Author Topic: Norton plunger suspension seized.  (Read 634 times)

Offline iansoady

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Norton plunger suspension seized.
« on: March 22, 2018, 03:47:49 PM »
I had a feeling this would happen.....

I'm starting to get down to some work on my 1952 Norton ES2. I did have a feeling the rear suspension wasn't working and have discovered that the alloy slider on at least one side (all I've looked at so far) is seized onto the bearer rod. After slackening the pinch bolt and freeing the taper the bearer rod is free in the frame but the slider just moves with it.

I've run penetrating oil down the join as much as I can but suspect large amounts of heat (which I don't have) will be needed, I don't really want to get down to the bare frame at this stage as I was hoping to get the bike up and running to discover what was needed. Seems I've got to this point already.

This is the arrangement:



Any helpful suggestions welcome.
Ian
1952 Norton ES2
1982 Moto Guzzi V50

Offline john.k

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Re: Norton plunger suspension seized.
« Reply #1 on: March 22, 2018, 09:01:00 PM »
A bit of heat applied to the ally will free the seizure.Be rust inside too,I would imagine.Be careful not to overheat,as the ally will certainly be heat treated,and you may weaken it...Usually,the sliders are flogged out.I always use molygrease with 30% MoS2 on mine.

Offline R

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Re: Norton plunger suspension seized.
« Reply #2 on: March 22, 2018, 09:53:27 PM »
There is a grease nipple dead smack in the middle of that beautifully done alloy casting.
Replace the silly original type with a modern one, attach a good grease gun to it, and pump away.
Grease guns can apply serious pressure, so with any luck grease may be forced through to where its needed.  Of course, if the seizure is above the nipple and the grease all goes downwards, or vice versa, then it may be no help - but it has to be worth a try. It must have been a lazy PO that let the grease dwindle to the point of allowing rust, plunger suspension is totally reliant on those alloy sliders being free to move.

P.S. Have you tried a good sharp WAP with a heavy hammer down on the rod, any initial movement may free it off ?  Probably with the wheel still fitted to restrain it all, and the frame jacked up a bit

Online mini-me

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Re: Norton plunger suspension seized.
« Reply #3 on: March 22, 2018, 10:04:04 PM »
Diesel is a better penetrant in these cases than oil, patience is needed.

As for heat, a  Black and Decker hot air gun should provide enough encouragement to  the alloy to get the diesel seeping through. It is best to have some kind of baffle behind to direct heat back.

Offline 33d6

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Re: Norton plunger suspension seized.
« Reply #4 on: March 23, 2018, 12:28:48 AM »
Are the sliders bushed or being alloy do they run direct on the central rod? I'm trying to attach a photo of the last plunger rear suspension I did. It shows both the clamp I used to fit the refurbished units plus the extra grease nipple I installed on the top.

Offline john.k

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Re: Norton plunger suspension seized.
« Reply #5 on: March 23, 2018, 12:54:44 AM »
They are not bushed,and if bushed will generally break in use because boring reduces the thickness too much........Im pretty sure new made units are avaiable.....but the originals would be forged RR50 alloy,and Ill bet any replacements are castings made in a cowshed in Mumbai by your friend and mine..Sunny Enfield.......the grease nipples are 1/4 BSF from memory.

Offline john.k

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Re: Norton plunger suspension seized.
« Reply #6 on: March 23, 2018, 01:30:35 AM »
Another bit of possibly unneeded advice......be careful how you reassemble the wheel bearings....if the spacers are wrong,its not too noticeable,but prevents the axle nuts from clamping properly before one side runs out of thread. Makes for a very wobbly ride.

Offline iansoady

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Re: Norton plunger suspension seized.
« Reply #7 on: March 23, 2018, 09:59:21 AM »
Many thanks all.

I'll try the grease idea - as you say, one of those daft early nipples where the grease goes everywhere except where you want it. The forging is as said a very nice component.

The previous owner probably did apply the grease gun but not effectively. Most things on the bike have been fairly well maintained (except for the use of metric threads here & there)

I have put a suitably sized socket under the bearer rod with a trolley jack pushing it up and the weight of the bike on it and left it overnight but as I expected no movement as yet.

I'm going to turn up a stepped drift to fit in the lower end and try with the trolley jack and blowlamp as suggested. Otherwise I'll probably need to strip it to a bare frame, which I was hoping to avoid at this stage, and take it somewhere - a proper job would be to get it hot then use a press to push the bearer rod out. The rod only comes out upwards as it is tapered on its bottom end to locate into the frame abutment.

I'm in no rush but was hoping to get it on the road before too long to discover what else needs doing.......

