home register FAQ memberlist calendar

Go Back   Turbobricks Forums > Mechanical > performance & modifications

Reply
 
Thread Tools Display Modes
Old 03-13-2019, 06:38 PM   #1
740atl
educator monkey
 
740atl's Avatar
 
Join Date: Apr 2010
Location: south jersey
Default 4l80e on the street. What rear gear?

I'm thinking about using the 4l80e behind the v8. What rear gears are people using with this transmission? I know there's a few v8 people out there with 4l80's behind them.

What rear gear do you have and what's your rpm at 70mph?

Also, does the 4l80e have an appreciable rpm drop once the converter locks? something like 300-500rpm?

Inquiring minds want to know.
740atl is offline   Reply With Quote
Old 03-13-2019, 09:20 PM   #2
Ilvmetal
Board Member
 
Join Date: Nov 2016
Location: Woodstock NY
Default

3.73 is what i'm building in the 8.8
Will work good with boost
__________________
1973 142 Turbo 8V build
1988 740 16V money pit
2004 V70R Wife's DD
2017 S60T5 Pole star ecu flash (still slow)
At any given time I have to many projects but not enough Volvos...
Ilvmetal is offline   Reply With Quote
Old 03-14-2019, 01:39 AM   #3
mck1117
Board Member
 
Join Date: Jul 2016
Default

RPM difference when the converter locks depends upon load. If you're coasting, it will be negative (engine spins faster when TC locked).

The math is pretty straight forward to figure it out yourself, this calculator even has a big list of transmissions from you to pick from: http://www.grimmjeeper.com/gears.html
mck1117 is offline   Reply With Quote
Old 03-14-2019, 02:02 AM   #4
Dan
TQ>HP
 
Dan's Avatar
 
Join Date: Jun 2002
Location: Superior, Montana
Default

I have a 700 r4 with .76 OD, 3.73 rear gears I turn 2450 at 70 with converter locked. I will probably go to a numerically lower gear when this one breaks, but I am a cruiser more than a racer
__________________
1985 Chevy TPI V8 740.

“Expertise in one field does not carry over into other fields. But experts often think so. The narrower their field of knowledge the more likely they are to think so.” – Robert A. Heinlein
“We must reject the idea that every time a law is broken, society is guilty rather than the lawbreaker. It is time to restore the American precept that each individual is accountable for his actions.” – Ronald Reagan
Dan is offline   Reply With Quote
Old 03-14-2019, 08:31 AM   #5
Rich Halsey
Board Member
 
Rich Halsey's Avatar
 
Join Date: Sep 2013
Location: Maryland
Default

Tire size is a big factor also when choosing rear gear. I started with 3:73 and found it to be a little too low for me with the turbo set up. I ended up doing 2 different rears because its so easy to change complete rears with the ladder bar set up and have a 3:08 rear I run with the stock tires and 3:27 rear with the 235/60/15 drag radials. Locked up it will cruise 70 below 2200 rpm
Rich Halsey is offline   Reply With Quote
Old 03-14-2019, 08:58 AM   #6
linuxman51
BRANDSCHUTZVORSCHRIFTEN!
 
linuxman51's Avatar
 
Join Date: Dec 2002
Location: mont, AL
Default

3:31 is what I put in the 940 (cause, drop in 960 axle). still kinda tall with the 225 55 16 (I think..) all seasons I've been running, but around town it's fine. It really wasn't that bad on the highway either, it turned in an average of around 20mpg's going to and from the mountain meet a few years ago.

rpm drop with lockup will depend on how tight the converter is and where you are in the rpm range.
__________________
"They bum rushed them in their own crib, they drank all their beer, they partied with their ladies and they left with the trophy"

Now with in-house Dyno tuning!

Megasquirt Tuning!
Plug and play LH 2.4 Megasquirt, now with stealth mode!
linuxman51 is offline   Reply With Quote
Old 03-14-2019, 09:53 AM   #7
cosbySweater
Board Member
 
cosbySweater's Avatar
 
Join Date: Jul 2009
Location: Monterey/Falun
Default

I will say I've been using mine as a daily on and off for about 3 years and on and off. My commute is highway mostly, the car has a 225/50r17 lockup 80e and 3.73 gears and it is..... Absolutely awful. I plan on doing 3.27 asap. 70mph is around 2650 rpm and you can literally watch the gas gauge going down as your driving. And it goes down with the quickness
__________________
1979 Volvo 244DL 5.3/4l80e,8.8,Ms3x goldbox ecu and Mircrosquirt tcu, GTX4202r, 226/230 turbo cam, tbss intake, 11.0@128mph 9psi, 3600lbs with driver
1974 AMC Gremlin, 401 v8, 727, 8.8
1974 BMW Bavaria, m30, dcoes, getrag 265
1995 Porsche 993
2013 VW Passat TDI
Quote:
Originally Posted by bricktop420 View Post
Thank you very much everybody... i now feel sufficiently retarded and will go cry in the corner...
cosbySweater is offline   Reply With Quote
Old 03-15-2019, 07:44 AM   #8
740atl
educator monkey
 
740atl's Avatar
 
Join Date: Apr 2010
Location: south jersey
Default

Quote:
Originally Posted by cosbySweater View Post
I will say I've been using mine as a daily on and off for about 3 years and on and off. My commute is highway mostly, the car has a 225/50r17 lockup 80e and 3.73 gears and it is..... Absolutely awful. I plan on doing 3.27 asap. 70mph is around 2650 rpm and you can literally watch the gas gauge going down as your driving. And it goes down with the quickness
That's kind of where I'm at right now. 25" tires, 3.92 stock 242 rear, 0.72 od. 70 is 2600ish.

