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Replacing the Marelli wiper motor with a Bosch motor

The wiper I got was described on ebay as for a VW Rabbit, Cabriolet, Jetta 77- 84, Bosch number 039 024 1058.

The motor has the 5 wires and the bent tab that James Seabolt refers to in his guide.

I have it working with 3 wires right now to get low and high speeds and no parking capability. I will get to the electrical later but now will discuss the physical aspects of this mod. I'm not sure if I have a different motor or if the Pininfarina is different underneath that cowl, or both, but I had significantly more to do to get this motor in there.

First, the bolt pattern is the same, sort of, same spacing but upside down. The 3 raised points that mount to the wiper frame or chassis are a different outer diameter. The original mounts are of a diameter that allows them to slide through rubber grommets in the chassis. The Bosch assembly mounts are too large for this. So I had to remove the grommets. This also mounts such that the motor extends to the outboard side as opposed to the inboard which is the way the Marelli mounted.

Click for bigger picture . . .

Next, the mounts are too long so that when mounted with bolts seated, the bolt heads interfere with (as in block) the first link to the wiper assembly. To correct this, I cut 1/4" off of the mounts. This allows the motor to mount closer to the chassis and the shaft to stick through further. This then allows full motion of that first link. A few things to be mindful of here. The more you cut off those mounts, the less threaded material there is for the bolt to hang on to. If you cut too much off, the motor itself will be in contact with the chassis and this you probably do not want. There is one other point and I will get to this further down**. The following shot is before I cut the mounts so you can see how low the shaft is.

Click for bigger picture . . .

To actually mount it, I used a flat washer on the mount, then the chassis, then another flat washer, lock washer and bolt, with threadsealer.

The wiring appears to be quite different in the Pinin and I haven't found a diagram for it yet. There are only five wires, 1 pair is blue/white and blue/red, the other pair is something/something and gray/yellow, and the fifth wire is black/purple which appears to be ground. So far, I have used the second pair for high and low speed positives. I haven't been able to make the park mechanism work yet, but it is at this stage that you would establish the park position.

Now, here is the other point** I was referring to. The fact that the motor now comes off the assembly in the opposite direction causes interference with the pan under the cowl. The less you cut off the mounts, the more interference there is. I used the rounded end of a large ball pean hammer to create a minor indentation in the passenger side of that pan to allow the motor to fit. About 3/8" deep and 2"x3" oval was enough.

There was alot more work here, and I don't know if it's just because I have a Pinin but it is still worth it.

Copyright 2009 CAD Concepts. All rights reserved.
Quick and dirty so I can show what I've been doing with my Pinin.

One day if there's some time I'll try to do a little better!