Inserting the Welsh Plug in the Mk3 Swingarm

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rick in seattle

rick in seattle

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Guys,

I 've just rebuilt the swingarm on my Commando Mk3 and CANNOT seal the welsh plugs. It is clear that they seat against the interior circular step in the swing arm tube, but no amount of pounding on the dome will seal the plugs. I've gone through 2 sets, using a 1/2" drift and bfh, but, although they do deform, they do not seal. Surely there is a better technology for the 21st century. Can anyone help?
 
Never had that problem, but what about a smear of RTV silicone around the edge before you smack 'em? Are they just loose or do they fall out?
 
They are universally loose and often fall out. I've resorted to silicone (Freddy at OldBritts told me today that he uses silicone and doesn't bother wacking on them). At this point I must have one of the largest collections of used Welsh plugs on the planet. The RHS is the more difficult, as it appears that the oil-saturated disk is interfering with the plug, but both vertical pins are neatly in place, so I believe that the spindle is in the right horizontal position.
 
I'm wacking them with a 2 lb copper hammer and a 1/2" drift, using a heavy and frequent stroke. Is this supposed to be a subtle operation?
 
Rick:

Mine were the same way. Did them with black rtv and they've been fine for the first 1,000 miles.
 
I used a couple of sets, before resorting to silicone.

I thought it was just me. This makes me feel a lot better :lol:
 
Ditto on the silicone. I used clear.

It does take a firm whack to get them to deform and stay in place. It annoys me that the resulting dent is obvious. I used RTV around the outside and have had no leaks there.

The rubber seals on my MKIIA swingarm however...
 
It annoys me that the resulting dent is obvious
Click to expand...

I'll admit it's been a couple years since I put the Mk3 cradle and swingarm in my '73 Interstate, but I didn't have this problem and I don't don't have an obvious dent in the plugs. I don't remember where the plugs came from, but perhaps there are some undersize ones on the market?

I don't wail at these with a BFH as you only want to remove the "cup" to the plug and make it stand mostly straight in the swingarm.

Now you have me paranoid and I'll have to check to see if mine have fallen out when I get home tonight!
 
I'm pretty sure that the plugs which have been available for some years are undersized or maybe too thin to make a decent edge contact. They can go 'over-centre' to the point of being inside out and not grip anywhere during the procedure.

I've also had stainless plugs which wouldn't stay in. I've tried everything from small to larger drifts, tubes to put a ringed indent in...nothing helps.

Araldite epoxy is my favoured adhesive !
 
This thread is comical!

I used Yamabond, which is grey and more or less matched the color of the plug. No whacking required!
 
Jason Curtiss said:
This thread is comical!

I used Yamabond, which is grey and more or less matched the color of the plug. No whacking required!
Click to expand...

Jason, do they do gold-passivated colour Yamabond 'cause that's the colour of my plug stock !
 
why not just use the earlier cap with rod that screws onto the other end cap? the longer rod can be cut shorter and tapped.
Eric
 
Commando74 said:
why not just use the earlier cap with rod that screws onto the other end cap? the longer rod can be cut shorter and tapped.
Eric
Click to expand...
MKIIA and MKIII spindles use oil impregnated felt "wicks" to lube the bushings. You can't use the thru rod.
 
maylar said:
Commando74 said:
why not just use the earlier cap with rod that screws onto the other end cap? the longer rod can be cut shorter and tapped.
Eric
Click to expand...
MKIIA and MKIII spindles use oil impregnated felt "wicks" to lube the bushings. You can't use the thru rod.
Click to expand...

No, but you can ditch the wicks and add oil as needed through the hole in the end cap. Probably better than relying on the wicks. The problem I have had is that these earlier type caps seem to leak pretty badly. The swingarm on my 61 Matchless G12 is pretty oil tight but my Commando is not. I have tried sealing with O-rings, paper gaskets, Wellseal etc. and nothing has worked all that well. Pretty idiotic design IMO.
 
there has to be some practical way to incorporate the two systems. maybe ditch the felt plug but keep the felt disc?
the rod can easily stay tight thru the felt.
Eric
 
When they sealed that area and specified oil for it was it to prevent stiction with the lubricants of the day? Grease used to harden, hold dirt, and all that sealed some areas like this were felt rings.
I wonder if anyone has tried more modern seals and something like disk brake wheel bearing grease that is resistant to hardening and stay put?
 
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