How to repair a broken
After way too long of not having a working
odometer and not wanting to shell out around $200 bucks for someone else
to do a simple job, I finally got around to fixing my speedo/odomoter unit.
on a scale of 1 to 10. (Easier than an oil change on a 993.)
TIME to COMPETE:
COST: $25 + $4
USPS shipping (As of 6/2005)
RISK: Cost of
new or used speedo if you break this one.
can drive your car without speedo. No cruise control or speed controlled
wing. (I think.)
Small (jewelers) regular screwdriver, small phillips screwdriver, small
to medium regular screwdriver.
I drank 3... but was regulating a new keg... Old Dominion Ale. Very nice.
Your speedometer works, your odometer quit.
Chances are, your drive gear has given up. The popular story is that you
hit the trip meter reset while the car was in motion. While it is entirely
possible that that particular event was the event that caused the actual
failure, the root cause lies at the VDO factory. The tiny, little, 15 tooth
planetary gear that drives the odometer and trip meter from the speedo
sensor has turned into a soft jello like rubber over the years due to excessive
heat and a corrosive oil lubricant that has turned that essential gear
into mush. The separation of a couple teeth from that gear has been inevitable.
Your repair choices consist of sending
it to a reputable speedo shop and dump a couple hundred bucks into a rebuild
and be sans speedo for at least a week, or give it a run yourself. Replacing
the gear is NOT that difficult. No crazy tools are needed. No special skills
are needed. But it is risky. The most finnicky point of the rebuild is
dealing with removal and reinstall of the needle pointer onto its shaft.
The shaft of the needle is tiny... very tiny. Break that and you are looking
at replacing your speedo. These aren't cheap speedo's... the broken gear
This DIY procedure will NOT help you change the mileage on your odometer.
The main assembly holding the numerical wheels in place is not easily opened.
You will not be able to roll your odometer forward OR back. Trust me...
I tried. I wanted to add a bunch of miles to get back to reality, but there
is no easy way to get the numbers free wheeling. Furthermore, tampering
with the mileage on your odometer is illegal... or something like that.
Anyway, I did this on my first attempt
with relative ease and great success. Your results may vary. Don't attempt
at home... unless you are willing to accept the risk of ruining your gauge.
STEP 1: Odometer Removal.
Using a cloth covered screwdriver, gently
pry the speedometer out from your dashboard. The rubber ring around the
edge comes out too so get under that with the flat screwdriver and pry
out. Do NOT use the neighboring gauge as a leverage point. The black trim
ring is very easily scratched. Once you get it started you should be able
to get your hands on it and pull it out. Unplug the connector and head
to a clean work area.
STEP 2: Disassembly
TRIM RING: Remove the rubber grippy retainer
ring. Remove the 4 screws from the back of the unit.
Now the soft metal trim ring needs removed
by gently prying around the entire edge of the assembly to bend/lift the
edge over the lip of the outside housing. This isn't pretty, but go slow.
Be careful not to scratch the ring beyond the lip. You won't see what you
have done to it once the rubber retainer goes back on so don't worry about
chewing it up a little bit. Keep slowly prying around the edge until it
can be pulled out.
STEP 3: Trip meter reset button removal
There is a thick post over the thin post
of the reset button. Support the button assembly below and pull the top
off. This will take some pressure, but be sure to brace the assembly from
below so you don't pull too hard on the lever where it clips to the drive
Note where the shaft gets thinner... that
is where it separates.
STEP 4: Speedometer needle removal
This is the trickiest part of the job.
The needle is pressed onto a shaft that is extremely thin. It feels like
a pretty tough metal, but you HAVE to be careful here. Do not pull straight
up. Do not put any torque on the shaft. Rotate the speedometer needle clockwise
until it hits a stop point. Gently continue to rotate the needle whil lifting
up gently at the same time. The friction is all that is holding the needle
to the shaft. Keep turning and prying until the needle comes off. Do not
force it. I don't know that that shaft assembly is user replaceable.
See how small the shaft is:
STEP 5: Disassembly
You've come this far, there is nothing
stopping you now. Take the two screws out of the faceplate.
Remove the circuit board.
Remove the motor.
STEP 6: The guts
Once the motor comes out, you will get
to the drive gear and pod. Inside the pod is going to be your broken gear.
Replace it with your new gear.
See the broken gear - and its yellow decay
- compared to the new gear.
STEP 7: Reassembly
This is completely reverse of everything
else. Nothing is too tricky. Continue to take your time paying particular
attention to the needle shaft. When reinstalling the speedo needle, make
sure you rotate while gently pushing down. Never simply compress the needle
onto the shaft. Once it is in firm enough, use the stop points at max speed
and 0 mph/kph to realign the needle with 0. Once everything is back together,
also gently recompress the trim ring around the back of the speedo housing.
