Rear drive failure...?

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OhioPinz
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Rear drive failure...?

Post by OhioPinz »

I was driving my 71 Pathfinder today, cruising along in 5th, when it suddenly lost drive to the rear wheels. No sound a all, no pop or zing or buzz, nothing. As if it slipped out of gear. Coming to a stop, I discovered all gears made no difference. Clutch is fine. HOWEVER, front wheel drive (4x4) still works fine. No grinding or and noises at all. So, suggestions where to start? Thanks in advance.
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TechMOGogy
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Re: Rear drive failure...?

Post by TechMOGogy »

Did you check the drive selector rod to make sure all is intact?
72 Pathfinder | 75 710M 2.7i | 96 350GDT Worker
Heinkeljb
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Re: Rear drive failure...?

Post by Heinkeljb »

First bit of investigation would be to jack the back end up and put it on axle stands. Then turn each rear wheel in turn.

Does anything feel wrong? It is possible that when you turn one side that the other side turns as well, but in the opposite direction - This is normal!

Put it in a gear and then turn the rear wheels again (If you can't turn the wheels, you could try taking out the spark plugs to reduce the compression resistance) - Do both wheels turn? Do this through all the gears.

If the wheels do not turn together, then I'm afraid it time to open up the gearbox / Diff to find out which bit has broken. Does sound like either a gear has snapped in two or a nut has fallen off.

I would be inclined just to take the rear drive shafts off the diff casing as the fact you have front wheel drive suggests the gearbox is actually working but that the rear diff is not.

John
Jim LaGuardia
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Re: Rear drive failure...?

Post by Jim LaGuardia »

Broken axle or spider gear in diff.
Put it in gear, raise it up lock the diff. The wheel that spins has the fault(most likely a sheared axle shaft).
Cheers, Jim LaGuardia
http://smg.photobucket.com/albums/v510/Goatwerks/
"Arch Magus of Machines."
OhioPinz
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Location: Middletown, Ohio

Re: Rear drive failure...?

Post by OhioPinz »

I was finally able to check out the Pathfinder today using the suggestions. The results are as follow, but I have yet to disassemble anything yet:

The failure appears to be directly in the left rear wheel, possibly in the portal drive itself.

1.Rear drive with locked diff does indeed drive the right wheel only (I was not fully engaging the locking lever on earlier attempt.)
2. Left rear spins freely, in fact so freely, it clearly is not even turning the driveshaft. It spins smoothly with no noise as all. No gear noise as with the rest of the wheels, and no adverse sounds either such as crunching.
3. Front works as normal.

So, I intend to disassemble the left rear portal. All I have is a parts book, so any special tools needed?

Any suggestions on what might have failed? The failure occurred just driving along on the street and there was no sensation or sound, it just lost drive.
Heinkeljb
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Re: Rear drive failure...?

Post by Heinkeljb »

No special tools required!

Obviously, rear wheel off.
Brake drum off.
Split brake line either at the wheel cylinder or at the flexible hose joint.
Drain the oil from the hub.
Remove brake shoes - only because it make it easier to get he hand brake cable off. You could undo the bolt that hods the handbrake cable arm on the shaft and take the arm off to be able to disconnect the handbrake cable if you want.
Undo the four nuts holding the square plate on the back of the hub - controls the bearing preload using washers so make a careful note of what you take out and in which order!
Undo the nut holding the wheel hub - you can put something like a tyre leaver between two wheel studs in order to provide a locking mechanism to allow you to undo the nut on the back.
Undo the nuts holding the two halves of the portal casing together.
Tap the casing "gently" to break the gasket seal and remove the outer half of the portal casing.
You should now be able to see if anything is amiss with in the portal casing.

One way to take the nut off the drive shaft is to wrap some cloth around the teeth of the small cog and then to use a large pair of plumbers pliers (slip joint pliers) or a pair of Stilsons to hold the small cog still whilst you undo the nut.

Hope that's really where the issue is or you will be undoing more things to find it!

John
Last edited by Heinkeljb on Tue Jun 16, 2015 1:46 am, edited 1 time in total.
OhioPinz
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Re: Rear drive failure...?

Post by OhioPinz »

Well, I pulled apart the portal axle housing today only to find everything in very nice shape. Axle spins very freely with no indication of breakage but pulling it is next.
Jim LaGuardia
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Re: Rear drive failure...?

Post by Jim LaGuardia »

You will most likely find it sheared before the "paddle" on the inboard end.(most common axle failure point)
Cheers, Jim LaGuardia
http://smg.photobucket.com/albums/v510/Goatwerks/
"Arch Magus of Machines."
OhioPinz
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Re: Rear drive failure...?

Post by OhioPinz »

It indeed feels like a sheared shaft. I have the axle tube and axle free on the outboard end. So how do I remove the axle from there? Does the entire axle tube need to be removed?

I have a parts book but no repair info. Is there an online source?

Lastly, assuming I need a left rear axle, 700.1.34.295.2, where is best source?
OhioPinz
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Re: Rear drive failure...?

Post by OhioPinz »

I have confirmed a broken axle.
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Heinkeljb
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Re: Rear drive failure...?

Post by Heinkeljb »

Are both rear axles the same? Or are they handed? Wouldn't have thought so, but with these beasts anything is possible!

Shame you have a couple of broken bits, but they don't look like it would really repair very well. So probably not worth even contemplating that - Replacement with preferably a new one, but if one can't be found then a good second hand one will have to do!

John
Jim LaGuardia
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Re: Rear drive failure...?

Post by Jim LaGuardia »

First one I've seen failed on that end :!: . I always find em on the inboard end.
Cheers, Jim LaGuardia
http://smg.photobucket.com/albums/v510/Goatwerks/
"Arch Magus of Machines."
OhioPinz
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Re: Rear drive failure...?

Post by OhioPinz »

Jim, can I give you a call with a few questions?

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OhioPinz
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Re: Rear drive failure...?

Post by OhioPinz »

Thanks for everyone's help. Removed the axle arm today and ready to install the new axle.
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pinzinator
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Re: Rear drive failure...?

Post by pinzinator »

I have tried to install an axle like you are going to do. I got so frustrated that I had to get Jim LaGuardia to help me out. Not sure how it was done at the factory, but they had to have a special tool or technique. Let us know how you did it.
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