Thread: TOTM: All About Axles

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  1. #1 TOTM: All About Axles 
    ....... Lifetime Supporter rstrucks's Avatar
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    What axles are recommended for different set ups, wheelin styles, tire size, terrain...?

    What axles have you run, broken, upgraded to, swapped in....?

    What aftermarket shafts, joints, lockers or gears have fixed a weakness on your axles?

    What HD axles under 'XX-'XX year trucks are a bargain?

    Try to keep this based on personal experience. The more info you can provide the better - spline counts, wms to wms measurements, bolt patterns, shaft/joint material, etc.... Dana 35 talk will not be tolerated.
    Last edited by rstrucks; 12-01-2011 at 10:50 PM.
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  2. #2 Re: TOTM: October - All About Axles 
    Senior Member Jeeptech01's Avatar
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    Subscribed. Interested in the fronts!!
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  3. #3 Re: TOTM: October - All About Axles 
    Senior Member ATL ZJ's Avatar
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    To run the trails I like to run (mix of Southeastern trails) you need a tire in the 40"+ range, decent gearing, and wheelspeed on demand. In order to have all those things and not break, it usually means one ton axles with chromoly shafts. I think that is the commonly accepted minimum required equipment for this part of the country unless you have an ultralight rig with deep gearing or you want to stick to less challenging trails... which there is nothing wrong with.

    To date I've broken:

    stock waggy d44 outer
    yukon waggy d44 4340 outer
    8.8 ARB, sort of (failed shortly after new owner had it)
    806-x spicer non greasable dana 60 U-joint
    yukon 35 spline inner (short side)- twisted at the splines- more on why this is "broken" later on

    Since the "what size tire can I run on my 30/44" question has been beat to death, a more interesting direction for this thread is why axles break at all. R&P size is the most obvious limitation, but shaft when shafts themselves break, when is the break due to diameter, shape, or material? And when is a smaller diameter shaft stronger than a larger diameter shaft of the same spline count, and why? These are the kinds of questions that help us make good decisions about aftermarket shafts. I could answer my own questions but I think it'll be more interesting if other people post up instead of me just blabbering on...
     

  4. #4  
    ....... Lifetime Supporter rstrucks's Avatar
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    I haven't broken that much stuff - luckily. I did break a couple of D30 u-joints which took out both the inner and outer shafts when I was on 35's. I also need to go up in pinion yoke size to 1350. I crushed the needle bearings in my 1310 series u joint last trip out. It didn't break but it shows there is a little too much load on too small a joint. The old joint was a TW's Gold Seal joint and the new one is a Spicer - we'll see if it holds up any better.

    IMO 33's are the safe limit for a Dana 30. A fully polished 30 may last for a while with larger tires but it's just a matter of time.

    The factory D44a is in the same boat - 33's.

    Dana 44's are good in the 35" range. A front 44 can be made to work with 37's but it's pushing it as far as reliability goes.

    A Ford 8.8 can work well with up to 37's.

    I'd save the one ton axles for tires 36" and larger due to ground clearance and weight issues.

    Obviously you can make anything work and make anything break depending on tire size and driving style so the above is a generic guide.


    As far as bargain axles go, I think the Super Duty (98-04) front 60's are a steal. Stock they are nothing too special but they can be upgraded to be fairly strong. I am running what is essentially a SD front with high steer and 35 spline shafts and I don't have that much in it. I paid about $150 for the axle and spent money on shafts, Warns, and machine work to run high steer and 5 on 5.5" wheels. For rear axles, well they are all pretty cheap but a 14 Bolt is tough to beat.

    Quote Originally Posted by ATL ZJ View Post
    Since the "what size tire can I run on my 30/44" question has been beat to death
    That is why this is the TOTM - so when a newb asks that exact question he can be pointed to this thread and have all his questions answered (pointing and laughing is optional ).
    Last edited by rstrucks; 10-01-2010 at 11:14 AM.
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  5. #5 Re: TOTM: October - All About Axles 
    Senior Member Jeeptech01's Avatar
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    Lets also consider failures of parts due to the weakness of others. For instance housing flex allowing ring and pinion or carrier damage.

    ed: and things we can do to combat these issues
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  6. #6 Re: TOTM: October - All About Axles 
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    Alright, I can add to this thread a bit from my experience.

