Front Axle Spiders Failing?

[Ellis6]

Hi - I'm a long time lurker and first time poster. A couple years ago I bought a 1975 M45A2 WO/W tanker to use as a water tender for my remote forest property in Western Oregon. The truck belonged to the U.S. Forest Service and according to a sticker on the dash was stationed at Elk River in Idaho.

I purchased the the truck a couple years ago in Spokane Washington and had it transported back to my shop in Canby Oregon. The tires were extremely weathered NDT's and the brakes were leaking big time, so I wasn't able to drive the truck prior to tearing in to it, other than around the parking lot. The truck is an LDT 465 and has an air shift transfer case.

Last year I pulled the truck into my shop to service the brakes and check the wheel bearings. All six wheel cylinders were leaking, as were many of the axle seals. Basically, the thing was a mess, and it hadn't been shown any love in quite awhile. On the bright side, the truck is rust free and the engine starts within a split second of hitting the starter.

i stripped the brakes and axles / hubs off all three axles and spent a ton of time cleaning. I've never seen so much grease and crap. I collected all new seals, wheel cylinders, brake shoes, hardware kits with springs, and a new master cylinder. Fortunately the air pack (short version) was recently replaced and looked as new inside.

Now to the problem: when I put the front axles back in, I got a funky noise when I rotated the left axle. I wondered if I had the axles swapped inadvertently, so I swapped them and determined they were in correctly to begin with. I called it a day and went home to read this forum looking for threads on axle issues.

After a bunch of reading, I had a hunch the spiders were toast, and decided to drain the front axle when I got back to work on it today. I expected to get a bunch of metal junk when I drained the gear lube, but to my amazement there was no metal, at all. The magnetic drain plug had the usual "fines" attached, but nothing of any substance. The gear oil was not milky, and was used but clean. The drain plug had not been out in a while as it was caked with crud on the outside, so it's unlikely a PO drained and refilled to hide a problem.

I was actually stumped to find the oil clean, as there was definitely something wrong with the internals. The truck is up on stands with all wheels off. When I rotate the front drive shaft by hand, the front axles rotate in opposite directions as they should. When you rotate the drive shaft by hand and hold one axle stationary the other axle rotates as normal.

Here's what has me stumped: when you rotate the left axle, there's a clunk at the same point every revolution. I'm working by myself, so in order to see how the axles are rotating I fastened a paint stir stick to the drive flange on each axle to act as flags I could watch. When I rotate the front drive shaft, the left axle actually stops rotating at the same point it was making the clunk, and the right axle continues to rotate. There's obviously a bit of a bind at the point in rotation where it clunks.

So, I have come to conclusion, for lack of a better explanation that the spiders are damaged and failing but not yet broken. My plan is to finish assembly and defer the fix to a future date. I have lockout hubs for the front, so I can drive the truck 4x6 mode, use 6x6 mode in an emergency, and then next winter pull the center chunk and repair. This truck has already been the model of "slippery slope" and I have had it apart way longer than intended. I need it to haul water for fire protection this summer, which I don't need 6x6 mode for, and if I pull the chunk now I'm afraid the truck will be apart thru this coming summer.

I work slow, and don't have as much time to work on the truck as I'd like, otherwise I'd pull I the chunk now, but don't want to miss another fire season.

Any ideas or suggestions would be greatly appreciated.

Thanks,

Dirk

 

[bachman502]

Ellis6, only you can make that decision on whether to remove the center chunk out of the axle now, later or never. Sounds like it’s a tool that you need to use for work not for pleasure. Removing center chunk requires removing u Bolts and lifting truck up to clear oil pan. Once you have it out you will possibly see your issue. It faster to remove it now since shafts are pulled. However if you work slow (which believe me I understand) then you will miss out fixing differential and not having truck for it’s intended purpose. Everyone has their opinions on their own truck. Some people treat them like they were never designed for work and baby them. Yours is a tool. Since you have locking hubs, I would run it like it is. And I would also lock it in 6x6 once it’s together and see if you even hear or feel anything. I would not worry about it now or possibly ever if it sounds ok driving. Worse case you blow a center section apart. So no big deal in my opinion.

