Re: [AMC-list] Differential number

[Frank Swygert <farna@xxxxxxx>]

"13/40" means the pinion gear has 13 teeth, the ring gear has 40 teeth. Divide 40 by 13 and you get 3.076923, which rounds up to 3.08 (some would call it 3.07, either is correct). 3.08 gears were only available in the AMC 15. It's strong enough for a 290 or 304 V-8 as long as you're not too hard on it. Even if you are it will last a while. If you plan on drag racing you will need a stronger axle sooner rather than later, but for a cruiser and mild 304 I wouldn't worry about breaking the AMC 15. Just have the axle nuts loosened then retorqued to 250-300 ft/lbs and you'll be good for a long time -- most likely will never need anything stronger -- unless you're really hard on it, and then it will most likely make some protest noises before it goes out.

Joe, the tag was used on all axles through 1969. Starting in 1970 the AMC 20 used an axle code stamped on the diff housing. The AMC 15 started using a stamped code in 1972.

--------------
Date: Tue, 25 Jan 2011 12:39:40 -0800 (PST)
From: Joe Fulton<piper_pa20@xxxxxxxxxxx>

Chad,

Your car has a 3.07 to 1 axle ratio.?? That's sort of an in-between gear:?
highway friendly but still able to deliver some torque to the rear wheels.?


If you have a tag, your car probably has the AMC 15 rear, right?? Normally, the
AMC rears had an alphabetic code stamped into the housing boss near the
passenger side axle tube (at the rear).? Joe



----- Original Message ----
From:"chadchadwick@xxxxxxxx"  <chadchadwick@xxxxxxxx>

Joe I checked? the defferential housing on my javelin? and i could'ent find a
number, but the tag is still there? it reads 13/40 does that help.? chad

--
Frank Swygert
Publisher, "American Motors Cars"
Magazine (AMC)
For all AMC enthusiasts
http://www.amc-mag.com
(free download available!)

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