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.
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.
You should now see the deteriorated gear as I did.
If not, you may not have the same issues as I and so many others before me. I ordered my replacement gear from
www.odometergears.com – 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:
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:
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.
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.
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.
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.
10. They're already removed in the pics, but you also need to remove the gear retainer circlips with a small screwdriver
10. Voila – you can now slip your new gear on!
SEE POST BELOW FOR PIX
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.
Craig
Edit: "image removed by BBS software", added in follow-up post