Ok I need someone to answer a few questions for me.

Whats the difference between limited slip (posi) and a locker? Which would be better for a hard driven DD that sees a little strip?

What is spline? And does it have to match up from the tranny to the driveshaft and the rear diff?

Reasons being, Im building a mean motor and am completely re-doing the suspension and drivetrain and I want it to work as close to perfect as possible. Also, this is an area that I havent learned much about yet so I want to get as informed as possible before I spend any money.

I am looking at a Moser 12 bolt rear 3.73 with Eaton posi and 30 spline part number 12-8292CA-373

And also a Performance Automatic 700R4 30 spline from summit, part number PA 70104.

Any input would help guys but keep in mind, Im a noob in this area! Thanks!

 

spline refers to the size of the axel, the higher the number the thicker it is. A locker does what it says, it locks the axels so they are both spinning at the same time and speed. A posi rear end is similar to a locker, if your going in a straight line they will be spin at the same time, but if your going around a tigher corner slower it will allow the inner axel to spin much slower so you don't get a jerking action. A locker is not a good idea for street rides. It does not matter what spline axel you have in conjunction with your transmission. Thats completely different. If anyone else reads this and has a different opinion, just let me know, I am no professional.

 

OK thanks for the input. I will go with posi.

I thought that spline was the number of teeth on the driveshaft and it had to match up? Like you cant have a 30 spline tranny and a 28 spline rear diff???? I dunno, Im still confused a bit.

Come on Alkyiroc! I know you got the knowledge! Gimme your input. Or anybody else please?!?

 

Splines are the "teeth" on a shaft. The transmission has nothing to do with the splines in the rear end. The 7.5 10 bolt in your car has 25 splines on the pinion shaft and inside the pinion yoke. The axles will have either 26 or 28 splines, depending on what year they were made. The differential will have the same number of splines in the axle gears to match the axles. A 28 spline axle is larger and stronger than a 26 spline axle.

The Eaton Posi is probably the best street/strip differential for most GM performance cars. It is smooth, strong, rebuildable and can be tuned to fit your needs. It's well worth the money.

 

You're learning and that's what we're all here for.
The spline count is the # of teeth on the ends of the axles that go into the rear end guts. The higher the count the better as it is stronger.
What you may be thinking about with the driveshaft is the yolk. The driveshaft connects to the output shaft of the tranny much like an axle and it also has splines.
The yolk is a female shaft that goes over the output shaft, which is the reverse of the axles, but same idea.
Hope that helps clarify.
As far as the rear end goes, joe told you right. You really don't want a locker with a daily driver.
To answer your first question, limited slip is one-tire-fire, posi is able to handle cornering but is lock-up and locker is tire and gear unfriendly for cornering.
Like Joe said, for a daily driver, you definately want posi.
Locker is for the track or 4x4.
Good luck with your buggy

 

Limited slip is better for street. I have a few things running around with lockers on the street, and they're not that bad. The drawback to a locker is that power is directed only to one tire in a turn and if you apply enough throttle to break loose the one tire it catches up with the other tire, and this cycles for chirping the tire around a turn. Again, that only happens with heavy throttle where a limited slip wont do this.

 

Posi is limited slip. "Posi" is Eaton's brand name for their limited slip differential. This is the limited slip differential that was used in the Chevy muscle cars of the '60s and early '70s. The name became so popular that it became the generic name for all limited slip differentials, the same way that roller blade became the generic name for all in line skates. Auburn called their limited slip a Suregrip in the Mopars, Spicer called their's a Power Lock, Ford's is a Traction Lock... These are all limited slip differentials, but most people just call them all "posi".

 

Thanks for all the clarifications
I was under the impression that limited slip meant one-tire-fire.
About the comment about lockers, I wanted to point out that you can break stuff on a daily driver with a locker and that's the reason why I recommended you go with a 'Posi'.
Hope we haven't confused you much.

 

That would be an open rear end/open differential.

 

The following will furnish some general info on 10-bolt rears that you may find useful:

https://www.thirdgen.org/forums/tran...-10-bolts.html

JamesC

 

Ya thanks guys. This all helps alot. Mine is an open diff and it sucks.

I cant understand for the life of me why GM decided to put open diffs on 75% of their performance cars!?!?!? Cheap back then I guess. But they suck on launches, I always fishtail during a shift in any turn under a decent amount of acceleration, and if I happen to hit a stop sign with a patch of ice under the passenger side rear tire???? Lotta fun getting out of that!

I will stick with posi. And I didnt know that the higher the spline, the stronger it is so that is a big help too! Im going 30 spline all around so I guess that works well!

Well, are the teeth on a driveshaft the same on both ends? If I got a 700R4 and a complete rear end, are all Chevy drifeshafts the same? I am planning on going aluminum.

 

The third- and fourthgen shafts are interchangeable, regardless of whether the trans is auto or man.

JamesC

 

Most people prefer the 4th gen driveshafts over the 3rd gens due to the fact some have aluminum driveshafts. LS1 type also had an additional dampner which makes them fairly popular on Ebay. I use to see them go around $100 + Shipping. There are plenty of aftermarket ones too though.

 

Some thirdgens were also equipped with the so-called 1LE alum shaft (RPO JG1).

JamesC

 

so ur sayin , that a 4th gen stock shaft will fit in a stock 3rd gen, cool

i run a mini spool on the street with 10inch bfg dragradials . just have to ajust ur cornering a little lol