8 3/4 rear end gears

[sublimeswinger]

he i recently found a 8 3/4 rear end im going to pick up this week.(its a really great story).but anyway how do i tell what gears are in it?Its drum to drum and off an A body.Im putting it my 72 dart.will i have to modify anything(drive shaft)?I want the car to be able to smoke the tires,is this possible if it has stock gears?what gears are stock? :tongue10:
any help would be great....Thanks

 

[Ace]

The gear ratio is stamped on the outer edge of the ring gear, and you will need a shorter driveshaft. There's been a couple threads about this over the past few weeks, do a search...

 

[fishy68]

There were several different gear ratios used depending on what was ordered by the original owner. You can tell which gear set it has by spinning BOTH AXLES EXACTLY one full revolution and counting the turns the yoke makes. This will take 2 people to do it properly unless it's a suregrip (posi) type rearend. For example if you turn both drums one turn and the yoke turns slightly over 3-1/2 turns you have 3.55 gears. Now whether or not your gonna be able to smoke the tires or not stands to be seen because your new rear may have the same or taller gears than your old rearend. It's a crapshoot. If it's a suregrip it won't spin as easy either. Another thing to consider is the 8-3/4 is heavier so it takes more power to pull it than your lighter stock rearend. If it has taller gears you'll be bummin cause you'll be slower than your stock rearend.

Ace is right about changing the driveshaft. More than likely your Dart has a 7-1/4 or 8-1/4 so you'll need a shorter driveshaft. Other than that it should drop right in.