good rear end?

69tobe · #1 10-08-2012, 02:53 PM

i am looking for a good rear end for my 69'. I want more speen than tork, i am puting a 350 4 bolt main in it. Any sugestions? thanks for the help.

69tobe · #2 10-08-2012, 02:54 PM

i am going to put a 5 speed manuel transmission in it btw.

RBeckman · #3 10-08-2012, 03:00 PM

GM 12 bolt will handle that small block all day long, they are cheap and easy to get.

69tobe · #4 10-08-2012, 03:27 PM

best place to get one?
and whats the difference between a 12 bolt and a 10 bolt?

RBeckman · #5 10-08-2012, 03:37 PM

I look on Craigslist, salvage yards....any 68-72 Chevelle 12 bolt will bolt right in...there could be others and maybe someone will chime in on them.

What is in there now?

If its not a 12 bolt, the 10 bolt that is in there should hold up unless you put some real sticky tires on it and are doing 5 grand hole shots.

Hank70SS · #6 10-08-2012, 05:41 PM

Quote:

Originally Posted by 69tobe

best place to get one?
and whats the difference between a 12 bolt and a 10 bolt?

A 12 bolt is a stronger rear end than a 10 bolt. SS (big block) cars came with a 12 bolt. Like Ric said a 10 bolt should hold up well behind a 350.

Why do you want to replace the rear that's in there, something wrong with it?

69tobe · #7 10-08-2012, 06:00 PM

well right now i dont actually know, i am doing a rebuild and its a old looking rear end, i was going to be replaceing it becuase i did not know what it is, and i am puttting an manuel tranny in it where it had a automatic.

RBeckman · #8 10-08-2012, 06:38 PM

If there is nothing wrong with the rear end that you know of, I would just clean it up and let it be. Rear ends usually don't break unless too much power via 5 grand hole shots or netural slams. In all my years I have to say I've blown a rear end.

Hank70SS · #9 10-08-2012, 06:41 PM

Not sure what to tell you. Is it a posi rear? If not then you might as well upgrade to a 12 bolt. On the other hand you said you want speed not torque, most likely the 10 bolt that is probably there now will have a gear ratio that will give you that.

If you find a used 12 bolt on craigslist it may not have the gear ratio you want and may also need a rebuild.

Count the the number of bolts in the rear cover, either 10 or 12 bolt. Lift rear wheels and try to spin one wheel, if one turns and the other turns in the opposite direction, trans in park, then it's an open or non-posi rear. If it's a posi rear you won't be able turn either wheel.

If it's an open rear then block one wheel and put the trans in neutral. Turn the other wheel one full turn and count the number of times the driveshaft turns. That will tell you what gear ratio you have. Could be anywhere from less than 3 to over 4, which I doubt. Be as accurate as you can while counting the driveshaft rotations.

If it's a posi rear end then leave both wheels in the air and put the trans in neutral. Then do the same, spin one tire one full turn, the other should also spin one full turn, and count the driveshaft rotations.

Driveshaft rotations won't be an even number of turns, could be 3.42, 3.73, etc.

erice924 · #10 10-24-2012, 07:34 AM

What rear end gears should i just for good highway and street use?
i have on my 70 gto th400 transmission and a 383 stroker with a mild cam i dont know the cam specs i forgot. and my rear end a 10bolt and my tires on the rear are 275/60/15s what good rear end gears would be good for highway and street use and i dont race it i just want that extra punch for the street and good highway performance aswell something in the middle of both highway and street