[Healeys] Mystery noise - Update

[Bob Spidell]

I can't offer any suggestions, or even a good guess, but I think you're 
going to have to pull your OD to find out what's causing the noise 
(after you've eliminated all other possibilities, of course). When I 
rebuilt my gearbox about 3 years ago I decided to go through the OD 
since it had over 205K miles on it. I found this (see photo; note the 
deformed thrust washer and the fretting on the inside of the annulus). 
But the OD operated perfectly and was no louder than normal (it's 
possible I didn't notice an increase in noise over the 135K miles I 
drove the car, on top of all the other Healey noises). Now, the rebuilt 
OD has a slight 'beat frequency' when engaged that you can feel through 
the floor pans; I suspect I didn't get the sun/planetary/annulus depth 
setting exactly perfect, but it's operated fine for over 6K miles and 
hasn't gotten worse so I can live with it. I'd consider going through it 
again, but with limited opportunities to take long drives in the near 
future it's down the list of priorities.

FWIW, I think a failed bearing would make a continuous, gruesome noise, 
though I did have a water pump fail on my dad's '55 T-Bird before I sold 
it. Sounded for all the world like rod knock.

Bob


On 8/22/2020 7:54 PM, David Porter wrote:
>
> Well, then it is rotational for sure, not a bearing that is failing 
> but perhaps already failed, perhaps allowing the O/D annulus to scrape 
> the surrounding housing...though it did not sound like steel on 
> aluminum to me. You have moved the noise from rear to midway.. perhaps 
> if you haven't, check for a failed motor mount and the crank pulley 
> scraping the cross member??  DP
>
>
>
> On August 22, 2020, at 6:46 PM, Roger Grace via Healeys 
> <healeys at autox.team.net> wrote:
>
>
> Not a lot of progress...
>
> Brake cable is well clear of propshaft and securely clipped.
>
> Universal U joint/spline phasing is correct.
>
> Been doing lots of listening with stethoscope.
> With propshaft disconnected, am able hear noise in 2nd or 4th when 
> slipping clutch (reduces speed)
> Assume is the same noise and less distinct because of the engine noise.
> Not nearly as distinct as when shaft is connected and rear wheels 
> freewheeling in neutral and engine off.
> Loudest area seems to be rear GB casing near rear bearing.
> This still does not sound like a bearing to my ears ?
>
> Plan to try to get a 2nd expert opinion with younger ears !
>
> rg
>
> ----- Original Message -----
> From: David Nock <healeydoc at gmail.com <mailto:healeydoc at gmail.com>>
> To: Roger Grace <roggrace at telus.net <mailto:roggrace at telus.net>>, 
> 'healeylist' <healeys at autox.team.net <mailto:healeys at autox.team.net>>
> Sent: Thu, 20 Aug 2020 12:47:51 -0600 (MDT)
> Subject: Re: [Healeys] Mystery noise
>
> Drive shaft hitting the handbrake cable when the car is jacked up. 
> Probably
> will go away when sitting on the ground.
> David
> Nock
> healeydoc at sbcglobal.net <mailto:healeydoc at sbcglobal.net>
> 209 948
> 8767
> www.britishcarspecialists.com <http://www.britishcarspecialists.com>
>
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> *From:*Roger Grace via Healeys
> *Sent:* Thursday, August 20, 2020 10:27 AM
> *To:*'healeylist'
> *Subject:* [Healeys] Mystery noise
> AH people - fighting a noise in my BJ8 that may or may not be
> serious.
> Reluctant to tear out the tranny unnecessarily and then to find it was
> something simple !
> Notice it at low speed (probably exists at driving speed but too much 
> wind
> and engine
> noise) if shift to neutral and cut ignition to minimize engine
> and exhaust noise.
> Noise is pulsating - like a tire with a bad spot but seems to be at
>
> prop shaft speed.
> At first thought that it was at wheel speed and from R side.
> So changed out the R wheel bearing.
> No improvement
> Then while looking below noted that universals had some play.
> So changed out both universals.
> Rear brakes not dragging and no binding of wheels.
> No improvement.
> Did listening on hoist with others listening too. Consensus was that 
> there
> was a noise at rear OD area as well as the pulsating one.
> So pulled annulus in situ and replaced both rear bearings. Quieter but
> still the pulsating noise while coasting in N.
> Sound file enclosed is a road test from about 15 MPH then shift to N and
> cut engine. Tunnel cover off.
> Able to replicate noise with engine on axle stands but not by turning a
> rear wheel by hand or with an e motor.
> Noise does appear to come from transmission.
> To verify is not diff removed one of the rear seats and noise doesn't
> appear to be coming from diff area.
> Disconnecting prop shaft to isolate diff not possible as need the inertia
> of the rear wheels to produce the pulsing.
> About 5k miles ago I changed out the larger OD front bearing (sourced 
> from
>
> Moss ... ?) in the OD.
> OD works fine and transmission shifts and works OK without unusual
>
> noises.
> The pulsating/cyclical nature of the noise baffles me and not consistent
>
> with a bearing failure ?
> Given that it occurs in neutral with no gears meshing it surely is not a
> bad gear tooth etc.
> OD not engaged so it is locked so not likely there.
> Removed gearbox top cover and did inspection - nothing obvious.
> So to my mind this only leaves the GB rear bearing ?
> Or maybe a broken circlip or thrust washer and probably on main shaft
> external to gearbox ?
> or half shaft ?
> Any comments/thoughts appreciated from the more experienced
> among us.
> Tkx
> rg
> ------------------------------------------------------------------------
>

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