Mk4 01M Spedometer Drive Gear DIY

[Vin_Maddux]

I've been searching high and low and have not found a DIY for spedometer drive gear replacement. I can't even find the procedural detail in the Bentley manual:

• Volkswagen > A4 > 1999-20064 speed automatic transmission 01M, 39 - Differential, Removing and Installing
  
• 2 - Speedometer drive With marking for oil level indication [Speedometer drive ]
  
• Speedometer drive - With transmission installed, check gear oil in final drive Final Drive Oil, Checking .

My symptom: spedometer starts twitching at approx 65-70mph and cruise control hunts. Tachometer and other gauges are stable and don't bounce while this is happening.

I've been told that the spedometer drive gear on the Mk4 01M automatic is known for this.

I was able to find the VW part: Mfg#: 01M409187 and am hoping to replace it, drain the final drive oil in the hope of removing the plastic debris and changing the differential gear oil for maintenance.

Any suggestions/tips are greatly appreciated.

[CoolAirVw]

there is no "how to" that I know of.

This is a very large job for such a small problem. For $89 dollars you can get a GPS that will show your speed.

Also there are other things that can cause this.

Note: I realize on cruise control it will probably jerk around with this problem but still the cost of replacing the speedo drive gear would be very large if a shop did it, and it would be difficult for a DIY to get done.

[Vin_Maddux]

Thanks again for the reply. I see in your signature that you are a master ASE so I appreciate your advice. I'm also very mechanical so if you reply to my posts I'd appreciate it if you were to be technical.

1. GPS = NO WAY that's happening
2. Big Job = I know this and am about to do the CV axles anyway. I've been living with this for a while. I understand that this spot is accessible when the CV axle is out. I can't remember which side but I want to say driver. I'm also aware that the Vehicle Speed Sensor can do this and will be replacing that as well.
3. Tools = I have the correct tools to do the work. All of them but a VAG-COM and am thinking hard about that.
4. Fast = Nope, but I am very thorough and enjoy mechanical work. I was a marine diesel mechanic as a young man.

I'm hoping for a few tips from someone who has replaced one. Anyone?

[Stangrcr1]

The speedometer drive gear is driven from a plastic gear on the differential.

I replaced the gear on the differential while rebuilding my tranny because the gear was cracked. It requires trans removal from the car, remove the rear cover, unscrew the bearing retainers(special tools which you probably don't have), pull differential, pull bearing off differential, then the gear can come off.

Reinstalling the diff is easy until you get to the bearing preload adjustment and pinion alignment. Without the special tools, I wish you luck. Been there, done that. If not properly done, your diff will live a short life.

BTW, I am ASE Certified Master Auto Tech too.

[vdubtech398]

The speedometer drive gear is driven from a plastic gear on the differential.

I replaced the gear on the differential while rebuilding my tranny because the gear was cracked. It requires trans removal from the car, remove the rear cover, unscrew the bearing retainers(special tools which you probably don't have), pull differential, pull bearing off differential, then the gear can come off.

Reinstalling the diff is easy until you get to the bearing preload adjustment and pinion alignment. Without the special tools, I wish you luck. Been there, done that. If not properly done, your diff will live a short life.

BTW, I am ASE Certified Master Auto Tech too.

You do NOT have to remove the trans or rear cover to replace the plastic speedo gear or the diff. remove the axle and bearing cap. mark and count the turns on the bearing cap. Remove the bearing on the end of the diff with the metal ring/retainer, then R&R plastic gear and re-install. NOTE: it requires a few different pullers/mechanical intuition to remove the bearing and the metal ring without damaging things. If you ruin the bearing then the cover and diff may have to come out. Last one i did took 2 hours. Order the metal ring that locks the plasstic gear on the diff just in case you damage it removing it.

[Stangrcr1]

You do NOT have to remove the trans or rear cover to replace the plastic speedo gear or the diff. remove the axle and bearing cap. mark and count the turns on the bearing cap. Remove the bearing on the end of the diff with the metal ring/retainer, then R&R plastic gear and re-install. NOTE: it requires a few different pullers/mechanical intuition to remove the bearing and the metal ring without damaging things. If you ruin the bearing then the cover and diff may have to come out. Last one i did took 2 hours. Order the metal ring that locks the plasstic gear on the diff just in case you damage it removing it.

Exactly the reason I would remove the trans. Much easier to pull the bearing with the diff out. And not everyone has those pullers.