scary experience!!

aliensecretion · May 29, 2011

So was heading down the road just now and hit a pot hole. All of the sudden I hear a loud noise from the back end and the truck starts shaking very violently! I was able to get slowed down and pulled into the median to check it out and It seems the driver's side rear wheel moves if you push back and forth at the top of the tire. After I checked for any thing else I tried to get it into a parking lot... it had stopped shaking so I checked it out some more and decided to try to drive it back the 3 miles or so to the house. Made it back without incident but I'm completely afraid to drive it now!

I'm not to knowledgeable about axles and stuff yet so any ideas what to check would really help!

nvrstuk · May 29, 2011

scary

Jack the axle off the ground so you can see "feel" what's going on. My guess is you've got a axle brg issue. You didn't notice it before because hitting the big bump took the load off the wheel and brg and then it started to shake. Kinda like what happens with the "death shake" up front...drives fine till you hit the bump THEN you get the death shake.

FIX it right away. If the brg fails, the axle/tire/wheel combo will walk right out of the axle OR the axle will break off and the odds are you will roll your Bronco.

We bought about 4 rolled Broncos back in the '80s...all from a brg wearing out!
All but one rolled!!!

Good luck, don't drive it

73stallion · May 29, 2011

check and see if the center pin on the leaf spring sheared, the entire axle could be moving on the spring.

DirtDonk · May 29, 2011

All of the above and then some. Look for anything else too. And even if it is not the bearings, if you don't know their history and don't know how many miles are on them, it might be time to replace both of them anyway. They have a very finite life, and I usually tell people to do it at 100k miles or so. All the failures I had happen to those I knew happened between 110k and 125k miles.
And that measly 10k miles comes up real quick once you get to 100k and decide to "just put it off for a little bit longer" and go on driving it.
When I did replace mine, they hadn't failed, but were completely worn out to a point they fully warranted replacement, at 100k.

"Your mileage may vary" of course. But don't put it off.

Paul

nvrstuk · May 29, 2011

scary

Here's another thought that probably isn't your case but might help others.

The early year housings- anything pre-late model '76 and all of '77 were very prone to bending. I had brgs wear out at the rate of 2-3 per year on both sides until I upgraded and bought a '77 axle housing. They are much stronger and much less prone to bending.

I've got a few stories about axles walking out of the tubes... one happened on Engineers Pass in CO... one at Gunnison CO...

Like Paul said, check everything...

aliensecretion · May 29, 2011

Well nothing on the back end looks out of the ordinary. No movement in the wheels/axles and leafs look ok. Going to jack the front up even though I'm pretty sure the noise came from the back end. I'm going to not drive it until I can replace the bearings since I have no idea how old they are.

aliensecretion · May 29, 2011

I'm going to replace the u-bolts just to be sure since it was the only thing I didn't put on new when I changed the springs and I'm going to price out the bearings. How difficult a job is that?

allenfahey · May 29, 2011

Assuming you have a 9".... Pretty straight forward. http://www.classicbroncos.com/rear_axle_removal.shtml
Then take the axle to a shop that has a press to press the old bearings off and the new ones on. Any garage or body shop will have a press.

Trapperbob10 · May 29, 2011

X2 on replacing bearings before failure, If the bearing fails at speed, there is not much keeping the axel from walking out of the housing.

Also, same goes for making sure housing is not bent. Would go thru a passenger side rear bearing every 1500 miles till I replaced rear housing.

Trap

croft75 · May 29, 2011

do you have a lift? I had something similar happen and I think it was the driveshaft overextending and going out of whack , I pulled over and it was the only thing that didn't look correct . I drove home slow as well expecting something to fall apart but nothing and it drives fine now but i am getting an extended driveshaft made>

aliensecretion · May 29, 2011

allenfahey said:
Assuming you have a 9".... Pretty straight forward. http://www.classicbroncos.com/rear_axle_removal.shtml
Then take the axle to a shop that has a press to press the old bearings off and the new ones on. Any garage or body shop will have a press.

That link was exactly what I was looking for... Pictures! Ok so this isn't one of those things that has to go back in aligned the specific way it came out? Sorry for the simple questions, my shop manuals are still packed and the cable guy hasn't come to turn on the Internet yet. iPhone is a life saver today!

So as far as the drive shaft... The one I have is new for no lift. Now when I changed the rear leafs (for better shape stockers) the back end lifted about three inches. I just figured because the originals were so worn out and since I haven't had any problems over the 6 months or so since then that it wasnt the issue. I could always be wrong.

DirtDonk · May 30, 2011

aliensecretion said:
I'm going to replace the u-bolts just to be sure since it was the only thing I didn't put on new when I changed the springs and I'm going to price out the bearings. How difficult a job is that?

