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Discussion Starter #1
Can I beef up my existing rear end or do I need to replace max power around 390 -400 planned? Came out of a saleen so I think it has the traction lock....
 

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It depends on what you want to do with the car. If you plan on drag and sticky tires, 31-spline axles and a good carrier would be a good idea. If all you want is street cruise, it's probably fine the way it is.
 

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I agrgee, upgrading to 31 spline axles and a stronger differential is about all the 8.8 needs. If you drag race and it hooks good then you might think about welding the axle tubes, but most of the time they are fine like they are. With 400 HP you shouldn't have any problems.
 

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The 28 spline axles are the weak link..they'll break before anything else
 

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WHat Need said and if you abuse it some the trac lok will give out.
 

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as long as you aren't running slicks or using a trans brake with a lot of drag time you should be fine, the 28 spline axles are the weak point though so another vote for upgrading those, if anything
 

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Discussion Starter #7
What about hardened or performance 28 splines? Need other stuff upgraded or would those hold fine with street drags?
 

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31's are the way to go.
 

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This whole 28 vs. 31 spline thing has had me confused for years.So whats the advantages of 31 spline?
I asked my buddy Mark at Progear what the deal was and this is what he told me. How often do you actually break the axle? Very very rarely he said,unless its due to damage(curb,wall etc). But the 31 spline is not a stronger axle than the 28,its the same. What he said is this; when cornering,accelereating, and and or lateral load is applied to the rear the spider gear actually moves outward onto the splines which in turn loads the clutches and helps to lock the rearend. Now heres the difference: The 28 spline has more torsional movement,or twists more than the 31 under torque AT the spline (obviously due to less material),well when that happens the spider gear binds up on that spline because its twisted more and cant move outward,the 31 doesnt do that as much he said. And from what he says,that is the only difference.
IDK...Hes been in the driveline business for many many years,and built countless race cars,and hes extremely reputable in the muscle car industry...so Im going to file that info as fact.

Whats everybody elses thoughts on that?
 

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I asked my buddy Mark at Progear what the deal was and this is what he told me. How often do you actually break the axle? Very very rarely he said,unless its due to damage(curb,wall etc). But the 31 spline is not a stronger axle than the 28,its the same.
i guess he's never been to a drag strip....

heres my father in laws FF Cobra kit car..GT40 top end.maybe 275-ish at the tires...2500lb race weight on 235/60-15 MT drag radials and stock 28 spline axles with a detroit True-trachttp://www.youtube.com/watch?v=s36VRFCCyUk

http://www.youtube.com/watch?v=pNkVJ4cUelc&list=UUKBWRkjy3-VzdwX6BWByilQ&index=27&feature=plcp

that was the 2nd time...not even much of a burnout either...
 

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I have hardened 28s in my Cobra...no problems, I don't beat the living daylights out of it however...
 

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also FWIW, my buddy owns a bone stock 4.6L convertible GT..Superior brand hardened 28 spline axles..5k launch on MT 275 radials..snap...he bought the aftermarket 28 splines after he snapped 2 stock axles..
 

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also FWIW, my buddy owns a bone stock 4.6L convertible GT..Superior brand hardened 28 spline axles..5k launch on MT 275 radials..snap...he bought the aftermarket 28 splines after he snapped 2 stock axles..
IDK...thats what he told me.
 

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also FWIW, my buddy owns a bone stock 4.6L convertible GT..Superior brand hardened 28 spline axles..5k launch on MT 275 radials..snap...he bought the aftermarket 28 splines after he snapped 2 stock axles..
Where on the axle are they breaking? @ the spline or the hub,middle?
 

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passenger side axles, right thru the splines...
http://t2.gstatic.com/images?q=tbn:..._eRzK43Wb33oEubvWrzO6RbHjE7FaXkm2Rcbx00Z_5-LA

and if you dont think there is any difference in the axles themselves, dead wrong..this example is a 33 spline(non c-clip) vs a stock 28 spline..the 31 splines arent quite as big as the 33's, but much larger than the 28's

http://i45.photobucket.com/albums/f79/mmb617/rear%20rebuild/axles001.jpg
http://i45.photobucket.com/albums/f79/mmb617/rear rebuild/axles002.jpg
 

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passenger side axles, right thru the splines...
http://t2.gstatic.com/images?q=tbn:..._eRzK43Wb33oEubvWrzO6RbHjE7FaXkm2Rcbx00Z_5-LA

and if you dont think there is any difference in the axles themselves, dead wrong..this example is a 33 spline(non c-clip) vs a stock 28 spline..the 31 splines arent quite as big as the 33's, but much larger than the 28's

http://i45.photobucket.com/albums/f79/mmb617/rear rebuild/axles001.jpg
http://i45.photobucket.com/albums/f79/mmb617/rear rebuild/axles002.jpg

Well then...that will be filed as useful info. Thanks for the clarification.
 

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Discussion Starter #17
Thanks guys for all the hard work. I now have been educated and will run street tires this first drag pass till I can save the money for a 31 spline upgrade. When I'm ready which will probably be tax time
:).... What is the easiest way to do a 31 spline upgrade and keep my 4 lug saleen rear disc brake setup?
 

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5000 launch? I haven't ever even thought about trying that
 

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you can buy 4 lug 31 spline axles...just get whatever length you need, fox, sn95,etc...
you'll also need to get the 31 spline differential of your choice..31 spline trac-lok, detroit tru trac, eaton posi, etc,etc...
 
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