Thanks for the wheel bearing tip as well.....
Ian
1952 Norton ES2
1982 Moto Guzzi V50

Offline john.k

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Re: Norton plunger suspension seized.
« Reply #8 on: March 23, 2018, 11:09:43 AM »
Ian,if you retighten the taper and pinchbolt,you may be able to rotate the slider on the rod,if it will hold....apply a bit of heat too.....preferably boiling water.....no oxy or concentrated heat ...make sure the taper and top clamp are perfectly dry of oil or grease ,or they wont hold.......put a big shifter on the axle mount and try to turn.........if you start hammering you will wreck the rod,and likely bend the frame..........talking of bends...is the rod straight? ..not bent in a rear ender?

Offline iansoady

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Re: Norton plunger suspension seized.
« Reply #9 on: March 23, 2018, 11:24:30 AM »
Thanks John.

The thread at the bottom end is very poor, at least on the bolt that screws into it, having been somewhat butchered previously (and the one on the other side has a metric bolt in it!!). I do suspect PO has had a go at removing these and having failed passed it on to me. It may explain why he fitted a 4.00 section rear tyre rather than the original 3.25".....

I've tried clamping both sides up at the top but the bearer rods still turn. I'll try cleaning out the penetrating old with brake cleaner, find a setscrew that will fit the bottom end (should be 7/16" cycle by the look of it - very hard to get at - and tighten it all up. I'm not hopeful at this stage as it all seems very firmly stuck together.

WRT grease nipples, as near as I can see it's .226" major diameter over the thread x 26 tpi which makes it look like 1/4" BFF. Is this a standard nipple thread? They're not something I'm familiar with, and BSP seem to be 28 tpi. There are only about 3 full threads showing so hard to tell......
Ian
1952 Norton ES2
1982 Moto Guzzi V50

Offline iansoady

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Re: Norton plunger suspension seized.
« Reply #10 on: March 23, 2018, 12:20:49 PM »
Progress? Not a lot....

The grease nipples are in fact the ball type so I can get the grease gun on properly. However, it just squirts out round the threads, even with several winds of ptfe tape. The threads are very wobbly so I suspect either the nipples are not original or someone has tried all this before......

The slightly good news is that there is a 7/16" Cycle thread at the top of the bearer bar (which is bored right through) so I should be able to make a puller to help apply some force to the bar as well as pushing from below with the drift (when I've made it) and the trolley jack. That added to heat hopefully will shift it.

The other side is seized as well.....

All good fun.
Ian
1952 Norton ES2
1982 Moto Guzzi V50

Offline john.k

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Re: Norton plunger suspension seized.
« Reply #11 on: March 23, 2018, 11:59:55 PM »
if both sides are seized,I would suspect bent rods from a rear end collision......you may have to compress the springs enough to cut the rods......When I restored my ES2,I had new oversize rods made and induction hardened,as the simplest way to eliminate wear in the sliders......if I did it again,I would probably use hardchromed rod from a hydraulic cylinder repairer,provided a suitable size was available.

Offline R

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Re: Norton plunger suspension seized.
« Reply #12 on: March 24, 2018, 12:58:41 AM »
If you can get the rods up out of their tapers even slightly, and then give them a wallop from above with a heavy hammer, this may be enough to free them inside the sliders - it may take only a good shock to break them free.  Hopefully....

The alloy would have to get extremely hot to alter its properties, if you were going to heat them to try to break them free, and the expansion alone of the alloy may free them off .
After all, its recommended to get crankcases smoking hot to insert and remove bearings - "hot enough that if you spit on them it will spit back" is the proverbial yardstick, and thats fairly hot.
Always waft a heat source onto alloy all over though, never in a concentrated spot...

Offline john.k

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Re: Norton plunger suspension seized.
« Reply #13 on: March 24, 2018, 03:51:30 AM »
Or,you could simply leave them seized.

Offline iansoady

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Re: Norton plunger suspension seized.
« Reply #14 on: March 24, 2018, 10:24:33 AM »
That was actually suggested elsewhere. They could I suppose be bent but I would have thought this would cause binding of the bearer rods in the frame abutments and they slide quite happily there. Unfortunately there's no way of seeing what's beneath the shrouds without destroying them. I suppose as a (very) last resort I could use an angle grinder to go through the shroud, spring and bearer rod, all of which could be replaced but I'll be patient.

I can in fact get the rods out of their tapers but of course they move together with the sliders. It does demonstrate to me that the springs work. The problem with walloping is that the whole lot bounces on the spring.

I'll probably try heat later in the week. Yes, I was thinking of the spit balling up as being the optimum temperature.

Meantime I continue to squirt penetrating oil down......
Ian
1952 Norton ES2
1982 Moto Guzzi V50