You could use a black permanent marker to cover any scratches. Plug the
unit back into the dash and reinsert into your gauge opening. Hopefully
all is now re-recording miles.
PARTS and BACKGROUND INFO:
The new gear cost me $25 as of this writing
in June, 2005. I found the gear at http://www.odometergears.com/. Jeff
Caplan at Odometer Gears is a top notch, class act. I called there looking
for help in isolating the part and he gave me spot on directions on how
to get into the speedo, what to watch out for, andPaul
United Kingdom. what to do once in there.
Once I got things figured out, he had a new part in the mail that same
day. You can call him at 757-593-3478 or email him at email@example.com.
My car is a '95 993 but I think all 964's, 968's and 993's will use the
same 15 pin gear found when you hit the "Porsche" link at their website
at http://www.odometergears.com/. Check with him first if you aren't sure.
Again, this is a VERY easy job. Not easy
like a tire change - but only because you are dealing with a delicate instrument.
If you have big, clumsy hands, you might want to forego this exercise and
send it to a pro. If you can be gentle with this, you should be ok.
Firstly let me thank you for suPaul
United Kingdom. ch a great
site. It’s a great contribution to 993 aficionado owners.
I have just successfully completed doing
the odometer DIY repair following your instructions and I have a couple
of contributions that I’d like to submit to you.
Firstly, I suggest that rather than assembling
the speedometer completely and reinstalling it in the car after replacing
the gears, do a partial assembly and connect it to their car to ensure
its working properly. I completed the repair, I put the speedometer back
together and when I installed it on the car, it didn’t work. I had to disassemble
it again right down to the gears and put it back together. The second time,
I didn’t install the needle or the trim ring/crystal and held it to the
case with only one screw. I connected it to the car and drove for 4 miles
to ensure it worked and then completed the assembly. This is a tedious
job and it sucks finding out that it doesn’t work after you’ve put the
whole thing back together.
Secondly, my trim ring got somewhat lopsided
during the prying stage. Not too much but I am a bit of a perfectionist
and the speedo is something you look at constantly. I corrected 90% of
the problem by gently rotating the outer edge of the trim ring against
a hard surface while applying pressure. I did this after the trim ring
was reinstalled on the unit and I used the edge of a table covered with
a towel so as to not damage or scratch either the trim ring or the table;
I gently applied pressure on the speedo unit against the table while rotating,
effectively ironing out the kinks. After doing this the trim ring looks
almost as though the unit was never opened.
||follow up Re: addendum to 993
||Fri, 29 May 2009 08:25:10 -0700|
I just finished replacing the gears ("pod" and little gear")
- the following
may be helpful
1. to verify that all is well when
you reassemble, use a pin, or a jewler's
screwdriver to turn the stepper
motor clockwise. you can touch the back of
the armature through the
laticework at the back of the motor, and you can
turn it enough to move it
to the next step - you should be able to see the
counters move after turning
it just 3 or 4 steps
3. to re-roll the bezel, use the round shank of a
screwdriver. Press the
assembled gauge, bezel down, against a flat surface -
press hard (remember
to have the odometer reset button located off the edge
of the surface so you
don't break it) and then pressing down hard on the
screwdriver shank, slide
it around the back side of the bezel holding the
shank tangential to the
case. this will make a reasonable rolling force on
the bezel and will close
it back up much more aesthetically than trying to
crimp it back with pliers
----- Original Message
From: "Bill Noble" <firstname.lastname@example.org>
Sent: Tuesday, May 26, 2009 8:28 AM
addendum to 993 odometer article
> Robin - an addendum to http://p-car.com/diy/odometer/
> my 993's "pod" - the assembly that holds the small gear -
> mm diameter, which is a bit larger than the "small pod"
- I talked to the guys there,
> very helpful - and they assured me that
the "small pod" will work for this
> On my
car, the small 15 tooth gear was actually stuck to the pod - the oil
had become glue - that contributed, at least, to the failure of the gear -
> the odometergears,com folks said that the rubber VDO used for the gears
> attacked by the oil they used, and so they recommended replacing
> pod and the small gear - at $25 each, that's not too much
> though it's a pretty easy job to get at the gears in
the 993 - at least
> you don't have to pull the whole dash like some
> One more hint to help separate the bezel from the
gage- once you get the
> bezel lifted slightly, you can put a (dull)
jewler's screwdriver under the
> edge, and holding the handle tangential
to the bezel, slide it around the
> gauge - this will roll the edge
upward smoothly and greatly reduce the
> risk of distorting the soft
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