Itinerant Air-Cooled

I have been annoyed by a repetitive whirr whirr noise from somewhere in the rear axle. My senses tell me it's the rear right hip area - but I'm not sure I trust those senses.

Salient points:

• A deep or low whirr whirr sound. Not loud, not resonating openly. You feel it in the seat of your pants as you drive.. I guess.

• Doesn't change with speed, direction, gear or whether clutch is engaged.

• No knocking or looseness when rocking rear wheels whilst on axle stands

• No roughness when rotating rear wheels

• Bearings greased in the last month

• CV Boots intact and not torn

• I have just removed right side Drive shaft. CV joints have good clean grease. I am currently cleaning and greasing them

Hope to finish CVs tonight / tomorrow but based on what I see this is not the cause.

Dang Tom, sorry to hear about the troubles. That car is too much fun to be laid up, so thanks in advance for the excellent bullet points. Have you safely put the rear of the car on jacks/stands and slowly engaged the clutch in third gear? Once there, get the rear wheels spinning and clutch into neutral as you cut the key power and let the wheels spin. A rear wheel bearing will manifest itself in a rumbling whirr, instead of a smooth whir.

Have you tried resting your hand on the shifter for a second or two at a time in each gear? Please don't ever do this during normal driving, but I've heard transaxles where a noise was placated by coercing the shift forks into temporary submission. It ended in a transaxle rebuild, but I know yours was done recently, so I'm not suspecting that as a necessary measure, but I would do it if the car was with me.

Glad you're not selling the car,
Robbie

Thanks Robbie. I will do that when I get this driveshaft back on. I'm also going to try putting the OG drums back on. These aren't really huge, journey stopping problems. I'm chasing down demons while I wait for parts to come back from Rimco for the bus engine!

This rumbly whirring really sound bugs me. It's not the sound imminent destruction.. just annoying. It bugs me and I can't enjoy driving when I hear it. Same with the steering, no-one else has pointed it out, you and Colin have driven it and it's no worse now than then!

Let me know when you're passing next and a you can take Herman for a spin - tell me I'm hearing things :)

tommu wrote: ↑

Thu Nov 30, 2017 12:11 am

Thanks Robbie. I will do that when I get this driveshaft back on. I'm also going to try putting the OG drums back on. These aren't really huge, journey stopping problems. I'm chasing down demons while I wait for parts to come back from Rimco for the bus engine!

This rumbly whirring really sound bugs me. It's not the sound imminent destruction.. just annoying. It bugs me and I can't enjoy driving when I hear it. Same with the steering, no-one else has pointed it out, you and Colin have driven it and it's no worse now than then!

Let me know when you're passing next and a you can take Herman for a spin - tell me I'm hearing things :)

Load up each side of the car with carefully applied swerves. Does the sound respond to loading up? Does it change based on acceleration/deceleration load?
Colin

Does not respond to swerves by getting louder. If anything it gets a little quieter.
The whirring sound seems to be around 2 to 2.5 revolutions per second at 20-30 mph. On acceleration it speeds up to at most 3.5 revolutions per second.

tommu wrote: ↑

Sun Dec 10, 2017 4:19 pm

Does not respond to swerves by getting louder. If anything it gets a little quieter.
The whirring sound seems to be around 2 to 2.5 revolutions per second at 20-30 mph. On acceleration it speeds up to at most 3.5 revolutions per second.

Tires.
Colin

Amskeptic wrote: ↑

Mon Dec 11, 2017 6:04 pm

tommu wrote: ↑

Sun Dec 10, 2017 4:19 pm

Does not respond to swerves by getting louder. If anything it gets a little quieter.
The whirring sound seems to be around 2 to 2.5 revolutions per second at 20-30 mph. On acceleration it speeds up to at most 3.5 revolutions per second.

Tires.
Colin

Oh. That would be nice. I'll move them around and report back.

tommu wrote: ↑

Mon Dec 11, 2017 6:51 pm

Amskeptic wrote: ↑

Mon Dec 11, 2017 6:04 pm

tommu wrote: ↑

Sun Dec 10, 2017 4:19 pm

Does not respond to swerves by getting louder. If anything it gets a little quieter.
The whirring sound seems to be around 2 to 2.5 revolutions per second at 20-30 mph. On acceleration it speeds up to at most 3.5 revolutions per second.

