How much power can the stock rearend take?

Thats one of those Q's thats gotta start with ... it depends

Honestly ... A N Y drive line part ... is very susceptible to shock :Word:

Just trying to say it is not so much about amount of power
but
How much of a load or shock are you gonna place on it

Example

Take a stock stick 5.0 Stang ... tiny hp is produced ... Right

Put a set of real slicks on it and dump the clutch at 5 Grand

See Where I'm Going With Things Here

Grady

so far ive been launching plenty on my nittos on stock rear end and its taking it fine

...and my rearend is making noise with the same tire. :-S

It's a crap shoot I think - if you plan on modding the car to run low 13s, I'd do the upgrade now... wish I had, now I get to do it all a 2nd time.

Wes

I wish I would have went 31 when I did my gears.

For what it's worth, a friend of mine had a 94 HCI 150 shot GT that he launched off the limiter on slicks and sprayed it out of the hole for about a whole summer with a stock rear end except it had 3.73s in it, then he built a new rear end and we put his stock one in my old pullied '04 Cobra which I put about 25k more miles on, some with DRs, some without, and some racing also, and it never broke. Perhaps we had a freak, but the 3.73s were setup wrong and whined on decel a little , so I installed some new ones a couple thousand miles before I sold the car, but the axle splines and diff still looked and worked good. I had a rebuild kit for the diff. expecting it would need it.

Now on the other hand plenty of people have busted up stock axles/diffs with 300rwhp and DRs. Most failures on the stock rears that I've seen are the splined part of the axle breaking. I think it's a good idea to upgrade to 31 spline stuff. $275 for axles, under $100 for a used 31 spline T-lok, $80 or so for a T-lok rebuild kit, maybe $50 for misc. stuff. When upgraded axles/diff. become necessary I think the torque boxes should also be reinforced/welded along with the axle tubes welded. Just my 2 cents.

Blaise had some good info

Be sure to note he was using a ratio that was ONE FULL TURN steeper
than most stock rear ends which are 273's

I point this out to show the 373's take a good bit of shock off the
drive line

As said ... it can be a crap shoot

Some get lucky and some do not

Its always a good idea to beef the d l up if you are gonna be driving
under conditions that put a lot of stress on things :Word:

Grady

I abused the stock rear end in my car for a long time and never broke it. I actually used a pinion snubber on all stock parts with slicks. Hooked solid at the track launching off the stock rev limiter. I am amazed at how much abuse it took and never broke. I currently run an 8.8 in my car that has all aftermarket parts in it and (knock on wood) I haven't broke it in a long time. They are capable of holding good power if you build them right.

If you are planning on doing any type of upgrade, do it right. Go 31 spline and go to good hardened axles. Do it right the first time so you don't have to do it again the second time.

I just upgraded my rear end for this reason. Ive been wanting to run MT ET Streets but did not fully trust the 28 spline axles. I upgraded to 3.73's FMS 31 Spline limited slip and 31 spline Moser axles. Have yet to make a track trip yet but am planning on it this friday or saturday.