From: Daryl Reece [dsr14@Cornell.edu]
Sent: Monday, July 29, 2002 9:21 PM
To: 928
Subject: [928] Re: Speedometer sticks until I hit 40 mph

> -----Original Message-----
> From: Constantine [mailto:dicongo@earthlink.net]
> Sent: 29 July 2002 11:47
> To: 928
> Subject: [928] Re: Speedometer sticks until I hit 40 mph
>
>
> Hi Carlos,
>
> The "Fonzie" manuever might be fun to do but can also jar something else
> and/or cause a fire in the pod.  There have been instances of people
> messing with their dimmer wheel under the pod and starting a fire due to
> old brittle wiring sparking.  I had my instrument cluster tested and my
> odometer fixed by a concern in Cali for about $120.00.  Chump change when
> compared to car fire damage repair bills.
>
> Best to you,
> Constantine
>
> > My 86.5 does the same thing.  The other day, my mechanic was
> test driving
> > it,  me as passenger.  Demonstrated a temporary fix: whack the
> pod on the
> > right side.  Wakes the needle up every time!
> >
> > He said the gauge is just showing its age and could be rebuilt, if I
> > wanted to bother. Personally, I like the "Fonzie" manuever!
> >
> > Carlos Hernandez
> > 86.5 928 S 5-Speed, 170K Miles
> > Gran Prix White / Black Leather
>
>-----Original Message-----
>From: Jon Holdsworth [mailto:jon.holdsworth1@virgin.net]
>Sent: Monday, July 29, 2002 4:30 PM
>To: 928
>Subject: [928] Re: Speedometer sticks until I hit 40 mph
>
>
>My 88 SE does that too sometimes. I always put it down to the sensor in the
>transmission dying. (Like the ABS sensors that I think have died causing ABS
>warnings)
>
>Cant see that failed sensors would be cured by hitting the dash though.
>Strangely my other car (GM) has the same speedo problem but its a mechanical
>speedo with a cable. Sounds like it is the mechanicals in the instrument
>pod. On air reasoning !
>
>Jon
>Black SE
>
>
I just tore the speedo apart to fix the odometer so I had a decent look at
what's inside mine.  I think this sticking behavior has to be lack of
lubrication in the speedometer's needle bearing.  There is a coil behind the
speedometer that generates a magnetic field, which in turn generates a
torque proportional to the current traveling through the gauge coil.  When
you get to 40, there must be enough torque to overcome the friction in the
bearing and pop off the bottom.  I oiled my bearings with some light weight
oil (3 in 1 or sewing machine oil are adequate).  The speedo bearing
lubrication would dry out over 20 years, just like any other lubricated
bearing.  This stickiness would be jarred loose by the whack on the side.