'B' series girders

[Greenfield]

My B21 restoration continues. Unfortunately so far very little is being restored and there are more and more parts needing restoration. So far I've drawn a blank with the kickstart bushes, so I may be looking for someone to make them.
Whilst working on the front brake I noticed a lot of movement in the top girder link. The parts book lists fork bushes 65-5078. Can anyone advise whether these are associated with the top link of the late '30s 'B' series?
Many thanks in anticipation.

[Greenfield]

Well, things are not quite what I was expecting. After over 40 years, things happen.
I think that the top links of a B21 are plain without pins. Mine have pins. One is threaded and the other not threaded. The centres are 3 3/8", the pins are just under 1/2" diam, 1 5/8" long with a 5/16" hole. Can anyone identify this? Is it from an M20?

[Y13 Alan G]

This fork link looks like all the BSA pre-war fork links. The scrolls on the pins are to allow grease lubrication. I have a 1929 Sloper, a 1932 G32/12 and a 1937 Y13 and all have the same looking girder fork links. BSA never originally had any bushes in the forks for these links. If there is play machining & bushes will be expensive. Luckily a friend did mine over 30 years ago. Best of luck.

[Greenfield]

Cheers Alan, I think they may be parts 15-5240 and 15-5241 and a quick google shows that they might be available. I just need confirmation of the dimensions before ordering. There is 15 thou variation in the diameter of the pins, so with new links, I'm hoping that the play will be significantly reduced so that bushing is not necessary.

[scifi]

That one pin is extremely well pitted, I don't know what would have caused that..  Maybe inferior contaminated metal used in the manufacture.  The other pin seems to be more like what should be expected.

[Y13 Alan G]

Pitting is caused by lack of greasing. Metal to metal contact causes severe wear and pitting. This from over 50 years experience with pre-war girder fork BSA's.

[Mark Cook]

Green field,

I expect I can help you with your bushing needs.

Mark

pes.sales@pesltd.uk

[scifi]

I don't know if it is a trick of the photography, but shouldn't those two pins be parallel, not splayed apart...?

[Greenfield]

Don't worry Scifi, they are parallel.

[Greenfield]

Update.
Having busied myself with gearbox and electrics, on returning to the links and giving them a thorough clean, I've found the part numbers which are 24-5090 and 24-5095, which makes them the top links from a B30 - but still unavailable. Looks like I'm going to have some made.

[militaryron]

Those same forks were used on the 1940 & 45 C10/11/12 range.

I'm sure Mark could replace the pins. I think they are just pressed into the links?

Ron

[Steve.S]

I wonder if there may be some confusion here? If your Parts Book shows bushes, then the forks and links should be as Ron describes.
However, if your forks have links as in your photo, then these are earlier forks and the pins ran direct in the forks without bushes.
You will probably find that not only are the pins worn, but the forks are worn oval. There's not much metal to bore out the forks to fit bushes.
I believe specialists bore out the forks and fit thin wall bushes, cut off the pins, make and weld on new ones. Of course, this has to be done very accurately, otherwise the forks will bind. You may want to talk to Jake Robbins.
Otherwise, if you're a bodger like me, you could just put them back together with shim stock and water pump grease.

[militaryron]

Indeed Steve I overlooked that. Your top link is nothing like a B30 nor a similar part number. Any chance of pictures of your forks. Here are my B30 forks. Ron

[Greenfield]

I'd be interested to know what girders are fitted to this B21.
Photos attached.

[Steve.S]

It's difficult to say, because forks of this design were fitted to all BSA models up to 1936....all different sizes.
My guess is that they are from a BSA B1, B2 or B18 forerunners of the B21.
In passing, the link pin hole in the forks look oval to me, but it may just be parallax. Otherwise they look in magnificent condition and well worth having done professionally.