Syncronauts: Rhythmic noise from front diff area.. [UPDATE]

[Mathew Zelezen]

I could use a little help.

I started to hear this faint rhythmic rubbing noise about 2 months ago when driving down the road. You know the drill.. you ask your girlfriend/wife if she hears that noise and she looks at you as if to say "Poor guy, he's finally starting to finally lose it.."
2 months later its a prominent rhythmic low growl that matches the speed of the tire rotation.

Here are the tests I performed so far:
1.Wheel Bearings- No play at all in front or rear tires at 12 and 6 or at 3 and 9.
2.Had the tires rotated and balanced. -No change in sound or location.
3. Pulled the drain from the diff. - Fluid is clear and magnet is completely bare of metal shavings.
4. Checked tightness of all front cv axle bolts and each axle nut.
5. Jacked up front end and rotated tires by hand. Diff rotates smoothly.

What am I missing here???
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87 Syncro Tintop
~Rocky J Motor
~Steedle Trans


Of all sad words of tongue or pen, the saddest are these: It might have been.

[MarkWard]

Syncro front wheel bearings can start making a growling noise long before you will feel play. If you don’t know the age or miles, might be time to replace them. Not a simple DIY job. What you want to avoid is damaging the wheel hubs running on worn bearings.
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[hardway]

When I am checking for rough wheel bearings I do it a few different ways. When driving turn to the left and right. They noise may change pitch as different bearing races are loaded. If you have the vehicle lifted, you can run it in gear and listen to things with a stethoscope. But the easiest and most conclusive way is to lift at least the front axle in your case. Place one or two fingers lightly on the suspension coil spring at the corner that you are checking. Rotate the wheel by hand. The spring picks up the vibration and vibrates in resonance. If the races are pitting, you will feel the spring vibrate.

[Sodo]

When I heard “that sound” it was the 32mm CV axle nut had loosened.
And by then I had destroyed an axle hub.

Recommend getting a 32mm socket and a breaker bar and check the tightness of the CV axle nut.
The spec is 258 ft-lbs

If you weigh 200 lbs, standing on a breaker bar
at 16 inches is 258 ft-lbs.

Syncro front wheel bearings run 250,000 miles, easily.
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'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb

[Mathew Zelezen]

Thanks for the replies gentlemen.

Mark, the wheel bearings were all replaced 7 months ago in December which is why I wasn't really focusing on them as the culprit.
But parts aren't what they used to be and I did put some miles on them when I drove across the country from Maine. Surely not 250,000 but the symptoms do seem to point towards bearings.
I bought all the bearings and grease from a reputable shop in Fort Collins.. is there a brand you would suggest?

Sodo, I checked the cv axle nuts today and they weren't loose when I put my weight on the breaker bar..

hardway, I'll check the springs for resonance and report back.

Thanks again for the help!
_________________
87 Syncro Tintop
~Rocky J Motor
~Steedle Trans


Of all sad words of tongue or pen, the saddest are these: It might have been.

[Mathew Zelezen]

Here's the latest on what I found when I pulled the front hub off of the Syncro

And yeah thats the inner race stuck on the hub..

I think I need a new hub but when I search I'm having a hard time tracking one down. Anyone have a lead on where I can order one?
_________________
87 Syncro Tintop
~Rocky J Motor
~Steedle Trans


Of all sad words of tongue or pen, the saddest are these: It might have been.