Unofficialbmw.com

[mcpham99]

Hi all,

Where can I purchase the rubber gears for the VDO Speedometer/Odometer on my 89 325ic. Most places in the internet want to fix it for $125. Please help!

[haber]

Mike

I'm not sure if your 89 is just like my 86 or not, but on mine it was the drive gear coming across from the odometer drive motor that went kaput. It was a plastic gear on brass hub pressed onto the shaft. The rest of the reduction gearset was fine. I got a replacement metric module 0.5, 12 tooth brass spur gear from Sterling Instrument / Stock Drive Products. I had to bore it our just big enough to press on the remains of the brass hub and it has been working great since.

The good news was $3 for the gear but the bad news was about $20 for small order charge and S&H. I bought 2 in case I messed one up. The spare is yours if that's your problem and you want to give it a try.

SDP part # A 1B 1MY05012

ps, make sure you clean out any pieces of old gears or they may jam up the works

[NN_Bob]

Haber - you wrote:
"I got a replacement metric module 0.5, 12 tooth brass spur gear from Sterling Instrument / Stock Drive Products."

Do you have a website or address for these guys?

Thanks,
Bob

[haber]

http://www.sdp-si.com/

I only needed the drive spur gear and I could get that. The rest of the reduction set gears had two different pitches molded into one unit. Not sure if you could even come up with any of those combinations but Sterling Instrument is the best source I found for metric module 0.5 gears.

If anyone is interested I'll post a few more details regarding just what I did to fix mine. Not too difficult...

[mcpham99]

Haber
Thanks for your responding. Yes it's the plastic drive gear coming across from the odometer drive motor. Would you let me have your spare gear and I'll reimburse your cost of S&H from Sterling Instrument. What do you use to bore the hole out. My email is mcpham99@yahoo.com
Mike

[NN_Bob]

Haber - Thanks for the website! I would appreciate a detailed account of your repair. Right now the most important thing for me to know is the size drill bit you used on the gear so I can find one.

Thanks again!
Bob

[charliesmith]

haber,

You might want to post a very detailed tutorial about the speedo repair task and ask webmaster dale to repost it on the homepage component repair links. The E30 speedo units are identical to the E28 series. These Bimmers aren't getting any younger and from the continuous broke speedo related chatter, the speedo units are definitely a weak link. Or else these cars are out living their expected BMW engineered lives.

[haber]

Here was my method of odometer repair. I hope it will prove useful to others and I wish now I had taken a picture to share as well. If someone can pass on to the webmaster as Charlie suggested, I’m not sure how.

After my speed/odometer was out of the instrument cluster it was obvious that the drive spur from the odometer motor was kaput. It is a small plastic drive gear on a brass hub that is pressed onto a shaft that crossed over from the odometer motor to the drive gear side of the mechanism. It appeared to me that BMW/VDO just picked the wrong plastic and durability is poor. Maybe they have recognized and fixed this on later models.

Remove the screws and cover to the reduction gear set on the drive side of the odometer. Slide out the reduction gears to avoid damaging them an inspect them. Mine, thankfully, were in very good condition. Make sure you get any pieces (teeth) from the drive spur out of works or they will bind it back up. I then cut the plastic inner portion that remained on the drive spur since primarily the teeth had stripped off. It was quite soft and no trouble to remove. The old gear had a knurled brass hub that measured about 3.4mm or .134" in diameter if I remember correctly. A caliper or micrometer to check this would be a good idea to guide you in the next steps.

At this point you might also check the working of the instrument. If you put the reduction gears back they should spin very easily and roll off some miles. If you put it back into the dash with the lens off you can feel the drive spur hub flip over now and then to verify the motor is good. (you need to be moving which is not such a good idea to recommend though) I did this and also drove around a few days with no instrument cluster or warning lights while waiting for the part I ordered. It's weird driving without them but the car runs fine with everything out.

I purchased a new gear from Sterling Instrument (www.sdp-si.com), part number 'A 1B 1MY05012'. This is a metric module 0.5, 12 tooth hubless pinion. There are no inch size gears that will substitute. This new gear has a 3mm bore or .118" and a 4mm face width and is made of brass. The gear is only about $3 but be prepared to pay a small order charge plus S&H. I bought 2 just in case and now wish I had bought more to share with others.

My approach was to bore this gear out and press it onto the remains of the old spur. There are metric drills available in increments of 0.1mm and there are number size drills that get close. I used a number 30 drill which brought the bore out to .1285". A number 29 is too big at .136" and a more commonly available 9/64" drill (.141") was much too big. Alternately you might be able to start with an 1/8"(.125") drill but then the next step will be more difficult. I was lucky to have a good model shop here were I work and can borrow odd items like this.

The next step was to hone the gear out until it was just undersized. This takes a little finesse but not too difficult. I used a Dremel tool with a 1/8" carbide bit to slowly hone the gear out until it was just slightly under. I put the Dremel tool in the bore and rolled the gear as light pressure was applied. Don't get in a hurry or you could overshoot your target. Periodically check to see when the gear is just starting to push on to the old spur hub being careful not to get it so big it slides right on. You might want to try to taper one side just slightly to get some lead in.

Remove the screws and plastic cover on the odometer drive motor (opposite side) and also remove the magnetic rotor and small ball bearing on the end of the shaft. Support the end of the shaft on something softer than the metal shaft like a block of wood or plastic and gently tap the spur gear onto the original brass hub. If it is not going on with a light force then it needs to be honed out a bit more. I used a 1/2" x 6" socket extension to tap it on with little more than the weight of the tool applying the force. I suppose LocTite, epoxy or the right glue would work if you get it too loose but I was afraid of getting that in the wrong places like gear teeth. A good press fit is best I think.

Re-assemble everything making sure the new drive spur is lined up with the first reduction gear. There was plenty of lube on the old gears to transfer to the new spur. Spin it for a few 'miles' forward and back to make sure everything is working. It should take very little force and if you meet any resistance then something else is jammed up. Now if you trouble was just like mine you’re good as new.

Mine has been good for a couple thousand miles or about an oil change now. I don't care about the actual mileage as much as keeping track of oil changes and service since my car is too old (86 ETA) to be worth anything. However, it is still a very reliable and fun daily driver I plan to pass on to my daughter in a couple years. Keeping it working without paying dealers and garages big $ is one of life's simple pleasures. Teaching my daughter to drive in this car we've had for 14 years now is priceless.

[NN_Bob]

Thank you VERY much!

[mcpham99]

Haber is so kind gave me his spare gear, instructions and measurements. I was able to install it on the VDO without a hitch. I'm so happy with the accomplishment because I can say I did it (with Haber help )
Thanks Haber for his time and kind heart.
This board is great!
Mike..

[LeeM]

Here's an alternative web site for the gears. I ordered one today, so I have no idea if it works. The owner seems genuinely interested in the quality. I'll let you know.
BMW Speedometer Gear

[ 09-18-2002: Message edited by: LeeM ]

[mcpham99]

!!!!bump!!!
I saw some posts regarding fixing the odometer recently. So I bump this one up for reference. Thanks Haber again. Mine still running strong.

[speed25]

Thanks for bumping the topic, Mike, and I'm glad to hear yours still works. So, I take it that your '89 was the same as the '86 version? The web site for the guy that builds the gears says "up to '88." I've e-mailed him, but no reply yet.

By the way, I'm in Lakeland, only about 30 minutes from you.

[mcpham99]

speed25,
If you also have VDO, it should be the same.
Glad to know another bmw owner nearby