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Thrasher 12-15-2004 12:58 PM

Odometer Gear replacement for Electronic Speedometers (long)
I recently went through this exercise, it's a classic for SC/Carrera. Mine was not related to resetting the odometer while moving, but just an old, tired, disintegrating gear that fell apart when I reset the odometer at the gas station.

Here goes:

This is for those of you with a lot of patience and self-control, because it’s tedious and delicate. I approached this one with the attitude that it might take me several sessions over the course of a week, but that I was saving over $100 by doing it myself – provided I don’t break something along the way.

1. The first step for me was removing my steering wheel, which was already done because I was replacing the turn signal switch because of the hi/low headlight switch malfunction. I don’t think it’s necessary, but may have made it easier to get access to everything.

2. Next, you remove the speedometer case from the dash. This is done by pulling or gently prying under the bezel. There is a rubber gasket surrounding the speedometer case that holds it in the dash – that’s it, no screws or other fasteners.

3. Once you have it free, you’ll need to remove the illumination bulbs and bases (as a unit), and disconnect the remaining wiring. I took some pics to aid in reassembly. To remove the lighting, get a small screwdriver and gently pry up the base; the bulb will stay in the base and it all stays attached to the wire, which remains in the car.<br>
4. Now, for the first fun part: If you’re feeling at all tense or agitated, put the speedo on your bench and get a beer or call it a night and return the next day. Removing the bezel and lens is done by many, many small prying motions along the lip of the press-fitting that holds the black bezel that you see from the drivers seat onto the silver aluminum housing that is normally out of sight.

I suggest looking closely at this fitting and look for the largest gap between black and silver – that’s where you want to begin “peeling back” the black lip with a small screwdriver. Think “baby steps” here. Otherwise, you’ll mangle it and it will “look like you dog has chewed on it” as Wayne wrote in his article. Just work your way around the perimeter, at least 180 degrees, then work your way back. Continue until it starts getting really loose – you’ll know when. Then, remove the bezel carefully by pulling it away from the case, using a tilting motion to pull on the loosened side.

The lens and another black piece will come off with the bezel. You should now be at the point where the needle and speedometer face are unprotected – so be careful.

5. Next, you’ll need to remove the “guts” of the assembly from the silver housing. On mine, there were 3 screws holding the guts in and 3 more on the plastic wiring bus. You’ll want to remove all 6 of these and then slide the wiring bus into the housing. I suggest inverting the speedo on a clean rag and slowly loosening these screws partially. As you do so, the guts will be lowering toward the rag. When you get close, use your hand (with a glove or other clean rag) to catch the guts as the last screw lets go. There will be one blue wire that is soldered to the case. I chose to leave it in place and work with the case attached, but you may want to remove and re-solder to avoid having the case in the way.<br> <br>

You should now see the deteriorated gear as I did. <br> <br>

If not, you may not have the same issues as I and so many others before me. I ordered my replacement gear from – it was just under $30 with shipping for a nylon-like gear smaller than a quarter and weighing a few grams. But, it beats the $150 to pay a speedo shop.

Here are the old and new gears side by side:<br> <br>

6. It may look like you’re just about done, but you need to remove a few items to get that gear out. This is where the biggest dilemma came into play: Remove the needle and lose calibration or try to get the internals out without doing so. I tried to pull the needle, but could not get it to budge, and I thought I’d break it if I tried to much longer.

I had found some posts in the archives where guys said that they removed the reset mechanism and then the two small black screws on the gauge face between the trip odo and regular odo numbers. I could not find a way to do that. Here's a pic of the reset mechanism:<br> <br>

Then another posted how he’d used a very small screwdriver on its side to loosen the 4 screws that hold the mechanism to the “frame”. This was very slow going, and it did bend the needle as the face was lifted to get to the screws. I kept the needle 180 degrees from the screw I was working on to minimize the bending.
<br> <br>

With a lot of small turns, I finally had removed the screws and the mechanism was free – well enough to proceed.

7. You’ll also need to remove the drive motor’s one screw and pull that out of your way.<br> <br>

If you're watching closely, you'll see my new gear already in place - I forgot to take pics of disassembly and these were taken during reassembly!

