follow ft86club on our blog, twitter or facebook.
FT86CLUB
Ft86Club
Delicious Tuning
Register Garage Members List Calendar Search Today's Posts Mark Forums Read

Go Back   Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community - FT86CLUB > Technical Topics > Suspension | Chassis | Brakes -- Sponsored by 949 Racing

Suspension | Chassis | Brakes -- Sponsored by 949 Racing Relating to suspension, chassis, and brakes. Sponsored by 949 Racing.


User Tag List

Reply
 
Thread Tools Search this Thread
Old 03-26-2017, 10:59 PM   #1
dutchman1
Senior Member
 
Join Date: Nov 2016
Drives: 2017 86 6-Speed
Location: Seattle
Posts: 138
Thanks: 35
Thanked 74 Times in 36 Posts
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Shock Rebound Tuning

So after doing a bunch of reading on suspension tuning online (fatcat, farnorth racing, etc, etc), I have arrived at a question.

There seems to be consensus that there is an optimal dampening curve for a shock, which is 60-65% critical (depending on the source). Obviously, the traditional way to finding that curve on your adjuster is using a shock dyno.

I was wondering if you could simply do a bounce test (pushing down on each corner of the car while it's parked, and releasing it quickly) and count the number of modulations the chassis makes before settling.

65% critical would be slightly stiffer than 2 modulations, if I'm correct.

You wouldn't be able to get it perfect with this method, but I think it should at least get you in the ballpark as a baseline for settings for shocks for autocross, etc.

Suspension gurus, does this sound feasible or am I missing something?
dutchman1 is offline   Reply With Quote
Old 03-26-2017, 11:46 PM   #2
strat61caster
-
 
strat61caster's Avatar
 
Join Date: Nov 2012
Drives: '13 FRS - STX
Location: SF Bay Area
Posts: 10,360
Thanks: 13,724
Thanked 9,470 Times in 4,993 Posts
Mentioned: 94 Post(s)
Tagged: 3 Thread(s)
What's the purpose? Daily, autox, track?

I think that's a pretty decent start, an interesting way to spend the afternoon at the very least if you're nerdy like some of us.

Ultimately what you as a driver like best is king, if you're autocrossing (presumably by the FatCat and FarNorth references), find a local club that gives you a shit ton of runs, or a test and tune day so you can go out drive a course (or skidpad), adjust, drive it again see how it feels, see if the time is faster, and if you can get data collection you'll hone in on a preferred setup. Something may FEEL slower, but maybe it's allowing you to power on earlier or use less steering input that ultimately results in a faster car. And the hardest thing is there's so many variables (especially if you can't drive like a robot) that it can be hard to pinpoint cause and effect.

Experimentation will beat out any internet advice, hell even professional advice, as far as I'm concerned. I would always think 'well, what if that guy hasn't tried X?' and end up going out and trying it anyway.

I recently saw the old quote: "The master has failed more times than the beginner has even tried."

So get on out there!


Check out Mark Donohue's book The Unfair Advantage if you're into the history of tuning cars, he was kind of a pioneer back in the 60's & 70's in setting up cars for racing. And I think his thoughts on using a skidpad to understand a car's dynamics are still relevant to this day.
__________________
Quote:
Originally Posted by Guff View Post
ineedyourdiddly
strat61caster is offline   Reply With Quote
The Following 2 Users Say Thank You to strat61caster For This Useful Post:
Captain Snooze (03-27-2017), dutchman1 (03-27-2017)
Old 03-27-2017, 06:17 AM   #3
Captain Snooze
Because compromise ®
 
Captain Snooze's Avatar
 
Join Date: Jan 2012
Drives: Red Herring
Location: australia
Posts: 7,711
Thanks: 3,984
Thanked 9,318 Times in 4,120 Posts
Mentioned: 60 Post(s)
Tagged: 0 Thread(s)
Quote:
Originally Posted by strat61caster View Post
Ultimately what you as a driver like best is king,
This with a capital you.
__________________
My car is completely stock except for all the mods.

Captain Snooze is offline   Reply With Quote
The Following 2 Users Say Thank You to Captain Snooze For This Useful Post:
strat61caster (03-27-2017), wparsons (03-27-2017)
Old 03-27-2017, 07:52 AM   #4
dutchman1
Senior Member
 
Join Date: Nov 2016
Drives: 2017 86 6-Speed
Location: Seattle
Posts: 138
Thanks: 35
Thanked 74 Times in 36 Posts
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quote:
Originally Posted by strat61caster View Post
What's the purpose? Daily, autox, track?

I think that's a pretty decent start, an interesting way to spend the afternoon at the very least if you're nerdy like some of us.

