Mike Holmen

Just found out my 2010 truck doesn't have a suregrip diff in the rear axle. Pricing out ARB, but the stock AAM 11.5 has axles with 30 spline axles. For a 11.5 ring gear sounds lame to me. Kinda mad about this as my bill of sale, it clearly says that the truck has a suregrip different. I got the truck stuck yesterday.

I'll take the truck into the dealer and see what they say.

Tate

AAM uses larger splines than Dana. The old 14 bolt axles were 30 spline too, but they were 1.5" diameter. Dana 30 spline are 1.29".

1-5-3-6-2-4

The GM corporate 14boltFF your talking about? I'm pretty positive they're 35 spline 1.5" like the D60 fronts were stock 35 spline inners and 30 spline outters and the up grade to 35 spline outters then it was 35 spline throughout. D60 rears were 30 spline.

StealthDiesel

Mike,

Are you sure you don't have a limited slip in your axle? The AAM L/S is a gear type differential that does not act at all like a clutch type L/S like in your 2nd Gen.
Have you checked the specs sticker in your glove box (or under the hood)?

If I recall correctly, with both rear tires off the ground both tires, if you turn one tire, the other tire will turn the same direction if you have the AAM L/S installed.
If you don't have a L/S, the other tire will spin in the opposite direction.

I do have a AAM L/S in my truck. I can spin both rear tires evenly on wet pavement but if one tire is on wet grass & the other on dry pavement,
I will dig a hole in the wet grass until I apply the parking brake slightly.


Wow, sure enough the stock AAM axles are only 30 spline:

http://www.ringpinion.com/DiffDetail...r%26DiffID%3d4


This sounds really wimpy (especially since my Mustang has 31spline Mark Williams axles in it!) but hopefully since it's a full floating axle the axles don't have to be as large.

I've never heard of anyone breaking one of these axles so they must be plenty strong. You can see from that website that there are 38 spline axle & differential aftermarket upgrades.

Tate

You may have 31 spline axles (like most ford junk), but they aren't 1.5" diameter like the 30 spline 14 bolt. Yours is 1.3" I bet.

And you're right about the FF vs. SF. Look at a D60. Full float is the 30 spline 1.29" axles, SF is 35 spline 1.5" axles, but are rated for lower torque.

morkable

Well I think that they are pretty tough,, I have been putting in excess of 1000 HP through mine for 3 or 4 years now...

1-5-3-6-2-4

I suppose the semifloater 14bolt is a 30 spline. but that doesn't rate in this group of 1 ton rear diffs.

StealthDiesel

Tate,

My understanding is that the axle splines are all the same, ie. industry standard. It is that way in passenger cars.
Each spline is physically the same size & the axle just gets larger as the spline count increases.

It must not be this way for the larger truck axles.


BTW, there is nothing wrong with Ford axles. The Ford 9" rear axle is the industry standard in the aftermarket.

The 8.8" Ford axle assembly in 5.0L Mustangs is an outstanding Salisbury style rear axle.

My 8.8" actually has 9" style non C-clip 31spline MW axles as the stock 8.8" axle housing ends are long gone.
It's been narrowed 1/2", 9" type MW axle ends welded on, 9" large "Torino" style C-clip eliminator type bearings, custom disk brake caliper bracket to hold the caliper plus retain the bearings.


I did all this 2 summers ago when I finally got fed up with all the Moser Engineering junk I had in the axle assembly previously.

Tate

That wasn't a shot at Ford axles. Most of the vehicles I have owned have been Ford's, all up until I bought the dually. I've had 6 Fords, and 3 Dodges. But only 1 Ford was ever a DD.

All splines are not the same. Most axles, you can take the number of splines, add one, then divide by 24 to get the diameter. But not all. Also, the splines are of different angles. Its been a while, but AFAIK, 9" uses a 45 degree pressure angle on the splines, while Dana uses a 60 degree angle. This will give a larger minor diameter for the ford, if the major diameters were the same between the two axles. AAM is a bit oddball, like I posted twice above. 30 spline axles, but they are 1.5" diameter, which is much larger than a Dana 30 spline. IIRC, AAM also uses a 45 degree pressure angle on their splines.

04ctd

most folks say the ford 9 inch is too "inefficient" and that it eats more horsepower than comparable strength axles. it's not the "be all, end all" solution that it used to be (from my reading while planning another project)

to the OP, IIRC, you have to HOLD THE BRAKE to get the Posi to work.

we work stuck in the snow this weekend, and my wife was able to get the posi to work. you have to modulate the brake & gas..
i think it's in the owners manual

1-5-3-6-2-4

right the truetrac style limited slips needs bias in wheel speed to function. so if you'r stuck and get 1 tire fire. slow speed down and drag the brake slightly it'll start to transfer power/.

Mike Holmen

Thanks guys, I forgot about Kev's big power truck. No I only get one wheel spinning, if my 11.5 AAM is a LSD unit, its junk. I can pin the throttle, and only one tire spins. Been driving up north with it for the last few weeks. The truck gets stuck everywhere. Going to see what the dealer says. Been told that the axles shafts are bigger in diameter, but have a low spline count. They are 37 spline axles available, like Luke said, but no ARB's units available for the larger spline count. I'm just going to ask for my money back for the LSD from the dealer, and just by a ARB unit. That way I get the best of both worlds.

Been eating abit of crow as I had to get a pull from my brother D-max the other day. Even beer doesn't fix the pain...

morkable

My truck has always spun both tires without having to use the parking brake. I can leave 2 really really long black marks if I get on it hard

JP-4.5

Same here..
Build just a little boost and there is 2 long marks that will get left behind the truck..
Something sounds wrong if yours is only spinning 1 tire..?

Happy New Year!

Mike Holmen

I just get one tire spinning. Don't even need to lift the truck up to tell that one these days. No liking the idea of going to visit the dealer, as I have to put my truck back to stock.

If the posi or ARB parts were cheaper I would just fix it myself and save the dealer heart burn for another day