    Moab has traction. Wheel speed isn't really a huge thing, but there are still situations where you need it and trails that require a little skinny pedal. I ran Dana 44's front and rear for 2 1/2 years with 35's and 37's. I broke 2 axle u-joints in that time which in turn caused the ears to break of the shaft each time. If you're going to run D44's (or most any axle choice for that matter) CARRY SPARE SHAFTS. The time will come when you break one. Shafts only get weaker over time after they've been twisted enough.

    One of the BEST things I ever did was used full-circle clips on my u-joints. From the time I did that on my front D44, I never broke a shaft on 37's until I went to a sticky 37. From my experience, the biggest reason why people break shafts is the c-clip holding on the u-joint cap pops off, letting the cap slowly slide out of the shaft, and then breaking on the knuckle. Usually this will also break the ears on the shaft, if it doesn't, they're sure to be bent/weaker.

    Most trails (85%) in Moab you will probably be just fine running Dana 44's and 35-37s. However, if you like the skinny petal or you plan on running a bigger tire than 35's, then 1-ton axles may be what you're looking for. I went to 1-ton axles after I snapped 3 outer Chrome-Moly D44 shafts and blew up my rear R&P, spool, and 1 rear shaft on my rear D44 with my 37" stickies.

    Currently I run 40" tires with a Dana 60 front. 35-spline Chrome-Moly outers and stock non-neckdown 35-spline inners. My rear axle is only a Ford 9" (so not technically a 1-ton axle) but I've got a Yukon Nodular 3rd, and Moser 35-spline Alloy shafts and spool. So far it's been good for quite a bit of gas pedal on the 40's, we'll see how the rear R&P hold up when I put some 40" stickies on it though.

    As for aftermarket shafts, front shafts are available in Chrome-Moly, rear come in Alloy. The difference is that Alloy allows for more "twist" than Chrome-Moly, so for rear shafts axle manufacturers design them to take more abuse rather than just shatter when you really hit the skinny pedal. Not something you have to look out for, but just some info that may give you a better understanding of different materials when looking at aftermarket shafts.
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  7. #7 Re: TOTM: October - All About Axles 
    Senior Member ATL ZJ's Avatar
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    Quote Originally Posted by Jeeptech01 View Post
    Lets also consider failures of parts due to the weakness of others. For instance housing flex allowing ring and pinion or carrier damage.

    ed: and things we can do to combat these issues
    Trussing from C to C or flange to flange is important if you are going to get serious about doing any go-fast or wailing on your rig on rockcrawling trails.

    Full floaters are more forgiving for obvious reasons, and allow for shafts to be made out of superior material.

    Extra pinion supports like in the 14b minimize ring and pinion deflection, and high pinion gearsets help add strength in frontend applications.
     

  8. #8 Re: TOTM: October - All About Axles 
    Senior Member ATL ZJ's Avatar
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    Quote Originally Posted by CrawlerReady View Post
    As for aftermarket shafts, front shafts are available in Chrome-Moly, rear come in Alloy. The difference is that Alloy allows for more "twist" than Chrome-Moly, so for rear shafts axle manufacturers design them to take more abuse rather than just shatter when you really hit the skinny pedal. Not something you have to look out for, but just some info that may give you a better understanding of different materials when looking at aftermarket shafts.
    I realize this is going to be a pretty basic thread but it's still worth calling things by the right names. Chromoly is a mix of different alloys. Most chromoly front shafts are 4340 and most aftermarket semifloat rear shafts are 1541 which is a carbon steel with some alloy added. Over the years I have heard that 1541 is a better choice for shafts that bear the load of the rig. Most front axles (30 excluded), use real hubs so the spindle bears the corner weight, so aftermarket front shafts are generally 4340 or 300m.

    Twist or deflection has a lot to do with material, heat treating, and shaft diameter and neckup... this thead is a great discussion about shaft technology today and the importance of deflection over ultimate stength. Carry on...
     

