Vibration diagnosis- Took off rear DS, noise gone. Questions.

[Bryan062087]

A few days ago, my 62 suddenly developed a vibration/rumble strip noise at speeds above 50 mph.

The whole car does NOT shake, its just a deep vibration that is very loud- sounds like you are driving over a rumble strip constantly. Most of the noise goes away if I take my foot off the gas driving at freeway speeds, but comes back instantly if I start to accelerate again.

Today I changed the transfer case oil- was pretty low and filled mostly with ATF which I guess had seeped in from the tranny. Drained this out and put gear oil back in. Cleaned drain plug magnet which was coated with a layer of very fine material (dust like) then underneath that a thin layer of small metal shavings.

Got back on the interstate and vibration did not change.

Took the rear driveshaft off, and running it front wheel drive, the vibration disappeared.

The u-joints on the rear shaft seem very solid with no movement that I could tell. The transfer case rear output bearing has very small amount of play in all directions. The x-fer case front output bearing has some play in all directions, noticeably more than the rear.

Does taking the rear shaft off isolate the problem to one of the u joints on the rear shaft / the shaft itself OR could the transfer case still be the cause of the vibration?

Also, do I need to cover the wholes left where the read DS connected to the differential or t-case? Can water get in there? I am going to be backing a boat down a ramp tomorrow, and the rear differential will be likely submerged. With the DS off, will this be an issue??

 

[Elbert]

Have you considered the noise might be coming from the rear differiential?

 

[Bryan062087]

Yea, that was another of my guesses, but after I took the rear drive shaft and the noise stopped, I figured the the rear diff was ok. If it was/is the rear diff, wouldn't the noise/vibration still be there with the rear drive shaft off because the diff is still being turned by the tires?

Also, I drained and refilled the rear diff a week ago. NO metal shavings on the drain plug, only a small film of dust like stuff on the magnet. The oil was pretty dirty (greenish) but no metal in it. The rear diff does make a slight whine/groan noise that varies with RPM speed though. Filled the diff with 80w90 and level is full as of today.

Any thoughts about covering up the place where the DS connected to the rear diff and the transfer case to make sure water does not enter when on the boat ramp?

 

[ntsqd]

Grab the companion flange of the rear diff and see how much it moves.

 

[rover67]

Is there a lot of slop in the pinion bearing? Try and wobble it up and down.

If the transfer case and diff aren't leaking oil out of the pinion/output shaft seals no water should be getting in there... Taking the DS off wouldn't affect their seal.

 

[TBIFJ40]

sounds like the preload on the drive pinion is bad, or the pinion bearing might be bad. Like Ntsqd said, grab the drive flange and see what you feel. does it move up and down, how far does it spin before engagement, is the flange tight enough (or too tight) it wont make noise when the rear DS is disconnected because it isnt under load, forcing the pinion into the ring gear. If the pre-load has changed, the flange has backed off, etc, the pinion is too far into the ring gear and it may be too late. You could try changing out the u-joints if none of the above apply (just to be sure and eliminate that issue) also make sure that the u-joints are in "phase". if theyre not, it'll create a vibration, but not really a rumble.

 

[Bryan062087]

No slop/movement in rear diff pinion bearing as far as I can tell - companion flange on rear diff completely solid- no movement.

Thanks Marco.

grab the drive flange and see what you feel. does it move up and down, how far does it spin before engagement, is the flange tight enough (or too tight) it wont make noise when the rear DS is disconnected because it isnt under load, forcing the pinion into the ring gear. If the pre-load has changed, the flange has backed off, etc, the pinion is too far into the ring gear and it may be too late.

How would I check how far it spins before it is engaged? Jack up the rear wheels then turn the companion flange? When i had the rear end jacked up earlier today, I was spinning the tires by hand and could here a rhythmic noise. Every other second or so it would make a slight interference/rubbing type noise, and you could feel it when rotating tires. They would not rotate smoothly and constantly, almost like they caught on something slightly then freed themselves every half turn or so. But I am not sure about this, that was with the driveshaft on. But it sounded like it was coming from the rear diff/axle area rather than the transfer case area. I will re-check tomorrow, I did not pay much attention to it at the time.

So taking the rear drive shaft off doesn't really mark anything off the list bc neither the rear diff or transfer case (specifically rear output bearing) are underload and both of these could still be the culprit?

