swap rotor 40 hp / 20 hp

[Michawilden]

Hi There,

I am having problems with a, new to me, 1992 johnson 20 hp starter. Done some voltage drop tests. There is no voltage drop over all connections. Battery puts out 12.5 Volts. It is the battery from my car and that one starts fine so I don't suspect the battery. However, the starter has no power. Can barely get it past one turn with the plugs in. Can turn it without the plugs but not the speed I am used to. I opened the starter motor and cleaned it out. It has farely worn brushes and the unit that holds the brushes is split. It is not possible to get an (cheap ) replacement for this part or the brushes so I am looking into second hand starters. I find it near impossible to find a starter for a 20 hp. The only one available is a 1988 40 hp starter (partnumber 389275). I was wondering if I can swap out the internals and put this in the 20 hp stator. Anybody any experience with this?
I live in the Netherlands, a replacement 20 hp starter is 200 dollars and a set of brushes is not available.

This is the 20 hp starter

 

[hardwater fisherman]

Arco marine sells a repair kit. Sold here at IBOATS for under 30 dollars. Goggle Arco marine repair kit SR376.

 

[racerone]

I doubt the 40 hp armature will fit part number is different.----New brushes are available and I install them all the time $ 4.50 a set.----Take an ohm reading from the shaft to the commutator, should read infinity.-----Your home town in Holland is ???

 

[Michawilden]

I did an ohm reading on the commutator and the shaft and on the individual commutator bars. No discrepancy was discovered. I managed to glue the unit that holds the brushes but this is just not sufficient. Starter still does not have enough power. The price to get the part here is 50 euro, about 65 dollar. I want to try if I can get brushes in simmilar shape and put these in the starter to see if this works out. If it doesn't than I will buy the whole unit. New aftermarket starter is 136 euro.

 

[Michawilden]

For the ones interested. I bought brushes for an landrover. These where similar in shape and with some grinding and shaping I managed to fit them in the holder. It was about half an hour work but that did it for the starter. Ran like a champ again. Total repair costs where 9 euro. So next time I have a faulty starter I will try this again first. ( this wasn't the first time I had this problem)