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D1 rear plunger dismantling problem
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bsa171gs
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February 5, 2020 - 9:03 pm
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The repair manuals say remove the pinch bolts from the top and bottom of the frame and using a soft drift drive out the center column.   They are definitely not talking about a almost 70 year old motorcycle that has been sitting in a damp basement for 30 years.  The center column is loose in the fame.    When I rotate the top shroud the center column rotates.  I think the center column is stuck in the column it slides up and down in.  I thought of using my Dremel with a cut off wheel and removing part of that top shroud so I could get some penetrating oil between the center column and the column it slides in.   Any help in solving this problem would be appreciated.

John  

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Blue Heeler
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February 5, 2020 - 9:19 pm
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I have had to do this and then mig shroud back together, however these shrouds are readily available and if you can`t find a replacement in a hurry, then there`s a chap in NI, on here I think, who has loads of Plunger stuff...or at least he did last year.

Blue

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JustinW
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February 6, 2020 - 9:36 am
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Looking at the exploded diagram, if you unclamped the centre column from the rear wheel bracket wouldn't the whole thing move up or down against the springs? Just maybe you might be able to get the shroud off then?

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Blue Heeler
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February 6, 2020 - 10:14 am
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JustinW said
Looking at the exploded diagram, if you unclamped the centre column from the rear wheel bracket wouldn't the whole thing move up or down against the springs? Just maybe you might be able to get the shroud off then?  

90-4113, the plunger tube, seizes onto 90-4121, the plunger column.

John is wanting to knock the column down out of the two frame lugs, and to do this, it has to pass through the tube, which is currently seized onto it.

If he cuts around the shroud near the top, the cut section will fall down over the shroud it covers, exposing the top of the column to soak in plusgas or other decent penetrating solution.

Blue

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JustinW
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February 6, 2020 - 4:17 pm
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What I was thinking was push down the column along with the seized tube. The only thing stopping it is the spring? Would need to remove clamp bolt from the rear wheel fitting piece. Once the column along with tube is pushed out of top lug pull it out and dismantle. I may be misremembering how it all goes together.

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Blue Heeler
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February 6, 2020 - 5:50 pm
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** Please log in to view **

Not a Bantam, but showing exposed springs. Bantam Plungers have the shrouds but with this gubbins beneath.

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bsa171gs
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February 6, 2020 - 11:26 pm
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Nice picture Blue Heeler.  JustinW, I have been trying as you suggested.  All pinch bolts have been removed including the center one.   I have been able to push the top shroud down until the top of the main column cleared the frame but have been unable to push the column sideways enough to clear the top of the frame so the whole unit could be removed.   So I am going to cut away part of the upper shroud.

Thanks guys for your help.

John

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bantammad
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February 9, 2020 - 8:14 am
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Hi bantammad ere how about applying some heat in moderation may break down the rust regards Les 

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bsa171gs
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February 9, 2020 - 6:02 pm
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Thanks for the suggestion bantammad but I have a heat gun and have tried heat.   The problem is that with the shrouds in place I cannot get  much heat to the main column in the area where it goes thru the tube it is seized to. 

John 

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NeilB
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February 9, 2020 - 6:40 pm
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Old chip pan, hot oil, done. 

I'm only suggesting this as from my understanding there is no pressure other than the spring, obviously can't do this with a modern shock as it would explode!! 

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bantammad
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February 9, 2020 - 6:52 pm
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Hi bantammad ere it’s got to be a blighter then John but no doubt you will beat it sooner or later have fun Les 

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JustinW
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February 9, 2020 - 8:39 pm
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Another idea, just drip penetrating oil on top of exposed column. The only way it can go is down the column, past the shrouds and some will go into the tube it's stuck in. Could turn it over after a few hours and drip it down the other way.