8. Two more screws hold the plastic housing piece, remove these are remove the housing piece.<br> <br>

9. You now have access to the axle of the other gear that’s in your way. Use a tiny drill bit, needle, or toothpick to push that axle out and you can remove that gear.<br>

10. They're already removed in the pics, but you also need to remove the gear retainer circlips with a small screwdriver<br> <br>

10. Voila – you can now slip your new gear on!<br>

11. Reassembly is somewhat the reverse of disassembly, with a couple of exceptions.

a. Getting those four screws back on under the face is a major *****. I wish you luck and patience. I was really worried about breaking the needle at this point, but mine was flexible and made it thru the ordeal. You may want to consider replacing the screws with shorter ones. I think it’ll hold together just fine.
b. I took a punch to set the bezel ring onto the case and it seemed to work well. Again, work slowly and methodically. It’s nearly as tight as factory and looks

So, I think you deserve a beer now, for sure. For me, being patient is not natural, so I’m particularly proud of this accomplishment. Many people will say “ah, don’t be cheap – send it to a pro” – fine, but they’ll never know the pride you’ll feel every time you look at that odometer spinning for the rest of the car’s life.

It will faithfully serve as a reminder that you have achieved a higher consciousness to become one with the odometer gear, grasshopper.

Enjoy that beer.


Edit: "image removed by BBS software", added in follow-up post

IceBlueSC 12-15-2004 02:20 PM

Excellent job! :cool: :cool: :cool:

ausgezeichnet 12-15-2004 04:57 PM

Nice job. Wish you would have done this before I had to replace mine. See if you can get this posted as a Tech Article.

rick-l 12-16-2004 09:34 AM

I wonder what it would take to get the individual that repairs these for Pelican to chime in on how they handle the speedometer needle removal problem?

Rutherford 12-30-2004 04:52 PM

great thread

greglepore 12-30-2004 05:48 PM

Good work. I did mine, and broke the needle trying to remove it. Used a piece of the red tube that comes with WD40 as a repair sleeve-actually worked well, and cal is ok, but damn it was scary.

Rutherford 12-31-2004 03:34 AM was excellent the gear came from VA to MA in three days for 30 dollars and fit perfectly. I plan on putting the speedo in and performing a ops. check before I recrimp the bezel ring just to make sure every thing worksTHANK YOU PELICAN PARTS FOR ALL THE GOOD INFO POSTED IN THESE FORUMS AND ALL THE AUTHORS.

vesnyder 12-31-2004 06:40 AM

Great thread. Much more detailed than 101 Projects. Get it published as a Tech Article.

78-911SC 12-31-2004 07:20 AM

Great job!!! Would also like to have some Pelican's chime in on how to remove the needle.

clevy70911T 01-02-2005 12:53 AM

I have repaired 3 speedos and a tach and just pulled the needle off with alittle well distributed force. Lucky to not have broke one, I guess. I also made a small reference point so re-installing needle doesnt need recalibrated. Check it with a GPS and tach (MPH/REVS), no problem.

Thrasher 06-09-2005 08:53 AM

I think this was the last image that the BBS software blocked.

vizail 06-14-2005 10:25 AM

Almost when I was done I broke the needle shaft. And found aut that the needle comes out of the shaft and not the shaft itself.. If you hold the shaft in place and pull the needle alone, it will come out. Too late now I have to get something and make an extention for the broken shaft.
I see that someone here mention WD 40 plastic tubing. Wish one?

Tham I'll keep you updated


Asjac 03-25-2006 02:36 PM

I know I am bringing this back from the dead, but this thread helped me SOOO much more than anything else I was looking at for my '87. Thanks for the pics and for helping me through the tediousness!

Thrasher 03-25-2006 10:15 PM

Glad to hear it! Yeah, it is tedious, but the beer tastes even better afterwards.

Congrats on the success.


Porsche_monkey 08-22-2006 08:00 AM

I just ordered my gear 4:30 PM Friday, it arrived Tuesday morning in Canada. Great service.

I found those side screws easier to get at by removing the faceplate screws and the three back screws.

Thrasher 08-22-2006 11:34 AM

I could see where that might buy you some room to move the faceplate for access, but I was concerned with breaking off the needle and/or marring the faceplate

jwt73 11-02-2006 05:25 PM

needle removal
Just wanted to add one comment to this wonderfully written tech tip. I attempted what was discussed but instead of getting the screws out slowly, the needle popped free, and I thought I was homefree, until I noted that the shaft was still attached to the needle and it was broken. For those of ignorant amateurs, I can't reiterate enough the needle and black housing come off in one unit (off of the shaft), and if they don't you screwed it up. (at least this is true for an 87 carerra) If you get as far as getting the needle off without bending or breaking the shaft, then you are homefree, because Jeff Caplan @ will get you the correct gear needed to complete the job.
29 dollars including shipping and available in 4 days. Hope this helps.

gordoncoll 06-13-2007 12:39 PM

excellent article. Which tooth size do i order for a 911 sc euro? Mine had gone completley so i couldnt count them.

Again great article


Porsche_monkey 06-13-2007 12:43 PM

Just call him, he'll probably know the answer.

gordoncoll 06-13-2007 12:50 PM

I sent an email, calling from england isnt really an option i want to pay for !

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