Pillion Footrest Adaptor

[Gavin]

Hi, i would be grateful for some help with the following:

I have included 2 pix of the pillion footrest adaptor for a plunger frame A10. I am looking to purchase a die to be able to thread cut 4 blanks that i am in the process of finishing. I have less than a sparrows knowledge of thread types but am hoping someone can enlighten me as to which die I need to purchase Please?

Just to keep me confused the parts books give the following numbers for the same adaptor (I think) 67 - 4183    67 - 4121     67 - 4122.

But I am chasing the die not the part. thanks.

[berger]

hello gavin I can't say what thread it is but thread gauges are a good thing to have on the bench

[Gavin]

Hi Keith, as you can see i have one, and the 20g meshes perfectly with the thread. If you could translate that info into a Thread size for ordering a die I'd be grateful.
Thanks.

[Swarfcut]

gavin  In the grand scheme of things BSA used the British Standard Cycle thread system. That thread should be BSCy also known as CEI (Cycle Engineers' Institute).  Measure the OD of the thread, that will give you the basic size eg 9/16", 5/8", whatever it is. The die you need is (for example)  5/8" Cycle.

 Above 3/8" the thread comes as either 26 or 20TPI, depending on application. Yours looks like 20 TPI. That is what you need to order.

 67-4183, the part pictured, appears in the '54/57 catalogue, carried over from '49/53.   67 4122 is the locking nut for a sidecar lug stud.

 Just examined my frame, one with a single seat, no rear footrests.  The hole is 15/16" on each side and neither side has a thread, which was a bit of a surprise.

 Swarfy.

[morris]

3/4 x 20TPI. Same as cush nut.

[berger]

gavin I know it was meant to be a funny because you have the thread gauge all you needed was the diameter

[AdrianJ]

Swarfy,
The sidecar lugs are a bit of a mystery on the plunger frames. 
The front (under headstock) and under seat ones have a double taper so that a chair can be fitted on either side. The pillion footrest fitting should be a shouldered cylinder with a thread on the end which allows the shoulder to be drawn up against the footrest lug. I would have found lugs more use, instead of the various cylinders and tapers, but I guess this system allows the fittings to rotate and for the side car to be on either side of the bike. The front lower fitting is an adapted engine stud which tends to interfere with brake operation if you have big feet.
Adrian

[trevinoz]

Gavin, why don't you screw cut it?
That is how I made them in the past.

[Peter in Aus]

Hi Gavin, Just had a look at my plunger it has a 15/16 hole so the die you want would be 15/16 CEI 20TPI that would be hard to come by I think and costly! May be our friend Orabanda could help you out there. I think Trevs idea is best, screw cut it. I assume you have the nut for it, if so it would be fairly easy to screw cut it.
Peter 

[terryg]

https://www.tracytools.com/index.php?route=product/product&product_id=1146

I think I would screw cut it, as already suggested, but Tracy Tools seem to have something.

[Swarfcut]

      Adrian, Not having a chair. I've never considered these lugs, and from the parts book, 67 4183 looks to screw into the frame. My frame is unthreaded. Is pete's threaded?  Your shouldered cylinder doesn't appear in the parts list but fits the bill.

    Even if frames are threaded at this size, the part 4183 won't screw into the frame because as morris says, the OD of the part is 3/4", yet the hole in the frame is 15/16. So is  something missing?  The shouldered cylinder?  If this was plain on the outside to fit the frame hole, threaded internally to suit 67 4183, that would be the answer.  Top hat bushes back to back and secured by the pillion footrest stud would be a simple  solution.

  Homespun screw cutting looks the quick answer.

  Swarfy

[AdrianJ]

Swarfy,
No it’s  not threaded. I think 61 4183 is just a top hat shaped bush.
I made a sidecar fitting for this, when I can find the drawing I’ll post it. It may give Gavin some ideas for his footrest.
I think the thread was smaller than 15/6 as it draws up against a washer, the original had a massive castellated nut according to the parts book.
Adrian

[Swarfcut]

Adrian.
    I was sure the threaded bush Gavin pictured was 4183, now looking closer at the parts drawing 4183 looks to be just a plain  bush unthreaded on the outside to fit a plain frame lug.  But still a mystery how it is held in the frame hole (from the parts diagram) and now what is the part Gavin actually has? Does this thread inside 4183, but is not shown on the parts diagram?

 Swarfy.

[AdrianJ]

I've found my drawing now.
It should work as a pillion footrest adapter if you replace the ball with the footrest hinge.
I used a metric thread for ease of availability of the fastener. The M18 nut is plenty big enough to pull the assembly up against a strong washer. I used a fine thread for security. The inch (2.54cm) section is the bit that goes inside the lug on the bike. I didn't turn the thread, used a die from Tracy Tools. Hard work at that size and started it held in the lathe to get it straight.
Seems to work - it's on the bike, tightened up and mobile.
Just seen you later post Swarfy. I don't think there is thread on the inside - it just holds in through lateral tension. The footrest adapter is a snug fit in the 4183 - it goes straight through and tightens against the frame with a nut on the back- I think. That's what my adapter does.
Adrian.

[Gavin]

Well thanks everyone for some interesting input. Whilst not knowing which part number goes with what I am aware that some frames have a thread in them and others do not. So yes there are 2 different Adaptors.

After a kind offer by Orabanda to ensure that I made the correct part, I discovered that these things are virtually throw away second hand items. So I have "banked" Orababda's offer to be drawn down on the next problem I encounter,  and solved this one simply with an order to my second hand parts supplier.

I'll return the one I have borrowed, and used in the pix, and just to clarify the matter for my frames, this one fits all 4 threaded receptors in the 2 frames I am working on. Seems to me that there may be different sized receptors, but as far as I can work out, mine are 5/8"

Thanks again for the "brain food" which has lead to a simple conclusion.