 

[Ellis6]

Thanks Bachman, You are correct when you say I bought this as a tool, as I was originally just looking for a water truck to keep water on my property in case of forest fire. I had no prior MV experience, but when I found this thing on Craig's List I drug a buddy of mine along for a six hour drive to look at it. I was immediately hooked, and bought it on the spot. I work on this thing in my spare time, which is pretty spare, as I run an aerospace manufacturing business and I have this in the back of my "work" shop. I need to move the deuce pretty soon to make way for a new CNC machine, otherwise I'd leave it where it is and continue to poke away at it. I can haul water on my 923 if I need to, but that means it's not available for other tasks.

One of the reasons I work slow is I tend to overthink things. I'm an engineer and a bit of a perfectionist, and I have a tendency to always try to improve or perfect whatever it is I'm working on. Hence things take way longer than they should. Knowing myself, I'm inclined to button it up and drive it. Like you said, it may be fine. Works case I replace the chunk at a later date. I have a spare donor axle.

cheers,

Dirk

 

[M543A2]

Dirk, being a design engineer and mechanic I can really relate to your thinking process! There are times it actually hinders me. I submit that if you had a spider gear problem you would hear or feel it no matter which axle you rotate. The spider gears travel around each other in the same manner, both sides, no matter which axle you rotate with the drive shaft secured. So, if a gear(s) were damaged, doesn't it make sense you would have the noise no matter which axle you rotated? I have had damaged spider gears and that is the way it was. A bit of missing information: when you said you rotated the drive shaft and the front axles rotated in different directions as they should did you hear the noise? Is the sleeve bearing in the end of the axle housing the outer end of the drive shaft rotates in in place and OK, and the same for the one in the hollow spindle? Did you check the universal joint on the wheel end of the axle, move it around to see if you feel a problem or shaft to shaft lateral centerline axis off-set through the joint being possible? Have you checked the bearings, put the hub on without the axle in and spin it to see if you find any binding? Is the long shaft straight, not bent which would cause a binding as it rotated with the of-axis centerline condition? It really sounds to me that this problem is with the axle shaft or other components on that side rather than center section spider gears. In all of this I am assuming the hubs were in place when you ran the tests, supporting the hub ends of the shafts. If not, then definitely look at the joint. Hopefully this evaluation is correct, likely it will be much easier to fix!

 

[gimpyrobb]

Front axle housing is the only one with the issue? Pull the spline cap off and see if the noise goes away. If not, its not the axle.

 

[LiveFreeOrDieTryn2B]

I agree you should check the axle shaft.

 

[Ellis6]

I agree you should check the axle shaft.

Agreed, I will pull the left axle and check for straightness, although visually it appears nearly new.

Thanks guys,

Dirk

 

[gringeltaube]

........... Is the sleeve bearing in the end of the axle housing the outer end of the drive shaft rotates in in place and OK, and the same for the one in the hollow spindle?

Just to clarify: there is only one such sleeve, and it is located in the spindle.

 

[bachman502]

Pull your axle shafts back out and rotate your front driveshaft. See if you feel anything binding up with no shafts installed.

 

[Ellis6]

OK Guys - I'm a Dork.

This morning I drug my buddy out to look at the truck. After a few minutes, he diagnosed that the noise was coming from the left u-joint body contacting the axle housing. Then it hit me like a ton of bricks. I didn't have the steering arm tightened down yet, so the knuckle was sitting lower than normal. Long story short, I tightened up the steering arm nuts and the clunk miraculously went away.

Needless to say, I'm quite relieved.

Thanks for the help guys.

Dirk

 

[cattlerepairman]

That's great! You now have plenty of time to take pictures and a video of your truck and post them!

 

[tennmogger]

Dirk, thank you for sticking around and following through on the cause of the problem for those of us trying to figure it out with you. You didn't just disappear when you found the (slightly embarrassing) cause, as too many do!

 

[Ellis6]

Dirk, thank you for sticking around and following through on the cause of the problem for those of us trying to figure it out with you. You didn't just disappear when you found the (slightly embarrassing) cause, as too many do!

Tennmogger, I can't tell you how many hours I have spent reading this forum in the last couple years. What a treasure trove of knowledge and help. I'm grateful to all those that have posted their experiences and also thankful to you folks that worked to help me thru my knucklehead period.

I will ill read up on posting photos and post up some of this truck back together.

Thanks again,

Dirk