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

Go Back   Scion FR-S Forum | Subaru BRZ Forum | Toyota 86 GT 86 Forum | AS1 Forum - FT86CLUB > Technical Topics > Tracking / Autocross / HPDE / Drifting

Tracking / Autocross / HPDE / Drifting What these cars were built for!


User Tag List

Reply
 
Thread Tools Search this Thread
Old 06-27-2019, 06:59 AM   #15
lutfy
Senior Member
 
lutfy's Avatar
 
Join Date: Apr 2017
Drives: 2009 E90 M3, 2015 FRS
Location: Washington, DC
Posts: 201
Thanks: 61
Thanked 167 Times in 90 Posts
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quote:
Originally Posted by Icecreamtruk View Post
Working on it, should have something up with ECU + GPS logging and video to correlate, I should have it before the 6th july which is my next day out at the track. What should I be looking at appart from the classic throttle, brake and steering input? Individual wheel speeds? Is it possible to get that over OBDII?


Mike had shared the video link with me earlier and I was amazed at the wheel speed delta.

Anyways, there are multiple variables which can be addressed logically (with data - cause effect) but on topic of diff; I got custom OSG because I couldn’t put the power down in slow to mid speed corners especially with fresh Hoosiers (inside wheel spin).

The behavior of the car changed significantly not just at exits but also entry, braking and mid corner (throttle sensitivity). It was worth it but required adjustments to make it work as a whole (shock settings mostly).

Will it solve the described problem? Not sure. Does the diff help (changing characteristic of the car) for the better? It was worth it for me. Are there multiple variables (shocks, tire pressure etc) that needs to be correlated with the new clutch type diff? Yes.

Not a direct/linear answer but hope you get my gist.

Best of luck.

Lutfy



Sent from my iPhone using Tapatalk
__________________
2015 FRS NASA TT5 (I love this car)
2009 M3 Go fast touring car
lutfy is offline   Reply With Quote
The Following 2 Users Say Thank You to lutfy For This Useful Post:
CSG Mike (06-27-2019), Icecreamtruk (06-27-2019)
Old 06-27-2019, 10:01 AM   #16
Icecreamtruk
Senior Member
 
Join Date: Dec 2015
Drives: Track preped NA FRS
Location: Montreal, Canada
Posts: 782
Thanks: 814
Thanked 525 Times in 317 Posts
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Thank you all for all of the answers, I figured it wouldnt be as dry cut as just slap on X part and be done with it, it never is really.

@CSG Mike, its similar to when you hit the kerbs in your video actually, it just does it for a longer period. Check in your video when you hit the kerb at 2:19 and the engines surges a bit (and wheel speed is aroudn 70 on one side, 80 on the other), but imagine it lasts longer for me, I dont know if the wheel speeds on my case are much farther appart than that or not, but possibly at least as much.

@lutfy Thanks for your input, its really nice since our cars arent that far off and I do plan to switch to hoosiers (As not Rs tho, time attack scenario calls for maximum grip for only 1 lap) and this is a problem that I think will get worse if I add more grip to the equation. Btw, how's your engine doing? have youdone any oil mods to keep it alive at those G forces?

To everyone else that talked about adjusting shocks, I can play with rebound only, so I assume softening the rear only would help there? I tried softer all around and the car felt worse and was slower, about half a second per lap consistently.

Quote:
Originally Posted by soundman98 View Post
Why are you running such stiff springs? Are you trading off for not running a sway bar or something?
Springs are for aero mostly. The car has significant downforce and some of the tracks I run at have very high speed turns (think 110-120pmh turns uphill). I like those tracks the most so I try to set my car so it performs well there, which it does, but it is a shit show on bumpy tracks, as I noticed last weekend. I was previously running 6k/8k springs and I was on the bumpstops for most high to mid speed turns.


