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> Speedo/Odometer questions, Gears, lube, and more
bbrock
post May 17 2017, 09:55 AM
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So I completed the odometer repair following the tech article on the bird. PIA but it seemed to go well enough. But I have a few questions before I button this thing up.
  1. It was recommended that I replace the plastic drive gear while I'm in there as they are prone to failure. But I"m not sure what gear needs replacement and the most likely suspects are metal on mine. Does this not apply to me?

    Attached Image

    Attached Image
  2. While in there, I freshened the grease on the worm, and other gears with multi-purpose grease. Later, I read that petroleum grease breaks down the plastic gears and is responsible for the failures. Should I clean out the grease and replace with a different lubricant? If so, what?
  3. In testing, my odometer advances the mileage when the trip meter reaches 9/10 of a mile. Is there a way to align these so the odometer advances in sync with the trip meter as it rolls over a new mile? My trip meter and odometer never worked since I owned the car so I don't know what is normal and maybe I'm being too picky.
  4. This is an idiot question but is there any magic that would whiten the tenth mile wheel short of removing and painting? Dreaming the impossible!

Thanks again for all the great advice from the brain trust.
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timothy_nd28
post May 17 2017, 10:59 AM
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The plastic worm gear will not break, never seen one yet. I think you are referring to the drive gears on a 911 electric speedos, which are notorious for breaking.

That tech article suggests that you pinch the odometer gear with vice grips, so it grabs better on the axle. If you went this route, I think you will be re-opening the gauge in the future for more repairs. Gluing the gear to the shaft is superior to the other method mentioned.

Did you remove the back half spinning magnet assembly? The grease has turned to wax in those bearings, spinning the magnet by hand you would be lucky to get 1/8th of a turn. After rinsing out the old grease and relubing (I use silicone spray), it should spin like those new fidget toys. This will keeps the speedo from making odd noises, ghost jumping in speed, and sparing your speedo cable from snapping.

Toward the yellowed odometer gear, I would suggest buying a broken core gauge and using a better looking gear from it.
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bbrock
post May 17 2017, 12:09 PM
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QUOTE(timothy_nd28 @ May 17 2017, 10:59 AM) *

The plastic worm gear will not break, never seen one yet. I think you are referring to the drive gears on a 911 electric speedos, which are notorious for breaking.


Probably so. Everything I've found on plastic gears deteriorating references 911 gauges.

QUOTE
That tech article suggests that you pinch the odometer gear with vice grips, so it grabs better on the axle. If you went this route, I think you will be re-opening the gauge in the future for more repairs. Gluing the gear to the shaft is superior to the other method mentioned.


(IMG:style_emoticons/default/post-2-1117899824.gif) (IMG:style_emoticons/default/headbang.gif) !!!! I did the pinch (followed by a counter clockwise swirl for you Seinfeld fans). Man I hate to think about pulling that thing out again. Took me forever to get that in at 00000.

QUOTE
Did you remove the back half spinning magnet assembly? The grease has turned to wax in those bearings, spinning the magnet by hand you would be lucky to get 1/8th of a turn. After rinsing out the old grease and relubing (I use silicone spray), it should spin like those new fidget toys. This will keeps the speedo from making odd noises, ghost jumping in speed, and sparing your speedo cable from snapping.


Nope. Can this be done without mucking up the calibration? I assume it is just the two screws on the back of the odometer bracket?

QUOTE
Toward the yellowed odometer gear, I would suggest buying a broken core gauge and using a better looking gear from it.


I'll just live with it. It doesn't really bother me and just adds some of that nice "patina".

Thanks for you help!
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burton73
post May 17 2017, 12:31 PM
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Hay Brock,

I guess I gave you some miss information on the drive but at least you got your speedo questions answered. My 911 Carrera 86 broke a couple of months ago when I pushed the trip reset.

Have you cleared you the plastic on the face with Novus 1 and 2 polish for plastic or am I wrong one more time and you have glass fronts?

Your doing great on your restoring of you baby.

Bob B
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mepstein
post May 17 2017, 12:40 PM
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Don't reset your odometer while driving. Only do it when the car is still.
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bbrock
post May 17 2017, 12:52 PM
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QUOTE(burton73 @ May 17 2017, 12:31 PM) *

Hay Brock,

I guess I gave you some miss information on the drive but at least you got your speedo questions answered. My 911 Carrera 86 broke a couple of months ago when I pushed the trip reset.

Have you cleared you the plastic on the face with Novus 1 and 2 polish for plastic or am I wrong one more time and you have glass fronts?

Your doing great on your restoring of you baby.

Bob B


No worries. And I think you helped me out regardless! I had a sneaking suspicion I wasn't finished with this gauge, so chose not to re-crimp the metal bezel. Had you not brought up the gear, I would not have learned about the magnet assembly grease. So there you go!

I think my car was in a transition phase from glass to plastic because my combo and speedo both have glass lenses, but my tach had plastic. I started to polish that one up with Novus but decided to have a local glass shop cut me a new one from glass. They did it on the spot in about 15 minutes. So all glass in the gauges now.

I'm still wondering about the syncing of the trip meter and odometers as the miles advance. When I first tested mine, the odometer was advancing when the trip hit two tenths of a mile but the 10 mile wheel on the odometer was misaligned after the advance. I fiddled with it a bit and really don't know what I did, but now all the odometer wheels stay aligned as miles advance, but they advance when the trip meter hits nine tenths. That's better than 2/10s but it makes me wonder why.
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timothy_nd28
post May 17 2017, 12:59 PM
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Yep, remove the 2 screws and its free. It won't affect the calibration, unless you place it on top of a 18" subwoofer. I usually go to town with GumOut and attack both sides of the bearing, while spinning the magnet with my finger. Rinse and repeat for 20 minutes to ensure you got all the old grease out. Once you relube that bearing, it should be a night and day difference with the amount of force needed to spin that magnet.

