Brush compatibility


whatscooking
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Brush compatibility

Post by whatscooking »

Recently I went through the alternator on a 82. I replaced the regulator and got the stator and rotor rewound by Ricks. I used new Honda brushes. I hooked my Fluke in at the battery and would get 14.2 V all was well. After around 1000 miles the volt meter would get lazy showing weaker and weaker output. I went back into the alt to find what I said earlier in a post that the slip rings looked like a Nascar track, looked like rubber buildup on the rings when I used a 40 power scope. Shine them up and volts went back up.
Well a trip to Indy last weekend about got me stranded. Volt meter not getting above 12V I noticed when I got there. I pulled the plug in the faring for the headlight and made it home, click click when I got back.
Went into the alt to find that build up again. This time I put in a set of Ricks brushes. I took my knife and did a little scratching on the brush side and could tell there is a difference in brush material, Ricks are of a softer makeup. My Fluke now shows a steadier and constant reading than before but time will tell if this happens again. I know I have good grounds everywhere and I have ran a relay direct off the battery to run the charging and ignition systems to eliminate problems with the original wiring so I know I have good connections.
I have got to believe there is a compatibility problem with the Honda brushes since twice shining the rings allowed the volts to come back up. There is no oil what so ever getting in there.
Last edited by whatscooking on Wed Apr 27, 2016 6:08 am, edited 1 time in total.

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NobleHops
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Re: Brush compatibility

Post by NobleHops »

What about the other end of the alternator? The spring that holds the clutch plates together is notorious for wearing out. A 1-2mm shim at one end of the spring will often restore good function, given all else that you have refurbed. Measure it and see. Consider flattening your clutch plates while you're in that side. Do a few searches on alternators here and you will find lots of threads on that topic.

N.
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daves79x
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Re: Brush compatibility

Post by daves79x »

Sure you're not getting oil into the dry side of the alternator? Sounds like an oil film build-up. Honda brushes are the best, by far, for wear and function.

Dave

whatscooking
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Re: Brush compatibility

Post by whatscooking »

Cleaning the rings have twice allowed output to return. I cannot detect an oil film anywhere in the brush side of the alternator.

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Re: Brush compatibility

Post by FalldownPhil »

+1 with Dave,
Honda brushes are by far the best. The spring should measure very close to 30mm.
Phil
When you are up to your ass in alligators it is sometimes difficult
to remember that your objective was to drain the swamp !!

whatscooking
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Re: Brush compatibility

Post by whatscooking »

Four hundred miles put on and so far the volt reading will hold a steady 14.1 while I ride with my Fluke hooked at the battery. Before start off the next day I check the battery and get a reading of 12.7

whatscooking
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Re: Brush compatibility

Post by whatscooking »

Well at 900 miles the volts have took a dive down. Could one of you take your dial indicator and measure the wobble or the flex that you have on a slip ring plate. When I got the first new rewound rotor there was .033 run out I found on the first time back in and interesting enough 400 miles would dirty the slip rings. The second rewound replacement rotor I got from them now measures .015, interesting now It goes 800-900 miles before all goes to hell. I have put in another call to Ricks Motorsports. .015 don't sound like a lot but at the RPMes these engines turns I can see how the sparks would be a flyin in there.

whatscooking
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Re: Brush compatibility

Post by whatscooking »

I realize that I am not the most articulated person here but I do have a habit of getting to the bottom a problem. I have put over 3000 miles on this bike this year. The bike has fins broken off the engine and scrapes and scuffs but I have got her running extra good and have made her my daily rider. I have other motorcycles but I like the thrill of the CBX.
I believe I have a valid idea on why this problem keeps happening but I was told by the rebuilder of the rotor, the first time that I called them, that this wobble I speak of is in spec. When they are reassembling the rotor after a rewind they are pressing this slip ring plate on and getting an uneven surface for the brushes to run on making it impossible for the brushes to stay in contact thus causing arching which means heat and smearing on the slip rings. I know this guy, he has a rail that he has built and drag races at Indianapolis Raceway Park. I took this alternator to him, I needed another set of eyes. He just smiled and said the brushes would only be hitting the high spots at speed.
I would just like for someone to open up a alternator that you have off a engine, prefer one that was working properly, split it open put it slip clutch down and see what kind of reading you have on the slip rings. Like I said the first one I got was .033 the second one is .015.