Tires.
Colin

Oh. That would be nice. I'll move them around and report back.

Remember to lose air for the new front positions and add air for the new rear positions. I hope this eradicates it.

Robbie popped over on Tuesday and help me diagnose this some more. We jacked up the left wheel, started the car, accelerated to 1250 rpm in second gear and left the wheel spinning while we shut down the engine. I could hear rumbling whir. It's the wheel bearings. And I should have listened to:

Dang Tom, sorry to hear about the troubles. That car is too much fun to be laid up, so thanks in advance for the excellent bullet points. Have you safely put the rear of the car on jacks/stands and slowly engaged the clutch in third gear?

tommu wrote: ↑

Thu Aug 16, 2018 12:44 pm

Robbie popped over on Tuesday and help me diagnose this some more. We jacked up the left wheel, started the car, accelerated to 1250 rpm in second gear and left the wheel spinning while we shut down the engine. I could hear rumbling whir. It's the wheel bearings. And I should have listened to:

Dang Tom, sorry to hear about the troubles. That car is too much fun to be laid up, so thanks in advance for the excellent bullet points. Have you safely put the rear of the car on jacks/stands and slowly engaged the clutch in third gear?

tommu!
Did you have both rear wheels spinning simultaneously here? If only one wheel was up:
a) don't do that, it is hell on the differential spider gears
b) the noise associated with pissing-off of the spider gears is itself rather "bearing" sounding.
Colin

We had one wheel spinning at a time, like Tom said in second gear just above idle...

...according to the excellent write-up by that Itinerant-Air-Cooled fellow:
viewtopic.php?t=11737

The tires were not balanced well enough to go any faster, and the whirr we heard on the road was bad enough for me to call it a “grinding” sound with the engine off.

Tom, one thing I didn’t explain that I should have when discussing sprung vs. unsprung jack points, is that using the hub to jack up the unsprung mass keeps the CV joints level and stress-free, while jacking up the sprung chassis places the CVs at perilous angles.

Tom, turning the wheel by hand of the ground with your free hand resting on the wheel bearing housing might help confirm that the noise is not differential bearings. I’m not sure if you’ll be able to spin it fast enough though..

Robbie

asiab3 wrote: ↑

Fri Aug 17, 2018 8:00 am

We had one wheel spinning at a time, like Tom said in second gear just above idle...

...according to the excellent write-up by that Itinerant-Air-Cooled fellow:
viewtopic.php?t=11737

The tires were not balanced well enough to go any faster, and the whirr we heard on the road was bad enough for me to call it a “grinding” sound with the engine off.

Tom, one thing I didn’t explain that I should have when discussing sprung vs. unsprung jack points, is that using the hub to jack up the unsprung mass keeps the CV joints level and stress-free, while jacking up the sprung chassis places the CVs at perilous angles.

Tom, turning the wheel by hand of the ground with your free hand resting on the wheel bearing housing might help confirm that the noise is not differential bearings. I’m not sure if you’ll be able to spin it fast enough though..

Robbie

That IAC guy is an idiot. I have been working on these cars for over forty years.
Colin
(Tom, let me know if you can discern a difference in sound based on:
a) following the write-up
b) lifting the entire rear off the ground and letting the differential remain out of the equation
Your reply will determine if I edit that write-up.
Thanking you in advance and thanking Robbie for keeping me on my toes)

Whew, you’re ten years past being a loser...


(Colin’s notes to me in 2015 when I struggled with a cocky machinist who screwed up my engine case....)

I think the bearing noise would have been noticeable in first gear just off idle, if it matters.

Robbie

asiab3 wrote: ↑

Mon Aug 20, 2018 9:09 am

I think the bearing noise would have been noticeable in first gear just off idle, if it matters.
Robbie

I do third gear just to get it up to noticeable then coast-down. I am sure that there are plenty of different ways of arriving at the same conclusion, but now I am all "differential gears paranoid". Have you ever heard a sloppy differential gear set (not ring and pinion but spider gears)?
Colin

What would the differential diagnosis be to narrow down spider vs. ring and pinion noise? (Puns might freely abound as our OP is out of country for the week...)