Alternator Rebuild


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ajs350
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Alternator Rebuild

Post by ajs350 »

My 80 alternator has a sporadic rattle when returning to idle after a quick rev; sounds like a stick on the spokes of a wheel. It does not happen all of the time but being as this is a new bike to me I thought I'd check it out.

(I also thought I'd document all of this in the hope that it helps someone else who does the job next. I've only had my 80 for 3 weeks but this forum and its members have been such a help. I'm not sure where I would be on my CBX without the forum and all who have answered my questions.)

From previous posts it seemed like the rattle was either the clutch plates or bearings. While addressing these two things I thought I'd replace the brushes and give the cases a polish.

Supplies needed: 2 bearings 6201 and 6203, bearing oil seal, alternator rotor spindle o-ring, alternator cover gasket, rear case rubber seal, wet and dry paper 120, 800, 1000, 1500 and 2000 grit, Mothers aluminum polish.

First disconnect the alternator plug from behind the right side panel.
Remove the front sproket cover as you'll need the space to get the alternator wire.
Remove the alternator cover bolts at the 10, 2 and 6 o'clock positions. Unscrew each one a turn at a time as the alternator is under pressure from the spring pressing against the clutch plates.
While holding the alternator with one hand pull through the alternator wire. This is where the removal of the sprocket cover will help.
With the alternator on the bench undo the remaining 3 bolts from the outer case.
Gently pull the outer case off as the alternator brush holder is attached inside.
This is what the inner case looks like full of brush dust.

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Undo the 2 brush holder bolts and remove the cover.

The inner cover will be then left as you see below with the alternator intact. To get to the inner bearing you need to remove the nut holding on the driven clutch plate. When I tried to do this the nut that you see here on the rotor spindle came off instead!
Only way to get the clutch plate nut off is with an air impact wrench. I took mine to my local car repair shop and Brrrrrp, Brrrrp, Brrrrp and it was off!

You can now pull on the spindle you see here and the rotor will come out.
With a little jiggling the stator will also come free.

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Next up is to remove the inner bearing retainer plate. The 3 philips screws are on tight so have someone hold the case while you give your impact wrench a good sharp whack with a hammer.

You also need to get rid of that pesky gasket which is stuck on. I used Permatex gasket remover to help soften up the gasket and then a wood chisel and a scotch brite pad.

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Removing the bearing from the outer case was pretty straight forward which surprised me after viewing many posts where it was stuck in hard. I heated mine with a propane tourch for a minute and it just dropped out. Lucky me.

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This picture shows one of the clutch plates which ressembles a worn brake rotor.

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I used 120 grit wet and dry with WD40 as lubricant and in a figure of 8 pattern sanded down both plates until the majority of the scoring had been removed.

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Now to the case polishing. To get the original paint off I used paintstripper. Dab it on and leave for an hour to do it's work. It will get most of the paint off but in the nooks and crannies you will have to use wet and dry to remove it completely.

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I'd bought a cheap polishing kit from Eastwood which had worked well on my clutch case but on the alternator cover it was not so successful due to all the little corners that needed to be polished. I'd read in another post to use wet and dry and Mothers polish so I gave it a shot. I went from 1000 grit to 1500 and then 2000. It's a bit worrying at first because it makes the case look very dull but with the Mothers it polished up great. Better than the clutch cover actually.

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Before putting everything back together you'll need to seat the new bearings and oil seal. I put the bearings in the freezer over night and then in the morning (when the wife was out) set the oven at 250 and put both cases in for 30 minutes. Both bearings just dropped in. No tools needed at all. The oil seal was pressed in using the back side of a large socket. The oil seal o-ring can now be replaced on the alternator shaft.

Replace the bearing retainer and tighten up the 3 screws with your impact driver.
Now insert the alternator rotor shaft through the inner case bearing and oil seal as you see below.

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Put back on the clutch plate and tighten the nut to 30 ft lbs.

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Next replace the brushes. Here's an old and a new one. My originals were not that worn but I decided to replace them anyway and keep the old ones as spares in my tool pouch.

