'76 F-250, NP-435 & 205. Got stuck in a snowbank tonight and the guy who winched me out said neither front wheel was engaging. 1 year old Warn lockouts were both in correct 4x4 position. I was in 4-low and also tried 4-hi with no difference.

Initial thoughts are to jack up front end with both wheels off the ground and see what happens when each wheel is manually turned. I was going to do this in 4H, 4L, and 2H. And also with the tranny in and out of gear.

Is this the right path? If not, what am I missing? Also, what results should I look for if everything is normal (because I know it isn't)?

Advanced Search yielded no results due to 'common terms'..

Thank you.

 

Yes that's a great test. You are looking for the driveshaft to be turning first of all, but since it can turn just from parasitic fluid drag when the rear is spinning, it's not the be-all and end-all of tests.
Even before you lift the front end up though, in the comfort of your driveway put it in either 4wd position and try to turn the front shaft by hand. If you can still turn it, the fault is in your transfer case shifting.
If the front driveshaft locks up, it's in 4wd and the problem is in front of that.

Aftermarket lockouts often fail, so it can easily be those. And we'll hope for that, because I think the only other possibility is the differential, as busted gears or axle shaft(s).

Paul

 

Thanks, Paul, for the quick reply! That is exactly what I was looking for!

"Comfort of my driveway" is relative though, as we've got about 3' of snow on the ground.

 

Haha! Yeah, happy new year, right?
I was going to write "...of your garage." at first, but thought that maybe not many of these rigs get the luxury of a garage.
Although I sure have seen a lot of nice shops/out-buildings/barns that some of the members here have for their trucks! Jealous for sure.

Paul

 

Should've thought about it a little more before replying, Paul. Assuming everything else is intact, what would happen if one hub failed? Would that axle definitely be the one turning, or trying to turn the wheel? (I think it's highly unlikely BOTH hubs failed at the same time.) Or is this a non-nonsensical question?

 

I had that happen a couple of years ago. I wondered why it wasn't pulling on a hill in low range. Got it home and started checking things out, everything seemed good. Pulled it back into low range, all good. Figured I hadn't pushed it all the way in and was in between N and 4 low, so it was only in 2 low. Long time ago I slid into the ditch in front of my house in the snow. Pushed it up into 4 low, hit the gas, and heard all kind of racket from the front axle. Sheared 3 teeth off the ring gear and 2 1/2 teeth off the pinion gear. It was no fun installing a new ring and pinion laying on my back on a piece of cardboard in the snow. Did you hear any nasty noises when you were trying to get unstuck?

 

Thanks for the reply, Mark.

No, I did not hear any attention-getting noises. The truck makes loud noises all the time, and I could have easily missed it simply driving around. I put the new Warn hubs in 2 summers ago and the noises calmed down considerably.

 

A single hub failure can cause both wheels to not turn, yes. If your front differential is "open" (which is standard on most vehicles) losing one will cause just the one axle to spin and the other to do nothing.
If you have a functioning "limited-slip" differential (optional on some trucks) losing one hub would not stop the other wheel from turning most of the time. With enough traction on the one good side, the clutches in the limited-slip would start to slip and both would then do nothing because most of the torque would be transferring to the spinning axle with the busted locking mechanism. But in the snow, neither tire is likely to get too much traction.

There are true lockers (with gears, teeth, and other implements of destruction) that will still get power to at least one of the wheels even if the other is not functioning properly. But even though the word "lock" or "loc" or "lok" or some variation was often in the name, I don't remember any factory ever offering an actual locker in a factory axle. Other than maybe the "Gov-Lok" in GM axles that did have a little bit of lockage after enough slippage. But that's another story.
Nowadays though there are actual lockers in some vehicles.

So a "four-wheel drive" truck with open diffs is actually only a two-wheel drive truck in reality. To be truly four-wheel drive, you need some sort of limited-slip or locking differential in both ends.

Too much information? Hah! It's fun though, all this typing.
The short version? Yes, you could have just one Warn hub not working and you would have had the results in the snow that you experienced.

