Rear Axle Spline Twist - Experienced Opinions Please

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Glenn-BJ74

Glenn-BJ74

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Below is a picture of the splines on my left hand (long-side) full floater rear axle. The truck has 162,000km (100,000 miles) on it, with ARB lockers since 105,000 km (65,000 miles) when I got the truck. The truck is used for expedition wheeling (including Moab once a year) and is not a DD

The twist is hard to see but the best I can measure it is about 0.003”- 0.004” over a distance of 1.4”, which is the wear portion of the 2.0” axle spline length. Put a straight edge along the unused spline to see the amount of twist.

The right hand (short-side) exhibits no twist, shown in the 2nd picture. Both are the original axles.

Should I replace this axle right away or leave it a while longer?
How much twist before failure is imminent?
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Fast Eddy said:
Does the collar slide all the way to the end of the splines? Stock axle shaft?
Click to expand...

It is a stock FF axle, which uses 1.4" of the 2" of spline as you can see in the picture.
 
Glenn-BJ74 said:
It is a stock FF axle, which uses 1.4" of the 2" of spline as you can see in the picture.
Click to expand...

When it's locked. When it's unlocked the collar slides past that twisted part. Eventually the collar is going to get stuck trying to make the transition.
 
High traction 35's with lockers - that is my worry.

Why only the long side axle shows spline twist in the two pictures. I would have guessed more twist on short side as the long side has a longer shaft to 'absorb' the torque before splines twist is evident at the drive end ??
 
i thought the same too mate but both my axles are just as bad as each other.

When u say high traction u talking stickys? Im running 40" stickys with standard rear axles
 
Just dragging this one up again, haven't been on 'mud in a while.

Personally, and knowing the type of driving you do - which is often in remote locations, I would replace the shaft with aftermarket chromoly units.

If the shaft end separates, it's going to be challenging getting it out. It can also cause damage to the differential if it snaps under load and sends a shockwave through the side gears and carrier (personally seen this happen on the trails - while in Moab and also the Rubicon a number of years back).

We have access to aftermarket shafts through our supplier network - made in the USA.

The example photo is a Ford 9" unit with a what I recall being an ARB Air locker, but it may have been a Detroit. There was at least one Air Locker in this truck... it took out the adjuster ring, left a hard to remove piece in the differential, and messed up the side gear. It took almost two days of total time to be back on the trail again (Rubicon, Granite Slabs, 2001) - we had full access to a shop in Placerville and full access to parts ordering (axle shafts etc.) through Danny Warden in Placerville. Without Danny's generous help, we'd have been there a fair bit longer.

~John
Flaccid9Incher(rwb).webp
 
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whitegoat said:
5 spd 3B diesel A/C
230000kms
33 bf goodrich TAs
ultra rare factory softtop
runs great
check out Island moose for posts on truck dated back to 2005
offers over 7k
check out profile for pics
Click to expand...

:confused:

Sent from my iPhone using IH8MUDu
 
From what I have read chro-moly axles are more break resistant, but the downside is they wear out faster.
 
Glenn-BJ74 said:
From what I have read chro-moly axles are more break resistant, but the downside is they wear out faster.
Click to expand...

You may be thinking about the CV/Birfs, tons of threads on that subject. The older chro-moly birfs would wear faster on the full time 4wd trucks like the FZJ-80s with constant day to day use. The newer ones are much better with wear. Wasn't really an issue with a part time 4wd truck unless you drove around in 4wd all the time.:p

Really no "wear" parts on a solid axle shaft except maybe where the oil seal is. However, the stock shafts are pretty darn strong and will probably less prone to twist as they are harder. They just don't take the shock loads as well as the softer chromoly shafts. And I have seen a time or two there the chromoly shafts stripped at the splines, but hard to tell if the chromoly or the abuse were the culprit.:meh:
 
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Behemoth60 twisted his a bit more than that at Rubithon one year and it caused his locker pawl to stick in place and made removing the axle nearly impossible. Once it was back in the shop it required many steps of increasing medieval devices to get it apart. If you wheel hard enough to twist those splines you should consider either a stronger axle shaft or another locker type. It would really suck to have to take a torch to your housing to get the third member out.

FTR I'm still running a stock 60 series cable locker with stock shafts so I don't take my own advise too seriously.
 
phrogg4evr said:
You may be thinking about the CV/Birfs, tons of threads on that subject. The older chro-moly birfs would wear faster on the full time 4wd trucks like the FZJ-80s with constant day to day use. The newer ones are much better with wear. Wasn't really an issue with a part time 4wd truck unless you drove around in 4wd all the time.:p

Really no "wear" parts on a solid axle shaft except maybe where the oil seal is. However, the stock shafts are pretty darn strong and will probably less prone to twist as they are harder. They just don't take the shock loads as well as the softer chromoly shafts. And I have seen a time or two there the chromoly shafts stripped at the splines, but hard to tell if the chromoly or the abuse were the culprit.:meh:
Click to expand...

Good points.
Its a twisted rear - turning all the time. I suspect the sand covered rock at Moab, where the locker is required, but where the sand is a bear on the rock it puts major stress on the splines, until its disengaged.
 
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