I will try to get as much data as possible, certainly wheel speed data at the very least on my next track day, I'll also see if I can setup a nice overlay to see it in action. That should be the 6th July so I'll update the post by then. If you have more ideas, keep them coming, I love a good conversation and I will keep it alive as long as there's interest.

Thanks!

Last edited by Icecreamtruk; 06-28-2019 at 01:08 PM.
Icecreamtruk is offline   Reply With Quote
The Following 2 Users Say Thank You to Icecreamtruk For This Useful Post:
CSG Mike (06-27-2019), soundman98 (06-27-2019)
Old 06-27-2019, 10:42 PM   #17
CSG Mike
 
CSG Mike's Avatar
 
Join Date: Jul 2012
Drives: S2000 CR
Location: Orange County
Posts: 12,633
Thanks: 7,811
Thanked 12,245 Times in 5,840 Posts
Mentioned: 862 Post(s)
Tagged: 13 Thread(s)
Quote:
Originally Posted by Icecreamtruk View Post
@CSG_Mike, its similar to when you hit the kerbs in your video actually, it just does it for a longer period. Check in your video when you hit the kerb at 2:19 and the engines surges a bit (and wheel speed is aroudn 70 on one side, 80 on the other), but imagine it lasts longer for me, I dont know if the wheel speeds on my case are much farther appart than that or not, but possibly at least as much.
Data will help determine, but you're definitely having a similar issue if the symptoms are similar.

Car in the video is on 7k/7k.

The LSD will 100% make power delivery more consistent and predictable.
CSG Mike is offline   Reply With Quote
The Following User Says Thank You to CSG Mike For This Useful Post:
Icecreamtruk (06-28-2019)
Old 06-27-2019, 11:26 PM   #18
strat61caster
Thread Killer
 
strat61caster's Avatar
 
Join Date: Nov 2012
Drives: '13 FRS
Location: SF Bay Area
Posts: 8,992
Thanks: 12,334
Thanked 8,131 Times in 4,245 Posts
Mentioned: 76 Post(s)
Tagged: 3 Thread(s)
Quote:
Originally Posted by Icecreamtruk View Post
To everyone else that talked about adjusting shocks, I can play with rebound only, so I assume softening the rear only would help there? I tried softer all around and the car felt worse and was slower, about half a second per lap consistently.
With a single adjusted (mostly rebound) shock I'd guess stiffening the rear would help 'lock it down' and add some confidence, you might be skipping the tire off the pavement but it could still be more predictable than what you've got now allowing you to hammer through the rough patches, counter-intuitive but it's one of the few things I've figured out on my setup that's carried across to different cars with the same adjustment. It'd be a bandaid to either the diff or a spring/sway change but it sounds like you're headed out for at least one more day with the current setup so try a knob or two after you've replicated the problem.
__________________
Quote:
Originally Posted by Guff View Post
ineedyourdiddly
strat61caster is offline   Reply With Quote
The Following User Says Thank You to strat61caster For This Useful Post:
Icecreamtruk (06-28-2019)
Old 06-28-2019, 09:42 AM   #19
lutfy
Senior Member
 
lutfy's Avatar
 
Join Date: Apr 2017
Drives: 2009 E90 M3, 2015 FRS
Location: Washington, DC
Posts: 201
Thanks: 61
Thanked 167 Times in 90 Posts
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quote:
Originally Posted by Icecreamtruk View Post
Thank you all for all of the answers, I figured it wouldnt be as dry cut as just slap on X part and be done with it, it never is really.


@lutfy Thanks for your input, its really nice since our cars arent that far off and I do plan to switch to hoosiers (As not Rs tho, time attack scenario calls for maximum grip for only 1 lap) and this is a problem that I think will get worse if I add more grip to the equation. Btw, how's your engine doing? have youdone any oil mods to keep it alive at those G forces?

To everyone else that talked about adjusting shocks, I can play with rebound only, so I assume softening the rear only would help there? I tried softer all around and the car felt worse and was slower, about half a second per lap consistently.


