Sealing of the speedometer drive M40/41/45/46
Volvo PV, 120, 140, P1800, 240, 700
01.12.2021Hint for sealing the speedometer drive at different volvo gearboxes
In many older volvos the mecanical speedometer drive is on the back side of the gearbox. It is moved by a worm running on the main shaft. This Speedometer drives are coordinated to the rear axle differential by the number of teeth on the driving pinion.
If a car is getting older, you will find sometimes leaks at this parts.
These speedometer drives normally have three sealing surfaces:
-The copper ring on the set screw which is holding the speedometer drive.
-An O-ring seal around the housing of the drive.
-A radial seal ring on the shaft of the drive.
The sealing procedere is nearly the same at all of these gearboxes. You only have different versions of sealings.
First you have to unscrew the speedometer shaft, which is fitted with an knurled nut on the speedometer drive.
If oil is leaking out of the speedometer shaft or drive, the radial seal ring is out of order.
Now you have to unscrew the set screw, which is holding the speedometer drive.
Now it`s getting a little excited because the speedometer drive can be adhered to his seat. For example you can take telephone pliers for throwing it off. You should be cautious, don`t damage the thread.
You also can throw it off with the speedometer shaft, but don`t screw it to tightly. If you take a new speedometer shaft, you can make a tool for this from the old one.
Now you have the drive in your hand, take the shaft out of it. The shaft is sealed with a radial seal ring. This seal ring exists in different versions as seen in the picture before. A regular one with a seal seat in the speedometer drive and a flat one which you can see in this picture. This will be pressed in its seat with the knurled nut of the speedometer shaft. Now, if you have changed the radial seal ring and the o-ring seal, you can plug the speedometer drive back in its seat. Therefor check the position of the borehole for the set screw. If it is not in its correct position, you can take a small screwdiver to adjust. Don`t plug the speedometer drive in its seat too hard, the plastic pinion can be destroyed.
Now you have to set the screw with a new copper ring and a little bit liquid seal if it is necessary.
Screw on the speedometer shaft, use a plier for that.
- All notes serve only as an example and do not replace the workshop instructions of the automobile manufacturers! All information is supplied without guarantee!