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Re: Brush compatibility

Post by Jim-Jim »

Let me see if I fully understand what you are describing as your problem:
Overall, you're saying that the Rotor is 'wobbling' in the shaft? (Runout)
If that IS what you are saying, then the problem may be in how the Rotor is pressed on the shaft (it's a taper fit). I would look more closely at the shaft. If one Rotor measured .015 and another measured .033, I would be concerned about that shaft.
It's probably not practical to see this in action so I would disassemble the Alternator and pull the Rotor off the shaft and chuck the shaft up in a lathe and see if the taper is smooth and continuous. I would then mount the Rotor on the shaft, put it in the lathe and check the face of the Rotor for runout. If there is any, I would turn a smooth surface across the face of the rotor, thus eliminating any runout. If you don't have a lathe (most of us don't), find a local hobby/amateur machinist to give you a hand. In a few years on these forums, I've never seen anyone with this problem and Ricks has an excellent reputation (but I would like to know how they arrived at any 'spec'; I've never seen one listed).
Let us know how this proceeds.
Jim-Jim

whatscooking
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Re: Brush compatibility

Post by whatscooking »

The rotor is on it's way back to Rick's. This wobble I say that I see is not the rotor itself on the shaft but the plate that is made onto the end of the rotor, the slip ring plate. If you look perpendicular at the rotor while on the shaft my plate looks like a roller coaster ride. I have an idea that they are distorting this plate when they are pressing the rotor back together after they rewind them. Not only would a dip of .015 drop but it would also bat the brushes up which is how the surface looks.

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Re: Brush compatibility

Post by daves79x »

You might be on to something there.

Dave

whatscooking
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Re: Brush compatibility

Post by whatscooking »

What is the name of the toy that has a ping pong paddle with a rubber band and a ball attached to it. This is what I believe is going on.

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Re: Brush compatibility

Post by Jim-Jim »

Ah, so if I understand more fully, then if the Rotor is rotated on the shaft, the back surface has NO runout on it (perpendicular to the axis of the shaft) while the front (slip ring) surface) DOES have runout (?)
If my (corrected) understanding is correct, then you, indeed, have a defective Rotor. IMHO, there should be ZERO runout (maybe a 'thou or two but no more). Because the face of the Rotor is so large, this surface wobble would be exaggerated mostly at the outer edge. I would wonder that the brush spring would not keep the brush pressed down on the surface evenly, especially at lower rpms. I have never seen any measurement for brush tension but I think .015 should NOT bounce the brushes off the surface; .033 probably would.
What I don't understand is why Rick's would dispute this. Surely they could mount the Rotor on a shaft and see the runout for themselves.
Very interesting problem; looking forward to end solution.

whatscooking
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Re: Brush compatibility

Post by whatscooking »

Got the rotor back, installed and test drove 130 miles today. Rick put the rotor in a lathe and got the surface flat. He wanted me to send the shaft with the rotor to make everything true. 14.22 was the highest volts I saw, and it will hold there. I have a Fluke meter in the glove box, a little higher on the volts than before. I just came back from checking the surface charge after the bike has sit for three hours and it has 12.8 plus volts on the battery.
It has taken eight hundred miles twice before it failed so I really don't know yet but I have a feeling that even .015 is enough to bounce the brushes and cause this. If I figured this correctly at 6,000 RPM that is 100 RPM per sec, more than those little springs on the brushes can handle. The slip ring surface looked like you had drug a welding rod over them. Now when I hook the fluke in on the black and white wires to check resistance, plug unplugged, with the engine running I see eight or nine ohm, before the reading would be all over the place.

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Re: Brush compatibility

Post by Larry Zimmer »

Thanks for the follow-up! Will be most interested how things are after 1000 miles, or so. Voltages sound about spot-on.
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