flywheel rubbing on timing plate

[rockytop93]

1959 johnson 40 hp. Engine makes kind of a clattering noise. If I turn the flywheel by hand, at one point of the revolution it will contact somewhere on the timing plate. At that point, if I rock the fw back and forth the timing plate will rock with it. It only does this for a short duration of the revolution. The only evidence I can see is scrape marks on the fw magnet and on one of the coil ends. I have tried reposioning the coil. No better.Anyone with any idea why this is happening? Thanks in advance, Allen

 

[Paul Moir]

Re: flywheel rubbing on timing plate

It's a common issue with that magneto system. The armature plate ends up loose and wobbles too much, allowing the coils to strike the flywheel. This causes two problems - first, that the engine is very noisy. Second, it causes the ignition timing to go off since the points move in relation to the cam.
The coils must be set to be even with the machined bosses they sit on. That is to say, surface A and Surface B:

Fortunately, Joe Reeves has come up with a excellent solution to wobbly armature plates which works great and costs nothing:
Click here and look for the photo

40hp engines didn't come out until 1960, before that they were 35hp. If you have the small flywheel nut that takes a 7/8" wrench it must be torqued to 65 ft/lbs. If it takes a 1"-1/16 wrench it needs to be torqued to 105ft/lbs

 

[rockytop93]

Re: flywheel rubbing on timing plate

1959 johnson 40 hp. Engine makes kind of a clattering noise. If I turn the flywheel by hand, at one point of the revolution it will contact somewhere on the timing plate. At that point, if I rock the fw back and forth the timing plate will rock with it. It only does this for a short duration of the revolution. The only evidence I can see is scrape marks on the fw magnet and on one of the coil ends. I have tried reposioning the coil. No better.Anyone with any idea why this is happening? Thanks in advance, Allen

 

[rockytop93]

Re: flywheel rubbing on timing plate

Thanks Paul, something I would not have thought of. Will give it a try tomarrow. Great post thanks a lot, It is a 40 hp but I do not know the year. I bought the power head at a salvage yard, but the model # was gone. I replaced the 35 with it. Allen

 

[Paul Moir]

Re: flywheel rubbing on timing plate

I see, that makes sense then.

Very few 40hp engines were made with the crankshaft that take 65 ft/lbs, and even fewer that actually survived since they caused serious trouble.

As for dating the engine, if it's set up for the fuel pump that mounts directly to the bypass cover, it's '63+. Carb without an adjustable high speed mixture adjustment is '64+. There's a few other things.

 

[sunnyskyguy]

Re: flywheel rubbing on timing plate

what is the solution here? the link is dead

Fortunately, Joe Reeves has come up with a excellent solution to wobbly armature plates which works great and costs nothing:
Click here and look for the photo
(near bottom of page)
http://forums.iboats.com/bbBoard.cgi?a=viewthread;fid=28;gtid=1135295;gpid=1136240#gpid1136240

I have a ~3deg of wobble (20~40 thou on magneto)

 

[Sea18Horse]

Re: flywheel rubbing on timing plate

Here's a post by Joe Reeves on the subject;

"(Magneto Armature Plate)
(J. Reeves)

If the armature plate has a a loose fitting, wobbling motion (the plate that the points, coils etc are attached to), it is usually caused by a slightly worn support ring. This allows the point setting to change erratically as the armature plate turns.

The cure is to remove the armature plate so that the support which is attached to the powerhead with 4 screws is visible. Then, with a screwdriver and hammer, or some tool of your choosing, and looking straight down at the support ring, make an indentation at what would be called the 12, 3, 6, and 9 O'clock positions. Install the armature plate and check for a smooth turning wobble free movement.

You may need to do that procedure a few times to obtain the proper fit (not too tight, not too loose), but it's worth the effort.

Use a small amount of anti corrosive grease between the aluminum ring and the brass support plate and also on the brass bushing of the armature plate when all is well."

 

[sunnyskyguy]

Re: flywheel rubbing on timing plate

the supporting brass ring seems to be flat. Not sure what putting an indent accomplishes to wobble other than putting a nick in the brass or adding surface runout. I noticed there is a retainer ring inside the brass plate which has some debris and grease underneath. Does this also contribute to wobble? Hmm

yet it wobbles in every angle with the 4 tray mounting bolts removed from the floating washer that rides on a crankshaft inner hidden surface. So that only applies when it is assembled. So is it supposed to wobble and float on a smooth surface and perhaps the crankshaft debris is creating the wobble which may be normal.

Perhaps lowering the brass ring puts more pressure on the inner ring and that slack is what may cause the wobble. I think I understand. Now I need a broad punch to lower that ring around the clock.

 

[Sea18Horse]

Re: flywheel rubbing on timing plate

By Jorge I think he's got it!

I might advise to go easy. I'm guessing it's easy to take up the slack. but a lot harder to get some back if you go too far!

