it, other - going all-out, which makes car frankly unbearable crap for anything but track. If one chooses to go that route, i don't get what is wrong with installing other things like bucket seats and such, as car's daily usability is already ruined.

[ForeverCar]

Originally Posted by churchx

"ease of use"? taking out each and every compliant bushing strikes that out. NVH will deteriorate so much, that it would be too unpleasant to daily drive for meaningful distances. Acceptable for some for track-only car, certainly not so for dual-use one.
One thing is to replace some of bushings to less compliant ones, where trade-off might be worth it, other - going all-out, which makes car frankly unbearable crap for anything but track. If one chooses to go that route, i don't get what is wrong with installing other things like bucket seats and such, as car's daily usability is already ruined.

I think it depends on context and priorities. This BRZ is car number 6 for me so daily usability is not important. Noise and vibration are okay. If I find a race seat that doesn’t trigger hip pain for me, I have no issue with that (haven’t found one yet).

Appreciate the inputs!

[timurrrr]

Originally Posted by ForeverCar

Appreciate your input. I expect significant increase in NVH. If tires, springs, anti-roll bars, and dampers remain mellow, I wonder how it would feel. Maybe there still won’t be sufficient compliance for road use?

When I had a 991.2 GT3RS, I didn’t think it’s very hard. Springs were a bit stiff and I think the tires (Cup 2) could use a softer sidewall for compliance. IIRC, the stock setup doesn’t use many “rubber” bushings.

It’s more a curious exercise to see what eliminating all the “soft” bushings while keeping compliance in the tires, springs, and dampers would do (and keep anti-roll bars stock or similar). Might be a bad idea. Since it’s not a daily driven car and one of the goals is feel, I wonder what it’d feel like.

I haven't owned a Porsche GT3/GT4/etc, but I have been to a tech talk by a local shop that specialized on 911 track and full race cars.
What I remember from the talk about suspension is that the "hard" bushings are used on the outboard ends of suspension arms, while inboard bushings are "civilized" (rubber?), specifically for NVM reasons.
Please double-check that before making any potentially costly decisions for your car.

Another thing is that I recently had a chance to drive my competitor's car, equally capable and communicative at the track. He has stiffer spring rates than mine, and yet for street driving his car was a lot more comfortable. To me the choice between "softer spring rates but high NVH" and "stiffer spring rates, but low NVH" is very clear.

[ForeverCar]

Originally Posted by timurrrr

I haven't owned a Porsche GT3/GT4/etc, but I have been to a tech talk by a local shop that specialized on 911 track and full race cars.
What I remember from the talk about suspension is that the "hard" bushings are used on the outboard ends of suspension arms, while inboard bushings are "civilized" (rubber?), specifically for NVM reasons.
Please double-check that before making any potentially costly decisions for your car.

Another thing is that I recently had a chance to drive my competitor's car, equally capable and communicative at the track. He has stiffer spring rates than mine, and yet for street driving his car was a lot more comfortable. To me the choice between "softer spring rates but high NVH" and "stiffer spring rates, but low NVH" is very clear.

Interesting! Now that you’ve shared this perspective, I think I understand how it might work more. I’m realizing that springs are more “low speed” side of things. Where as bushings are more “high speed”. So some strategic softer bushings make sense as an overall system just like high&low speed compression adjustments.

[grumpysnapper]

Originally Posted by ForeverCar

Appreciate your input. I expect significant increase in NVH. If tires, springs, anti-roll bars, and dampers remain mellow, I wonder how it would feel. Maybe there still won’t be sufficient compliance for road use?

When I had a 991.2 GT3RS, I didn’t think it’s very hard. Springs were a bit stiff and I think the tires (Cup 2) could use a softer sidewall for compliance. IIRC, the stock setup doesn’t use many “rubber” bushings.

It’s more a curious exercise to see what eliminating all the “soft” bushings while keeping compliance in the tires, springs, and dampers would do (and keep anti-roll bars stock or similar). Might be a bad idea. Since it’s not a daily driven car and one of the goals is feel, I wonder what it’d feel like.

One thing that almost no one does, and I mean pretty much no one (myself included), is to start the whole process with yourself.

(I absolutely include myself in the following. And this is in no way meant as a criticism of you, or anyone else here.
And this is soooo long winded.)

I think one of the car worlds biggest problems is the assumption that we think we can all basically drive well, and that if we just had the right equipment or mix of equipment we would be even better.
If we are slower on the track than another guy, its because he has more power. His brakes are bigger. That wing is carbon.
If we are passed on a mountain road, well, its because his tyres are stickier. His spring rates are more suitable. His car is better.

The simple truth is that if we invested time, energy and money into our driving it would be the single greatest performance/enjoyment improvement that we could make.
With the added bonus that it would be transferable to any car we drove.

And here is the irony...when/if we do get driver training its usually from those that perhaps can help us the least.... a racing driver may be a very good racing driver...but why do we think he can teach, ie has the ability to clearly impart knowledge? Why do we think he can automatically drive anything else well (that is not his own racing car)? Why do we think he has any insights at all into driving on anything that is not a race track?
A racing driver is (most) often not a great driver in other circumstances. In fact often they can be rubbish.