  9. #9 Re: TOTM: October - All About Axles 
    My avatar isn't animated Lifetime Supporter SirFuego's Avatar
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    Here is a list (and approximate dates) of stuff I've broken on my HP30 (I've had zero issues with my 8.8):

    May 2009 -- Broke a stock D30 shaft just past the splines (most common point of shaft failure). The shaft broke at an angle. As it was rotating, the "long" end of each side of the broken shaft pushed off of each other and caused ring gear deflection, which took out the Ring, Pinion and Carrier. This failure was due to my tire being wedged between two large rocks and trying to "bump" it out. I upgraded to RCV shafts since my mentality was immediately turned away from the "if I break a shaft, I'll just replace it and keep on wheeling" mentality.

    September 2009 -- Broke a crosspin in three on Otter's in Rausch -- but didn't realize it until later in the weekend. I was trying to climb a ledge with my front tire as my rig was pointing downhill, so there was a LOT of force on that tire. After that trail, I heard a "clicking" coming from the CVs when turning. My buddy is running the RCV Dana 60 shafts and has experienced a similar thing -- so I kept on wheeling. Later in the weekend my driveshaft was spinning, but my tires were only doing so intermittently. We determined it was something internal.

    The verdict was that I broke my crosspin in three. The cross pin was banging off of the pinion -- and the sound was reverberating down the tube and out at the CV -- which is why it sounded like the CVs were clicking. This ended up taking out the ring/pinion and carrier. I upgraded to a hardened crosspin from Richmond, hoping this would help.

    August 2010 -- After a good year of wheeling (with some other non-axle issues), I went through a log trap at a local place. It got nice and slicked up and required some throttle. I got in the habit of letting off of the trottle as soon as I felt my front end come off the ground -- but I failed in this case. The force from the shockload of the front end hitting the ground while I was on the throttle twisted the carrier beyond it's limits -- took out the R&P, too. It even damaged a spacer in my locker. I had known for a while that with my style of wheeling, 1 tons were a necessity, so I just decided to cut my losses and am saving up for big boy axles.

    I'll add a "post-assessment" later, but I will say that I think that my HP30 failures were due to my mentality on the trails. If I didn't let myself get into precarious situations on harder trails, I'm sure I could have made the HP30 last a LOT longer on 35s...
    Quote Originally Posted by SB406
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  10. #10 Re: TOTM: October - All About Axles 
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    Cam yeah, you're correct. I should've said 4340 and 1541. Companies just refer to 4340 as Chrome-Moly and 1541 as Alloy from what I've seen.

    edit: side note, I've always known it to be Chrome-Moly. Is it actually Chromoly? Not that this is a lot of tech, but different companies use it both ways...
    Last edited by CrawlerReady; 10-01-2010 at 01:07 PM.
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  11. #11 Re: TOTM: October - All About Axles 
    Senior Member AgitatedPancake's Avatar
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    I ran the stock D30 with 33" MTR's and broke a CV like it was nothing, so I built myself a front LP44 a couple years ago.

    I'd rate the a bone stock dana 44 to a 36-37" tire if you drive with a little finess. I broke a U-joint last year with zero wheel speed, I had a tire jammed up in some rocks really good, gave it gas from a stop and just heard a pop. Mine was kind of an odd break, it only snapped 1 side of the u-joint, but that let it stretch the ears of one of my inner shaft. There is an asterisk with the break, and that is the U-joints were the ones that were in the axle when I pulled it from the junk yard, which looked like they could have been 15 years old. I replaced it and tacked the caps on the loose ears, and have had a good time rompin on it with 36's (BUT I'm still not locked)




    Ahhh I found a pic of where I broke. I broke the drivers side u-joint exactly where I am in this picture, you can see how wedge that tire is. It could NOT move.



    I'm running a 35 spline rear 9" like Tyler is, so I'm not even getting close to pushing the limit of it with the 36" tires right now.

    The rear 44a I'd rate strongly for 33's, and 35's with a concious mentality about it. I ran it on 33's for years locked with no issues. I moved up to 35's and had no issues for a while, until it happened. I had an axle shaft breakage while stuck in a hard rock obstacle at barrett lake. I limped it out 5 miles on the broken shaft, threw a replacement in (that my dad brought from sac!) sitting in the staging area the next morning, then ran the 6 mile trail in to save the weekend, and back out. That trip was the end of my 44a, I pulled the shafts and found the broken shaft peices had destroyed the housing around the carrier bearing, so the housing was trashed. I pretty much expected that though, the scary thing though is that BOTH the axleshafts had twisted splines. Even the one I put in 12 trail miles ago...