Thanks!
The car has been fine mate. No issues with oil issues (maybe I am not aware of potential issues So far running like a champ. Fingers crossed.

Regarding rebound, doubt that would do much other than fine tune. If you go down too much, the rear ends up dancing (un easy) at curbs and bumps hence unable to put power down effectively.

Try disconnecting the rear bar. That should help a bit with reduced spin coming out of turns but may give you a disconnected feel overall (which is what I found and didnt like it).

Keep us posted.

Cheers,

Lutfy
__________________
2015 FRS NASA TT5 (I love this car)
2009 M3 Go fast touring car
lutfy is offline   Reply With Quote
The Following 2 Users Say Thank You to lutfy For This Useful Post:
Icecreamtruk (06-28-2019), rice_classic (06-28-2019)
Old 06-28-2019, 10:01 AM   #20
Icecreamtruk
Senior Member
 
Join Date: Dec 2015
Drives: Track preped NA FRS
Location: Montreal, Canada
Posts: 782
Thanks: 814
Thanked 525 Times in 317 Posts
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Thanks for the extra info.

@strat61caster I tried stiffening and softening rebound and softer felt worse, but I only went 2 clicks in each direction. Counter intuitive as you said but stiffer produced better times and the rear was still lifting, maybe I needed a bigger change, like a full soft vs full stiff for comparisons' sake.

@CSG Mike I had planned doing the diff once the car had more power, in my head there was no need at NA power levels but it seems like a stiff enough suspension and bad enough track conditions might do it. Consistant power delivery is very much what I want. "Guessing" every time I hit the gas if the rear is going to slide, jump, hook or a mix of all those is getting old really quick. On a smooth and high speed track it was predictable and would slide always, that was probably a function of aero helping load the tires more.

@lutfy Thats great to hear man, gives me hope for next year trying the hoosiers, if the delta in time from entry level Rs and A7s is as big as I've read around, I will be in contention for the FTD overall, while being 3 classes down from the unlimited guys, it would be hilarious to see the look on their faces. Also, I tried disconnected the sway bars before (front, then rear), I did not like the feeling of the car at all and it did not produce better lap times, but it was a good experiment as it showed me what those actually do (aside from changing the balanced if you change their relative stiffness). A stiffer front sway might help, but that will introduce understeer on corner entry, and I hate understeer with a fiery passion.

Last edited by Icecreamtruk; 06-28-2019 at 01:08 PM.
Icecreamtruk is offline   Reply With Quote
The Following User Says Thank You to Icecreamtruk For This Useful Post:
strat61caster (06-28-2019)
Old 06-28-2019, 11:10 AM   #21
CSG Mike
 
CSG Mike's Avatar
 
Join Date: Jul 2012
Drives: S2000 CR
Location: Orange County
Posts: 12,633
Thanks: 7,811
Thanked 12,245 Times in 5,840 Posts
Mentioned: 862 Post(s)
Tagged: 13 Thread(s)
Just a FYI, you're not tagging me. I have no idea who @CSG_ is .
CSG Mike is offline   Reply With Quote
Old 06-28-2019, 01:08 PM   #22
Icecreamtruk
Senior Member
 
Join Date: Dec 2015
Drives: Track preped NA FRS
Location: Montreal, Canada
Posts: 782
Thanks: 814
Thanked 525 Times in 317 Posts
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quote:
Originally Posted by CSG Mike View Post
Just a FYI, you're not tagging me. I have no idea who @CSG_ is .
I boy, I kept adding a _ thinking there was one. Going to correct the posts, so you'll have a bit of a spam on tags, sry
Icecreamtruk is offline   Reply With Quote
Old 06-28-2019, 02:33 PM   #23
rice_classic
Senior Member
 
rice_classic's Avatar
 
Join Date: Jun 2012
Drives: Nevermorange FRS
Location: Seattle, WA
Posts: 3,761
Thanks: 674
Thanked 3,471 Times in 1,547 Posts
Mentioned: 58 Post(s)
Tagged: 1 Thread(s)
Agreed with Lufty. It's been my experience that on dry pavement and due to the way torsens work, their effectiveness as an LSD improves with the more traction you throw at them. Single adjustable shocks, as far as I'm aware, are only rebound so you can only adjust the rate at which the spring returns the spring to the ground (and the rate of body roll).