Watch a current Formula 1 driver try and drive a manual well. Watch a Formula 3 driver try and slide a car cleanly. Watch a modern (4wd) WRC driver (ok, maybe not a Finn) try to drive a rwd car properly quickly on the dirt. There might be the odd exceptions (stand up Walter Rohrl)...but it will simply prove the rule.

Ditto for brake experts, suspension or engine guys, tyre techs etc. They can be experts in their chosen fields but their driving skills are usually not up to the level of their technical or mechanical mastery... for them to be at their best they need to work with a driver who can accurately describe/feel/repeat what a car is doing when he is driving in particular ways, in particular environments.

I will never be a geat driver, I will never truly understand the complexities of suspension or engines and I will never be able to extract %100 from any car I drive.
BUT, I am lucky to have a close friend who can. He is a freak. He is the guy that Audi gets to slide their R10 for TV adverts, he's that guy that AMG gets to teach people how to drive in the snow in their C63's. He can slide an old 911 on dry bitumen all day long. He will embarass a Ferrari in the hills in an MX5.
His Porsche collector friend gives him a 993 GT2 (right hand drive....google the value of those 9 cars...) and says go out and have fun, show me what it can do.

But his crowning glory is that on a drive day (or any version thereof) he must be able get into a strangers own car and immediately drive it quicker than they can... from the get go. Think about that...(I'm "all at sea" in a hire car I pick up at the airport for the first few miles)... their own cars, from lap 1.

He's the one that helps me understand what a car is doing, and why.
The one that sits next to you as you drive and desribes why the rear sway bar is too thick, and then sits next to you again when you put the standard one back on and lets you understand the feeling.
He's the bloke who gives the feedback to the damper guy who then makes my perfect dampers from scratch.
He's the bloke that helps find the perfect brake compound for my uses.
He's the guy who talks me out of putting "too much" tyre on my car.
He's the guy that persuades me to give up on left foot braking...because I will never develop the "feel" in that foot that I need.

But more importantly he has taught me so much about driving, about getting more out of a car. About road craft. About the psychology of driving. Driving quicker and safer. Driving around a cars "problems". About driving fun.

These guys are out there, but they are rare.

If I had the resources, I would find the perfect teacher to learn from.
Best investment ever.

[Ohio Enthusiast]

Originally Posted by grumpysnapper

If we are slower on the track than another guy, its because he has more power. His brakes are bigger. That wing is carbon.

Gear Acquisition Syndrome is certainly a contributing force to people's buying decisions, but I'd posit another (big) factor - some people (myself included) enjoy the feel of a modified car. They like the car being more solid, the bushings less compliant, the ride stiffer. This is done for its own sake as much as it is done for any tangible gains.

A great chef will be able to cook up a fabulous meal with a $5 knife and $10 pan on a camping burner. I won't be able to match them with a $10,000 kitchen, but I would still enjoy buying and using higher grade equipment. If I can afford a $100 knife, it doesn't matter that it won't make my food any better if I enjoy owning and using it.

In all likelihood I will be just as fast in a stock Twin as in a highly modified one (as I don't drive well enough to take advantage of the mods), but some mods will certainly increase my enjoyment of the car (which I have achieved with some stiffer bushings and inserts).

I think rule zero of modifications (and even of which car to buy initially) should be "what is your goal". There's a big difference between modding for feel and modding for speed (and that would also vary between track/autocross, different classes, etc.). If your goal is to improve your personal enjoyment of the car (which I'm sure is the bulk of the discussions on the forum), go ahead with what works for you. If your goal is to actually be faster, listen carefully to the wonderful collection of people here who are great drivers, have a lot of experience and actually understand how modifications affect the car's performance.

[ForeverCar]

I agree with @grumpysnapper and @Ohio Enthusiast points. If one is after lap times, driving is one of the biggest components. Great drivers are not necessarily great coaches. Sim is also a good tool to improve driving as well.

At the end of it, it comes down to what one is after.

[Racecomp Engineering]

Wow, a lot of good posts here!

Originally Posted by ForeverCar

I took delivery of a 2022 BRZ about a week ago and am considering suspension upgrade. I would like to get @Racecomp Engineering input on some options.

My use of the car is likely atypical (for more context, my intro thread https://www.ft86club.com/forums/showthread.php?t=147938).

Goals for the car,
1. The most connected driving experience
2. A learning platform for myself

Big questions to start are:

1. What is your driving experience?
2. What is your suspension tuning experience?
3. What specifically do you want to learn more about?

For #1, some of the best suspension tuners and engineers I know aren't racers and don't track their personal cars. But being consistent and able to feel/describe what is happening is helpful when you don't have a pro driver to work with.

For #2, have you experimented with suspension/chassis adjustments in the past? Read any books? Do you understand suspension frequencies, damping ratios, and nerd stuff like that? Do you want to learn about those too?

For #3, are you interested specifically in how low/high speed adjustments to compression and rebound affect the car with a 4 way shock? Or do you want to go through the process of choosing spring rates and initial damper valving?

