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Discussion Starter · #1 · (Edited)
Just wondering if anyone is running 40 spline axles in their ford 9 inch? I'm wondering if it is worth the extra expense for the bigger shafts or will 35 spline shafts exceed the strength of the rest of the 9" components? I'd like a 40 spline ARB but it doesn't appear that they make one, in fact I've found several spools available in 40 spline but no lockers. Anyone have any info?

All I came up with was a post from 2002 and obviously the info is a bit dated:http://www.pirate4x4.com/forum/archive/index.php/t-100151.html
 

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from what i can remember when i was hunting down parts for my axle is that a spool is your only option when it comes to 40 spline. as for the extra expense, i think it will be the last axle shaft you buy for a long LONG time, thes things are HUGE! i was told the main market for these were desert racing so you might want to hunt around those sites and see what they say too.
 

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I have a 40 spline 9" that I run in my mud racer and have not had any problems. I was running a 1100 hp 632 and it laughed at it. It was being run behind a 3000hp Aries Fontana and they never broke the shafts, Broke other parts but not the shafts.:flipoff2: I think that the 35 spline would handle what most people need. Thats wwhat I am going to run when I build my next 9". Spools are ur only option that I have ever seen.
 

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Cory, in my opinion, the 35-spline would be more than strong enough for the front, but I wouldn't hesitate to do the 40-spline in the rear. The 1.5" shafts are substantially larger than the factory 404 front shaft size - with the exception of the splines. Just my 2 cents. I looked at hybrids when I first built my rig, but couldn't afford it at the time. Are you looking at 300M shafts or Astralloy?
 

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Discussion Starter · #6 ·
xtremexj94 said:
Cory, in my opinion, the 35-spline would be more than strong enough for the front, but I wouldn't hesitate to do the 40-spline in the rear. The 1.5" shafts are substantially larger than the factory 404 front shaft size - with the exception of the splines. Just my 2 cents. I looked at hybrids when I first built my rig, but couldn't afford it at the time. Are you looking at 300M shafts or Astralloy?
It's not actually for a 404/9" hybrid...it for something else:flipoff2: I'm sure the 35 spline astralloy or 300M would be more than strong enough. Unfortunately I don't have the option to run either of those materials which is why I was
thinking 40 spline would be the way to go.

I've found 40 spline detroits and with some swapping you can get a 40 spline ARB for a dana 60 but I haven't found anything for a 9" yet.
 

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I have a 35-spline 9" rear now, I was looking into changing to 40-spline shafts/spool(for a desert racer) and here is the advice I was given. i was told that for the semi-floater 9" that 40-spline shafts would actually be bad as the bearing id becomes too large(from 35 to 40 splines), making for thin bearings that wear very fast, the best option for strength and low maintenance is a full floater with 40-spline shafts(overkill for full floater), otherwise you may as well stick to the 35-spline shafts in the semi-float configuration. Hope this makes sense, I am now gathering parts for a full floater housing. Let me know how your experiences turn out, I am very curious.
 

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skullver said:
i was told that for the semi-floater 9" that 40-spline shafts would actually be bad as the bearing id becomes too large(from 35 to 40 splines), making for thin bearings that wear very fast,
X2. My buddy shopped for a new rear axle last year and found that the thin bearings needed to run 40 spline axles in a SF 9" would wear quickly especially if the vehicle was used with big tires and sidehills as the leverage would bend and break the bearing cages.
 

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I was at DTS a few months ago gettin my axle back and there was a guy in there pickin up a 40 spline 3rd. 5.13 IIRC and it ran him 1200 bucks total. He was usin it for some crazy sweet drag car.
 

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35 and 40 spline axles are about the same cost.
I think the only difference is the spool for a 40 spline is a tad more $.

The only reason I did not go 40 spline is the 9 inch bearings get pretty small with used with a 40 spline.
 

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A 40-spline spool for a 60 cost the same as a 35spline spool; but looking at DTS's site, it looks like a 40 spline 9" spool is about $65-$150 extra depending on which you buy.
 

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Discussion Starter · #13 ·
Bearing size isn't an issue for what I'm thinking about doing (yes I'm keeping it quiet for the time being). The only issue is getting 40 spline into an ARB. IIRC there is a guy here on the board that works as a tech at ARB... anyone know who that is?
 

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Tech tim. But he doesn't anymore. And IIRC you can't put a 40 sp in a 35sp arb. I don't really see the point though...The rest of the 9" will explode before the 35 spline chromo shafts. As to bearings...trophy trucks run 40 spline axles, so I'd say that's a pretty good testament to bearing longevity.
 

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braxton357 said:
...trophy trucks run 40 spline axles, so I'd say that's a pretty good testament to bearing longevity.
They're ALL running FF setups though.
 

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braxton357 said:
...trophy trucks run 40 spline axles, so I'd say that's a pretty good testament to bearing longevity.
Do they run 42"+ tires and sidehill up tight notches? Are they semi-float or full-float? Do they have the cash to put in new bearings every race? Not being a dick, but I don't know if the "trophy truck=wheeling rig" equation is a good example.
 

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zachv said:
Do they run 42"+ tires and sidehill up tight notches? Are they semi-float or full-float? Do they have the cash to put in new bearings every race? Not being a dick, but I don't know if the "trophy truck=wheeling rig" equation is a good example.
It's a fair comparison, but they ALL run full-floating axles so it's a moot-point.
 

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Do they run 42"+ tires and sidehill up tight notches? Are they semi-float or full-float? Do they have the cash to put in new bearings every race? Not being a dick, but I don't know if the "trophy truck=wheeling rig" equation is a good example.
try new ring gears every race. its similar to drag race setups where the rign gear is a softer material to handle shock loads better. but being softer they do wear out a lot faster. a trophy truck is a race truck so your right there is NO accurate way to compare it with anything else besids another trophy truck. that and the parts that go into them would uhh out budget most inf not all wheeling rigs budgets.
 
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