If too soft it won't properly dampen the shock and become bouncy but too stiff and during transition or rapid direction change, you can find you pick up the inside rear because the shock doesn't allow the spring to decompress fast enough. Therefore, once your in the window of rebound that neither of these two things occur - you need to address roll stiffness across the axle (sway bar) or droop. To Lutfy's point - I've raced with a sway bar removed on 1 end before (different car) and experienced a front and rear that simply didn't communicate with each other. In a few weeks I will be testing rear bar settings: Eibach rear bar stiff and soft, OEM bar and No bar. You may want to consider softening the rear bar or going to a softer rear bar if yours isn't adjustable.

With all that being said - once rebound, roll stiffness and droop are addressed then at THAT point would I be looking to address things with a shiny new clutch diff. In my previous race car I switched from torsen to clutch and guess what - I didn't "just go faster", in fact, I went slower. The diff bound up the power in some circumstances so I had to learn to drive differently to get back to my original pace. The clutch diff outperformed the torsen when I applied too much throttle out of a hairpin or was in a low tractive environment like rain.
__________________
SCCA T4 - FRS
rice_classic is offline   Reply With Quote
The Following User Says Thank You to rice_classic For This Useful Post:
Icecreamtruk (06-28-2019)
Old 07-08-2019, 11:36 AM   #24
Icecreamtruk
Senior Member
 
Join Date: Dec 2015
Drives: Track preped NA FRS
Location: Montreal, Canada
Posts: 782
Thanks: 814
Thanked 525 Times in 317 Posts
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Updates for those interested:

I went to the track last weekend and had 2 drivers (me and the local Alien) on the car the whole day, chasing time with what little we could adjust on the setup. Sadly, I couldnt get the datalogger I had borrow for testing to work, its supposed to pair with the phone and send the data from the OBDII port to its phone app but it kept unpairing non stop every 15 seconds, will have to try again.

Anyways, the second driver on the car is a much better driver than myself and could tell things about my setup that I didnt feel. First, the setup had no rear grip on exit, according to him, this was not a diff problem, but rather a suspension problem. Secondly, the ABS intervenes too much during trail braking, so much so that he had to reduce pressure during trail to the bare minimum for the car to turn properly. His thoughs overall on the car are that it is easy to drive just at or before the limit of grip and fairly fast, but that past that limit it is too twitchy and unpredictable, he found the window of grip at the limit was just too narrow. He also hates how little power the engine has at lower RPM. (like 5-5.5 low, not like 4k low). He did not personally found the diff to be obstrusive to lap times, not more than the car's twitchyness at least. He recommended bigger and ajustables sway bars to have more tools to fine tune the car with.

Here's a video of a side by side comparison of him and me driving (him on top, me on the bottom) after we dialed the setup a bit more:

Icecreamtruk is offline   Reply With Quote
Old 07-09-2019, 08:39 PM   #25
oinojo
STAC Member
 
oinojo's Avatar
 
Join Date: Feb 2013
Drives: 2015 Ford Focus ST
Location: Gardena, CA
Posts: 41
Thanks: 0
Thanked 57 Times in 23 Posts
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
i would check to see if you are sitting on the bumpstops
__________________
OS Giken / Bridgestone / Lot-USA BRIDE
oinojo is offline   Reply With Quote
Old 07-09-2019, 08:54 PM   #26
CSG Mike
 