At least yours didn't break when you put the new springs in. Lots of the original u-bolts are so rusted up that they actually snap when you put a wrench on them to loosen the nuts.
Maybe yours aren't original? Possible after all this time.

If the current ones are tight, then that's likely not any kind of issue, but nothing wrong with putting new ones on. You should be able to replace one pair at a time without too much fuss.
You don't need to jack anything up, but it doesn't hurt to use a pair of jackstands to at least stabilize the rig in case someone (like you!) bumps it while you're working on it.

Just remove the four nuts, let the bolts fall out, slide the new ones on up and into the retainer plate, and run the new nuts down.
Proper torque is important, and re-torquing them after a few hundred miles is just as important sometimes.
And doing one side at a time can let you take a quick look at the other side in case you can't remember which way the plate faces. I've seen them put on sideways before.

Good luck. Let us know what you find with the axles and bearings.

Paul

aliensecretion · Jun 3, 2011

Got to work on it today... the bearings look ok. The right one is practically new and the left is a little worn (worth replacing) but nothing too bad. I replaced the ubolts on the leafs with WH's heavy duty kit so if that was the problem, those things shouldn't be going anywhere now.

Anyhow, here's the question. Bronco is still on jacks since i have to take the left axle over tomorrow to get the bearing pressed on. But i finished putting the right side back together and with it still in the air and the trans in park, the wheel still turns but not the drive shaft... that's not right is it? With it in neut or drive the wheel turns with the drive shaft. I know i'm tired but that seems wrong.

Viperwolf1 · Jun 3, 2011

aliensecretion said:
Anyhow, here's the question. Bronco is still on jacks since i have to take the left axle over tomorrow to get the bearing pressed on. But i finished putting the right side back together and with it still in the air and the trans in park, the wheel still turns but not the drive shaft... that's not right is it? With it in neut or drive the wheel turns with the drive shaft. I know i'm tired but that seems wrong.

It's normal if the axles were spinning in opposite directions. If only one was spinning and the driveshaft wasn't I'd look for a broken axle or differential.

broncnaz · Jun 3, 2011

Also keep in miond that you need to retorque the ubolts after 100 or so miles. I've yet to find ones(either replaced or reused) that were still at correct torques after that first 100 miles.

aliensecretion · Jun 4, 2011

Ok, makes more sense after a good nights sleep!
One more question while I'm doing this... I can't find in the shop manual what kind of oil to use in the diff. All I can find is 5 pints. Is it the same as what you use for the t-case?

DirtDonk · Jun 4, 2011

aliensecretion said:
...what kind of oil to use in the diff... Is it the same as what you use for the t-case?

It can be for some of us, but it's not what's specified.
Factory called-for T-case lube is 50wt "non-detergent" (Racing) motor oil.
Diffs are typically a 90wt gear lube.
Both vary slightly by temperature/use conditions.

However, with modern lubes and a wide range of uses, quite a few of us here are running a modern 75w/90 gear lube in all of our boxes. T-case, front and rear diffs, manual trannies, AND, in some cases, the old manual steering gear box.
Sure makes it simple to replace the lubricants at the specified intervals.

And since it's not done that often, quite a few of those that do (myself included) use a full synthetic gear lube. With all of it's advantages, the disadvantage of cost is lessened.
The main reason I chose synthetic though, aside from the performance gains on paper, was that the one I chose (Redline) didn't have any additives that attack soft metals, like bronze and brass. Which is the reason the factory specified non-detergent oil for the t-case in the first place.

Paul

Action · Jun 4, 2011

Front

It may of just sounded like the rear? I would also check the front as that is what causes these types of symptoms. Track bar and such!
Jack

Revelation · Jun 4, 2011

def. check the front, sounds more like "death Wobble" than an issue with the rear. Bronco's are notorious for having a noise that sounds like it is on one end but is on the other.
The noise you heard may have been something else shaking around from the front shaking. Could you feel the shake in the steering wheel?

DirtDonk · Jun 4, 2011

Speaking of Death Wobble, even though it's not usually an recurring issue on the rear, your pothole experience could have damaged a tire and, and, at the same time, induced a wobble that would shake the truck. But since it's on the rear, it would not be as likely to come back once you slowed down and it stopped shaking.

Still sounds like you needed to replace the bearings of course, but the main wobble might have been the tire, in conjunction with the loose bearing allowing for some extra movement.

On the front though, that tire would probably cause a wobble every time you hit a slight bump just right. Especially if you have any loose components up front too, like a worn trackbar bushing or loose bearing.
With luck though, it won't happen again on the rear.
That's if it was indeed a DW. But it sure has the symptoms of one, like Revelation said.

Paul

scary experience!!

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