[Healeys] Mystery noise

Michael Salter michaelsalter at gmail.com
Thu Aug 20 13:05:23 MDT 2020


Hi Roger, you say "Disconnecting prop shaft to isolate diff not possible as
need the inertia of the rear wheels to produce the pulsing."
I think that is unlikely and would look into that more closely.
If you can get access to a "Chassis Ear" that would probably help a lot.

M


On Thu., Aug. 20, 2020, 1:28 p.m. Roger Grace via Healeys, <
healeys at autox.team.net> wrote:

> 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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