Cheese grade odometer gear rational

About 6 months ago I ordered my second and third set of Dave Barton odo gears, this time 2 sets for the 240 clusters, one was needed then and done then, and the other bound to be needed and done a day or two ago. Tonight I put the cluster back in and went for a short drive to the hardware store. On the way home I heard the tick tick, just like the other 240 I had done 6 months ago. The two were a bit different, though, the one I did a while back, and my 740 sedan one, both super crumbly/weak, whereas this recent 91 240 gear though it had lost 2 teeth was still kinda solid, but flexible, took a bit of force to fold it in half. In any case, the odo didn't tick before, and now it does. Which is when it hit me, they made them soft becaue it's a luxury car and they wanted the odo to be quiet despite being run by a stepper motor. So now with hard plastic in there you hear it quite clearly. Hmmmm. I don't recall hearing the 740 one after I did it, nor since. Maybe a better insulated cluster design or something. But both 240s with hard gears now tick almost annoyingly. So what I may attempt to do is copy these plastic ones out of some grade of urethane and see if I can make a quiet replacement gear to restore that silky luxury to my precious champagne coloured 240 wagon. Excuse the run on paragraph, it's late, and I'm tired. Hope this inspires someone to make a quiet and reliable odo gear themselves.

Until now, no one has ever considered a 240 as a car that's quiet, let alone quiet enough on the road to hear the meshing of two tiny plastic gears inside the speedo.
Dave B

I DREAM of my car being quiet enough that I can hear my odometer gears.

Did you lube the gears?

Nylon is self lubricating.

Then there must be wear on the other gear or something isn't right. These aren't the first gears Dave sold and we have never heard of this before. Two tiny plastic gears meshing inside a gauge cluster shouldn't make any audible noise.

If nothing else turns out wrong, I would lube them with silicone, it can't hurt.

Have you considered that it may be the number wheels making the noise and not the new gear?

Who among you have used a stepper motor, or even observed one in action? They move suddenly and sharply. A fact of life, and very useful. I'm certain these will outlast me, however they don't perform like the originals did until a few weeks ago when they failed from fatigue (as with anything that flexes, eventually it'll fatigue). This was not a critique of Dave's product, really, just an "ah ha!" moment shared with the community. I'm not convinced a fine urethane casting would offer the reliability desired, but I'm willing to try it

I have no idea what y'all have done to your Volvos to make them roudy and loud and obnoxious. Are they all track cars with no interior??? the high-density sound isolation layer under the carpet does a stellar job. With the windows up, bone stock everything, she's a purring pleasure and it's *easily* quiet enough to hear a pin drop.

My other 240 with the B234F in it has Yoshifab mounts which are noticably stiffer than stock, and it makes some noise at idle and other places - took me a while to realise it was the stiffer mounts causing it.

Re the last comment about number wheels making the noise, not really important what's making the noise, but one can guarantee it's *after* the stepper motor, and the only thing that changed is the gear, so one could therefore assume that the gear is *transmitting* the shock of the stepper movement more efficiently into the rest of the odo. It did cross my mind that this may accelerate wear, but I'll die before that is an issue, so whatever. The ticking is audiible in the louder 240, too. Also, I religiously use hearing protection with power tools and rock concerts and block my ears around machinery etc. I rarely see anyone else do those things, but still enjoy a 20-20kHz listening range unlike most 40+ males. IE, my ears are in good condition, are yours?

For the record, I'm grateful that Dave's gears are available, as 3 of my cars now sport them and record mileage, two of which were broken when I bought the cars, and on recently having failed. Without the product I'd be guessing mileage and maintenance etc, not ideal at all. The 740 came to me from a woman who ran it out of fuel multiple times and burned out and replaced the fuel pumps I've run that car out twice myself, but not tried to crank it as I knew it was going dry. Fuel gauge/sender repair is next for the 740, but I'm happy these cars have working trip/odos - Thanks Dave (and your supplier).

This was more of a "I've always wondered why those gears are so soft and crap" and the answer is "degraded over time from a highly plasticised plastic designed to cushion shock from the stepper"

FreeEMSFred said:

This was more of a "I've always wondered why those gears are so soft and crap" and the answer is "degraded over time from a highly plasticised plastic designed to cushion shock from the stepper"

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Since I do know you, my Kiwi friend, and am aware of your skills, it was readily apparent to me you were not criticizing anyone, but merely posing a hypothesis toward explaining the need to replace this gear. I don't know of any other forum where you could discuss this seriously.

I'm impressed by your hearing ability and the discipline used to maintain it. I destroyed mine by age 20 with loud music, knowing it then because I could no longer tell when a TV was on by the rattling of the flyback core at 15,750.