    Now I'm building a high pinion 609 front so stay tuned

    Here's a pic of my 44a shafts when pulled. As said, one only had the one trip on it where I was a very concious driver!
    Last edited by AgitatedPancake; 10-01-2010 at 01:19 PM.
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  12. #12 Re: TOTM: October - All About Axles 
    Senior Member ATL ZJ's Avatar
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    Quote Originally Posted by CrawlerReady View Post
    Cam yeah, you're correct. I should've said 4340 and 1541. Companies just refer to 4340 as Chrome-Moly and 1541 as Alloy from what I've seen.

    edit: side note, I've always known it to be Chrome-Moly. Is it actually Chromoly? Not that this is a lot of tech, but different companies use it both ways...
    I think the correct spelling is chromoly, but I have friends who are MEs that type it out as chro-moly. I guess any spelling is acceptable if it communicates the idea clearly...
     

  13. #13 Re: TOTM: October - All About Axles 
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    Yeah, just curious.
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  14. #14 Re: TOTM: October - All About Axles 
    Senior Member Jeeptech01's Avatar
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    Quote Originally Posted by rstrucks View Post
    IMO 33's are the safe limit for a Dana 30. A fully polished 30 may last for a while with larger tires but it's just a matter of time.


    A Ford 8.8 can work well with up to 37's.
    Are we talking about low pinion or 30's in general?

    I believe the weak spot of the thirty besides the small gearset and carrier is the weak housing. The tubes are tiny and there isnt very much ribbing on the pumpkin. From the research I've done sleeving the tubes, a simple truss and good aftermarket cover will go a long way without dumping too much coin into a turdy.

    Cheap 8.8 insurance: Weld tubes to the pumpkin.
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  15. #15 Re: TOTM: October - All About Axles 
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    Quote Originally Posted by Jeeptech01 View Post
    Cheap 8.8 insurance: Weld tubes to the pumpkin.
    I think that is a good idea for ANY axle personally. I've welded the tubes to the pumpkin on every axle I've swapped in. My brother pulled a tube on his D35, and since then, every axle gets burned together.
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  16. #16 Re: TOTM: October - All About Axles 
    My avatar isn't animated Lifetime Supporter SirFuego's Avatar
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    Quote Originally Posted by rstrucks View Post
    IMO 33's are the safe limit for a Dana 30. A fully polished 30 may last for a while with larger tires but it's just a matter of time.
    I would agree with this. I ran my HP30 pretty hard on 33s with stock shafts. That bump up from 33s to 35s is where the axle CAN hold up, but you need to be VERY cautious on the trails. If you upgrade tires to make your current trails/obstacles/lines easier, then you can probably have it hold up. If you upgrade to 35s so that you can run more difficult trails/obstacles/lines, that's when it becomes "a matter of time".

    Quote Originally Posted by CrawlerReady View Post
    I think that is a good idea for ANY axle personally. I've welded the tubes to the pumpkin on every axle I've swapped in. My brother pulled a tube on his D35, and since then, every axle gets burned together.
    Agreed. My HP30 and 8.8 both had welded tubes. My new axles will definitely have the tubes welded to the housing.
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  17. #17 Re: TOTM: October - All About Axles 
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    Quote Originally Posted by CrawlerReady View Post
    One of the BEST things I ever did was used full-circle clips on my u-joints.
    I would definitely have to agree with this, but only if you stick to 33's or less on a D30! Prior to doing this I broke 5 shafts on the old D30, two on 32's and three shafts on 35's, four of which where short side shafts and I suspect the caps came loose after spitting out the c-clip which then let the u-joints snap the ears off the axles the fifth shaft was a short side stub that snapped at the splines. I heard pop but couldn't see any of the damage and ended up loosing a wheel driving down the road from the trail. After I took a dremel to to the shafts to accept full circle clips the first axle break was a catastrophic one, didn't break a u-joint but I believe either the teeth on the ring and pinion let go, which then completely destroyed the ARB and then the short side inner at the splines by the locker, or it could have been the axle shaft inner which took out the ARB and then the fact that the carrier was shattered then took out the gears... either way it wasn't good. Putting full circle clips on the u-joints shifted the "weak spot" to something else which resulted in MORE carnage in my situation.

