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 - FT86CLUB > Technical Topics > Engine, Exhaust, Transmission

Engine, Exhaust, Transmission Discuss the FR-S | 86 | BRZ engine, exhaust and drivetrain.


User Tag List

Reply
 
Thread Tools Search this Thread
Old 11-21-2015, 12:57 PM   #1
Toyota86.ir
Mike Tune HKS E85 FD 4.88
 
Join Date: Jan 2015
Drives: Toyota GT86 AT NA Stage 2
Location: Tehran
Posts: 172
Thanks: 213
Thanked 35 Times in 27 Posts
Mentioned: 1 Post(s)
Tagged: 1 Thread(s)
Automatic Gear Ratio change

Hi guys
I have AT GT86 and after FD swap 4.88 i am thinking about changing Gear ratio in my AT gearbox. maybe it seems dummy idea but i should add there is no MT GT86 for shopping in my country.
Is there any after market company for changing gear ratio of AT gearbox?
AT gear ratio is :
3.538
2.06
1.404
0.713

my idea :
3.50
2.50
1.80
1.35
1
Toyota86.ir is offline   Reply With Quote
Old 11-21-2015, 08:14 PM   #2
FirestormFRS
Senior Member
 
Join Date: Jul 2012
Drives: 2013 FR-S
Location: Anytown
Posts: 920
Thanks: 73
Thanked 641 Times in 302 Posts
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Changing ratios in an AT is probably not an option unless you have thousands of $'s.
FirestormFRS is offline   Reply With Quote
The Following 2 Users Say Thank You to FirestormFRS For This Useful Post:
Freeman (11-21-2015), Toyota86.ir (11-22-2015)
Old 11-21-2015, 11:09 PM   #3
KoolBRZ
Senior Member
 
KoolBRZ's Avatar
 
Join Date: May 2014
Drives: Silver 2013 BRZ Ltd Auto 45,000 mi
Location: Vancouver, WA.USA
Posts: 965
Thanks: 86
Thanked 449 Times in 277 Posts
Mentioned: 60 Post(s)
Tagged: 2 Thread(s)
Garage
Quote:
Originally Posted by Toyota86.ir View Post
Hi guys
I have AT GT86 and after FD swap 4.88 i am thinking about changing Gear ratio in my AT gearbox. maybe it seems dummy idea but i should add there is no MT GT86 for shopping in my country.
Is there any after market company for changing gear ratio of AT gearbox?
AT gear ratio is :
3.538
2.06
1.404
0.713

my idea :
3.50
2.50
1.80
1.35
1
The Auto has the following ratios;
I=3.538, II=2.060, III=1.104, IV=1.00, V=0.713, VI=0.582

All the ratios you want to change are going to rev higher at a lower speed, If that's all you want, then why not just change your FD to 5.29, or even 5.71?
__________________
If I say yes, will that make you think I understand?
KoolBRZ is offline   Reply With Quote
The Following 2 Users Say Thank You to KoolBRZ For This Useful Post:
FRS Justin (11-23-2015), Toyota86.ir (11-22-2015)
Old 11-21-2015, 11:25 PM   #4
Dustin
Twin Screw You
 
Dustin's Avatar
 
Join Date: Nov 2012
Drives: 2013 Supercharged Whiteout FR-S
Location: Burleson, Texas
Posts: 1,231
Thanks: 464
Thanked 620 Times in 332 Posts
Mentioned: 37 Post(s)
Tagged: 0 Thread(s)
Change your final drive. Much easier and will get you the same results. Maybe not down to the number, but close enough where no one would know the difference.
Dustin is offline   Reply With Quote
The Following User Says Thank You to Dustin For This Useful Post:
Toyota86.ir (11-22-2015)
Old 11-22-2015, 12:07 AM   #5
PantsDants
Senior Member
 
Join Date: Jul 2013
Drives: Scion FR-S A/T, Whiteout
Location: Seattle
Posts: 329
Thanks: 57
Thanked 218 Times in 89 Posts
Mentioned: 16 Post(s)
Tagged: 2 Thread(s)
OP, I don't think anyone makes gear sets for the automatic. Other issue is no one (to my knowledge) is capable of tuning the transmission control unit, which could be a huge problem if the computer is expecting stock gear ratios for any of its calculations.
PantsDants is offline   Reply With Quote
The Following User Says Thank You to PantsDants For This Useful Post:
Toyota86.ir (11-22-2015)
Old 11-22-2015, 01:19 AM   #6
Toyota86.ir
Mike Tune HKS E85 FD 4.88
 
Join Date: Jan 2015
Drives: Toyota GT86 AT NA Stage 2
Location: Tehran
Posts: 172
Thanks: 213
Thanked 35 Times in 27 Posts
Mentioned: 1 Post(s)
Tagged: 1 Thread(s)
Quote:
Originally Posted by FirestormFRS View Post
Changing ratios in an AT is probably not an option unless you have thousands of $'s.
how much ?

