Here is how I fixed the leak coming from the speedo drive on my automatic transmission.
First, it seems there are 2 types of speedo drives. The 'cylinder' of one is made out of some plastic material (ABS?), on the left in the first picture below. Another type is made completely out of steel, on the right of the same picture. This one also leaks and came out of a spare transmission I've had for over 30 years.
The fix is for the 'plastic' type which I had in my transmission. You can see the difference in the construction of the two types in the second picture picture. The plastic one has a sleeve which is inserted into the cylinder. The metal one has no sleeve and is basically made out of two parts, the cylinder and the gear. Have no idea as to how the o'ring was put in there by BMW so no idea as to how to fix that type. The last picture is a view from the top of the two types
The leak was coming from the center where the speedo cable is attached. This was a result of a defective washer/o'ring encased in a metal band inside the 'plastic cylinder. This o'ring is NLA. This o'ring is at the top right of the third picture. The other two o'rings in the same picture was my first attempt at fixing this leak which didn't work.
I searched for a suitable o'ring and the only thing I found is a grommet which fit perfectly over the shaft of the gear and was the same diameter of the indside of the cylinder. Its a snug fit.
Below is a picture of it with the bag (for size purposes if you want to do the same) I bought it a Lowes for about $0.89. The only problem was that it was too thick. So, I cut the grommet in half. You may be able to see from that picture that this grommet has a 'channel/groove in the middle. This is where I cut it.
I left the original o'ring in the cylinder then put this 1/2 grommet on top of it. Then the sleeves goes in holding this 'new o'ring' in place as the gear shaft would turn when driving..
I put the spedo drive back in and drove the car for about 5 miles. Not a drop leaked. Is this a permanent fix? Time will tell. If it lasts a couple of years I'll be happy. I still have 2 1/2 grommets left so that would be 10 years of fix.
This fix may or may not work for you if you have the same problem.
First, it seems there are 2 types of speedo drives. The 'cylinder' of one is made out of some plastic material (ABS?), on the left in the first picture below. Another type is made completely out of steel, on the right of the same picture. This one also leaks and came out of a spare transmission I've had for over 30 years.
The fix is for the 'plastic' type which I had in my transmission. You can see the difference in the construction of the two types in the second picture picture. The plastic one has a sleeve which is inserted into the cylinder. The metal one has no sleeve and is basically made out of two parts, the cylinder and the gear. Have no idea as to how the o'ring was put in there by BMW so no idea as to how to fix that type. The last picture is a view from the top of the two types
The leak was coming from the center where the speedo cable is attached. This was a result of a defective washer/o'ring encased in a metal band inside the 'plastic cylinder. This o'ring is NLA. This o'ring is at the top right of the third picture. The other two o'rings in the same picture was my first attempt at fixing this leak which didn't work.
I searched for a suitable o'ring and the only thing I found is a grommet which fit perfectly over the shaft of the gear and was the same diameter of the indside of the cylinder. Its a snug fit.
Below is a picture of it with the bag (for size purposes if you want to do the same) I bought it a Lowes for about $0.89. The only problem was that it was too thick. So, I cut the grommet in half. You may be able to see from that picture that this grommet has a 'channel/groove in the middle. This is where I cut it.
I left the original o'ring in the cylinder then put this 1/2 grommet on top of it. Then the sleeves goes in holding this 'new o'ring' in place as the gear shaft would turn when driving..
I put the spedo drive back in and drove the car for about 5 miles. Not a drop leaked. Is this a permanent fix? Time will tell. If it lasts a couple of years I'll be happy. I still have 2 1/2 grommets left so that would be 10 years of fix.
This fix may or may not work for you if you have the same problem.
