Author Topic: The immovable flywheel  (Read 1273 times)

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Offline tck

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The immovable flywheel
« on: 30 Jun 2020 at 13:06 »
Well perusing this forum I am not the first
My Mk flywheel has 2 X  5/16" BSF cap bolts in a piece 3/8" steel plate  in position and pressure applied by a 1/2" whitworth bolt to the center of the crankshaft end via a copper coin and I have wound it up to about 35ft lbs on a large torque wrench and socket I do not think I dare increase it further.
It has sat all night and I have given it "The sharp blow" as recommended with a suitable hammer.(a few times)
I knew I was going to have problems there was no split pin on the nut and the nut undid with a preliminary pull of the ring spanner
There is some perceptible play in the big end and I guess sludge is in the crank otherwise the top ends have looked OK but with the cycle parts almost done and the gearbox on its way I have come to a halt  so I need help to get the bottom end done.

Offline Jonathan Hewitt

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Re: The immovable flywheel
« Reply #1 on: 30 Jun 2020 at 17:05 »
To my mind 3/8 plate is no where near thick enough 3/4 to 1" would be more suitable as the pressure from your pulling studs will just be preloading and springing the cross piece . The cross piece must not bend at all.
   Jonathan

Offline tck

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Re: The immovable flywheel
« Reply #2 on: 30 Jun 2020 at 19:23 »
Easy done! I will weld on some angle iron  and wind her up again

Offline AJWBREW

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Re: The immovable flywheel
« Reply #3 on: 30 Jun 2020 at 21:20 »
I always find a very long soak in diesel helps with anything that won't move and maybe apply a little heat to the flywheel whilst you have it tentioned up.

Offline tck

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Re: The immovable flywheel
« Reply #4 on: 07 Jul 2020 at 10:18 »
I built a dam of plasticene round the center and filled it with penetrating fluid I beefed up the extractor and tightened up the 1/2 whit bolt a tight as I could hammer it with 10 inch spanner and mallet I have given it 'smart' cracks with a hammer I have left it over night there is a very deformed copper coin twit bolt and crank end
consider also that it was held on with a nut  easily undone and no split pin, it certainly diddent move in use!
I could purchase a block of 1" steel and mill an even heavier extractor but it all comes down to those 2X5/16 cap screws inserted about 5/16-3/8 depth....
I have removed bearings by a ring of weld so I wonder if a ring of stick weld round the recess might thermal shock it - you can tell I am getting desperate
is it possible to come in the other way??! has anyone a solution? I am mobile

Offline eddie

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Re: The immovable flywheel
« Reply #5 on: 07 Jul 2020 at 12:28 »
As you say, the limiting factor when applying the load is the strength of the 2 5/16 studs screwed into the flywheel. I use an alternative method that has always proved successful. You need a 3" dia x 5/8" thick steel disc drilled and tapped to take a 3/4" x 20 tpi bolt, a suitable length 3/4" x 20 tpi bolt, a second flywheel, and 6 5/16" allen screws.
   Leave the crankshaft nut loose by about 3 turns. Start by undoing the six nuts on the engine side of the clutch guide pins (working through the clutch inspection hole). Undoing the nuts will cause the clutch springs to load up the clutch thrust, thus making the crank stiff to turn. With all 6 nuts removed, the pressure plate (complete with the guide pins) and clutch disc can now be removed. Now fit the 3/4" x 20 bolt through the centre of the second flywheel (from the back), and screw on the 3" dia disc. Bolt the 2 flywheels together (face to face) using the 6 Allen Screws (you may need heavy duty washers under the heads). Use an air ratchet to tighten the extractor bolt until the flywheel pops off the taper. At this point, unbolt and remove the second flywheel, then slowly undo the crankshaft nut to fully unload the clutch springs.

  Hope you find this useful,
                                           Regards,
                                                          Eddie.

Offline tck

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Re: The immovable flywheel
« Reply #6 on: 07 Jul 2020 at 13:01 »
Thanks Eddie
I have already removed all the clutch plates etc when I tried some heat so I just have a bare flywheel facing me. I can feel the nuts through the clutch inspection hole so I can undo those without too much trouble
I can source the disc and have the 3/4 X20 tpi  taps and allen screws. that just leaves locating a second flywheel as my problem

Offline tck

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Re: The immovable flywheel
« Reply #7 on: 08 Jul 2020 at 14:05 »
Using Eddies suggestion and without an extra flywheel I wonder if the following will work
I can get a steel blank the same size as the flywheel I can then drill a set if 5/16"clearance holes to match the tapped holes in the clutch when the nuts from the reverse side iare removed and the pins are screwed out I can also drill and tap the 3/4"X20 hole in the center
I can then add the coin buffer and bolt the disc on the clutch and then add bolt and burp gun as Eddie suggests.
My only worry is that the blanks are only 10mm (3/8") thick and I wonder if I should double them up (at extra expense) and bolt 2 of them together I suppose I could try with one disc first. comments?