Ultimately what you as a driver like best is king, if you're autocrossing (presumably by the FatCat and FarNorth references), find a local club that gives you a shit ton of runs, or a test and tune day so you can go out drive a course (or skidpad), adjust, drive it again see how it feels, see if the time is faster, and if you can get data collection you'll hone in on a preferred setup. Something may FEEL slower, but maybe it's allowing you to power on earlier or use less steering input that ultimately results in a faster car. And the hardest thing is there's so many variables (especially if you can't drive like a robot) that it can be hard to pinpoint cause and effect.

Experimentation will beat out any internet advice, hell even professional advice, as far as I'm concerned. I would always think 'well, what if that guy hasn't tried X?' and end up going out and trying it anyway.

I recently saw the old quote: "The master has failed more times than the beginner has even tried."

So get on out there!


Check out Mark Donohue's book The Unfair Advantage if you're into the history of tuning cars, he was kind of a pioneer back in the 60's & 70's in setting up cars for racing. And I think his thoughts on using a skidpad to understand a car's dynamics are still relevant to this day.
Sounds good, that's more of less what I was thinking. And thanks for the reference, I'll check it out.
dutchman1 is offline   Reply With Quote
Old 03-27-2017, 02:47 PM   #5
Racecomp Engineering
 
Join Date: Nov 2011
Drives: 2016 BRZ, 2012 Paris Di2 & 2018 STI
Location: Severn, MD
Posts: 5,393
Thanks: 3,406
Thanked 7,233 Times in 2,957 Posts
Mentioned: 303 Post(s)
Tagged: 9 Thread(s)
Send a message via AIM to Racecomp Engineering
Quote:
Originally Posted by dutchman1 View Post
So after doing a bunch of reading on suspension tuning online (fatcat, farnorth racing, etc, etc), I have arrived at a question.

There seems to be consensus that there is an optimal dampening curve for a shock, which is 60-65% critical (depending on the source). Obviously, the traditional way to finding that curve on your adjuster is using a shock dyno.

I was wondering if you could simply do a bounce test (pushing down on each corner of the car while it's parked, and releasing it quickly) and count the number of modulations the chassis makes before settling.

65% critical would be slightly stiffer than 2 modulations, if I'm correct.

You wouldn't be able to get it perfect with this method, but I think it should at least get you in the ballpark as a baseline for settings for shocks for autocross, etc.

Suspension gurus, does this sound feasible or am I missing something?
A test day with data collection (like @strat61caster suggested) is very valuable and what I would recommend. It's extremely difficult to count modulations on a car with firm springs, even with very soft or no damping.

- Andrew
Racecomp Engineering is offline   Reply With Quote
The Following 2 Users Say Thank You to Racecomp Engineering For This Useful Post:
dutchman1 (03-27-2017), wparsons (03-27-2017)
Old 03-27-2017, 03:38 PM   #6
jamal
Senior Member
 
jamal's Avatar
 
Join Date: Nov 2011
Drives: Legacy GT
Location: compton
Posts: 534
Thanks: 9
Thanked 365 Times in 204 Posts
Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Yeah all of my weight will not compress a corner of my car much more than a 1/2" and I can't really tell a whole lot from that.

Giving one specific damping ratio as "best" is vastly over-simplifying things.

The "ideal" ratio is not the same for ride quality as it is for handling performance. And the ideal ratio in roll is not the same as in pitch or heave. And the ideal ratio is not the same for all shaft speeds and frequencies.

Generally, for a fairly smooth auto-x course, more that "65%" damping will be faster. But given a shock with a knob or two you really just have to go out and test.
jamal is offline   Reply With Quote
The Following 3 Users Say Thank You to jamal For This Useful Post:
dutchman1 (03-27-2017), Racecomp Engineering (03-30-2017), wparsons (03-27-2017)
 
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Koni Yellow Rebound Settings dutchman1 Suspension | Chassis | Brakes -- Sponsored by 949 Racing 2 02-26-2017 10:03 AM
Raceseng Shock Top - Rear Upper Shock Mount with 1” Increased Travel RJasonKlein Brakes, Suspension, Chassis 2 01-18-2017 04:33 PM
KW V3 Can't Adjust Rebound Rulin Suspension | Chassis | Brakes -- Sponsored by 949 Racing 2 06-20-2015 02:42 PM
Compression/Rebound Adjustments amaciose Suspension | Chassis | Brakes -- Sponsored by 949 Racing 8 12-10-2014 04:51 AM
Tein SRC rebound and compression set up for track mtsui Tracking / Autocross / HPDE / Drifting 13 02-27-2014 08:36 PM


All times are GMT -4. The time now is 05:15 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
User Alert System provided by Advanced User Tagging v3.3.0 (Lite) - vBulletin Mods & Addons Copyright © 2024 DragonByte Technologies Ltd.

Garage vBulletin Plugins by Drive Thru Online, Inc.