Any way to Id rearend and gear ratio in 1967 Mustang? - Ford Mustang Forum
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post #1 of 6 (permalink) Old 04-01-2010 Thread Starter
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Question Any way to Id rearend and gear ratio in 1967 Mustang?

Is there an eay way to ID the rearend and gear ratio in my car? It came factory with a 289 2v, five lug.
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post #2 of 6 (permalink) Old 04-01-2010
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There should be a tag attached to one of the bolts that surround the center section (3rd member). Otherwise there is a door tag on the drivers door that has a letter for the differential that will identify which gear was in the car originally.

Post either or both of these numbers/letters and someone can identify it.

'67 Coupe 289 stroked to 333, AOD, 9" w/3.50:1, PDB, Candyapple red w/red deluxe int., PS, ext. decor group, light group, foxbody seats.
'09 Black Warriors In Pink with glass roof - the wifes Mustang.
"If it ain't broke, I haven't fixed it yet" -Jon
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post #3 of 6 (permalink) Old 04-01-2010
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You can also lift the rear end up, mark the rear drive shaft & also a tire & count the revolutions. 1 full revolution of tire to 3 revolutions of drive shaft= 3.0 to 1, 1 revolution tire to 3 1/4 driveshaft revolutions= 3.25 to 1, etc. Also you can look to see if the opposite rear tire spins in the same direction means limited slip, locker I believe. This is what I did to figure mine out recently.
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post #4 of 6 (permalink) Old 04-01-2010
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If the numbers are not available as Jon mentioned - This is a great write-up on 8 & 9 inch rear ends. Take a look...

Kevinstang's Ford Nine Inch Differential Page +

And the ratio is the number calculated by how many times the input shaft turns divided by the number of times the wheels turn.

First you have to determine if it is a single track or trac-loc differential. If you jack the rear wheels off the ground and turn the driveshaft and Both wheels turn in the same direction, then it is a trac-loc (or posi). If only one wheel turns and/or the other turns backwards, then its a single track.

For a posi - mark the tire and turn the drive shaft until the wheel turns one full revolution. Keep a count on the turns of the input shaft and that number is your ratio. If you have a 3.73, for example, the input shaft will turn 3 times plus almost 3/4 of a turn while the wheels only turned once.

The single tracks still confuses me. I beleive you have to have some helpers and get both wheels to turn forward at the same time you are turning the input shaft. Otherwise the process is the same. Maybe someone will confirm/correct this idea.

Ride On,

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post #5 of 6 (permalink) Old 04-01-2010
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Kinda sounds like what I said Sick ! I think anyway !
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post #6 of 6 (permalink) Old 04-05-2010
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looks like your getting pretty sound advise here.
if that car came with a C4 trans, i'll bet it has an 8" with 2.73 gears. thats what my 2bbl. 289 car had in it stock.

anyone can restore an antique,... but it takes a REAL man to cut one up!

1968 convertible
302 v8, afr heads, stealth intake, ford f-cam, roller rockers, edelbrock carb, headers, 2-1/2" flow masters/ h-pipe, t5z trans w/pro 5.0 shifter, 9 inch posi w/3.55 gears, traction bars, 4 wheel disc brakes, 1" shelby drop, 21MPG/hwy
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