TheAMCForum.com Homepage
Forum Home Forum Home > The Garage > Transmission & Drivetrain
  New Posts New Posts RSS Feed - Standard rear differential gear ratio question
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Click for TheAMCForum Rules / Click for PDF version of Forum Rules
Your donations help keep this valuable resource free and growing. Thank you.

Standard rear differential gear ratio question

 Post Reply Post Reply Page  12>
Author
Message
Rambler Mexicano View Drop Down
AMC Apprentice
AMC Apprentice
Avatar

Joined: Mar/05/2011
Location: Guadalajara
Status: Offline
Points: 206
Post Options Post Options   Thanks (0) Thanks(0)   Quote Rambler Mexicano Quote  Post ReplyReply Direct Link To This Post Topic: Standard rear differential gear ratio question
    Posted: Apr/10/2011 at 6:16pm
Hi,

I have some questions regarding the AMX, Javelin, Rebel and the Matador. What is the STANDARD gear ratio for the rear differential in all these lines?

I know that within Group 19 parts you had the option of five different gear ratios: 3.73:1, 3.91:1, 4.10:1, 4.44:1, 5.00:1, at least in the 1968-1974 Javelins and AMXs, I don't know if they were available in the Rebel Machine, Hornet SC/360 or any other line.

Is the standard ratio the same for all units regardless if they are six cylinder cars or V8 cars?

If not, what's the standard ratio for the sixes and what's the standard ratio for the V8s?

What ratios were available as optional equipment (excluding the Group 19 ones) in these four lines?

Thanks in advance.
Mauricio Jordán

Cuando no se es una empresa famosa se deben hacer mejores automóviles.
- Vehículos Automotores Mexicanos S. A. de C. V.
Back to Top
poormansMACHINE View Drop Down
AMC Addicted
AMC Addicted
Avatar
Charter Member

Joined: Jun/28/2007
Location: Shoemaker-Levy9
Status: Offline
Points: 12322
Post Options Post Options   Thanks (0) Thanks(0)   Quote poormansMACHINE Quote  Post ReplyReply Direct Link To This Post Posted: Apr/10/2011 at 6:26pm
2.87 with a factory option 3.15 was usually the common with V-8 car.
Back to Top
Rambler Mexicano View Drop Down
AMC Apprentice
AMC Apprentice
Avatar

Joined: Mar/05/2011
Location: Guadalajara
Status: Offline
Points: 206
Post Options Post Options   Thanks (0) Thanks(0)   Quote Rambler Mexicano Quote  Post ReplyReply Direct Link To This Post Posted: Apr/10/2011 at 6:55pm
Thanks Ron,

I just found this.

http://www.amx-perience.com/1971JavAMX.htm

Specs for the 1971 Javelin AMX,

It came standard with the 2.87:1 gear ratio with the 360 cubic inch V8 regardless of carburetor and exhausts, and had the 3.15:1 and the 3.54:1 gear ratios as optional equipment.

Also, the same car with the 401 V8 already had the 3.15:1 as standard equipment even though the 2.87:1 was still available as optional equipment as was the 3.54:1 gear ratio.

Thanks again.
Mauricio Jordán

Cuando no se es una empresa famosa se deben hacer mejores automóviles.
- Vehículos Automotores Mexicanos S. A. de C. V.
Back to Top
ramblinrev View Drop Down
Moderator Group
Moderator Group
Avatar

Joined: Dec/28/2008
Location: Wisconsin
Status: Offline
Points: 3709
Post Options Post Options   Thanks (0) Thanks(0)   Quote ramblinrev Quote  Post ReplyReply Direct Link To This Post Posted: Apr/10/2011 at 9:04pm

Often there was a difference between a manual transmission car and an automatic equipped car.

'70 AMX with Go-Package, for example: 3.15 with automatic, 3.54 with 4-speed.
74 Hornet Hatchback X twins
62 American Convertible
70 AMX 360 4-speed
70 Javelin SST 390
Back to Top
billd View Drop Down
Moderator Group
Moderator Group
Avatar
Forum Administrator

Joined: Jun/27/2007
Location: Iowa
Status: Offline
Points: 23379
Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Apr/11/2011 at 8:53am
Originally posted by poormansMACHINE poormansMACHINE wrote:

2.87 with a factory option 3.15 was usually the common with V-8 car.


Yes - my 70 (390 auto) is stamped with the code for 2.87 yet the gears are actually 3.15
The invoice that the original owner got said "gear ratio" on it, and it cost about 10 bucks.
Back to Top
Rambler Mexicano View Drop Down
AMC Apprentice
AMC Apprentice
Avatar

Joined: Mar/05/2011
Location: Guadalajara
Status: Offline
Points: 206
Post Options Post Options   Thanks (0) Thanks(0)   Quote Rambler Mexicano Quote  Post ReplyReply Direct Link To This Post Posted: Apr/11/2011 at 1:04pm
Originally posted by ramblinrev ramblinrev wrote:

Often there was a difference between a manual transmission car and an automatic equipped car.

