Diff and Axle question

[rgrmoreira13]

For anyone here who has the 3.91 gears
What and how much power can that diff hold?
and how much power can the stock axles hold ?
and would it be better to just change the axles before the diff ?
Sorry for the 21 questions
I want to make sure I get as much info as possible before I pull the trigger and get everything done.

[13SSCamaro]

Thats a hard question to answer. People have broken their stock axles and diffs on stock power and some have held up over 700hp. Some have been into the 9's with stock rear, axles and suspension, some shatter running 13 second 1/4 runs. A lot has to depend on wheel hop, tires you are running, how hard you are launching, M6 vs Auto. There is so much to that question that sounds simple. My stock rear and axles have handled my 512 rwhp just fine with track runs and beating on the street. I have yet to run drag radials though.

[Black_SS10]

I agree with above.

Yea, a lot of variables at play. The 1LE diff housing is the same as the SS, just has different gears. Wheel hop can destroy diffs and axles.

[Pro-tuned]

This is like building an engine a lot of things have to work together. If you address a variable then it will only move the weak point elsewhere. A simple gear change may help but it’s possible you may have other issues. I did the gears, tires, axles, diff, and full BMR. It’s just the price of business.

[acammer]

These guys are on point, there are guys cutting 1.5 or faster 60' times season after season on sticky tires, good prep, and stock axles and rears. There are also guys that can take a freshly built rear end and thrash it their first time out - it's really about how you use it. Being setup well goes a long way, and I believe the LPW cover is also worth the money for the added strength and stability. But usage will usually dictate the life of the drive line. Drive line shock (clutch dumps, wheelhop) will kill things in a BIG hurry - and sticky tires will amplify the ill effects of those things. I believe a little drive line preload on any hard launch goes a LONG ways to keeping things alive.

My personal preference is to have a well built SS diff (quality gears, TruTrac posi, LPW support cover) with stock axles. Stock axles are pretty decent in what they will tolerate, but will fail eventually under hard enough use. I like to think of the axle as a fuse for the drive line - I'd rather pop one of those once and a while than continue to rebuild rear ends (done that too many times).

[rgrmoreira13]

I am going to get the car boosted (eventually)
I know down the line I would need to change the driveshaft, and axles. I didn't know if the 3.91 gears can hold a boosted application. That was my question

[Black_SS10]

Originally Posted by rgrmoreira13

I am going to get the car boosted (eventually)
I know down the line I would need to change the driveshaft, and axles. I didn't know if the 3.91 gears can hold a boosted application. That was my question

You should have stated that question initially. Most will tell you 3.91 are too much gear for boost, and to stick with 3.45. Any gear will "hold" the boost...but just like everything else....they can break.

[acammer]

Originally Posted by rgrmoreira13

I am going to get the car boosted (eventually)
I know down the line I would need to change the driveshaft, and axles. I didn't know if the 3.91 gears can hold a boosted application. That was my question

It's definitely still a "it depends" type of situation. The longer 1st 2nd 3rd of a MM6 trans in a 1LE will help tame a forced induction application to some extent - but eventually a change to a 3.73 or even 3.45 ratio might benefit the car, depending on the type and amount of boost, and how you're going to use it. If you plan on drag racing the car I would imagine once boosted you're going to need to upgrade everything from the crankshaft back, except for the transmission itself.

[rgrmoreira13]

Originally Posted by acammer

It's definitely still a "it depends" type of situation. The longer 1st 2nd 3rd of a MM6 trans in a 1LE will help tame a forced induction application to some extent - but eventually a change to a 3.73 or even 3.45 ratio might benefit the car, depending on the type and amount of boost, and how you're going to use it. If you plan on drag racing the car I would imagine once boosted you're going to need to upgrade everything from the crankshaft back, except for the transmission itself.

In regard to the type of boost it will be a procharger and as far as upgrading the drivetrain the only I am going to change when I add the procharger would be the clutch. In what I am going to use it I would want to take my car to the track eventually but it is my daily for the moment and for a while down the road.

[acammer]

Originally Posted by rgrmoreira13

In regard to the type of boost it will be a procharger and as far as upgrading the drivetrain the only I am going to change when I add the procharger would be the clutch. In what I am going to use it I would want to take my car to the track eventually but it is my daily for the moment and for a while down the road.

I'd probably just leave the 3.91 in it and send it. If you want to reinforce the rear pop an LPW cover on it. I think the longer 1-2-3 in the MM6 is gonna work good with 3.91s and a centrifugal. A PD blower will pull up in first so hard that the longer rear gear helps too, but a centrifugal rolls in a little softer, more like a BIG N/A motor.