follow ft86club on our blog, twitter or facebook.
FT86CLUB
Ft86Club
Speed By Design
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 > Tracking / Autocross / HPDE / Drifting

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


View Poll Results: Weight Reduction vs Weight Distribution (if you have to pick one)
Weight reduction because "every ounce matters" 21 52.50%
Weight distribution because balance is more important 15 37.50%
Other: Explain 4 10.00%
Voters: 40. You may not vote on this poll

User Tag List

Reply
 
Thread Tools Search this Thread
Old 06-30-2014, 06:01 PM   #1
glamcem
Senior Member
 
glamcem's Avatar
 
Join Date: Oct 2013
Drives: 2022 BRZ Limited
Location: Orange County
Posts: 1,553
Thanks: 997
Thanked 607 Times in 404 Posts
Mentioned: 32 Post(s)
Tagged: 1 Thread(s)
Exclamation Weight Reduction vs. Weight Distribution (for track use not for drag..etc)

As you may know our cars have 53/47 weight distribution from factory and easiest way to reduce the weight is from the trunk area since there are more easily accessible items which don't hurt the driveability such as spare tire, tools, seats, aftermarket exhaust etc . It looks somewhat harder to reduce the weight without hurting the balance of the car.

In addition to that, I learned when GM was working on the Camaro Z28 they decided to put back the back seats instead of completely eliminating them (Like the Boss 302) since it reduces the rigidity and they ended up adding denser foams and changed the materials to reduce weight. I never really thought about this (the impact on our cars might be smaller or negligible of course, due to weight and size differences )

Please briefly share your opinion/experience
glamcem is offline   Reply With Quote
Old 06-30-2014, 06:11 PM   #2
tahdizzle
So elite I'm 1338
 
Join Date: Feb 2014
Drives: WRB Subaru BRZ
Location: California
Posts: 3,008
Thanks: 1,835
Thanked 1,934 Times in 982 Posts
Mentioned: 32 Post(s)
Tagged: 0 Thread(s)
Garage
While weight and power to weight ratio is very important.

I chose distribution, based on my opinion that it is easier to add HP/lb than to reduce lb to HP.
tahdizzle is offline   Reply With Quote
The Following 2 Users Say Thank You to tahdizzle For This Useful Post:
glamcem (06-30-2014), suaveflooder (06-30-2014)
Old 06-30-2014, 06:23 PM   #3
7thgear
i'm sorry, what?
 
7thgear's Avatar
 
Join Date: Jan 2012
Drives: Canada
Location: I rock a beat harder than you can beat it with rocks
Posts: 4,399
Thanks: 357
Thanked 2,506 Times in 1,268 Posts
Mentioned: 40 Post(s)
Tagged: 3 Thread(s)
both are important


the question thought is what is more important to YOU


I've been leaving my spare inside the car for a better planted rear, which translated into more confidence FOR ME, which translates into better consistency, which under my current circumstances generates the best results


the most confidence I've ever had in my car was when I was with an extra two people and 50 kilos in the trunk, I felt like I could be as aggressive as I wanted to and it wouldn't snap on me


is it slower? yes


but confidence tends to build speed


so you do what fits your needs
__________________
don't you think if I was wrong, I'd know it?
7thgear is offline   Reply With Quote
The Following 2 Users Say Thank You to 7thgear For This Useful Post:
glamcem (06-30-2014), wparsons (07-01-2014)
Old 06-30-2014, 06:36 PM   #4
rice_classic
Senior Member
 
rice_classic's Avatar
 
Join Date: Jun 2012
Drives: Nevermorange FRS
Location: Seattle, WA
Posts: 4,160
Thanks: 755
Thanked 4,200 Times in 1,803 Posts
Mentioned: 77 Post(s)
Tagged: 1 Thread(s)
"Percentage"

What percentage of the weight of the car are you removing? How much power-to-weight are you changing? Percentage change on weight distribution? Changing to 54/46 is different than changing to 60/40 for example.

"Variables"

What's the car's shock/spring/tire combination? Configuration of the track; long straights that are all about power or all corners with little to no straights?

"Data"

Take the weight weight out, run at the limit. Put the weight back in, run at the limit. Look at Data and you will have your answer. Before that I would put the car on scales to check the corner balance before and after weight removal. That will give you good baseline idea of the change you've induced to the balance.
__________________
SCCA T4 - FRS
rice_classic is offline   Reply With Quote
The Following User Says Thank You to rice_classic For This Useful Post:
glamcem (06-30-2014)
Old 06-30-2014, 06:52 PM   #5
glamcem
Senior Member
 
glamcem's Avatar
 
Join Date: Oct 2013
Drives: 2022 BRZ Limited
Location: Orange County
Posts: 1,553
Thanks: 997
Thanked 607 Times in 404 Posts
Mentioned: 32 Post(s)
Tagged: 1 Thread(s)
Quote:
Originally Posted by 7thgear View Post
both are important


the question thought is what is more important to YOU


I've been leaving my spare inside the car for a better planted rear, which translated into more confidence FOR ME, which translates into better consistency, which under my current circumstances generates the best results


the most confidence I've ever had in my car was when I was with an extra two people and 50 kilos in the trunk, I felt like I could be as aggressive as I wanted to and it wouldn't snap on me


is it slower? yes


but confidence tends to build speed


so you do what fits your needs
I actually tried to emphasis that on the poll question by saying "if you have to pick one" but maybe I should've mentioned that in the thread title too