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Blue Heeler
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February 9, 2020 - 10:37 pm
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Neil`s hot chip pan oil, with caution, sounds good. As Les suggests, heat. Maybe oxy-acetylene welding gun with big nozzle fitted &  turned up, or cutting torch on tick-over, if you can get it between the spring coils, if you can find anyone with bottles

First, in preparation before application of your heat source, how about this? :-

Clean off any residual oil with thinners/petrol, so you can tighten the two frame clamps top&bottom, around the column/shaft/spindle, in a dry condition. Same with the centre bracket(wheel spindle fork) and clamp bolt. Get a couple bits of 1/4" plate and sandwich fork of bracket, tightening jaws of a very hefty adjustable spanner over that. Pour Neil`s chip fat over it and try to waggle the wheel spindle fork (attached to the seized tube), backward and forward.

Obviously you`ll have to cut your shrouds for access, as suggested previously. Careful not to cut into your springs or weaken them if you use the "hot spanner".

Blue

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bantammad
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February 10, 2020 - 9:14 am
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Hi bantammad ere that’s a cracker Blue I’ve had a thought why not roast the whole thing on a fire and use a big hammer just joking sooner or later something going to give happy days regards Les 

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February 10, 2020 - 9:24 am
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Nice one Les, yes just take it to the local village Blacky and for a flagon of cider, he`ll chuck it on his forge and couple of minutes later, Bob`s yer uncle, job`s a gudun. The old ways are the best ways 😉

Blue 

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Number6
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February 10, 2020 - 8:36 pm
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Blue Heeler said
try to waggle the wheel spindle fork (attached to the seized tube), backward and forward.

http://livinginthepast-audioweb.co.uk/imagex/misc/hand-point-up.gif I like this, is what I thought of doing with mine if stiff (but not sure that they are)

Mike H --

Murphy's 4th law of motion states that any small object that is accidentally dropped will immediately hide itself under a larger object.

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Blue Heeler
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February 10, 2020 - 9:36 pm
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#6, The ones on my `54 D3 waggle just fine, previous owner must have shown them the grease gun regularly 🙂

I have a D1 that has well-weathered seized examples. I`m in no hurry, so will try Justin`s drip method, invert frame and try from the bottom too. Then remove grease nipples and "broggle" out the muck with a Tech Drawing compass point and squirt my favourite rust softener, plusgas in there too. 

Cheers

Blue

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bsa171gs
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February 12, 2020 - 5:51 am
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I finally got that plunger dismantled   ----  but it wasn't easy.   To start at the beginning the left side plunger wasn't too hard to dismantle.  It was full of grease and well lubricated.   The right side (silencer side) was the one I had all the problems with.   I cut away almost all of the two top shrouds with my Dremel.   The only grease lubrication was some at the bottom of the bottom shroud.  The top and center were dry and with some moisture inside the center column had seized to the center tube and (I found out later) the top collar.   So I stood the frame up and applied penetrating oil around the center column where it enters the center tube.    I let it sit overnight.   Then I did as Blue Heeler suggested, tightening all thee pinch bolts and waggling the center bracket back and forth.  It came loose sooner than I expected.   I though my troubles were over but they had really just begun.  The center column would not budge.   After much pushing on the springs I noticed when I pushed the top spring in it forced the center column out the bottom of the frame. This meant that the top collar was seized to the center column.   When I pushed the bottom shroud in it just slid up on the center column.  I pushed the top spring (I was pushing on the very top of the shroud which was still in place)  in and on the center column that was below the frame I placed a pair of vice grips so the spring wouldn't move the column & top collar back in place.   This gave me some working room between the top collar and the frame.    I tried heat with my heat gun but it didn't help.  That top collar is not very wide but it was just like it was welded to the center column.   I then checked with Dragonfly and they had all the new parts I might need as I was now going to destroy the top collar and spring.   I took my angle grinder with a cut-off wheel and cut thru thru the top collar and spring in a couple of places.   I then was able to remove the top collar and then the center column.  So, always keep the rear plunger suspension well lubricated.

John 

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bantammad
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February 12, 2020 - 9:55 am
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Hi bantammad ere cracked it then.just being persistent wot satisfaction to right happy days Les 

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February 12, 2020 - 5:56 pm
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What a nightmare, but congratualtions.

Mike H --

Murphy's 4th law of motion states that any small object that is accidentally dropped will immediately hide itself under a larger object.

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