Offline tck

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Re: The immovable flywheel
« Reply #8 on: 24 Jul 2020 at 19:27 »
Well, a week of construction. I drilled 6 concentric holes in the round steel plate and turned up 6 matching sleeve nuts, tapped center hole in Plate and turned a 3/4" extraction bolt.  bolted all into position rattle gun applied nothing moved, after a hard struggle the 3/4" CEI thread striped in the extraction screw. :cry: I will now open up center hole to 1"or 1-1/4" and make up a longer threaded center portion which I shall weld in place on plate and a make a new extraction screw. One of my many advice givers suggested the taper may be loctited on :-0  (which would account for the flywheel staying on in use with a loose center nut) so I shall attempt to heat the assembly again but that flywheel mass may take some heating to get to loctite fail point....

Offline tck

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Re: The immovable flywheel
« Reply #9 on: 30 Jul 2020 at 20:49 »
Well that's a full canister of propane and while hot I also tried the two 5/16 pullers onto steel packers and sharp blows no results.
I am pressing on with beefing up the disc and  adding 6 welded deep radial ribs to a new central boss


Offline isettaman

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Re: The immovable flywheel
« Reply #10 on: 31 Jul 2020 at 00:27 »
A shot in the dark.
What about using a slide hammer?
Dave

Offline tck

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Re: The immovable flywheel
« Reply #11 on: 31 Jul 2020 at 06:45 »
Its an idea Dave! (I am ready to try anything) I will tap a 12mm hole in the new extractor screw head when I make it ready some all thread for a slide hammer and add it to the methods I can try.
I have to get this B**tard flywheel off somehow or I dont have an engine to mount in my refurbished frame and  I have just paid for two new wheels ......

Offline eddie

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Re: The immovable flywheel
« Reply #12 on: 31 Jul 2020 at 07:07 »
I have never heard of this happening on a postwar engine, but the early dirt track engines suffered from flywheels welding themselves to the crankshaft. Evidently, it is something to do with the harmonic frequency of the crankshaft and flywheel being similar! On the dirt track engines we used for sprinting, we made smaller diameter but heavier flywheels - and that cured the problem! (all a bit technical for me!).

  Regards,
                 Eddie.

Offline tck

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Re: The immovable flywheel
« Reply #13 on: 31 Jul 2020 at 18:33 »
Thanks Eddie I didnt want to be the first!
Probing the keyway slot I hit the obstruction blocking the entire square hole which I think is the key its at about 1/8"-3/16" from the face of the flywheel. The surface of the taper seems smooth to there and  I imagine I can feel a slight curve to the obstruction so I am guessing its a standard key in the correct position without and bodges or pins.
Any fluids I have placed in the flywheel recess (with the  5/16 extractor holes closed) dissipate into the taper/flywheel interface very quickly.
modified tool work starts tomorrow when it not so hot in the workshop.

Offline otaio26

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Re: The immovable flywheel
« Reply #14 on: 01 Aug 2020 at 10:40 »
You say ,using propane gas.I presume this is the DIY canister type.My opinion is that in heating the flywheel which would be slow using this form of heat ,would enable heat to transfer to the shaft.If you do not have access to oxy-acetylene take the package to a local engineering shop who have this equipment and direct the direct heat to the area of the keyway only.Flywheel taper will heat up far quicker and also expand keyslot from woodruff key.Give a hard whack on the puller centre bolt and flywheel should release itself from taper.In my working life was involved in many seized on couplings etc.plus my flywheel stubborn like yours,but succeeded in the end.Best of luck.

Offline tck

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Re: The immovable flywheel
« Reply #15 on: 03 Aug 2020 at 14:45 »
Well I beefed up the pandandrum extractor and tried again and it would not budge
(picture)

Then I sat and re read the advice Otaio suggested more heat  so I returned to my original extractor with the 2 5/16 studs beefed up the center puller to take the 3/4 CEI extractor from the pandandrum and took the whole lot to a mate who builds steam engines (I figured he would not even call that douglas item a flywheel)
 the extractor was done up as tight as I could then he heated it up with oxcy cet everything was smoking braving the heat I gave the nut a final strain and BANG! off it came! in a shower of springs
Thankyou all for your advice Heat indeed does the trick

Offline AJWBREW

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Re: The immovable flywheel
« Reply #16 on: 03 Aug 2020 at 17:33 »
Great news enjoyed reading you exploits hope all goes smoothly from now  :D

Offline Doug

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Re: The immovable flywheel
« Reply #17 on: 03 Aug 2020 at 17:41 »
Any evidence of white powder (decomposed Loctite) or fret-welding to explain why it was so tight?

-Doug

Offline tck

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Re: The immovable flywheel
« Reply #18 on: 03 Aug 2020 at 20:23 »
the surfaces of the taper were clean and uniform the key was in the taper slot I can see know reason for the problem. I can go back to 1985 when I acquired the bike and it has been stored ever since (it took lockdown to bring it to the workshop :-)

 

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