How can I tell what is in my '65 Conv. with a Jetaway,
Without opening it up? Going to change gear oil soon.
Has 45,000 on it.

 

A 65' in Willow Springs?!
NICE!!

It's probably a 2.78:1 ratio.
You'll confirm when you change the oil.

 

Last cruise nite in Downers Grove

 

If you have a non-posi, jack up one rear wheel and count the number of turns the driveshaft makes when you turn the wheel one revolution. If it is posi you'll need to jack up both wheels. You can also clean off the right axle tube to look for the numbers. On our 64 they were on the rear near where the tube meets the carrier (cast iron part).

 

That will only get you half way. The spider gears will cut the driveshaft revolutions in half if you only turn one wheel.

 

If you jack up both wheels, then spin one, the opposite wheel is going to spin couter to the one you are turning and the driveshaft will probably stay in one position. Note I did say to turn the wheel one revolution and count the number of times the driveshaft turns, not turn the driveshaft. In any case, with one wheel held, all the torque is transfered to the wheel with least resistance.

 

Very nice ride Snowdog.

 

Yes and because of the spider gears the amount of revolutions that one tire will spin while the other is stationary changes to double. So if you jack up one side only to count the revolutions of the driveshaft while turning the tire one revolution you will get half of the number of turns of the driveshaft that you would get if both tires were turned.

 

What #'s am I looking for?

 

They vary from year to year. On our 64 it has "P 3.08". Of course, this will be the ratio installed at the factory, and not necessarily what someone else may have installed. You can always pull the cover and check the numbers on the ring gear. They will show ring gear teeth and pinion teeth count. In our case it's 40 13. Then you divide the ring gear count by the pinion count. There is a whole section on differentials in the Tech portion of this site (see the top bar).