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Now refit the stator to the inner case aligning the wire boot with the flat area on the case that corresponds with the boot slot on the outer case.

Position the brush holder in the outer case and tighten up the two 10mm bolts.

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Match the inner and outer cases together and replace the 3 bolts that hold the 2 halfs.

Insert the large diameter rubber seal into its grove on the back side of the inner case.

Thread the alternator wire and plug between the engine and carbs towards the right side.

Position the alternator against the engine and replace the other 3 bolts tightening each one in turn until the alternator is tight agianst the engine.

Re-attach the alternator cable socket to its counterpart behind the right side cover.

Job done!

4350

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Don
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Re: Alternator Rebuild

Post by Don »

Excellent write-up - Very detailed and great pictures. I'm sure it will help many readers in the future. Once the discussion has run it's course, we'll move this to the 'Best of Electrical' forum for posterity. Jan is always looking for detailed 'How To' articles for future issues of the CBX Express . . . . you might consider sending it to him

Your clutch disks may look like 'worn brake rotors' to you, but when it comes to CBX alternator clutch plates, those are about as new as you can get . . . . without installing NOS parts of course - You'll get another 50,000 miles out of those . . . . at least

But . . . . did it solve your problem? Everything in the photos looks like a very low mile, well cared for bike - I didn't see anything that looked like it had or was about to fail. The photos look a lot like those in the factory manual

Don

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Re: Alternator Rebuild

Post by NobleHops »

Fantastic write-up, and an excellent contribution to the knowledge base. Thank you very much for taking the time and doing such a thorough, well documented job!

N.
Nils Menten
Tucson, Arizona, USA '80 CBX, sort-of restored :-)

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Re: Alternator Rebuild

Post by ajs350 »

Don, As for solving the problem I'll need to wait a bit to be sure as the noise came and went anyway. At this point the Alternator is charging at 13 and no noises so far. If it warms up a bit here tomorrow I'll take it out for a longer ride.

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Re: Alternator Rebuild

Post by daves79x »

Great job on the write-up and pics. I'll tell you from working with these things for 30 years what you'll likely find. Your alternator was likely chirping on decel after a high speed run (such as running down the freeway). Many of them do in that instance and pulling in the clutch will make it disappear. Even after all you did and the couple of additional things I'll add here, some still do it sometimes under the above conditions.

The thing now is that you've removed even more clutch material than was worn off. They still look good and what you did is a good thing. You now will likely have to shim your spring with another steel washer to make up for what had been removed. Then the spring may have sagged a bit also and that further reduces the needed pressure on the plates. Ideally, you should replace the spring with a new one and add a washer. Problem is that the spring just became NLA from Honda and the washer hasn't been available for years. You can find a sutable washer to shim with but the spring is a problem.

A new spring measures 31mm. The stock steel washer is 1mm thick. Springs that have been squished for 30 years, but not overheated or otherwise abused will like measure no more than 29mm. I've seen many springs sagged much more than 1 or 2mm. Anyway, right there you need 2mm more shim to duplicate new. Then take 1 or 2mm from the clutch plates and that requires more shimming. Any alternator can benefit from at least one more shim washer and as you can see, probably quite a few more. I wouldn't shim more than 3mm, or you can get into coil bind, which actually may not be a bad thing, since these will run the rotor direct without need for clutch slippage.

So my point is that, once you have renewed the bearings, spring sag and clutch thickness (or lack of) play the biggest role in whether the clutch chirps on deceleration. Remember, the clutch is there to slip in some instances.

Sorry for hijacking your excellent article, but I wanted to make you aware of the above in case your alternator still chirps.

Dave

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Re: Alternator Rebuild

Post by ajs350 »

Dave, Great addition. I will measure my spring and shim accordingly. Thanks. Ross

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Re: Alternator Rebuild

Post by daves79x »

By-the-by, if you want to renew the black background of the 'HONDA' on your crank end caps, it's easy to do. Many guys do what you did and polish them completely and let them that way. If you want the black background, just mask off the outside carefully and spray the entire logo indent with satin black. The take a thin straight edge, wrap one edge tightly with a heavy paper towel sprayed with brake cleaner and drag that over the HONDA to expose the polished letters. It really works well and looks just like the original.