    Now I'm running a HP D44 narrowed to wagoneer width with warn inner and outer shafts and yukon superjoints. Only issue I've had blowing out one of those oldshool warn hubs (non-premium) that I picked up the the JY when I first built the axle. In that particular situation the tire was bound up pretty bad and the weakest point gave out which I'm fine with that. The rear I'm still running the Ford 8.8 with minimal issues, bent a flange on an axle shaft about a year ago, also right before the GSR I opened it it to inspect everything and noticed that the "shims" had walked out of place on the pass side of the carrier. Put them back in and it's all good so far but I did get two loud pops during GSR that I've never heard before that I don't believe to be locker related so I have to check that out. In all fairness it did get me through the trail and the 5 hour drive back home so it's probably nothing.

    Fred R.
    Last edited by fredr1980; 10-15-2010 at 07:37 PM. Reason: inserted image of D30 carnage...
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  18. #18 Re: TOTM: October - All About Axles 
    Senior Member dp96zj's Avatar
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    For future reference, I think this thread should be linked in here:
    http://www.mallcrawlin.com/forum/showthread.php?t=19280

    That aside, sure, tons are great, but what about the little guys?

    Ex: I'm on a budget, mine is my daily driver. Sure, it may be built in the future, but as of now, I don't have the time or money to go LA's and tons. For the guys that are hovering around 33" tires or so, if a rear axle swap is desired, the cheapest and easiest route would be an 8.8 swap. They're cheap, a shit-ton stronger than a turd-5, and much more reliable than 44a's. The aftermarket support is MUCH better for an 8.8 over a 44a or d35, and it's been proven on this board that these axles, when built, can hold up to some romping on 35"+ tires. At the very least, the tubes should be welded and quality brackets used.

    The easiest place to find a decent 8.8 would be under 1996+ Ford Explorers, as these came with disks and 31 spline shafts. Most came with 3.73's, some had 4.10's. For a front axle to compliment the 8.8, the cheapest and easiest bolt in axle would be an HP30. This combo should hold up to 33's.

    Here are some more links for future reference if someone is looking into an 8.8 swap:
    http://www.mallcrawlin.com/forum/showthread.php?t=2880
    http://members.cox.net/quanno/ford88.html
    http://www.jeepsunlimited.com/forums...d.php?t=371713

    The axle shaft strength tested by Warn Ind:
    F8.8= 6,500 (lb. ft.)
    D44= 4,600-5,000 (lb. ft.)
    D35C= 4,000-4,300 (lb. ft.)
    Dana 35 rear axle COT: 870 MOT: 3480
    Dana 44 rear axle COT: 1100 MOT: 4460
    Ford 8.8 28spline COT: 1250 MOT: 4600
    Ford 8.8 31spline COT: 1360 MOT: 5100
    Dana60 semifloat COT: 1500 MOT: 5500
    I'm done.
    Last edited by dp96zj; 10-01-2010 at 03:10 PM.

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  19. #19 Re: TOTM: October - All About Axles 
    My avatar isn't animated Lifetime Supporter SirFuego's Avatar
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    Quote Originally Posted by ATL ZJ View Post
    Twist or deflection has a lot to do with material, heat treating, and shaft diameter and neckup... this thead is a great discussion about shaft technology today and the importance of deflection over ultimate stength. Carry on...
    I've been following that thread a bit. It's interesting that there is a LOT of research on rear axles due to car racing, but very little (relatively speaking) seems to be known about front axles.

    I was reading BillaVista's Axle Shaft Bible (which was written a while ago) and it talks about "equal torque". The basic idea, from what I understand, is that both axles should react "equally" in terms of how much they twist under the same amount of torque. As a result, in an offset differential, the shorter shaft needs to have a smaller diameter than the longer shaft. I would be very curious for folks to take a caliper reading on the short and long inner shafts in various applications and see if the shaft diameters differ. There never really seems to be any discussion about this...
    Last edited by SirFuego; 10-01-2010 at 03:25 PM.
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  20. #20 Re: TOTM: October - All About Axles 
    ....... Lifetime Supporter rstrucks's Avatar
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    Quote Originally Posted by ATL ZJ View Post
    I realize this is going to be a pretty basic thread but it's still worth calling things by the right names. ...
    Don't let the basicness (new word) stop you from bringing some good tech.