Also, I tend to get better lap times maybe it's because I don't want to scare the passengers with me



Quote:
Originally Posted by rice_classic View Post
"Percentage"

What percentage of the weight of the car are you removing? How much power-to-weight are you changing? Percentage change on weight distribution? Changing to 54/46 is different than changing to 60/40 for example.

I am not exactly sure about the exact numbers at this point and I do understand the differences between too.. Ideally, I would prefer removing from the front and keep the balance in controls.. battery relocation kits for trunk might be a good example but with the added complexity and efforts I am not sure if it's worth it.. at that point lightweight battery also makes sense..

"Variables"

What's the car's shock/spring/tire combination? Configuration of the track; long straights that are all about power or all corners with little to no straights?

R compounds, relatively stiff coilover setup and you know I attend the events at local tracks in PNW region (PR,RMP and ORP)


"Data"

Take the weight weight out, run at the limit. Put the weight back in, run at the limit. Look at Data and you will have your answer. Before that I would put the car on scales to check the corner balance before and after weight removal. That will give you good baseline idea of the change you've induced to the balance.
good idea, I will try to get more data with and without seats next time to see if there's any quantifiable difference between two..I will report back
Please see above
glamcem is offline   Reply With Quote
Old 06-30-2014, 07:10 PM   #6
juliog
Senior Member
 
juliog's Avatar
 
Join Date: Jan 2013
Drives: 86
Location: Green Hell
Posts: 930
Thanks: 1,269
Thanked 925 Times in 390 Posts
Mentioned: 55 Post(s)
Tagged: 1 Thread(s)
Garage
OP what is your question exactly?
juliog is offline   Reply With Quote
Old 06-30-2014, 07:45 PM   #7
jvincent
Senior Member
 
jvincent's Avatar
 
Join Date: Sep 2013
Drives: 2022 WRB BRZ Sport-Tech
Location: Ottawa, Canada
Posts: 1,746
Thanks: 131
Thanked 1,411 Times in 715 Posts
Mentioned: 25 Post(s)
Tagged: 2 Thread(s)
No real opinion here, but I wanted to chime in with a comment about weight distribution that has annoyed me for a while.

From a physics point of view, splitting the car into equal halves isn't really that meaningful for weight distribution IMHO. There are a LOT of ways to get 50/50 balance that will behave very differently on the road.

For example a 25/25/25/25 distribution will have a very different rotational inertia than 10/40/40/10. Or 40/10/10/40. I think you get the idea.
jvincent is offline   Reply With Quote
Old 06-30-2014, 07:49 PM   #8
tahdizzle
So elite I'm 1338
 
Join Date: Feb 2014
Drives: WRB Subaru BRZ
Location: California
Posts: 3,008
Thanks: 1,835
Thanked 1,934 Times in 982 Posts
Mentioned: 32 Post(s)
Tagged: 0 Thread(s)
Garage
Quote:
Originally Posted by jvincent View Post
No real opinion here, but I wanted to chime in with a comment about weight distribution that has annoyed me for a while.

From a physics point of view, splitting the car into equal halves isn't really that meaningful for weight distribution IMHO. There are a LOT of ways to get 50/50 balance that will behave very differently on the road.

For example a 25/25/25/25 distribution will have a very different rotational inertia than 10/40/40/10. Or 40/10/10/40. I think you get the idea.
Agreed. But no one said a 50/50 split was ideal in all scenarios.

Weigh distrubution and alignments all need to be tuned for your needs and driving style.
tahdizzle is offline   Reply With Quote
Old 06-30-2014, 07:52 PM   #9
brz7400
Senior Member
 
brz7400's Avatar
 
Join Date: Jun 2012
Drives: Subaru BRZ
Location: Los Angeles, CA
Posts: 138
Thanks: 84
Thanked 30 Times in 22 Posts
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
glad to know someone else keeps the spare in!
i thought i was the only one that autocrossed with the spare in.

every time i take out the spare, the rear becomes too loose and i lack the skills to control it properly.
it's also why i am scared to change the exhaust for weight savings...
and keep the gas tank filled anywhere more like 1/3~2/3.

i'm looking at lightweight wheels as my next allowed mod, since a nice young man asked me to drive his brz at a practice event a month ago and i immediately noticed the car accelerated off the start line much quicker than mine.
but then he also had the spare tire removed for additional weight savings and i ended up spinning his car on the first sweeper.

so i'll agree that both matters.
if i was a better driver, i would run without spare and low gas tank and muffler delete and lightweight wheels.
but for me, i'll have to stick to keeping the spare in, plenty of gas, regular muffler and hope to pick up some speed through lightweight wheels.
brz7400 is offline   Reply With Quote
Old 06-30-2014, 07:54 PM   #10
jvincent
Senior Member
 
jvincent's Avatar
 
Join Date: Sep 2013
Drives: 2022 WRB BRZ Sport-Tech
Location: Ottawa, Canada
Posts: 1,746
Thanks: 131
Thanked 1,411 Times in 715 Posts
Mentioned: 25 Post(s)
Tagged: 2 Thread(s)
On the topic of keeping the spare in, the groups that run events at the track near me require you to take the spare/jack/etc out of the car for safety reasons.