CSG Mike's Avatar
 
Join Date: Jul 2012
Drives: S2000 CR
Location: Orange County
Posts: 12,633
Thanks: 7,811
Thanked 12,245 Times in 5,840 Posts
Mentioned: 862 Post(s)
Tagged: 13 Thread(s)
Is he pedal danced? What pads/tires are you on?
CSG Mike is offline   Reply With Quote
Old 07-10-2019, 12:26 AM   #27
soundman98
Boost is Whack. N/A4LYFE
 
soundman98's Avatar
 
Join Date: Sep 2013
Drives: '14 brz limited
Location: chicagolandia
Posts: 2,382
Thanks: 3,916
Thanked 1,712 Times in 1,031 Posts
Mentioned: 24 Post(s)
Tagged: 0 Thread(s)
Quote:
Originally Posted by Icecreamtruk View Post
First, the setup had no rear grip on exit, according to him, this was not a diff problem, but rather a suspension problem. Secondly, the ABS intervenes too much during trail braking, so much so that he had to reduce pressure during trail to the bare minimum for the car to turn properly.

His thoughs overall on the car are that it is easy to drive just at or before the limit of grip and fairly fast, but that past that limit it is too twitchy and unpredictable, he found the window of grip at the limit was just too narrow. He also hates how little power the engine has at lower RPM. (like 5-5.5 low, not like 4k low). He did not personally found the diff to be obstrusive to lap times, not more than the car's twitchyness at least. He recommended bigger and ajustables sway bars to have more tools to fine tune the car with
*note: i have no clue what i'm talking about, here to learn just as much as everyone else.*

so the the car is twitchy. my pickup truck is twitchy when not loaded down too. both are what i would consider problems with running too heavy of springs. i don't see how getting bigger sway bars could improve this situation in any way because you're already getting odd wheel speeds and numb handling, both something i would attribute to rigidly connecting either sides of the axles... what it seems is missing is low speed reaction times.

which brings to mind, how lowered are you and how much sag is in the suspension when the car is at rest?

i'm also curious what drive mode the other driver was using that ABS was active.

my first thought was to run 5k/12k double-rate stacked springs like they do in the offroad world



running a small softer spring should make the contact patch a little more predictable and able to react faster, which should make track imperfections less obvious, but would increase spring sag under aero load.

at least that's the reasoning bouncing around in my head.
__________________
my '14 brz limited "the return to normal" (or is it?)
led mods-10%(planning/designing/sitting on hands)audio mods-99%(done is never done)

hidplanet build log
soundman98 is offline   Reply With Quote
Old 07-10-2019, 11:22 AM   #28
Racecomp Engineering
 
Join Date: Nov 2011
Drives: 2016 BRZ, 2012 Paris Di2 & 2018 STI
Location: Severn, MD
Posts: 4,314
Thanks: 2,234
Thanked 5,181 Times in 2,211 Posts
Mentioned: 258 Post(s)
Tagged: 9 Thread(s)
Send a message via AIM to Racecomp Engineering
Springs that stiff, real aero, sticky tires, and a bumpy track will really show the weakness of suboptimal damping (which is one thing I see in your video). I don't think a diff change alone will solve your issue.

- Andrew
Racecomp Engineering is online now   Reply With Quote
The Following 2 Users Say Thank You to Racecomp Engineering For This Useful Post:
Icecreamtruk (07-10-2019), wparsons (07-11-2019)
 
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
SOLD: OEM Clutch, Pressure Plate, Clutch Fork and Pivot, Exedy TOB zc06_kisstherain Transmission and Driveline 3 10-17-2018 10:31 PM
Won't start after clutch change RenegadeReaper Issues | Warranty | Recalls / TSB 21 09-19-2018 09:21 PM
FS: SSP AT Clutch Pack! NIB nlowell Transmission and Driveline 12 03-09-2018 04:31 PM
Oil Change Interval Change (Subaru recommended) Flow Mechanical Maintenance (Oil, Fluids, Break-In, Servicing) 34 09-10-2014 07:27 PM


All times are GMT -4. The time now is 11:16 AM.


Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Garage vBulletin Plugins by Drive Thru Online, Inc.