Norton plunger suspension seized.

[Rex]

That's the thing about these old bikes now they're just old bikes rather than transport...no need to rush and destroy old parts when you can spend time and patience and reclaim them (hopefully!)
My A7 (a different design, I know) had one seized plunger due to the steel ring in the base of the top shroud seizing on the carrier, but PlusGas, time and a big persuader sorted it eventually.

[iansoady]

I made a puller from a length of 1/2" UNF stud which previously saw service as a Commando clutch compressor, a box spanner and a chunk of flat bar (also from the clutch compressor). Turned down to 7/16" for an inch at one end, 26 tpi thread cut and screwed into the top end of the bearer rod, it actually slid out fairly easily without the use of heat or frantic hammering. I just hope the other side comes out as easily.....

[Martin_UK]

If yo give them a wallop from above with a heavy hammer, this may be enough to free them inside the sliders -

Wow.....and who thought back street bodgers were a dying breed.....

[iansoady]

Sadly, the other side is proving much more reluctant even after getting it to 200 C. I'll persist with the penetrating oil after letting it cool down a bit. The bar has moved a couple of inches however so maybe whacking it down may help to free things off (we don't do bodging on this forum.....)

[R]

Wow.....and who thought back street bodgers were a dying breed.....

How do you think a "professional" would tackle this if you took it to them ?
Pussy footing about is likely to achieve not much, reading most repair manuals when they refer to "returning it to the factory" is when stuff like this is required.

Having a press may do the same work, but you have to be careful with those plunger frame setups, the plunger supports are prone to cracking on Norton frames, even in normal road use...

[R]

it actually slid out fairly easily without the use of heat or frantic hammering.

It shouldn't be a matter of "frantic hammering", the idea is to shock it loose.
As every apprentice knows - hit once, hit it hard, hit it square.
Might need a cap over it to stop it belling out.

If you already have it moving though, then shocking it loose is no longer in the plan.
Oil/grease/penetrating fluid sounds like the next move, if heat doesn't free it off. ?

[iansoady]

Yes, I think patience is probably the key as I'd left the first one for several days soaking in penetrating oil. The problem is that the shrouds stop me applying the oil to exactly where I want it.

I've been thinking about a "last resort" and think it would mean sacrificing the top shroud (I can probably find something else that can be adapted), the top spring (I can get one made in Redditch) and the bearer bar (I can make a new one myself).

But I hope to avoid all that as it will be a bit fraught to say the least and the angle grinder is not my tool of choice.

[Rex]

Worth remembering that as the springs are in compression they'll tend to grip the disc if you go down the angle grinder route.

[iansoady]

Yes, I find the prospect pretty scary so am putting it off as long as possible.....

[R]

How did you get on with the "springs in compression" in the one they you did get apart.
I can remember a dent in someones ceiling from when one came apart.
I think it is recommended you constrain them somehow, I've just used rope to sort of wrap them up, before fully withdrawing the rod.

[33d6]

I used an old bed sheet when disassembling my effort. I wrapped it around the whole shebang several times until it looked like a mummy and then gently tapped away. It caught everything comfortably. Nothing shot off anywhere.

For reassembly I made the clamp as shown in the earlier photo. I first assembled everything on the bearer rod which lined everything up. Then clamped it all up tight with the bearer rod still in place. The it was just a matter of removing the bearer rod, popping the unit in the frame and slipping the bearer rod back in. As everything was new, straight and well greased it was surprisingly easy.

The only fussy bit was not scratching the new paint on the spring covers. You can see the thin card protectors between the clamp and the covers..

I think you've done the hard bit Ian. It's all cruising from now on.   

[john.k]

My suspension was worn,but because of spring pressure I made up a threaded puller ,and didnt attempt to drive the bits apart....You can get away with hammering Caterpillar parts with a sledgehammer,but not bikes.I also used a car spring compressor to restrain the bits as they came free of the frame......Now here a story of bike hammering......professional restorer? attacks a Matchless V twin with hammer to release the timing gear......bashes the shaft to bits,then cuts the gear and shaft endwise with a cutoff wheel.......he s been told the shaft and gear are available from the Morgan club......Anyhoo,orders shaft and gear,when it comes the shaft is the wrong length.....he s got a 1937 motor,shaft is for 1938,doesnt fit.!937 is unobtainable......customer is a outlaw bikie...not amused......

[iansoady]

The Norton approved spring compressor is an old rear brake rod(!) with cut off penny washers and wing nuts so I will knock up something similar. The idea is to slide the assembly sideways till the 1/4" rod will enter then tighten it down. What can go wrong?

Getting back to the one which is stuck, no movement. I'm coming to the conclusion that there's a build up of rust on the lower end of the bearer bar stopping it from going far into the slider (although it has moved a couple of inches), and I'm concerned that if I try too hard it may split the slider by the wedging action.

So I'm leaving it under pressure for a few days. If I see no movement I will hacksaw round the top shroud so it drops down and will give access to the top spring. Use an angle grinder to cut through the spring as near half way down as possible (probably finish with a hacksaw taking Rex's warning into account) which I should then be able to wind the top half into the bottom to get access to the top of the bearer rod. Then cut off the top of the bearer rod with the angle grinder, releasing the whole lot.

I'll probably finally withdraw the remains of the rod downwards. In a worst case I'll take it to someone who can bore the remains of the bearer out, or maybe press it (beyond my skills and equipment).

I'll get a pair of springs made using the good one as a pattern (many years ago I used Paul Savage in Redditch and I see he's still around). If I'm careful I should be able to get the top shroud welded back up, and I can make a new bearer rod.

In the meantime while I wait I've pulled the primary drive apart and note that the gearbox mainshaft appears to be bent, along with about 1/8" end float (probably the bronze thrust washer on the sleeve gear). And the clutch centre is badly worn....

[iansoady]

I made a compressor using penny washers and the "correct" old brake rod which I found under the bench.....



In situ with rather rickety spacers on top.



close up of the cut down penny washer.



And the components separated. The main spring is a substantial item......



You can see the build up of rusty muck around the bottom which is what I think is stopping the bearer rod on the other side shifting.

[iansoady]

Shroud cut (not very elegantly) giving access to the spring. The gap between the coils looks enough to get the angle grinder direct to the bearer rod without cutting the spring (which is a bit frightening given it's under compression). We'll see......