Paul

 

Resurrecting this thread as I was finally able to diagnose my 4x4 issue. I removed the front diff cover and to my surprise, nine of ten carrier bolts were in the bottom of the diff! No idea where number ten is. Five were mostly intact and the rest were in pieces. (see pics).

My hypothesis is that the intact ones backed out one at a time till finally the rest couldn't handle the torque and sheered off. I'm also assuming the remnants of each sheered off bolt is still in the bolt hole and will have to be drilled out.

I have a set of new bolts but I'd like to ask you guys to look at some pics of my damaged ring gear and see if it's absolutely necessary to replace said ring gear? I can't tell if the pinion is damaged or not.

This truck is used sparingly around my property and to run to town (20 miles) once in awhile.

I looked at R&Ps on JBG and would really like to spend less money on this truck.

Suggestions are appreciated. New R and/or P? New carrier? Just the bolts?

Thanks as always.


Both carrier and ring are damaged


No idea what happened to bolt #10

 

Well isn't that just all exciting and stuff! Not what I'd hoped you'd find under the cover, but not unheard of either.
I can't remember ever hearing it happening to a factory assembled piece, but many rebuilds (especially in the rear) lose their bolts for some reason. The "assumption" is a careless installer. But it seems more common than that would indicate.
But I suppose if a truck is used hard enough, just about anything can happen.

To your question of what to do, I'd say more parts are needed than just the gears. While you might get away with it, and depending on how you use it in 4wd, might get away for a long time, I think there is too much potentially unseen damage to just go with the minimum.
The differential carrier assembly is obviously damages heavily on it's ring gear flange. This could just be cosmetic, but it could easily have compromised the housing and started cracks. When that thing rolled over a bolt or three, that was a crap-ton of force!
Way too many crack in a circle around the ring gear bolts, but in an open diff I don't thing they have the same stresses during normal use. But in this case, it's had plenty of stress from other sources.

Nope, I'd do a "while I'm here" thing again and replace all the usual suspects. New parts all around. Including a new carrier.
A new open carrier is pretty cheap, and a limited slip probably starts at just under $300 or so and goes up to $800 lockers (that you end up spending $1500 on!). Or whatever an ARB costs these days.
But even for me, and even in a "while I'm here" scenario, if I don't need a limited-slip or locker, I'm not paying extra for one either. So at the very least, a new or used open carrier, new ring-n-pinion gears, new bearings and get 'er done.

In this case, if it's just a work truck, or around the ranch truck where you might use 4wd a lot, but not under a lot of stress, used parts would be perfectly fine.
Lots of people upgrade or change the gearing in their rigs and would love to get a few bucks for their old stuff before they throw it all away. Maybe someone has some in the classifieds right here on the forum?

Good luck.

Paul

 

Deleted...

 

How is $250 for a front axle assembly? It’s a closed knuckle from a ‘74 but the ratio is the same.

 

$250 for a bolt and goable one ? Sounds ok.

 

Yeah, but it'd be a shame to go backwards in time and make more work for yourself down the road.
A closed knuckle is not going to be able to use disc brakes, unless someone has come up with a work-around in the last few years?
And the maintenance of a closed knuckle when they start to leak out the ends (which they always do) is more involved than an open-knuckle too.

Might not be a bolt-n-go if you have to rebuild the outer ***** and seals. Assuming the pivot-ball surface is in good shape still.
Be very sure you need one then, before you go closed. It's a good price for a part someone is looking for to do a restoration of an older rig, as long as it's in great shape.
But otherwise it's a downgrade for you.

Paul

 

You can use the carrier and the ring and pinion from the $250.00 axle in yours or you can source them from any LP DANA 44 from a wreaking yard. The easy part about using the parts from the complete axle is you know it has the same gear ratio as the one in your truck. You would also get the bolts that need to be replaced as well as the bearing caps/bolts in case the ones in your axle are beat up from the metal shards getting into them. Replace the seals and bearings with new and you're on the road again. You can also probably sell the inner and outer axle shafts /hubs, etc... to someone who needs them for a closed knuckle axle.
Mark.