    Quote Originally Posted by AgitatedPancake View Post
    Now I'm building a high pinion 609 front so stay tuned
    What are you going to run for outers? King pin stuff?

    Quote Originally Posted by Jeeptech01 View Post
    Are we talking about low pinion or 30's in general?

    I believe the weak spot of the thirty besides the small gearset and carrier is the weak housing. The tubes are tiny and there isnt very much ribbing on the pumpkin. From the research I've done sleeving the tubes, a simple truss and good aftermarket cover will go a long way without dumping too much coin into a turdy.
    I was referencing 30's in general. I also think that the 30 is pretty well matched from the factory and it is what it is - just a small, lightweight axle.


    Also, axle shafts should have raised splines as to not create a weak point at the inner end of the spline. Maybe a clearer way of saying it would be - the diameter of the splines should be larger than the smooth shaft just to the inside of the splines. That way you just have added material for the splines instead of cutting into the shaft to create them thus eliminating the weakness of cut splines.
    Last edited by rstrucks; 10-01-2010 at 03:42 PM.
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  21. #21 Re: TOTM: October - All About Axles 
    My avatar isn't animated Lifetime Supporter SirFuego's Avatar
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    Here is my "post-assessment" in regards to my previous post about my HP30 failures:

    1) A truss (even a mini-one) that covers as much of the axle as possible is necessary. This greatly reduces the chance for movement inside the axle -- which causes failure.

    2) 4.10s allow more teeth engagement between the ring and pinion. Yes, I went through 3 ring and pinions running the D30, but based on my assessment (validated by others) the ring and pinion was never the CAUSE for the failure. I don't know that I would ever run 4.88s in a D30. FWIW, I did get my second R&P cryo treated, but like I said, the R&P was never the cause of the failure, so I don't know if the cryo treatment helped any.

    3) If you run chromolly shafts, a carrier replacement locker (detriot, grizzly, arb, zip, etc.) is probably a better choice than a lunchbox locker. When I dismantled my internals after my last break, it was very obvious that the stock carrier couldn't handle the shock loads.

    4) If you run a lunchbox locker, get a replacement hardened crosspin from Richmond. Well worth the $15-$20 it costs.

    5) I'm not a big fan of u-joints. I really think that CVs are going to become more commonplace and more affordable in the future -- I'm anticipating a viable competitor to RCV to crop up in the next couple years. I noticed a LOT less wheel hop running CVs. In addition, you don't need to worry about "laying off" if you are at full steering lock. Finally, when a CV does break, it basically just freely spins, so you don't have any axle ears to break or push apart (potentially causing worse failure). Don't get me wrong though, high quality U-joints and shafts still are more than sufficient -- some even claim that they broke RCV's then switch to 300M u-joints without any problems (heck, I'm admittedly debating what to do about this for my upcoming build right now). That comment alone might be the sole reason I might be wrong about CVs becoming more popular if they don't come down in price.
    Last edited by SirFuego; 10-01-2010 at 03:48 PM.
    Quote Originally Posted by SB406
    I think that's your signature move.
    "The Former"- Lay Jeep against obstacle in trail. Mat gas pedal. Form Jeep to the shape of obstacle.
    Robot
     

  22. #22 Re: TOTM: October - All About Axles 
    Senior Member ATL ZJ's Avatar
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    Quote Originally Posted by SirFuego View Post
    I've been following that thread a bit. It's interesting that there is a LOT of research on rear axles due to car racing, but very little (relatively speaking) seems to be known about front axles.

