KT 17 starter rebuild?

[midpack 942]

I was thinking this starter needed new brushes but looking at them, I'm not sure. 

Would you run these brushes?

[953 nut 57,078]

Brushes look good from here. What was going on to make you think a rebuild was needed?

[oliver2-44 10,148]

Brushes look Ok,

Do the brush spring feel like the each have the same compressive force, or does one feel weaker?

The reason I ask, is there seems to be a fair amount of black carbon buildup on the commutator.  A very fine microscopic film of black is normal and needed.  But the picture makes it look like there is more than a normal film.  A weak spring might cause this.

I suggest, before you reassemble that you clean the copper commutator with scotch brite. Do not use sand paper.

 

For what its worth!

From working on Hydro Generators I learned that the brushes do not physically touch the commutator. 

They ride on a film of gas created by the electrical flow from the carbon to the copper. 

This "gas film" needs a slight film of carbon on the copper. 

We used specially made giant "rubber erasers" on an insulated holder to slightly clean the commutators monthly or as needed. 

This was done done with the the generator on line and a steady hand. 

500v Dc can be quite a torch when there is a brush failure!

[midpack 942]

11 hours ago, 953 nut said:

Brushes look good from here. What was going on to make you think a rebuild was needed?

Well, the bendix definitely needed replacement and I think that's why I had it in the parts "bucket". Once I got that off I figured I'd take a look inside. One bolt was easy, I had to be really careful with the 2nd one. It would have been sooooooo easy to break, but I got it! 

[gwest_ca-(File Mod) 11,195]

A dab of grease in the end bushings usually speeds the motors up.

Polish up the rim of the end cap. That metal to metal contact with the motor housing is what powers (grounds) the motor.

[midpack 942]

50 minutes ago, gwest_ca said:

A dab of grease in the end bushings usually speeds the motors up.

Polish up the rim of the end cap. That metal to metal contact with the motor housing is what powers (grounds) the motor.

Thanks!

[kpinnc 13,284]

14 hours ago, gwest_ca said:

A dab of grease in the end bushings usually speeds the motors up.

 

Also makes for a much quieter starter. Once that bushing gets dry, that style starter makes some horrible squeals!

[ebinmaine 70,046]

21 hours ago, gwest_ca said:

A dab of grease in the end bushings usually speeds the motors up.

Polish up the rim of the end cap. That metal to metal contact with the motor housing is what powers (grounds) the motor.

 

6 hours ago, kpinnc said:

 

Also makes for a much quieter starter. Once that bushing gets dry, that style starter makes some horrible squeals!

 

 

Some good information there.  Thanks folks.  

 

 

[WHX?? 50,132]

On 1/3/2025 at 5:03 AM, oliver2-44 said:

clean the copper commutator with scotch brite.

and don't forget to clean in between the segments ... under cut if required... 

[oliver2-44 10,148]

1 hour ago, WHX?? said:

and don't forget to clean in between the segments ... under cut if required... 

 

and do it very carefully

[Handy Don 13,148]

On 1/4/2025 at 2:29 PM, oliver2-44 said:

 

and do it very carefully

 More is NOT better in this situation. When done undercutting, be sure to use fine emory paper to smooth any burrs on the edges of the commutator contacts and thoroughly blow out the entire unit with compressed air at moderate pressure. 

Edited January 5 by Handy Don