How do i find out what size rear end i have in my 79 nova? As far as 7.5, 8.5 or 10in is concerned?

Asked by Jan 11, 2013 at 09:40 AM about the 1979 Chevrolet Nova

Question type: Maintenance & Repair

Trying to figure out what size gears i
need to use in order to install a 3.73
gear ratio and a posi unit....or what
rear end with all that cud bolt right up
without any mods being needed...

5 Answers

There a a few ways. If you can't find out any other way, like from some forum that somebody knows, then 1) if it has a bolt on cover, take it off and count cogs on main, or ring gear and cogs on spider gears, then do the math. Or, jack it up and turn a rear wheel. Turn it exactly one time, 360 degrees, and at the same time watch the driveshaft and count the turns it makes with one 360 of the tire. Then, again, do the math...if the tire goes 360 ONE time and the drive shaft turns say 15 times around, this is oversimplified but accurate, then figure it from that

1 of 1 people found this helpful.

How do you do the math though? do you devide 360 by 15 that equals 24 so would that mean it is a 2:40 gear ratial?

1 of 1 people found this helpful.

And fred there should be a tag on the rear end with numbers on it that will give you the info. If you have never but gears in your self I would not recomend doing them If you don't know what you are doing you would probly be throwing your money away. Call your local auto salvage yards and see what they have for compleat rear ends. We just did one in a 95 suburban 3:73 gears new were over $300 and to have a shop install them was any wheres from $240 to $600. We found a compleat rear end at the auto salvage yard for $330 only took about 4 hours to remove and replace

1 of 1 people found this helpful.
Best Answer Mark helpful

Thanks R

Thanks not doing da work myself... Im just tryn to find out what i have b4 i start buying stuff...i will call da local salvage yards tho...hadnt thought about that...thanks

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