New member 1951 A7 plunger

[Esimon]

Hello my name is Eric Simonson, I'm 22 years old and I'm located in colorado springs Colorado. I got stock BSA A7 plunger in a trade around a year ago.  I immediately tore it down to see what I had to work with.   It spent 50 years in Burma, so it had some incredibly shoddy work done in the past, the fender and gas tank were severely rusted, and the frame was slightly bent from having a side car on it all those years.  I had to significantly rebuild most of the bike to get it back in a presentable condition.  I didn't rebuild the motor or transmission because I was told they were in working condition.  I've taken it on several rides since I got it all back together, but unfortunately the 50 years of jostling around Burmese roads with a side car nearly destroyed second gear, it's very rough shifting and constantly slips out of second.  I know a local BSA mechanic who helped me get running, he said he could rebuild the transmission, but I would like to do
 as much work myself as possible. I'm a fabricator and a machinist and have plenty of experience with Harleys and classic American cars, so this should be a fun and different project that I've fallen in love with.  I intend on thoroughly rebuilding the entire bike and am looking for lots of information.  Thanks for your time.

[muskrat]

G'day Eric, welcome to the forum from downunder.
                                                                    Handy to know a mechanic who knows their war around an A7/10 and being a fab/machinist will help you do most things.
 You will probably know by now most g/box work can be done with it in the frame but to do a full job has to be removed (with the motor).
Be careful when ordering parts, the plunger box is a bit different to the S/A. Do a few searches, most problems have been sorted here.
 I love my '51 A7.
Cheers

[Esimon]

Thanks for the greetings!  Your  right luckily I realized the plunger transmission is a bit different than a s/a, as it is not a true pre unit.  My bike is a bit of a frankenstein, your could call it a bobber more or less (hopefully that's not a taboo on this forum). Iv'e been considering doing some frame modification.  I have just found a plunger transmission online for a reasonable price which would be ideal considering I modification would then not be necessary, and the fact that I was told it would cost around $700 to rebuild my transmission.  But would a s/a transmission work with my motor if I ran an open primary, and did some frame modification? And why does the transmission bolt to the motor if there are no oiling connections (besides rigidity and strength)?  Thanks for your time.

Eric

[muskrat]

G'day Eric,
              we call it a semi unit. Stick with it as moding for a S/A box in your frame would be a nightmare and the motor will have no rear mounting. As for the cost of a box rebuild I can't see it costing 1/2 that much with all new bearings, bushes and a new 2nd gear which is the same as a S/A gear.
Cheers

[phread]

Pity I don't still live in CO.  I have a '52 A10 that I bought in the Springs a few years ago and it's my favorite bike!

Have you joined the BMAC?  That was one club/group that has more knowledge about British Iron than anyone else
I've ever encountered.  http://www.bmacinc.com  And unlike the local HOG chapter, these guys actually know how
to work on their own bikes!

[a10 gf]

Welcome Esimon, hoping you will enjoy the forum.

& welcome back Phread, I remember you were a member in the past (deleted for non-activity\few posts, sorry for that). Am enjoying reading about the Highlander Warriors\Swords\Tube Audio. Great bike.

e

[RoadRunner]

Hi Eric,
Welcome to the forum; apologies for asking straight away but does your stock plunger have original pillion pegs fitted? My plunger (project in progress) is missing the LHS fitting for the pillion peg. The manual doesn't show what should go in the hole and I could do with someone who has the original fitting in place.
Don't know if you can help or not?
In anticipation?

Cheers
RoadRunner

[Brian]

Hello RR, I have come across a couple of different set ups for pillion pegs on the plungers. Does yours have a thread in the frame, if it does you need the piece at the top in the photo. It screws into the frame and the pillion peg goes through the middle of that.

If the frame doesnt have a thread you may need the piece in the bottom of the photo. My 53' plunger A10 does not have threads and had these in it when I bought it. There were two normal splined footpegs on these same as used on most B31/33's etc. These splined ones are the only ones like this I have ever come across.

Hope this helps.

[RoadRunner]

Hi Brian,
Many thanks for photographing said parts - I've not come across the screw thread-in frame before.
On the RHS of mine, the top hat type bush in place is circular and has a 1/4" round recess (to accept the pillion footpeg presumably) hence it?s doubtful it's screwed in? Guess it must be an interference fit but is quite different to the top one in your photo.

The splined version with the top hat with screw thread on the reverse appears logical but the footpegs I have only have the round shafts to go in the recess (as in the RHS)?
So I'm still not sure what is correct, I've not found a diagram in the manual I have ? have you ever seen a diagram or have a part number?

I think this is the idea excuse to visit a few auto jumbles and do some more rummaging or just don?t carry pillions!

Thanks for helping ? at least I have a few more options to explore.

RoadRunner

[Brian]

Here's a scan of the area in question. It shows the top hat bush you mention. This scan was from the 49' to 53' book but the 53' to 57' book shows the same with the same part numbers.

Be like me, dont carry pillions. Not that I wouldnt carry a pillion its just that I cant find anyone silly enough to get behind me.

[RoadRunner]

Thanks Brian,
I've the same diagram; I'll start sourcing a good machinist to cut a top hat with interference fit or some method of securing the back of it to hold in the frame. Got the pegs and fairly determined to get them on the bike just to make it look pucker - plus gives the option of pillions. It won't stop it running and can be fixed in due course. Thanks for the diagram/photos.

Cheers
RoadRunner

[RichardL]

Eric,

I'm a bit late with the welcome, but "welcome" nonetheless. I believe we here in the U.S. are in the minority as forum members. I'm in Naperville, outside Chicago. I'm wondering if you've done anything with your gearbox yet. With no previous gearbox rebuilding experience, I rebuilt my own from Haynes manual instructions and found that to be adequate guidance. I didn't need to replace any gears or bushing, so the the total cost of the rebuild was ball bearings and gaskets. I've since had to some other repairs on the outer cover and kick-start bits, but still a long way from $700 invested.

Richard L.

[phread]

That exploded view is quite helpful for many things.  Going to rebuild the plunger suspension on mine this winter.

Cheers,

Phread