 

[fjman]

Not to hijack, but is driving around and pulling a boat in FWD a bit rough on the front axle...? Not sure, just a question that came to mind.

 

[TBIFJ40]

sounds like you have a bad bearing, a bad tooth on a gear, something like that. could also be the oil slinger flange, but Id guess its one of the previous. pull the cover and look inside. May also need to pull the axles, and the third. keep digging till you find it.

Ive driven my cruiser a ways on just the front drive shaft, but never pulled a boat with it!! As long as you dont have front ds vibrations, youre probably fine, cruisers are so damn tough. It is a lot of extra wear on the birfs and front tires tho. Be best to fix it.

 

[ntsqd]

How do the U-Joints feel? Move them around and see if there is any slop or tight spot(s).

 

[Rig of Mortis]

...Also, I drained and refilled the rear diff a week ago.

There is a possibility that your driveshaft was put on "out of phase", did you have it removed recently prior to the driveline vibration? If, when it was reinstalled, your rear driveshaft was accidentally turned even a quarter turn from how it was removed, then this is called "out of phase" and spins unbalanced.

Try the simple things first, keep your loot!

 

[Trapper50cal]

Could it be....

This may be stupid but....couldn't the rear DS need balancing? DS there...vibration...DS not there, no vibration. Did the DS take any big hits? Could be a bad u-joint too

 

[Bryan062087]

Drive shaft was not taken out recently- I've never had it out since I've owned it. No big hits either recently. Got it hung up on a big stump about a month ago off roading but had been driving it since then with out problems.

Only thing I can think of being unusual is the many times my truck has been used to back boats into the water in the past week or two. The ramp is not very steep at the end so I have to go pretty deep to launch it, rear axle/diff gets submerged a lot.. I've done this maybe 10-15 times in the past 2 weeks. I do have extended breathers though. Drained and refilled diff before all this, and checked diff fluid yesterday, still clean.

Don't really have the experience or knowledge to be trouble shooting the more complicated things i.e. taking the axles/3rd out etc. Not even sure what to look if I had the rear diff cover off. Just going by the POS haynes manaul.. But i will see what I can do, go after the easy stuff first.

 

[Cruiserdrew]

My money is on the rear diff. The symptoms are classic for a worn pinion bearing. Most FJ60s have lots of miles and indefferent maintanence, and the pinion bearing pays the price. Look for any slop-like at the t-case output or companion flange. You might also check to see if the flanges are perfectly parallel.

U-joints could do it as well, but Toyota u-joints don't go bad that often (In ten years and 4 Cruisers, I've never seen a bad u-joint in any truck)

 

[Bryan062087]

t-case rear output has a little slop and the front has more.. and found metal shavings on t-case drain plug

 

[Cruiserdrew]

t-case rear output has a little slop and the front has more.. and found metal shavings on t-case drain plug

There's your answer! Time for a rebuild.

 

[Bryan062087]

There's your answer! Time for a rebuild.

Really think this is the problem? How much is too much play in the rear output bearing? I have maybe 1/16 inch play

I know my t-case is due for a rebuild, but I was hoping to get some more miles out of it. Planned on replacing the fubard t-case and transmission with rebuilt transfer case and h55f sometime down the road. Wanted the t-case to last at least as long as the automatic trans... maybe like you say, its time is up and I should rebuild the case. If its the cause of the rumble/vibration im getting, I guess I have to. Also, it leaks from pretty much every gasket...If i could hold off not rebuilding it just yet, that would be great tho..

Any methods for narrowing it down to the rear output bearing without tearing the transfer case apart? Tape a garden hose somewhere and listen through it?

 

[lehiguy]

Check the nut on the front output. A friend had his come loose and the whole thing vibrated like crazy. Barring that, You need to get into the T-case which, frankly, isn't all that bad to do yourself. If you're feeling lucky, you can remove the rear output flange and the cover behind it and reset the bearing preload on the output shaft without doing the whole T-case, but that's a gamble.

 

[FinHJ60]

Rear axle submerged many times, but drive flange has no play. When have you greased rear U-joint last? I bet there is the problem. It get's submerget when the axle does.

 

[John Smith]

Rear axle submerged many times, but drive flange has no play. When have you greased rear U-joint last? I bet there is the problem. It get's submerget when the axle does.

X2 on the ujoint being shot due to constant dunking and no greasing.