'70 AMX with Go-Package, for example: 3.15 with automatic, 3.54 with 4-speed.


Thanks Rev,

I actually saw that now also engine and transmission combination are vital to the gear ratio but also the shift control configuration.

The 401 1971 AMX with automatic transmission on the column has a gear ratio of 3.15:1 while the same car with the same engine and transmission with floor shift has the 2.87:1 ratio.

I'll keep on investigating.
Mauricio Jordán

Cuando no se es una empresa famosa se deben hacer mejores automóviles.
- Vehículos Automotores Mexicanos S. A. de C. V.
Back to Top
farna View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum
Avatar
Moderator Lost Dealership Project

Joined: Jul/08/2007
Location: United States
Status: Offline
Points: 7879
Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Apr/12/2011 at 12:46pm
Six cylinder cars most often used 3.08 gears in the Javelin, 3.15 in the bigger cars -- auto and manual trannys (from the 71 TSM). The Hornet and Gremlin used a bit taller gearing -- 2.73 was most common. Hornets with manual used a 3.08, Gremlins 2.73 with auto or manual. Without AC both used a 2.37 with auto trans.

Note that Mexican built cars (VAM cars) most likely have a bit lower gearing due to the high elevation in the vicinity of Mexico City.
Frank Swygert
American Motors Cars Magazine
www.amc-mag.com
Back to Top
70bigbadorange View Drop Down
AMC Fan
AMC Fan
Avatar

Joined: Nov/30/2012
Location: AZ
Status: Offline
Points: 4
Post Options Post Options   Thanks (0) Thanks(0)   Quote 70bigbadorange Quote  Post ReplyReply Direct Link To This Post Posted: Jan/10/2013 at 11:13pm
guys, thanks for all the info on diffs. I have a 70 Javelin. don't know about stamps or stickers but I'm putting in a lock right so I got mine apart enough to count the ring gear and pinion teeth and I got a 3.15. wish I had the 3.54 but I guess this will do for now.
Mine also came with the 904 3 speed auto trans (i believe)... years ago I put the 727 in it. now I would like to upgrade to a 4spd auto. does anyone have advise for me on that???????? 
does anyone know the best way to go if I want to put a 4sp auto in it.
Back to Top
FuzzFace2 View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Jul/05/2007
Location: Connecticut
Status: Offline
Points: 8087
Post Options Post Options   Thanks (0) Thanks(0)   Quote FuzzFace2 Quote  Post ReplyReply Direct Link To This Post Posted: Jan/11/2013 at 9:18am
I am hoping my 70 Javelin has 3.54 gears too and should because it is a 390/4sp car but will not know till I drop the cover for oil change and count the teeth.
 
As for the 4 sp auto you may want to do a search or make your own post for it.
In short AMC only had 1 and it was used in later Jeeps.
Could use any og the GM atuo 4sp but need adapter to use them.
Lastly Gear Venders OD unit bolts on the back of your auto trany (727?) and turns it into a 6sp with OD.
Dave ----
75 GremlinX v8

76 GremlinX i6 (sons)

70 Javelin SST 390/4sp (360/5sp now)

70 Javelin 1/4 Drag car 360/auto
Back to Top
sidewinder View Drop Down
Moderator Group
Moderator Group
Avatar

Joined: Oct/07/2007
Location: Niagara Falls,
Status: Offline
Points: 5192
Post Options Post Options   Thanks (0) Thanks(0)   Quote sidewinder Quote  Post ReplyReply Direct Link To This Post Posted: Jan/11/2013 at 9:52am
About a year or so ago I discovered my 70 AMX with auto transmission and go-pac had 2.87 gears.  With the go-pac it should have had 3.15 gears.   I assume that the original owner opted fore the 2.87 for better highway driving ( calif. car)   I bought a set of new NOS 3.15 gears from a forum member here and changed the gears.   Not really a tremendous difference but a noticeable one.  Also had to change the speedo gear......

Chuck Page
Chuck Page, AKA Sidewinder,Niagara Falls
http://www.amxsidewinder.com
Back to Top
 Post Reply Post Reply Page  12>
  Share Topic   

Forum Jump Forum Permissions View Drop Down



This page was generated in 2.375 seconds.
All content of this site Copyright © 2012 TheAMCForum unless otherwise noted, all rights reserved.
PROBLEMS LOGGING IN or REGISTERING:
If you have problems logging in or registering, then please contact a Moderator or