On the workbench I can hear the odometer, but not in a moving car. If not the 4 types of tinnitus offering desensitization, the tires and wind shrink the signal to noise ratio. The gears I collected from the PnPs 20 years ago were not all made of cheese, but they did get lubed by VDO. I concluded that lube was partly responsible for polymer returning to monomer, never once considering they were soft on purpose. Interesting, but I'm not sure I buy it quite yet. Yes, some of the failed gears were yellow and felt like a cheap urethane suspension bushing.





The yellow gears turned to cheese; the failed black and gray gears seemed brittle. Now, I don't guess that Dave makes the gears he sells, but I've tried a variety of them from other sources, both molded and machined from Delrin, with the oldest of the replacements still in use 19 years. None have failed yet. On the other hand, I follow the threads on the forums, so I know not everyone has the good luck I've had. There are some poor imitations of that gear floating around.

So, whether it is age, environment, strength of material, it is an interesting question with a very small interest group. Especially limited by hearing ability.

Those photos are awesome - I'm now wishing I had kept the ones I took out in a corner like a hoarder Maybe just maybe I have a few photos, let me see...

740 one juxtaposed with old/new and new/old: https://pbs.twimg.com/media/CVcnPAOUsAAgvov?format=jpg&name=large

Comment on above "perfect fit" - did not test the latest 240 ones, as I had faith OOTB (out of the box, that's me, not the gears).

740 odo as I found it: https://pbs.twimg.com/media/CTuxE57UcAIw_QP?format=jpg&name=large

First 240 one I did 6 months ago: https://pbs.twimg.com/media/D_WJYtuUYAArt5t?format=jpg&name=4096x4096

I have more, but not online ready to share.

What's interesting in your shots is that the backing plate clearly has the larger gear cast into it in a different material. You can see the sort of torque lugs sticking through the transparent one upper right first photo. That's the sort of engineering you'd do to transmit torque through a soft thing. Drive couplings in marine propulsion and many BMW drive shafts both do this. IIRC so do old air cooled VW shifters.

With respect lube acting as a cushion, I may try that with some sort of grease that could damp the movement appropriately. The nylon should take it fine. I foolishly oiled my 240 one that I just did when I had it apart years ago, and when I pulled it out recently it had rid itself of the oil through gravity.

Thanks for the compliments on the hearing - I don't have a perfect record, but I've done well enough to have good hearing half way through life, partly due to watching my father (who is over 50% deaf) systematically destroy his with power tools and the impact that had on our relationships with him and his guessing what he heard. I have one friend with hearing aides who is even more strict and has been recently encouraging me to do better - and I have been.

And equally, condolences on your hearing loss - not being able to hear those old TVs screaming was probably the only benefit of it, I would imagine. In general women heard them more clearly anyway, though.

If I had the file, I could print a gear for you in urethane with my 3d printer and see if that makes it better. I'll look on Google and see if anyone has a file...

Edit.

Yeeup, got a 3d file. It's for the small gear,, 25 teeth I believe. Is that what you need? If you or anyone else would like to try a urethane gear that is soft, I think about 95 shore hardness, let me know.

Does anyone produce straight cut gears in the aftermarket? I'm really after that race car gear-whine sound for my instrument cluster.

FreeEMSFred said:

I'm now wishing I had kept the ones I took out in a corner like a hoarder

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I never throw anything out. That makes me a hoarder. That needs to change soon.



Despite my hearing impairment, I really dislike the common quartz wall clock with its stepper clicking away the seconds. My better half likes to put them in all the rooms. I wonder if I could just gob them up with some silicone lube instead of loosening the AA cell. Next year this country is supposed to enjoy a reform to its medical device classification of hearing aids which is now a racket.

Alrighty, here is my first attempt at printing a urethane gear. Came out pretty well knowing how small these are... Doesnt look the best but the teeth and the gear itself are close to accurate, which is the important part. And it is soft! You can bend it. May need the gaps between the teeth filed down slightly.

If anyone wants to give it a go, PM me. Pay for the stamp and you can have it. 25 tooth version.



Edit: Making another now to see if I can get the teeth sharper. Super hard to 3d print this small.

Stiggy Pop said:

Does anyone produce straight cut gears in the aftermarket? I'm really after that race car gear-whine sound for my instrument cluster.

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I had to import mine from Japan but they whine real loud now. Really impresses the girls in the Taco Bell parking lot when I drive around with my windows down.

Nice work making the odometer gears!

So to clarify what is being said here, it is loud because it's a stepper motor that is now engaging a gear made from a harder material?

Doesn't sound right to me. Stepper motors are louder than a regular motor but not really loud. Not sure why the gear material would matter if the gear fits correctly. Clicking or tapping suggests wear on a part.

IansPlatinum said:

I DREAM of my car being quiet enough that I can hear my odometer gears.

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It is when it's broken down on the lawn