I figured that would be the case for everyone.
jvincent is offline   Reply With Quote
Old 06-30-2014, 08:06 PM   #11
D K
Stig's dark passenger
 
Join Date: Dec 2013
Drives: FR-S
Location: I work abroad
Posts: 724
Thanks: 60
Thanked 316 Times in 186 Posts
Mentioned: 20 Post(s)
Tagged: 1 Thread(s)
I'm actually blown away how much more front bias our car has...
D K is offline   Reply With Quote
Old 06-30-2014, 08:32 PM   #12
rice_classic
Senior Member
 
rice_classic's Avatar
 
Join Date: Jun 2012
Drives: Nevermorange FRS
Location: Seattle, WA
Posts: 4,160
Thanks: 755
Thanked 4,200 Times in 1,803 Posts
Mentioned: 77 Post(s)
Tagged: 1 Thread(s)
Quote:
Originally Posted by glamcem View Post
Please see above
Quit denying your addiction and where it's taking you... Takin' out interior bits, thinking of relocating the battery, buying R-comps for a street car... Just stop monkeying with the FRS and embrace the inevitable already.

Go buy a damn racecar.

Resistance if futile.

__________________
SCCA T4 - FRS
rice_classic is offline   Reply With Quote
The Following 4 Users Say Thank You to rice_classic For This Useful Post:
Deep Six (06-30-2014), glamcem (07-01-2014), SportInjected (06-30-2014), SuperTom (12-31-2019)
Old 06-30-2014, 08:39 PM   #13
bimmer635csi
Senior Member
 
bimmer635csi's Avatar
 
Join Date: Apr 2014
Drives: 2013 Cayenne turbo
Location: Basement of the Alamo
Posts: 254
Thanks: 6
Thanked 72 Times in 47 Posts
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
I'd say weight reduction first, then weight balance second because:

1) When the car accelerates, weight shifts to the back anyway, balancing out the small imbalance (which is the opposite under braking, but that should be a lower percentage of a lap time)

2) You can tune to the small imbalance with springs, air pressure, sway bars, driving style, etc. You can not tune less weight (or more power) in the car as easily.

3) A lot of classes have minimum weights, so if you can get below the minimum, then you can place ballast where you need it to tune the car.

Forgive me if this seems basic, but the OP's question did also.
__________________
bimmer635csi is offline   Reply With Quote
The Following 2 Users Say Thank You to bimmer635csi For This Useful Post:
glamcem (07-01-2014), renfield90 (06-30-2014)
Old 06-30-2014, 09:04 PM   #14
renfield90
The Stig's German cousin
 
Join Date: Mar 2013
Drives: 2013 FR-S
Location: Tempe, AZ
Posts: 1,069
Thanks: 140
Thanked 517 Times in 343 Posts
Mentioned: 8 Post(s)
Tagged: 2 Thread(s)
Removing weight will, by the simple laws of physics, make the car faster. You will go, stop, and turn faster. Period.

The same cannot be strictly said for weight distribution unless you're racing in Formula 1 and the fancy computer spits out the perfect weight and alignment settings for the exact track you're on. (I'm treating weight distribution strictly from the perspective of the weight on each tire; a more complex discussion involving where the mass is located and the resulting moments of inertia is probably beyond the scope of this thread.)

Ideally, your car will have some sort of adjustable ride height so you can tune the weight distribution a little bit. This is the key; your weight distribution is a tool you can use to tune the handling of your car, and it's a small tool at that. Your shock settings will have a greater impact on the balance of the car than your weight distribution.

The raw weight of your car is an impediment to your performance. It is NOT a tool. Don't use it as such.
renfield90 is offline   Reply With Quote
 
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
weight distribution Nardi330 Suspension | Chassis | Brakes -- Sponsored by 949 Racing 11 08-26-2013 06:06 AM
Weight reduction in the front only KevinBRZ Scion FR-S / Toyota 86 GT86 General Forum 16 04-12-2013 12:25 AM
Weight distribution SubieNate Tracking / Autocross / HPDE / Drifting 44 04-06-2013 07:53 PM
the weight reduction of FR - S? raiden8383 Scion FR-S / Toyota 86 GT86 General Forum 22 11-30-2012 06:10 PM
FT-86 weight distribution? tranzformer Scion FR-S / Toyota 86 GT86 General Forum 15 04-04-2011 10:58 AM


All times are GMT -4. The time now is 03:20 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.