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whos runnin neck down D60 shafts???

01maroonz71

01maroonz71

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anybody running these and not breaking them...i have another project im starting and the new (used) D60 i got has them....would these be ok ok 40mtr's??? im thinking about running them and seeing what happens...this truck will be in mud only...and no front locker/lsd...just 5.13 gears. anybody runnin them successfully????
 
I had the stock neck-down shafts when I first installed my D60. The long side broke about the 3rd trip out (38" TSL's, locker). Since I replaced them with non-neck down shafts I busted 3 30-spline stubs, so I would have to say they are even weaker than 30-spline stubs.
 
They really do neck down a lot, I would expect to break them with 40's.

I ditched them immediately because I was afraid one would break and take my detroit with it.
 
Neckdown shafts should be '80 and older.

I got mine from a place called Drivetrain Industries here in Denver and they were $60-70 per shaft. If I had to do it again I would consider getting Alloy USA shafts from the beginning (~$200 per side).
 
well my 60 is out if a 81+ so i should be ok...
Guess i need to take it apart and look... Thing is so freakin heavy i've just kinda been waiting for it to be on the truck so it's more managable...

To swap to 35 spline outers dont you just need the stubs and new hubs?
 
Thanks everyone for giving something new for me to worry about. :mad:

Surely they are better than the stock D44 I was running? :what:
 
reddog64 said:
well my 60 is out if a 81+ so i should be ok...
Guess i need to take it apart and look... Thing is so freakin heavy i've just kinda been waiting for it to be on the truck so it's more managable...

To swap to 35 spline outers dont you just need the stubs and new hubs?
Click to expand...

YZEATER said:
correct
Click to expand...


Doesn't the hole in the spindle need to be bored out also?

Thanks,
Mike
 
UPS said:
Doesn't the hole in the spindle need to be bored out also?

Thanks,
Mike
Click to expand...

To get 35 spline shafts in a rear FF60, yes.

The spindles on front dana 60's are larger and don't require any modification to use 35 spline outer shafts.
 
mrk5 said:
Thanks everyone for giving something new for me to worry about. :mad:

Surely they are better than the stock D44 I was running? :what:
Click to expand...

Primarily from this article:

Minor diameter of neckdown long side shaft: 1.318"
Minor diameter of non-neckdown long side shaft: 1.441"

Minor diameter of neckdown short side shaft: 1.318"
Minor diameter of non-neckdown short side shaft: 1.445"


That means that the non-neckdown long side shafts should be 43% stronger than neckdown shafts and that the (non-neckdown) short side shafts should be 44% stronger than the neckdown shafts.

This doesn't take into account fatigue or changes in metallurgy (which have a huge effect on the strength of the shaft).


The 30 spline outers have a minor diameter of 1.281" and (Spicer) 35 spline outers have a minor diameter of 1.377". That is a strength difference of 34%.

I suspect (from pictures and comparison to my own Alloy USA outers) that the aftermarket 35 spline outers don't neck down as much as the Spicers do. Next time I have them out I will measure them.


Dana 44 outers have 1.128" 19 spline outers. 30 spline 60 outer shafts are 66% stronger than dana 44 (or 10 bolt) outers assuming they are made of the same material.


It all depends on what you think the weak point is on any axle. If you think that the outer shafts are the weak point on a dana 44 (which it likely is) and you think the (stock 30 spline) outers on a dana 60 are the weak point on a dana 60 (which it likely is) then the D60 is 66% stronger.

Even the neckdown inner shafts should be significantly stronger than the (30 spline) outers, both because they have a larger minor diameter and because they are longer (longer shafts can sustain higher torque loads without reaching their yield (fail) strength).

Of course with used shafts you never know...
 
38377k5 said:
To get 35 spline shafts in a rear FF60, yes.

The spindles on front dana 60's are larger and don't require any modification to use 35 spline outer shafts.
Click to expand...


Thanks for the clarification I was wondering where I got that from.
Mike
 
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Okay, as long as they are stronger, I'm happy again. :D Especially since I'm running sans locker for the moment.

38377k5 said:
Pven the neckdown inner shafts should be significantly stronger than the (30 spline) outers, both because they have a larger minor diameter and because they are longer (longer shafts can sustain higher torque loads without reaching their yield (fail) strength).

Of course with used shafts you never know...
Click to expand...
We know how strong 30spline outers are. :wink1: :whistle:

I've always wondered why full-floater shafts aren't hollow. I remember learning that a hollow shaft can take more torque than a solid shaft. Maybe the other variables like overall diameter and length make the differences neglible or even negates the added benefit of a hollow shaft.
 
mrk5 said:
I've always wondered why full-floater shafts aren't hollow. I remember learning that a hollow shaft can take more torque than a solid shaft. Maybe the other variables like overall diameter and length make the differences neglible or even negates the added benefit of a hollow shaft.
Click to expand...

A solid shaft is always stronger than a hollow one.

The thing is that OD is MUCH more important in torsion/bending than anything else. Take for instance a comparison between a 1" solid rod and 1.5" .120" wall tubing:

The bending strength is based on the moment of inertia (there are other equations that actually calculate the bending strength but they are all linear and not relevant to what I'm trying to show).

The moment of inertia (for round tubing) is I = (pi/64)*(D^4 - d^4) with D being the major diameter and d being the minor diameter.

The 1.5" tubing would have a moment of inertia of I = (pi/64)*(1.5"^4 - 1.26"^4) which equals .1247

The 1" round stock would have a moment of inertia of I = (pi/64)*(1"^4 -0) which equals .0491

.1247/.0491 = 2.540 which means that the 1.5" .120" wall hollow tubing is 2.54 times stronger in bending/torsion than the 1" solid stock.

Even though the amount of steel in them may be similar, making the OD larger and making the rod hollow will make it much stronger in bending/torsion.



To compare 1.5" .120" wall hollow tubing to 1.5" solid stock goes as follows:

Moment of inertia for 1.5" solid is (pi/64)*(1.5"^4 - 0) = .2485

The moment of inertia of the hollow tube is .1247 from above so to compare:

.2485/.1247 = 1.993 so the solid piece of tubing is ~2 times as strong in bending/torsion.
 
I think my brain just exploded :doah:..... yep gotta go clean the blood outta my ears :o
 
muddermilitia said:
I think my brain just exploded :doah:..... yep gotta go clean the blood outta my ears :o
Click to expand...

:doah:

Summation:

A solid shaft is always stronger than a hollow one

Outside diameter is much more important for bending/torsion than the shaft being solid, which is why hollow tubing is so popular; it saves weight and cost but can still have more bending/torsion strength than solid stock.
 
38377k5 said:
:doah:

Summation:

A solid shaft is always stronger than a hollow one

Outside diameter is much more important for bending/torsion than the shaft being solid, which is why hollow tubing is so popular; it saves weight and cost but can still have more bending/torsion strength than solid stock.
Click to expand...
You know I think I'm thinking about the air craft carrier. The main shafts were hollow, and I'm sure a lot that has to with weight. Could you imagine a 4' diameter SOLID shaft. :yikes: But those bad boys handle a lot of torque. I don't remember the torque but the shaft HP is about 70,000.
 
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