Preludes from 1988 and 1989 have a mechanic speedpulse which is transferred to the cockpit by a rotating cable. Preludes from 1990 and 1991 have an electronic speedpulse, which is transferred electronically. This pulse is generated by the speed sensor, mounted on top of the transmission. On this picture you see my old speed sensor from the 88-89 type. Because I will use a cockpit from the 90-91 type, that's not going to work on this speedsensor.

I'll have to remove my old speedsensor, buy the new type and mount it in my tranny. The removal is pretty straightforward. The sensor is only mounted onto the transmission with one screw. Once this is unscrewed, a little twisting and turning will get the sensor right out.

On the junkyard I spotted a Prelude from 1990-1991 with an intact speedsensor. For 15 euro the sensor was mine. This new type sensor was as easy to unmount as the old type - again just one screw held it in place. Beside you clearly see the differences between the two types. The left one is the mechanic old type, the right one being the electronic new type.

Fact is, the new speedsensor won't just fit in my transmission. Although the lower part (going into the transmission) of the two sensor types are equal, the mounting points don't match. So I'll have to combine the lower part of my old sensor with the upper part of the new one. Unfortunately, they cannot easily be swapped. The mounting points do match here, but the shafts in the lower parts are different. That's why the lower part has to be disassambled to swap shafts.

As you can see beside, one pin is considerably longer than the other. The longest of the two was seated in the mechanical old type sensor, and thus has to be replaced by the shorter one coming from the electrical new type. Besides the length, they are equal.

These are the two different lower parts. From the bottom to the rubber seal they are equal. Just above the seal there's a support on the right sensor (88-89). I need to use that support because it mounts to the correct spot on the transmission. In this right lower part the (shorter) shaft of the left one (90-91) is needed. And on top of the right part, the top of the left one (90-91) is needed.

While on the junkyard, I also took the support bracket for the shifter cables. As I had anticipated, this turned out to be different from the old type I already had. Due to the top of the electronic sensor being much bigger, the old bracket didn't fit anymore at all. This new bracket fits way better, but is still too close to the sensor. That's why I grinded off some material on the side to give it a clearance of half a millimeter.

This is how it's going to be installed. It's quite closely spaced, but there's no movement in these parts and at least I didn't have to drill additional holes in the gearbox.

Test fitting the shifter cables... and they fit perfectly. Before definitely bolting anything to the gearbox, I still have to clean the speedsensor and the bracket will be powdercoated black. And finally, I'll have to do some rewiring.

Here it is, the (modified) speedsensor I'm going to use, now cleaned.