Toward the pot metal gear, I can tell you from experience that the pinching method didn't last long for me.

By oblonging the hole on that gear, you are essentially making 2 pinch points on the gear to grab that axle shaft. This is inferior to the OEM way of press fitting, which gives you much more surface area, but this isn't a option anymore. This is why I use Locktite and I haven't had one fail yet.

If you do decide to go the glue route, keep the speedo apart for a few days. The locktite will glue the shaft to the frame, which you will need to break free and lube.

The job sucks, and I hate making these repairs but it's better to do it once.
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jrblackbox
post May 18 2017, 03:51 PM
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QUOTE(timothy_nd28 @ May 17 2017, 10:59 AM) *

Yep, remove the 2 screws and its free. It won't affect the calibration, unless you place it on top of a 18" subwoofer. I usually go to town with GumOut and attack both sides of the bearing, while spinning the magnet with my finger. Rinse and repeat for 20 minutes to ensure you got all the old grease out. Once you relube that bearing, it should be a night and day difference with the amount of force needed to spin that magnet.

Toward the pot metal gear, I can tell you from experience that the pinching method didn't last long for me.

By oblonging the hole on that gear, you are essentially making 2 pinch points on the gear to grab that axle shaft. This is inferior to the OEM way of press fitting, which gives you much more surface area, but this isn't a option anymore. This is why I use Locktite and I haven't had one fail yet.

If you do decide to go the glue route, keep the speedo apart for a few days. The locktite will glue the shaft to the frame, which you will need to break free and lube.

The job sucks, and I hate making these repairs but it's better to do it once.



Tim, When gluing the shaft to the gear, can I simply apply the glue to the gear at the end of the shaft without removing the shaft from the gear assembly?
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bbrock
post May 18 2017, 04:08 PM
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QUOTE(jrblackbox @ May 18 2017, 03:51 PM) *

Tim, When gluing the shaft to the gear, can I simply apply the glue to the gear at the end of the shaft without removing the shaft from the gear assembly?


And are you using locktite red or blue?
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timothy_nd28
post May 18 2017, 05:29 PM
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I don't think gluing that gear while it's still in place would work very well, very tight spacing, not sure how you would even gain access. Also, the surface areas of the shaft and the inner gear needs to be thoroughly cleaned before it can be glued.

This is what I do when making these repairs. Since I typically don't charge for this repair when doing my LED upgrades, it's not a trade secret (IMG:style_emoticons/default/smile.gif) There is a upper shaft that holds a bunch of the smaller plastic following gears. Each end of this upper round shaft is squished flat from the factory, this was done to keep the shaft secured. Most of these upper shafts have 1/16-3/16" worth of material protruding the gauge frame before the factory stamped the end flat. I observe both ends to see which one has more material, the one that has more material will be sheered off with my side cutters.

At this point, I slide out the upper shaft and remove all the upper follower gears. With this out of the way, you now have a great window to see that pot metal gear.

Next, you will need to separate that back half spinning magnet by removing the 2 screws, now remove the worm gear. I then orientate the speedo so the pot metal gear is pointing up toward the ceiling while the opposite side of the shaft (brass gear) is facing the floor. Next, remove the main shaft (brass gear side) by pulling it down toward the floor. Keep the speedo orientated the way you just had it so the odometer wheels stay stacked nicely for the next step.

With the shaft out, go ahead and wipe it clean with carb cleaner and set it aside. Next, grab that shitty pot metal gear from the gauge and clean the inside hole with a tooth pick/paper towel and carb cleaner.

You need to be quick with the following steps. With RED locktite, apply a small dab inside the hole of the pot metal gear. Then use a tooth pick to trace the inside of the hole, ensure that you have a light even coat all around. Then, wipe both faces of the pot metal gear with a paper towel to remove any loctite glue that leaked out of the hole. Slide the main shaft back into the gauge frame and thru each odometer wheel. Don't worry about lining up the wheels at this time. Insert the pot metal gear back into the gauge, and hurry up to push the shaft thru the pot metal gear and thru the gauge frame. You need to be fast with that last part, as the glue will start to set when metal to metal contact is made.

Once done with the last step, wipe down the end of the shaft that protrudes the gauge frame, remove any residue locktite. I then start spinning the brass gear with my finger and put a dab of turbine oil on the shaft where it protrudes the gauge frame. Keep spinning the brass gear back and forth so that the oil will work into this area and to help the locktite from gluing the shaft to the frame. At this point, walk away from the assembly for atleast 12 hours. After that, recheck the main shaft to see if it still spins freely, also check each odometer wheel spins freely, relube the end shaft if necessary.

Realigning the odometer wheels along with the plastic follower gears are a PITA, but take your time, taping them together does help to keep things straight. Reinstall the upper shaft with the follower gears, and crimp the end of the shaft that you previously sheered with side cutters, hopefully there's just enough material left over to make this happen, if not, you could also use locktite but I never had to resort to this before.

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bbrock
post May 19 2017, 11:11 AM
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Thanks a million for your help. This answers a ton of questions! I got the dried up goo at the spinning magnet cleaned out and relubed. You are right, night and day difference. I've decided to just wait and see how long the pinch holds on the pot metal gear. Everything is aligned, reset, and working right now and I just don't feel like clipping shafts and digging back into that mess. It's not like pulling the gauge is major surgery. But now I know how to proceed when that day comes.
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