'72 Bus - Transmission - Grinding Sound

[Sluggo]

I get a grinding sound coming from my transmission while driving. I really cant figure out what it is. Colin's guess when he was here was the throwout bearing. When I pulled the engine I checked it and replaced it. It's not as loud as before. But still pretty loud.

Any suggestions?

[vdubyah73]

Grinding or bearing growl? Mine has quite a bit of internal bearing noise. Not positive which one but if I try to pull it into gear, while rolling, without the clutch or grinding the growl speeds up or slows down to match the the speed that gear would need the engine rpm at. That tells me it's probably the input shaft bearing. This is hard on syncros but you only need to do it a couple of times to check it. I'm gonna tackle the problem this winter. Along with an engine rebuild. and finishing the Westfakia conversion.

Bill

[kool aid]

Mine did this once. I drained and refilled the oil in the transmission and it went away. Might work for you?

[Sluggo]

Mine did this once. I drained and refilled the oil in the transmission and it went away. Might work for you?

I did that before I ever pulled the engine & replaced the throw out. Everything was pretty much the same.

[Amskeptic]

Some of the early 002 transaxles were noisy mostly in 1st and 2nd gear. They changed the gear teeth numbers and they started adding ribs to prevent torsional loads from wearing out the bearings and changing the gear mesh contact.
You need to localize when this sound occurs.
At rest no clutch pedal?
At rest clutch pedal down?
Under load? When coasting?
Follows engine rpm? Follows vehicle speed?
Colin

[Sluggo]

Some of the early 002 transaxles were noisy mostly in 1st and 2nd gear. They changed the gear teeth numbers and they started adding ribs to prevent torsional loads from wearing out the bearings and changing the gear mesh contact.
You need to localize when this sound occurs.
At rest no clutch pedal?
At rest clutch pedal down?
Under load? When coasting?
Follows engine rpm? Follows vehicle speed?
Colin

I put a little more slack in the clutch cable and now I only get the sound while pressing the clutch. Brand new Sachs throw out bearing.

[DurocShark]

Could the pressure plate cause uneven pressure on the throw out bearing?

[Amskeptic]

Some of the early 002 transaxles were noisy mostly in 1st and 2nd gear. They changed the gear teeth numbers and they started adding ribs to prevent torsional loads from wearing out the bearings and changing the gear mesh contact.
You need to localize when this sound occurs.
At rest no clutch pedal?
At rest clutch pedal down?
Under load? When coasting?
Follows engine rpm? Follows vehicle speed?
Colin

I put a little more slack in the clutch cable and now I only get the sound while pressing the clutch. Brand new Sachs throw out bearing.

Either a lousy brand new Sachs release bearing, or possibly damaged pressure plate fingers as per DurocShark. Was there a slight WHOOOAAAAA HOLD ON TO THAT THING! WHERE ARE YOU? GEEZE when mating it?
Colin

[Sluggo]

Either a lousy brand new Sachs release bearing, or possibly damaged pressure plate fingers as per DurocShark. Was there a slight WHOOOAAAAA HOLD ON TO THAT THING! WHERE ARE YOU? GEEZE when mating it?
Colin

I'd lean more towards the Pressure Plate fingers. The Throw Out Bearing I took out was really rough and you could hear it grind when spun by hand. The new one seemed nice & smooth. We re-use the old Pressure Plate & Disc becuase they seemed to be in really good shape.

I guess we'll add this to the list for your visit. Maybe not repair but at least diagnosis.

[DjEep]

Not to hijack, well yeah, to hijack...
bought a '71 yesterday and there is a slight high pitched grind when I push in the clutch. It only happens when rolling, not when putting it into first from a stop. My guess is pilot bearing, because when you push in the clutch to say, shift from 1st to 2nd, and let off the gas, the fast spinning input shaft spins in the bearing of the now-slowly spinning engine. Is this a correct assumption/understanding of processes involved?

[Amskeptic]

Not to hijack, well yeah, to hijack...

Best test of pilot bearing is to put foot on clutch, stick into first gear, KEEP foot on clutch and rev engine with FOOT ON CLUTCH. Stationary input shaft in rapidly rotating bearing.
Next test, foot on clutch at speed, select a gear like 2nd at 20 mph and kill engine, now you have rapidly spinning input shaft and stationary engine, plus you can hear a bad bearing in the relative quiet.
Let us know.
Colin

[Sluggo]

Did a little more testing on this today. For some reason there was less traffic around. Sound is constant and depends on speed. Definitely gets louder when you engage the clutch. No grinding at idle even with clutch pressed in.

[Sluggo]

The more I drive it, the more I analyze this noise. I think it may be two different unrelated noises. I get the grinding sound constantly while moving any faster than 10 mph. I get a seperate grinding sound when I engage the clutch at speed. I think maybe the cobstant sound could be the brakes. New drums, shoes & hardware on the back. Checked the front & they seemed okay.

[vdubyah73]

If its a brake noise it should change when you apply the brakes. Worn disc pads and sticky caliper get louder when applying brakes. Lots of squeaky type noises stop when brakes are applied.

Bill

[Sluggo]

I've determined that the sound is coming from the right side. Had the wife in the Bus yesterday and had her hang her head out the window. She said it's coming from the rear. So Right Rear is the sound location. It only occurs over 15 mph. It doesn't get louder with brakes applied. The only time I hear the clutch is when I press it while moving over 15 mph. these are two seperate sounds I think. Or it's all the same sound and just gets louder when you press the clutch. This will be fun to track down.