Right now the car has a stockish v8 (cam, headers). Won't the performance tank if I drop in a 3.31 with the 4l80?
740atl is offline   Reply With Quote
Old 03-15-2019, 04:38 PM   #9
cosbySweater
Board Member
 
cosbySweater's Avatar
 
Join Date: Jul 2009
Location: Monterey/Falun
Default

What engine is it behind?
cosbySweater is offline   Reply With Quote
Old 03-16-2019, 01:30 PM   #10
mikep
The MP
 
mikep's Avatar
 
Join Date: May 2003
Location: 38° 27' N 75° 29' W
Default

Quote:
Originally Posted by 740atl View Post
That's kind of where I'm at right now. 25" tires, 3.92 stock 242 rear, 0.72 od. 70 is 2600ish.

Right now the car has a stockish v8 (cam, headers). Won't the performance tank if I drop in a 3.31 with the 4l80?
Do the math on the different first gears and final drives.
Multiply the current first by the current rear. See what final drive comes out the same with the different first gear.
Then compare current OD x rear with the new OD x rear.
__________________
Quote:
Originally Posted by Lando View Post
ass-thrush.
Quote:
Originally Posted by kyle242gt View Post
TBOT is like Google, run by Underpants Gnomes.
mikep is offline   Reply With Quote
Old 03-17-2019, 08:53 AM   #11
linuxman51
BRANDSCHUTZVORSCHRIFTEN!
 
linuxman51's Avatar
 
Join Date: Dec 2002
Location: mont, AL
Default

Quote:
Originally Posted by cosbySweater View Post
What engine is it behind?
lt1

Quote:
Originally Posted by mikep View Post
Do the math on the different first gears and final drives.
Multiply the current first by the current rear. See what final drive comes out the same with the different first gear.
Then compare current OD x rear with the new OD x rear.
it is a little tough with a 4L80 as it has a .75 final, so a more "fun" final drive ratio to go with the first 2 gears (2.48 and 1.48) that doesn't end up spinning the engine high on the interstate is a little tough.

Generally you'd compensate for that with a good converter and stall speed. a number of folks are running 3.08 8.8's in the ellis world. Those ratios also work out fairly well in a turbo application by stretching the gears a little and cutting some of the tq multiplication that tends to result in instant tire smoke
linuxman51 is offline   Reply With Quote
Old 03-17-2019, 12:52 PM   #12
DET17
Reformed SAABaholic
 
Join Date: Nov 2009
Location: NW Georgia
Default

Quote:
Originally Posted by Dan View Post
I have a 700 r4 with .76 OD, 3.73 rear gears I turn 2450 at 70 with converter locked. I will probably go to a numerically lower gear when this one breaks, but I am a cruiser more than a racer
I'm planning a future 700 r4 (gearing, I believe, same as the OP's later designation gearbox).

Using the V8 calculators, I settled on a 3.36 final gear for my 70 Malibu with SBC. This puts first gear in the ~ 10:1 torque multiplication (ignoring a stalled converter) and the highway RPM at 70mph was in the lower 2's.

Insert "it really depends upon the application, there is no perfect final gear answer" comment(s) here.
__________________
Project "cheap thrills" build thread: http://forums.turbobricks.com/showth...67#post4211467

Feedback thread: http://forums.turbobricks.com/showthread.php?t=198746
DET17 is offline   Reply With Quote
Old 03-17-2019, 05:27 PM   #13
73amc
Board Member
 
Join Date: Nov 2014
Default

I run a 3.27 rear gear with my 6 liter. It's great.
73amc is offline   Reply With Quote
Old 03-18-2019, 05:17 PM   #14
MikeSr.
What, me worry?
 
MikeSr.'s Avatar
 
Join Date: May 2003
Location: Acworth, Ga. USA
Default

T56 6th w/3.73
Attached Images
File Type: jpg ACB6DCA4-99A4-4E76-8D8F-A1077ADEA31E.jpg (187.9 KB, 71 views)
__________________
I coulda had a V8!
MikeSr. is offline   Reply With Quote
Old 03-19-2019, 11:41 AM   #15
freevolvos
Board Member
 
freevolvos's Avatar
 
Join Date: Jan 2011
Location: hillpoint
Default

4:56 go deep or go home I'm used to cruising at 3300 at 60
freevolvos is offline   Reply With Quote
Old 03-22-2019, 12:34 AM   #16
cosbySweater
Board Member
 
cosbySweater's Avatar
 
Join Date: Jul 2009
Location: Monterey/Falun
Default

im gonna say 3.27 if you plan to drive it alot.
cosbySweater is offline   Reply With Quote
Reply

Thread Tools
Display Modes

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 On

Forum Jump


All times are GMT -4. The time now is 11:17 AM.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.