Quote:
Originally Posted by KoolBRZ View Post
The Auto has the following ratios;
I=3.538, II=2.060, III=1.104, IV=1.00, V=0.713, VI=0.582

All the ratios you want to change are going to rev higher at a lower speed, If that's all you want, then why not just change your FD to 5.29, or even 5.71?
FD 4.88 is good , in my mind close ratio gears give better result than upgrading FD 4.88 to FD 5.71 because gear 1 is more usable and after shifting to next gear we loss less torque. shifting 7400rpm to 5500rpm is better than 7400rpm to 4800rpm.

Quote:
Originally Posted by Dustin View Post
Change your final drive. Much easier and will get you the same results. Maybe not down to the number, but close enough where no one would know the difference.
i have no experience with close gears but in mathematics tell me close gears are better than higher FD.

Quote:
Originally Posted by PantsDants View Post
OP, I don't think anyone makes gear sets for the automatic. Other issue is no one (to my knowledge) is capable of tuning the transmission control unit, which could be a huge problem if the computer is expecting stock gear ratios for any of its calculations.
MFactory and Cusco make close gear for MT but i did not find any close ratio kit for AT.

I have no idea about affecting closer gear on TCU.
Toyota86.ir is offline   Reply With Quote
Old 11-22-2015, 02:30 AM   #7
KoolBRZ
Senior Member
 
KoolBRZ's Avatar
 
Join Date: May 2014
Drives: Silver 2013 BRZ Ltd Auto 45,000 mi
Location: Vancouver, WA.USA
Posts: 965
Thanks: 86
Thanked 449 Times in 277 Posts
Mentioned: 60 Post(s)
Tagged: 2 Thread(s)
Garage
Your shifting rpms will be the same as a close ratio, with the 5.71 FD, but without the transmission actually being a close ratio. The higher the number FD, the closer your shift points become. It also takes some of the strain off your FD, transmission, and engine, and puts it on your axles and tires.
__________________
If I say yes, will that make you think I understand?
KoolBRZ is offline   Reply With Quote
Old 11-22-2015, 02:51 AM   #8
PantsDants
Senior Member
 
Join Date: Jul 2013
Drives: Scion FR-S A/T, Whiteout
Location: Seattle
Posts: 329
Thanks: 57
Thanked 218 Times in 89 Posts
Mentioned: 16 Post(s)
Tagged: 2 Thread(s)
Quote:
Originally Posted by KoolBRZ View Post
Your shifting rpms will be the same as a close ratio, with the 5.71 FD, but without the transmission actually being a close ratio. The higher the number FD, the closer your shift points become. It also takes some of the strain off your FD, transmission, and engine, and puts it on your axles and tires.
The purpose of changing the gears in the transmission is to change them relative to each other. This will change how much the RPMs drop/rise between shifts. It's easier to figure out where you're going to land in the rev range after a shift if the change in RPM is consistent between gears. Another benefit could be to make your 6th gear really tall for cruising but make your other gears shorter for better acceleration.
PantsDants is offline   Reply With Quote
The Following User Says Thank You to PantsDants For This Useful Post:
Toyota86.ir (11-22-2015)
Old 11-22-2015, 07:22 AM   #9
Toyota86.ir
Mike Tune HKS E85 FD 4.88
 
Join Date: Jan 2015
Drives: Toyota GT86 AT NA Stage 2
Location: Tehran
Posts: 172
Thanks: 213
Thanked 35 Times in 27 Posts
Mentioned: 1 Post(s)
Tagged: 1 Thread(s)
I think FD 5.71 make gear 1 so aggressive . Below are Approximate numbers :
5.71 * 3.538 = 20 vs 3.5 * 4.88 = 17
5.71 * 2.060 = 12 vs 2.5 * 4.88 = 13
5.71 * 1.404 = 8 vs 1.8 * 4.88 = 10
5.71 * 1 .000 = 6 vs 1.34*4.88 = 7
5.71 * 0.730 = 4 vs 1 * 4.88 = 5

Gear 1 20 vs 17
Gear 2 12 vs 13
Gear 3 8 vs 10
Gear 4 6 vs 7
Gear 5 4 vs 5
Then as pantsdants mentioned we could use gear 6 for economy
Toyota86.ir is offline   Reply With Quote
Old 11-22-2015, 07:10 PM   #10
FirestormFRS
Senior Member
 