But if you like the covers totally polished - that's great too. Great looking bike you have there!

Dave

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Re: Alternator Rebuild

Post by SteveG »

Excellent! Thanks for taking the time to post your write up with the SUPER pics. If a picture is worth a thousand words, I just read War and Peace. OK, the Cliff Notes :oops:

What are you going to fix next?

Steve
82 CBX, 82 CB900F Project, 81 CB900(985)F, 79 CB750(810)F, 06 Wee-Strom

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Re: Alternator Rebuild

Post by sixofsix »

Yes, excellent article! I just tie a string onto the alternator wires when removing the alternator from the bike. The string threads through the frame, then you un-tie it to do the rebuild and use the string to re-thread the wire through the frame..easy-pleasy.

Tony

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Re: Alternator Rebuild

Post by Don »

A word of caution about sanding down the clutch plates - In many cases, you may actually be doing more harm than good

If your plates are badly worn and you sand away 50% of the ridges on each plate, the net result is that you'd have very little friction coupling left. The grooves remaining in each plate would no longer have the matching ridges from the other plate touching them becase you sanded away all the high spots which leaves you with flat sanded spots on each plate matching up with grooves on the other plate. . . . you newly polished plates could have only a small percentage of matching friction surface left, which would cause increased slipping and much faster wear

Probably a better solution than sanding them would be to leave them alone and add a thin shim to make up for the wear already on them

Don

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Re: Alternator Rebuild

Post by SanDogDewey »

Nice write up. I would also recommend gently cleaning the copper pickup strips on the rotor with some very fine steel wool or scotch pad. Don't forget to lube up the couplings with Moly B prior to installing it back into the engine.
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Re: Alternator Rebuild

Post by NobleHops »

Mike Nixon posted a 'secret' tech bulletin from Honda on his site indicating that one of those two clutch plates was manufactured wrong, resulting in reduced contact surface. Lapping them as was indicated restored mine to flat, increasing the contact area significantly, and necessitating shimming the spring to compensate. His thoughts, and a link to the bulletin are here:

http://www.motorcycleproject.com/motorc ... lutch.html

There are pictures of the before and after on my Smugmug site. Apologies for the inconsistency of the photographs, but you scan still clearly see the difference:

Before:

Image

After:

Image

Not to speak for him but ISTR that Mike is also of opinion that one should NOT lube these plates on reassembly, but I imagine they are pretty quiet when they are.

N.
Nils Menten
Tucson, Arizona, USA '80 CBX, sort-of restored :-)

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Re: Alternator Rebuild

Post by EMS »

I would agree with the "not lube" procedure.

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Re: Alternator Rebuild

Post by NobleHops »

Don wrote:A word of caution about sanding down the clutch plates - In many cases, you may actually be doing more harm than good

If your plates are badly worn and you sand away 50% of the ridges on each plate, the net result is that you'd have very little friction coupling left. The grooves remaining in each plate would no longer have the matching ridges from the other plate touching them becase you sanded away all the high spots which leaves you with flat sanded spots on each plate matching up with grooves on the other plate. . . . you newly polished plates could have only a small percentage of matching friction surface left, which would cause increased slipping and much faster wear

Probably a better solution than sanding them would be to leave them alone and add a thin shim to make up for the wear already on them

Don
Don,

Are you thinking of drive clutch plates? In the alternator (as pictured) one side is flat, the other has 4 grooves. Not what you described above.

N.
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Re: Alternator Rebuild

Post by EMS »

NilsMenten wrote: Are you thinking of drive clutch plates? In the alternator (as pictured) one side is flat, the other has 4 grooves. Not what you described above.

N.

The way I understood it, Don was talking about this: On worn plates, the grooves match up, i.e.: a "valley" lines up with a raised part and the surfaces make contact. (left)
When you grind off the tips of the raised parts, the flat portions do no longer reach to the bottoms of the "valleys" and you lose contact surface (right)

Did I get this right Don?

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