Damper adjustments are the fine tuning. You need to be in the ball park before worrying about them, both with spring rates and base valving and the rest of your suspension. What happens frequently with even a 1 way coilover is people try to fix all their handling problems by turning knobs without even looking at their tire pressures or temperatures or the other basics. I can't stress enough how often that exact scenario happens.

Accurately interpreting what's happening (by feel or with logging), identifying the problem, and deciding on a solution...each of those steps are difficult. Turning knobs on a 4 way shock is just 1 possible solution and very frequently not the best one.

This car is a fantastic platform for learning when it comes to driving, wrenching, and tuning. It sounds like you'd like to take the learning to tune a suspension part seriously and it is really fun (at least to me).

- Andrew

[Racecomp Engineering]

@Ohio Enthusiast I like the expensive knife metaphor btw!

And @timurrrr had some good points on damper tuning being fine tuning.

Good stuff on bushings here too from @grumpysnapper and others. I personally like the "feel" of spherical bearings and have a lot more to say about them, but have to go use my mediocre knives to make a hopefully slightly above average dinner.

- Andrew

[ForeverCar]

Originally Posted by Racecomp Engineering

Wow, a lot of good posts here!

Big questions to start are:

1. What is your driving experience?
2. What is your suspension tuning experience?
3. What specifically do you want to learn more about?

For #1, some of the best suspension tuners and engineers I know aren't racers and don't track their personal cars. But being consistent and able to feel/describe what is happening is helpful when you don't have a pro driver to work with.

For #2, have you experimented with suspension/chassis adjustments in the past? Read any books? Do you understand suspension frequencies, damping ratios, and nerd stuff like that? Do you want to learn about those too?

For #3, are you interested specifically in how low/high speed adjustments to compression and rebound affect the car with a 4 way shock? Or do you want to go through the process of choosing spring rates and initial damper valving?

Damper adjustments are the fine tuning. You need to be in the ball park before worrying about them, both with spring rates and base valving and the rest of your suspension. What happens frequently with even a 1 way coilover is people try to fix all their handling problems by turning knobs without even looking at their tire pressures or temperatures or the other basics. I can't stress enough how often that exact scenario happens.

Accurately interpreting what's happening (by feel or with logging), identifying the problem, and deciding on a solution...each of those steps are difficult. Turning knobs on a 4 way shock is just 1 possible solution and very frequently not the best one.

This car is a fantastic platform for learning when it comes to driving, wrenching, and tuning. It sounds like you'd like to take the learning to tune a suspension part seriously and it is really fun (at least to me).

- Andrew

Thanks Andrew @Racecomp Engineering. +1 on a lot of great posts (this community is great!)

>> 1. What is your driving experience?
~1000 hours of road course time. Repeated driving schools but did not go for racing license. Average driving skills is probably where I would put myself. In a sense, I am at a stage where I am not after the quickest lap times as I know I won't be truly competitive and outright performance is not what I enjoy the most. These days, I enjoy driving as a form of "meditation" if that makes sense. I find focusing on driving and feeling the car to be relaxing and joyful. Perception wise, I'm probably also average. Part of my goal is also honing my perception. From theory, to adjustment, to feeling what the car is doing.

>> 2. What is your suspension tuning experience?
Relatively basic. I understand most of the mechanical concepts and would like to refresh and learn more. I read "Race Car Vehicle Dynamics" long time ago.

>> 3. What specifically do you want to learn more about?
My original thinking is likely quite flawed. First, I was thinking going with spherical bearings & hard bushings will simplify things a bit. With the platform pretty well known, fixed tires & spring rates, that leaves the 4-way adjustment to "feel/log, solve, adjust, repeat". Ultimately, I'd like to learn about chassis and suspension design (and beyond). The end goal, if I get there, is designing & building a car myself. Think Ariel Atom 4 & GMA T.50 cross.

4-way being the "easiest" mechanically to mess with is one of the primary attractions. Of course, I don't mind having to swap springs and other relatively simply mechanical tasks. I'm letting wanting to be lazy influence my thinking for sure.

I'd list my priorities as,
1. driving enjoyment in terms of being connected to the car, being to feel what the car is doing, translate that into a mental model of the mechanical aspects, problem solve and "tune" it to make it more how I want it (of course, preferences and goals are dynamic as well).
2. learn tuning and design.
3. wrenching is likely the lowest on the list.

[ForeverCar]

Originally Posted by Racecomp Engineering

@Ohio Enthusiast I like the expensive knife metaphor btw!

And @timurrrr had some good points on damper tuning being fine tuning.

Good stuff on bushings here too from @grumpysnapper and others. I personally like the "feel" of spherical bearings and have a lot more to say about them, but have to go use my mediocre knives to make a hopefully slightly above average dinner.

- Andrew

Do share more on spherical bearings when you get a chance!

[Jdmjunkie]

Originally Posted by ForeverCar

Do share more on spherical bearings when you get a chance!

I have all the SPL parts on the front end along with SuperPro steering rack bushes. I love the feel, the front end is better than the GT3RS I rented.

The other option for rose joints is WiseFab.