    I was reading BillaVista's Axle Shaft Bible (which was written a while ago) and it talks about "equal torque". The basic idea, from what I understand, is that both axles should react "equally" in terms of how much they twist under the same amount of torque. As a result, in an offset differential, the shorter shaft needs to have a smaller diameter than the longer shaft. I would be very curious for folks to take a caliper reading on the short and long inner shafts in various applications and see if the shaft diameters differ. There never really seems to be any discussion about this...
    I'm not aware of any mainstream shaft manufacturers that build their short side shafts to a smaller diameter, although some may. I know yukon doesn't. And their neckdown profile is just plain bad. I was running a pair of their 35 spline chromo inners and twisted the short side shaft past its range of elastic deformation. I swapped a 10 factory shaft in, which is shaped properly, and is very arguably stronger due to its design. Here's a pic for reference.



    The 10 factory shaft (on the right) has an operating diameter that I measured as .017" smaller than the yukon shaft for the same application next to it (on the left). The operating diameter of the 10 factory shaft is also smaller than the root of the splines, like it should be, according to carroll smith and a lot of other people way smarter than I am.

    Look where the yukon bent. At the stress riser where the splines and spider gears of the diff engage. If the operating diameter had been smaller, I think the load would have been distributed more evenly over the entirety of the shaft and maybe the long side shaft too, and the shaft may have even been able to deflect a greater number degrees due to the smaller diameter. I can't be sure whether the 10 factory shaft would have suffered the same fate but I have a hunch that it would have taken more force or more repeated stress to do it.
    Last edited by ATL ZJ; 10-01-2010 at 03:51 PM.
     

  23. #23 Re: TOTM: October - All About Axles 
    My avatar isn't animated Lifetime Supporter SirFuego's Avatar
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    In regards to my comment on axle diameters. Assuming a 35" long shaft that is a diameter of 1.5", I calculated that an 18" short side shaft would need to be 1.27" for the same theoretical "twist" characteristics. For reference, a D44 30 spline shaft is about 1.31" and a D30 shaft is 1.13".

    IMO, whether manufacturers "neck down" their shafts depends a lot on cost/benefit. From my understanding, a neck down shaft is more expensive and complicated to manufacture, so the added strength it gives might not be worth the extra cost to the manufacturer. In addition, assuming the Yukon shaft splines weren't twisted, 99 out of 100 random people would probably look at your picture and immediately gravitate towards the Yukon shaft, because it's counterintuitive to most people that a narrower shaft will (in theory) hold up better.
    Last edited by SirFuego; 10-01-2010 at 04:14 PM.
    Quote Originally Posted by SB406
    I think that's your signature move.
    "The Former"- Lay Jeep against obstacle in trail. Mat gas pedal. Form Jeep to the shape of obstacle.
    Robot
     

  24. #24 Re: TOTM: October - All About Axles 
    Senior Member dp96zj's Avatar
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    Very interesting data posted in that p4x4 link. I went ahead and watched the video coverage of them breaking the different shafts, shown here if you don't feel like searching. The actual shaft testing starts about 46 minutes in:

    http://www.pirate4x4.com/tv/live12.php


    So although the Yukon "Hardcore" shafts stood up to 6100 ft lbs, they only had 55* of deflection, while the Ten Factory shafts were 5100 ft lbs and nearly double the deflection. Or take the Superior import, with 5800 ft lbs and 130* of deflection! In terms of axle shafts, I'm assuming most people would sacrifice torque in order to achieve more deflection? ...as shown by Cam's photos above.

    On a side note, do you think that Yukon is intentionally putting out shafts with higher torque yields, because people tend to look at torque rather than deflection?

    EDIT: I think that it's funny that in the video the Yukon shaft split lengthwise, not directly at the splines. Right before that, Randy said they're made to break specifically at the splines
    Last edited by dp96zj; 10-01-2010 at 04:23 PM.

    Quote Originally Posted by Derek33
    Its a jeep, it doesn't have to make sense.
     

  25. #25 Re: TOTM: October - All About Axles 
    Senior Member MallCrawlin Supporter biggoofy's Avatar
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    I really dont have much to add here since everything I know has already been covered but I would love to see some simple and easy truss ideas for the 8.8 and hp30 as im about to swap them into my rig!
    93 ZJ long arms, 35's, F/R Long arms, 4.56 gears, and a bunch more
    98 5.9 slate gray 4" lift with stuff (sold)
    96 ZJ Lift, Long arms, 35's and a bunch of other shit! (RIP)
    [ IRONMAN 4X4 FAB ] [ RACELINE WHEELS]
     

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