Join Date: Jul 2012
Drives: 2013 FR-S
Location: Anytown
Posts: 920
Thanks: 73
Thanked 641 Times in 302 Posts
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
AT's are not as simple to change ratios in. You have to change a lot of parts that do not exist.
FirestormFRS is offline   Reply With Quote
The Following User Says Thank You to FirestormFRS For This Useful Post:
Toyota86.ir (11-23-2015)
Old 11-22-2015, 10:06 PM   #11
KoolBRZ
Senior Member
 
KoolBRZ's Avatar
 
Join Date: May 2014
Drives: Silver 2013 BRZ Ltd Auto 45,000 mi
Location: Vancouver, WA.USA
Posts: 965
Thanks: 86
Thanked 449 Times in 277 Posts
Mentioned: 60 Post(s)
Tagged: 2 Thread(s)
Garage
What about installing a Gear Vendor Under/Overdrive? It installs on the tailshaft, so would require a shortened driveshaft. But it's outside the transmission. An Overdrive would give decent highway mpg, but in normal mode with a 5.71 FD it would really scream.
__________________
If I say yes, will that make you think I understand?
KoolBRZ is offline   Reply With Quote
The Following User Says Thank You to KoolBRZ For This Useful Post:
Toyota86.ir (11-23-2015)
Old 11-22-2015, 10:20 PM   #12
SUB-FT86
86 Member
 
Join Date: Dec 2010
Drives: 2013 Toyota 86 2.0T (Asphalt)
Location: Atlanta, Ga
Posts: 3,068
Thanks: 108
Thanked 457 Times in 263 Posts
Mentioned: 2 Post(s)
Tagged: 2 Thread(s)
I want to be the first guy that tried the 5.29 fd on the auto. A 29% increase sounds crazy!
SUB-FT86 is offline   Reply With Quote
The Following User Says Thank You to SUB-FT86 For This Useful Post:
Toyota86.ir (11-23-2015)
Old 11-23-2015, 01:06 AM   #13
Toyota86.ir
Mike Tune HKS E85 FD 4.88
 
Join Date: Jan 2015
Drives: Toyota GT86 AT NA Stage 2
Location: Tehran
Posts: 172
Thanks: 213
Thanked 35 Times in 27 Posts
Mentioned: 1 Post(s)
Tagged: 1 Thread(s)
Thank you guys

It seems changing AT gears is not logical and I should try to buy manual transmission GT 86 for the next year.
Toyota86.ir is offline   Reply With Quote
Old 11-23-2015, 03:39 AM   #14
KoolBRZ
Senior Member
 
KoolBRZ's Avatar
 
Join Date: May 2014
Drives: Silver 2013 BRZ Ltd Auto 45,000 mi
Location: Vancouver, WA.USA
Posts: 965
Thanks: 86
Thanked 449 Times in 277 Posts
Mentioned: 60 Post(s)
Tagged: 2 Thread(s)
Garage
Nooooooo

Quote:
Originally Posted by Toyota86.ir View Post
Thank you guys

It seems changing AT gears is not logical and I should try to buy manual transmission GT 86 for the next year.
With an AT, and a 5.71 FD you could probably leave rubber in the first 5 gears, and get sideways in the first 4. Of course you'll still only be going about 30 mph, but those tires would be smokin'!
__________________
If I say yes, will that make you think I understand?
KoolBRZ is offline   Reply With Quote
The Following User Says Thank You to KoolBRZ For This Useful Post:
Toyota86.ir (11-23-2015)
 
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
Change gear ratio? Afdad120108 Engine, Exhaust, Transmission 61 08-17-2016 11:44 AM
4.556 final drive with TRD gear ratio change - good or bad idea? nzer Engine, Exhaust, Transmission 51 12-26-2015 10:15 PM
Gear Ratio Change Lunatic Wheels | Tires | Spacers | Hub -- Sponsored by The Tire Rack 34 06-26-2014 11:20 PM
Change FD ratio to 4.56 by changing only pinion peachch Engine, Exhaust, Transmission 1 08-31-2013 02:25 PM
86,BRZ MT gear ratio Yobiwan Engine, Exhaust, Transmission 1 01-26-2012 03:40 AM


All times are GMT -4. The time now is 11:12 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.
User Alert System provided by Advanced User Tagging v3.3.0 (Lite) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.

Garage vBulletin Plugins by Drive Thru Online, Inc.