Cheers................Todd

 

[sunnyskyguy]

Re: flywheel rubbing on timing plate

that inner ring seems to have too much slack. I found some recent broken keyway tiny bit, but that didn't cause any slack. So I cleaned it out with wd40, next find some anti-corrosive grease.

The inner ring slack must be almost 60~100 mil. and the brass plate is ~ 20mil? the radial slack on the magneto hub is maybe 5~10 mil. with some inner wear marks. So it would seem it is better to prevent wobble with clean grease and a smooth surface rather than restrict wobble with an irregular depressed plate surface.

 

[sunnyskyguy]

Re: flywheel rubbing on timing plate

I'm afraid to take up the slack by bending the brass stator ring more than its thickness by 3x. I read others tried brass sheetmetal shim inside the brss stator race to reduce the gap and restrict the wiggle. but then the aluminum inner ring will probably chew that up quick.

a little worried of causing more damage than fixing it.

ideas?

Cheers
Tony in Toronto

 

[Joe Reeves]

Re: flywheel rubbing on timing plate

The proper method, if you care to spend the $$$ is to purchase a new magneto ring (303277) and support(303278), present list price is approximately $112.95.

The method of mine, as entered by Sea18Horse, has been used by myself and many others since 1960 that I'm aware of with great success, resulting in a financial savings to many boaters. Simply cleaning and greasing will result in absolutely no improvement so don't waste your time.

You asked a question and have been given a logical answer. I fail to see your logic UNLESS you intend to install a new ring and support.

Occasionally my wife will ask me a question as how to do this or that, the this or that being something that I've done hundreds of times and done to perfection..... something I could do in my sleep without error. However, she will then argure that there must be some other way to do it. This reminds me of one of those times.

 

[sunnyskyguy]

Re: flywheel rubbing on timing plate

i agree.

but the magnet rotor rides on the flat brass stator and depressing the edge would not depress the stronger outer shoulder as much, so I am wondering .

How much slack on the inner ring to brass stator is too much to correct using this method.?

I appreciate your wisdom.

If my 60~100 mil slack is excessive , I think I can get the parts for about the same as I got the flywheel today for $75. But the 4 fat panhead screws wont come off. Bad grip on big blade and wont budge before slipping. Otherwise I would have replaced all these with used parts too.

 

[sunnyskyguy]

Re: flywheel rubbing on timing plate

Thanks for your help. I could not fix it to my satisfaction, due to my inexperience in light taps on 4 corners. but I probably could fix it in another 4 iterations. (my fault overdid it 1st time)

But I got rid of all the wobble except in certain magneto positions one one side and now its a tad sticky in 3 other parts. Since the torque is low on the magneto retraction assy, I am afraid it might restrict full end stop. but just guessing.

I had no spark last time I checked a week ago and since then replaced flywheel, coils, sparkplugs, wires and cleaned /gapped points, but the wobble was terrible. Coil resistance to plugs is 6kohm to 8Kohm and I can verify current induced into sparkplugs with an ohm meter and see the contacts closed by resistance being more constant and changing due to slow rotation when open. So that is why I am addressing wobble.


But I get the idea... great advice. I will pickup an undamaged used brass stator plate tomorrow... and some non corrosive grease.

Two new related questions (I hope its not too far off-topic for this thread.)

1) I noticed that the ignition points dont ride the cam ride all the way around the cam and just on the lobes.. Is this normal? Gapped to 20 mil ok though. and new wick inserted, although limpy.

2) should hand rotation cause a healthy spark in twilight? got nothing visible even with starter although I did have it running once recently with difficulty starting.


Cheers

 

[sunnyskyguy]

Re: flywheel rubbing on timing plate

? used $75 flywheel now fits perfectly with no runout and perfect keyway snugness, torqued to spec 105 ft-lb and the starter teeth were virgin.
? Replacement brass ring $20 that supports magneto tray still wobbled, so I analyzed the wear and determined it was the aluminum surface underside of the magneto tray that was worn, (wished I hadn't tapped it in the 1st place)
? so I grinded about 10 mil from the tray bearing shoulder that was created by 40 years of throttle wear on the surface until smooth, polished mating surfaces (alum and brass ring) and then used a custom 10 mill polycarbonate shim, packed with marine grease( washer shim cut like an annular ring from a coke bottle (polycarbonate)
? ,,,, now the magneto tray rotates smoothly with no tilt/wobble?and the mating surfaces are very smooth. *hope it works*
? removed generator and used marine metal epoxy to repair broken aluminum bracket *hope it works* (broken by previous owner)
? used coke bottle material to gap the points to 20 mil precisely. Since the new plugs were 30 mill using 3 shims, each thickness was 10 mil.
? Assembled everything and rotated flywheel very, very slowly and felt sparkplug pulse with hand *Yeaaaaa* with zero wobble and also at top dead center in idle position. (I think thats correct)

? This magneto rotation is very fussy and I made sure the spark plug wires and magneto wires move smoothly without snagging, rubbing or drag

? Next .. repair ignition switch kill switch wiring/contacts to make sure I can *stop* engine next time, now that I *think* I can start it ok ?-)