Suspension modeling

[00Zero]

Based on this diagram, with my winter tire/wheel setup:
B=13.75in
A=19in
MR @ wheel=0.72
Strut angle=10deg
MR of strut=0.973

For the rear I calculated:
B=15in
A=27.25in
MR=0.55

This puts my winter setup ride frequencies at:
F=0.93
R=1.35

Adding my race springs, but not accounting for the wider wheels:
F=1.45
R=1.85

@JackRabbitSLIM

Guess what spring rates you need for a true 2.0/2.2hz split?
800/1050

I've been schooled.

The dude abides.

I thought the knuckle and strut move as 1 piece so the motion ratio is determined mainly by the strut angle (the topic is reported widely across the internet with many different diagrams).

I think your suspension analyzer post with an output of 0.93 is likely the most correct.

 

[xXDavidCXx]

I thought the knuckle and strut move as 1 piece so the motion ratio is determined mainly by the strut angle (the topic is reported widely across the internet with many different diagrams).

I think your suspension analyzer post with an output of 0.93 is likely the most correct.

0.93 is referencing what? The front ride frequency or front motion ratio?

 

[00Zero]

0.93 is referencing what? The front ride frequency or front motion ratio?

Motion Ratio

About halfway down the screen shot below there is "Mtn. Ratio Sprng/Shck/RBar > output > 0.93" and this aligns with the line above it where spring rate 425 equals a wheel rate 367.5 (425 * .93^2 = 367.5)

Changed the front page to reflect my move to using Suspension Analyzer.

View attachment 194874

 

[JackRabbitSLIM]

@JackRabbitSLIM

Guess what spring rates you need for a true 2.0/2.2hz split?
800/1050

!!!
Do it.

 

[launchd]

I'm just wondering...

Since you all seem to be getting pretty deep into the woods with all this analysis to really dial in/fine tune your suspension SPECIFICALLY for the track... Is anyone running a real LSD in this thread? If not, how are you solving for the GLARING issue VAQ (stock controller software) or the Haldex 5 system have related specifically to track use?

This is a serious question, I'm curious if someone has their hands on the VAQ controller software that VW Motorsport uses on their track DSG VAQ cars or came up with an unknown solution to the Haldex 5 system flaws.

Also, I'm going to assume (unless you have a real LSD) that XDS(+) is still turned ON in some degree for most, if not all of you. You are all aware that you're cooking your brakes/heating them up WAY FASTER and losing serious performance, brake application after brake application, corner after corner, right?

No mention of XDS, VAQ, Haldex 5 or LSDs and lots of talk about dialing in your suspension on cars that you intend to track (unless you're dialing in your suspension for... street use?), so I figured I'd ask. You guys seemed to be taking this pretty seriously, maybe not that seriously though?

 

[bfury5]

I'm just wondering...

Since you all seem to be getting pretty deep into the woods with all this analysis to really dial in/fine tune your suspension SPECIFICALLY for the track... Is anyone running a real LSD in this thread? If not, how are you solving for the GLARING issue VAQ (stock controller software) or the Haldex 5 system have related specifically to track use?

This is a serious question, I'm curious if someone has their hands on the VAQ controller software that VW Motorsport uses on their track DSG VAQ cars or came up with an unknown solution to the Haldex 5 system flaws.

Also, I'm going to assume (unless you have a real LSD) that XDS(+) is still turned ON in some degree for most, if not all of you. You are all aware that you're cooking your brakes/heating them up WAY FASTER and losing serious performance, brake application after brake application, corner after corner, right?

No mention of XDS, VAQ, Haldex 5 or LSDs and lots of talk about dialing in your suspension on cars that you intend to track (unless you're dialing in your suspension for... street use?), so I figured I'd ask. You guys seemed to be taking this pretty seriously, maybe not that seriously though?

I have an LSD planned to be installed this winter. Mechanical wavetrac unit. I also always run XDS off. I believe lots of folks here run reduced XDS as well for the exact reasons you've mentioned.

I'm guessing VW uses a mechanical unit in the TCR cars with the sequential gearbox. You can add a mechanical LSD unit to the DSG cars with VAQ to makeup for the lack of full locking ability of the VAQ.

While an LSD and suspension tuning work together, I can't say I would design my suspension any differently whether I had an LSD or not

 

[JackRabbitSLIM]

I don't think this is right thread for the discussion, but this might be relevant to you.
https://www.golfmk7.com/forums/inde...-discussion-setup.366133/page-56#post-7541526

My opinion is that the base model without VAQ is the best starting place. Aftermarket diff and XDS off.

 

[launchd]

I have an LSD planned to be installed this winter. Mechanical wavetrac unit. I also always run XDS off. I believe lots of folks here run reduced XDS as well for the exact reasons you've mentioned.

I'm guessing VW uses a mechanical unit in the TCR cars with the sequential gearbox. You can add a mechanical LSD unit to the DSG cars with VAQ to makeup for the lack of full locking ability of the VAQ.

