ConcoursMustang Forums

Restoring - General discussions that span across many different groups of years and models => Drivetrain => Topic started by: 68 S Code on April 24, 2011, 03:17:24 PM

Title: Rear axle ratio test
Post by: 68 S Code on April 24, 2011, 03:17:24 PM

Need to get a speedometer cable drive gear so want to verify my rear gears. Is the method of jacking up car and counting turns of the diff front yoke for one revolution of the axle/brake drum accurate? It will be clear whether it's 3:00, 3:25 or 3:50? Don't want to do any disassembly at this point.

Title: Re: Rear axle ratio test
Post by: carlite65 on April 24, 2011, 04:12:14 PM

that usually works for me although i give it several turns and use a helper to count. is the axle tag not present?

Title: Re: Rear axle ratio test
Post by: 68 S Code on April 25, 2011, 08:36:09 AM

Axle tag states 3:25 but after doing the test I'm only getting 3 revolutions of yoke. So I'm wondering if someone changed gears or if the test method is flawed?

Title: Re: Rear axle ratio test
Post by: steve_f on April 26, 2011, 01:26:18 AM

Try spinning the wheel ten times.  See if you get 32.5 or you still get only 30.

Title: Re: Rear axle ratio test
Post by: 68 S Code on April 27, 2011, 10:04:58 AM

Tried both directions (forward and reverse) about three times and 3 is all I got. Will try some more and will see if rh and lh side makes any difference.

Title: Re: Rear axle ratio test
Post by: gjz30075 on April 29, 2011, 07:37:17 PM

Axle tag possibly swapped out at one time?

Title: Re: Rear axle ratio test
Post by: 68 S Code on May 02, 2011, 11:33:31 PM

No because the casting dates fall within the dates of some other parts. I'm thinking maybe a gear swap? The 3;00 would be a better more fuel efficient highway gear. Maybe less tail happy with the lighter back end? Hard to say. Tried it again multiple times and it looks to have been changed internally. I won't swap unless its a dog out of the hole. Too much time spent detailing the diff.