Odd transmission noise

[hop2itinaz]

Greetings All

I have a unique noise happening with my transmission on my 86 Westfalia. Subie 2.2 motor. Installed a Steedle rebuilt trans about 30k ago. A very comprehensive build (oiler plates, new gear carrier and well…pretty much new everything else).

Lately I am hearing a buzzing sound while coasting…in gear….clutch pressed. It sounds like a faint whirring noise as I decelerate that stops once stopped. If I am in say second gear it is clearly more pronounced than if I am in say third so it is definitely in gear train. If in NEUTRAL no noise. If I am standing still at idle I hear nothing with clutch pressed or not. Shifts fine. No howls or whines at highways speed and in fact quite smooth.

This is a new one to me. A fellow Vanagon group member has allowed me use of a good used trans while I get this one dialed in but wondering if anyone may have experience with this type of symptom.

Thanks!

Michael

[MarkWard]

I’d reach out to Matt. Maybe record the sound. There used to be a German member that was very hands on with these transaxles. His experience was to go through them every 60,000 miles.

[hop2itinaz]

[Sodo]

What does the drain magnet look like? Pics?
Sometimes a 1st/2nd hub cracks, but seldom, thus often re-used.
You are 10 easy bolts from looking at the R&P.
_________________


'90 Westy EJ25, NEW oil rings (!) 2Peloquins, 3knobs, SyncroShop pressure-oiled pinion-bearing & GT mainshaft, filtered, cooled gearbox.
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered original gearbox
....KTMs, GasGas, SPOT mtb

[?Waldo?]

What about the pilot bearing? If I'm not mistaken, it seems like it might fit the described behavior. While coasting in gear the input shaft spins (at a different speed from the crank). Higher gears would have the input shaft spinning slower (less noise?). In neutral, the input shaft is not spun by the trans (no noise). No noise when stopped might not fit as the input shaft would be stopped, but the crank would not.

[Sodo]

[AndyBees]

Anytime the clutch is engaged, the Crankshaft and Pilot Shaft (input shaft) are rotating in unison. The pressure plate clamps the clutch disc to the flywheel which is bolted to the end of the crankshaft. So, coasting in gear or going down the highway underload in any gear, they rotate together (crankshaft is not spinning on the input shaft in those conditions). And, the same applies if the engine is idling in neutral if the clutch is not depressed. The only time that the crankshaft/pilot bearing spins on the input shaft is when the clutch is not engaged (clutch pedal pressed to the floor).

The pilot bearing keeps the splined input shaft and splined clutch disc centered between the flywheel surface and the pressure plate surface. The tolerance is close enough to maintain the balance of the components as a whole. That's the primary purpose of the pilot bearing. A bad or missing pilot bearing would likely be noticed while pressing the clutch pedal with the transmission in neutral (engine idling, of course). Other variables could come into play, such as a badly worn input shaft nose.

Tell me what I am missing.

OP, how fast is the Van going when in 2nd gear with the clutch depressed?
_________________
'84 Vanagon Tin-top, ALH TDI, two trips to Alaska, 2014 & 16. 1989 Tin-top unmolested.
1983 Air-cool, 225k miles, 180k miles mine, seven trips to Alaska from 1986 thru 2003. 1975 Bay hopeful.

[?Waldo?]

AndyBees, you are correct. Thanks for correcting my poor thinking.

[MarkWard]

Andy you saved me some typing. Thanks. Gears are actually sets or pairs. 2 gears per gear ratio. One gear is fixed the other “idler” freewheels on needle bearings. When decelerating in neutral, the pinion drives all 4 pairs. So no side loads are being forced.

Now when you decelerate in a gear, the gear selected is being driven and the others are “idling”. So, since 2nd gear is fixed to the main shaft, on deceleration, there is side loads being transferred by the pinion so to speak.

When the clutch pedal is depressed, it actually frees the input shaft from the engine. This could allow more thrust movement/noise. But you experience the opposite.

If it’s making noise decelerating, assume noise goes away accelerating? For now, I’d stop doing that. I’m am old man, brakes are cheaper than transmissions. Shift into neutral and use the brakes to slow the van vs engine compression. Be curious to see what is found. Hope you report back. In talking with Matt, he seems knowledgeable and experienced. While he’d likely not want a customer to have a problem, I’m sure he can resolve it.

Would be interesting to find a long hill. Remove the CV shafts and try your test again. I’m betting no noise.

[AndyBees]