While an LSD and suspension tuning work together, I can't say I would design my suspension any differently whether I had an LSD or not

The results you get from tuning your suspension will absolutely be different with a mechanical LSD in place and XDS turned off. You can easily assume grip issues are a result of your suspension when in fact, they could be caused by the reduced performance of one of these systems (used heavily in cornering).

And yes, VW uses a mechanical LSD on the sequential TCR and a HIGHLY MODIFIED controller software on their VAQ DSG cars.

 

[launchd]

I don't think this is right thread for the discussion, but this might be relevant to you.
https://www.golfmk7.com/forums/inde...-discussion-setup.366133/page-56#post-7541526

My opinion is that the base model without VAQ is the best starting place. Aftermarket diff and XDS off.

I'm just wondering how they're determining if grip issues are indeed the suspension or one of these systems (which have not been mentioned once). Near-zero axle-load and no traction can absolutely be mistaken as a suspension problem and cause an endless loop of adjustments without realizing you've just hit the limit of your systems.

 

[bfury5]

Guess what spring rates you need for a true 2.0/2.2hz split?
800/1050

While I won't argue with the math here (because it's clearly thorough), it feels opposite to the experiences we've been having so far. Given your experience upping rear springrate David, it would seem counter to your experience to almost double the front springrate and not expect it to push, while only upping the rear ~30%.

Again, it's hard to argue with the math though. If it takes that much front springrate to prevent roll / ending up in the undesirable part of the camber curve then it might work.

I know your calculations assume you have -2.1deg static camber, which will really drive up the need for stiffer springs / bars to reduce roll and prevent the car from going +camber. How do the spring values change when running -3 or -3.5deg? I'd be curious to see those, I anticipate they'd be a bit lower.

 

[launchd]

I have an LSD planned to be installed this winter. Mechanical wavetrac unit. I also always run XDS off. I believe lots of folks here run reduced XDS as well for the exact reasons you've mentioned.

I'm guessing VW uses a mechanical unit in the TCR cars with the sequential gearbox. You can add a mechanical LSD unit to the DSG cars with VAQ to makeup for the lack of full locking ability of the VAQ.

While an LSD and suspension tuning work together, I can't say I would design my suspension any differently whether I had an LSD or not

Also, just an FYI, I wouldn't turn XDS+ off if you're relying on the VAQ system...

The Vehicle Dynamics Manager needs the XDS+ system to work in tandem with VAQ. You're removing one function that makes up the "ediff" your car has, VAQ alone is not sufficient and it's been proven. Even VW Motorsports has the XDS+ system engaged on the TCR DSG VAQ cars.

Edit: By it's been proven I mean, they (Borgwarner) designed the two systems to work together (XDS+ and VAQ) and even Volkswagen's motorsports division uses them as such. XDS (no plus) is found on base model trims with no VAQ or Haldex 5 system. Whether the actual system (XDS) is different (from XDS+) or the software controlling the system is just different, I have no idea. Maybe the system isn't different a crossed the models and they just added the "+" for marketing.

Edit 2: "Borgwarner's FXD (aka VAQ) technology supplies a torque vectoring effect by directing more power to the outer wheel to reduce inner wheel slip. In addition, the technology can enhance vehicle stability by shifting more power to the inner wheel creating a yaw damping effect which REDUCES (not eliminates) the need for intervention by the brake-based stability control system (XDS)."

 

[bfury5]

Also, just an FYI, I wouldn't turn XDS off if you're relying on the VAQ system...

The Vehicle Dynamics Manager needs the XDS system to work in tandem with VAQ. You're removing one function that makes up the "ediff" your car has, VAQ alone is not sufficient and it's been proven. Even VW Motorsports has the XDS system engaged on the TCR DSG VAQ cars.

I don't have VAQ

 

[JackRabbitSLIM]

I'm just wondering how they're determining if grip issues are indeed the suspension or one of these systems (which have not been mentioned once). Near-zero axle-load and no traction can absolutely be mistaken as a suspension problem and cause an endless loop of adjustments without realizing you've just hit the limit of your systems.

I agree with you.

 

[launchd]

I agree with you.

The suspension number crunching is interesting though and something I would never do so I envy you guys. I just think (who cares what I think) at some point you're going to hit a limitation ceiling and it won't be because of your suspension, it'll be because of these consumer-in-mind software driven systems.

 

[xXDavidCXx]

The suspension number crunching is interesting though and something I would never do so I envy you guys. I just think (who cares what I think) at some point you're going to hit a limitation ceiling and it won't be because of your suspension, it'll be because of these consumer-in-mind software driven systems.

Possibly, but we have to start with the basics and do testing.

I feel like my last year verified a lot of what the data now tells me. And now I have another target, and more data to analyze and test.

I think your assumption of grip, VAQ related, is acceleration grip. Which is not my focus right now.

I’m just trying to get steady state balance right.