"Jam pot" rear shock Excelsior Universal

[Paullowe]

Hi all knowledgeable members.

I am about to embark on Excelsior Universal 125 and I know nothing of the little rear shock/spring set up except that they are referred to by some as jampot. On my bike a bar has been welded in to make rear end ridgid. I would assume and dampening is shot.
Are these a standard type or brand and do they make kits?  I have manufacturing capability if needed but would love an exploded diagram or some advice before I start.

Thanks Paul

[R]

I think you are slightly off on the wrong track here.
These are commonly known as plunger rear suspension, and the concept of being 'damped' in any fashion is wishful thinking !!?

There is nothing to them really, at least in the ones I've had to do with - just a central rod,
the sliders in some fashion, several sets of springs and the tin covers to cover the whole lot.
Oh, and large dollops of grease, which may give some damping.
Whether the Excelsior version is any more sophisticated I'll wait and watch with interest.

Jampots were always associated with Ajays and Matchies' rear swingarm damper units,
which were large bulbous things - looked impressive but the actual damping was minimal,
and were famous for how many ways they leaked. !
http://i.ebayimg.com/00/s/MTIwMFgxNjAw/z/ENAAAOSwA3dYmp7d/$_57.JPG
hopethishelps

[33d6]

R is right. They are very simple devices with no damping at all. The only tricky thing with the Excelsior version is the fancy large chromed nuts at either end. They have a fine thread which is noted for cross threading on assembly and many of them broke up the minute you put a spanner on them for dismantling. Most restorers make new out of bronze that doesn't rust and easily takes a nice chrome finish.
Cheers,

[mini-me]

It would help if I did not have to go into the room next door to see all the photo!!

and the right up up helps, I cannot seeany welded in rods, it would not make sense anyway, once these things top working they are rigid near enough.

R is correct Jampots are unique to AJS/Matchless of a certain era, in fact thats why the club  magazine is called that.

[Rex]

If the rear rim and hub condition is typical, then I reckon there's more pressing issues that stripping the plunger units! With all due respect, if you're at the level of terming plungers "jampots" then maybe you should begin with the easier tasks and leave the more complex parts until later? You may find the constant problem-solving aspects to be too much and only want to throw it all in the shed in disgust.

[iansoady]

You also may need to be careful when dismantling as some plunger springs are under considerable compression when assembled and can make a scary break for freedom when dismantled.

[mini-me]

Losing your front teeth is a small price to pay for knowledge

[33d6]

Releasing those welds is possibly half an hours work with a cutting blade in your angle grinder and that includes cleaning off the dags afterwards. It's no big problem.
I have a big old bath towel that I wrap around jobs like that to prevent things flying away when I undo them. Nevertheless a good pair of gloves doesn't go astray.  Plunger springs aren't under a great deal of tension, just enough to be a tricky nuisance. Remember they've got to be soft enough to move up and down with the average rider bouncing on them.
Have fun.

[Paullowe]

Thanks all for your input. I'm not a newb and have rebuilt from scratch many bikes. My use of terminology came from others. As suspected these are little more than a spring with "spirit".
I will free the rear end from its rigid constraint and let free the uselessness of the original design.

No diagrams available?

[Paullowe]

For the visually impaired I include a close up of the "rigid" modification.

[mini-me]

After putting my specs on , I still can't see the point of that mod. I wonder what is missing from inside the units if the purpose was to make the frame rigid?

Old bike, a bundle of surprises mostly.

[33d6]

I do have a diagram but it is tiny and is determined not to be attached to this message. Possibly we can get somewhere if you send me a pm. If you try I'm away for the weekend.
Cheers,