Adapting 5 wire 128 motor to the Spider (6 wire)

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miker
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Adapting 5 wire 128 motor to the Spider (6 wire)

Post by miker » Fri Sep 13, 2019 1:40 am

When I've had some sleep, I can probably figure this out, but just in case someone has done this...

My windshield wipers got really, really slow after working for many years.

So, I lubed all the linkages, and took apart the motor and cleaned the park relay contacts, and used some spray electrical cleaner on the brushes and put it all back together. After some fits/starts it started to work consistently enough that I buttoned it all up and thought I was done. Then I found a small ball-point style spring on my workbench. This appears to have been sandwiched between the motor wiring cap and the base and I have no idea what it's purpose is. Anyway, I put it in where it seems to go and now the motor doesn't work at all. There was also a thin washer that seems to have appeared although I don't know where in the motor, if at all, it seems to go. There are no starter-like parts diagrams for these things.

As it turns out, I have a brand new Marelli 5 wire motor that appears to have been for a Fiat 128. I don't even recall buying it, when, how much I paid, etc. But it's here, it's new, and I'm going to make it work. The size/shape/mounting all seem identical.

It has the same connector as the Spider, with one less contact. I'm pretty sure from my 128 days that the difference between these is the intermittent function (Spider has it, 128 does not).

If anyone has done this swap, chime in, I'll post my results as I figure this out.
MikeR (mirafiori.com since 1995)


1977 Fiat 124 Spider
Previously owned:
2012 Fiat 500 Prima Edizione #236 (now owned by my son David)
'86 Bertone X1/9
'81 Fiat Spider 2000 #236
'78 Fiat 131 four door
'76 Fiat 128 4 door
'74 Fiat 128 4 door
kendall
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Re: Adapting 5 wire 128 motor to the Spider (6 wire)

Post by kendall » Fri Sep 13, 2019 1:45 am

Just a quick "dummy check" type question. I haven't taken one of these motors apart but the first place I think of where you would have a spring in a motor is behind a brush so it contacts the commutator bar. Is it possible you left it out? If the brushes are not in a configuration like that you can disregard this.
1975 Fiat 124 Spider
1982 Mercedes Benz 300D Turbodiesel
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Re: Adapting 5 wire 128 motor to the Spider (6 wire)

Post by miker » Fri Sep 13, 2019 10:30 am

No, it was not a brush spring.

I was able to find the part number (very faded) on the box of the new one - 9924387. There is one on Ebay now for $72.90 with free shipping, so if I make this work, someone else with a Spider can get a great deal. Midwest Bayless sells them for $108.79 which is still much less than the Spider motor.

The five wires I do have on this motor (colors, anyway) seem to be a subset of what is in the six wire, but it does not work either. At some point I blew a fuse (easy check- the heater fan motor does not work and it's on the same circuit).

So, it's off to buy some 8 amp fuses since I have everything but :).
MikeR (mirafiori.com since 1995)


1977 Fiat 124 Spider
Previously owned:
2012 Fiat 500 Prima Edizione #236 (now owned by my son David)
'86 Bertone X1/9
'81 Fiat Spider 2000 #236
'78 Fiat 131 four door
'76 Fiat 128 4 door
'74 Fiat 128 4 door
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miker
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Posts: 4175
Joined: Sun Jan 24, 2016 7:55 pm
Last Name: Richmond
First Name: Mike

Re: Adapting 5 wire 128 motor to the Spider (6 wire)

Post by miker » Fri Sep 13, 2019 10:42 pm

So the 128 motor connector has five wires in the same housing as the six wires in the Spider 6 wire motor. The motors on the outside are the same size/shape, no differences in mounting.

The colors of the 128 wires and where they are in the housing are the same as the colors of the wires in the 124 motor. There is just one less wire.

But if you take off the plastic caps over the wires on the motor you find out that the same color wires go to different places in the 128 motor than they do in the 124 motor. So when I just plugged in the 128 motor, I was creating a dead short.

I used a soldering iron (not a gun) and a desoldering suction tool to remove the 128 5 wire harness then moved the 124 6 wire harness over to the new 128 motor, using some notes I made to make sure I got the wires in the right spot.

No more shorts but the new motor didn't run any better than the old one had before I took it apart (and broke it). But in any event, if you do need a new 124 motor, you can save some money by buying the 128 motor and moving the 6 wire harness.
MikeR (mirafiori.com since 1995)


1977 Fiat 124 Spider
Previously owned:
2012 Fiat 500 Prima Edizione #236 (now owned by my son David)
'86 Bertone X1/9
'81 Fiat Spider 2000 #236
'78 Fiat 131 four door
'76 Fiat 128 4 door
'74 Fiat 128 4 door
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