(not) good vibrations in the syncro.

r.e.wing_fc3s

my syncro (88 with stock 2.1 drivetrain) has a strange vibration/resonance between 45-50 mph. Ive already removed the drive shaft which made no difference. The noise is road speed dependent. it is unaffected by engine speed, clutch or gear selection. Its pretty loud almost as if the whole van is vibrating. its perfectly smooth above and below that speed range. its not an unbalanced tire either. wheel bearings feel sound smooth with acceptable play. im wondering if there is a resonance in the gearbox/engine that is amplified because the fuel tank straps have rusted away and the tank seems to be partially resting on the trans?

I really want to go play with it but i also most definitely dont want to risk screwing up the transmission which is deep down what im afraid the noise vibration is. Im going to try running it on the lift to see if the noise happens when the front wheels arent turning to try and eliminate the front diff. Anyone have any similar problems/experience to relate?
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Reference Automotive: NW Washingtons Vanagon Specialist. (360)366-6965. referenceautomotive.com

morymob · Posted: Sat May 04, 2013 3:08 am Post subject:

I had a similiar vibe on my 2-wheeler,was a very worn axles cv joints but it didn/t cllick.

insyncro · Posted: Sat May 04, 2013 6:53 am Post subject:

Motor mounts
Wheel bearings
CVs and hardware all should be checked.

Balance wheels and tires
Have a professional driveline shop balance the driveshaft after verifing that the UVs are still good.

r.e.wing_fc3s · Posted: Sat May 04, 2013 8:08 am Post subject:

thanks ill check the mounts etc. open to further suggestions.
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Reference Automotive: NW Washingtons Vanagon Specialist. (360)366-6965. referenceautomotive.com

Farf · Posted: Sat May 04, 2013 4:37 pm Post subject:

X2 on motor mounts, check the clearance of the skid plate to the bottom of the engine and take a look at your exhaust piping in the same area. Goog luck.

Mike

Farf · Posted: Sat May 04, 2013 4:39 pm Post subject:

X2 on motor mounts, check the clearance of the skid plate to the bottom of the engine and take a look at your exhaust piping in the same area. Goog luck.

Mike

IdahoDoug · Posted: Sat May 04, 2013 11:16 pm Post subject:

Bummer with running it on a lift is that the suspension is then distended and the CVs are not in their "road" position while running so things won't be the same. If you put all four suspension members on jackstands instead, you might be more likely to discover a noise. However, either way you'll discover the Syncro system won't power all 4 wheels at equal speeds as they'd rotate on the road. I've done this and it's extremely dangerous. If you do it, a simple mechanic's stethescope touching each component in turn will immediately zero in on the suspect component.

Can you wedge a piece of soft foam rubber above the trans to isolate the possibly sagging fuel tank onto the trans. That would definitely transmit road speed vibes effectively as it's a hollow drum like a speaker.

DougM
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1987 2WD Wolfsburg Vanagon Weekender "Mango", two fully locked 80 Series LandCruisers. 2017 Subaru Outback boxer. 1990 Audi 90 Quattro 20V with rear locking differential, 1990 burgundy parts Vanagon. 1984 Porsche 944, 1988 Toyota Supra 5 speed targa, 2002 BMW 325iX, 1982 Toyota Sunrader


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