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D3 second gear issue
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Paul W.
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March 4, 2021 - 9:57 pm
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I have had a quick look through gear box issues on here and the ones about jumping out of 2nd, but the issue i have is not being able to select 2nd with the engine running, it just grinds, engine off 1st 2nd and 3rd no issues, if I start it in 2nd rides fine, can select 3rd and back to 2nd and down to 1st, but not back up to second. I have stripped it checked it all, and everything seems fine, so not sure what is wrong, any ideas please

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Stoo63
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March 6, 2021 - 9:49 am
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Hello Paul and we,come to the Forum. It's nice to post an intro in the Introduce Yourself section s o wwe  all know who we are dealing with. Just a brief idea of location /experience - itmakes a huge difference if users arwe replying to someone who has never touched a bike before or have 60 years experience.

You will find just about everything you could ever want on the Forum via the FAQs and technical sections;  ** Please log in to view **

Have a really good nose around the forum and enjoy yourself. Looking forward to seeing your progress.

Good Luck!

All the best,

Stewart

 '55 D3 Battery; '58 Square Four (project); '59 D1 direct lighting plunger; '59 Tiger Cub; '60 5TA;  '76 FS1-E; '91 GTR 1000;  '97 Honda Sky SGX50.

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cocorico
Central France
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March 6, 2021 - 4:51 pm
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Hello and welcome. As Stoo says, it helps to know what experience you have with old bikes. If you are coming from a more modern machine (or none at all) you may not be aware that the Bantam needs a good, positive move up the box. Try taking up any movement in the gear lever before declutching, then carry on with a firm action - don't expect a quick, slick action.

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mike p5xbx
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March 6, 2021 - 5:11 pm
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it can be so many things with the early 3 speed
but normally it is jumping out of gear that is the problem
so I would first have a close look at the faces of the layshaft bushes

D? - D10- D14 Bantams 350 AJS -500 Triumph http://bsanotru.....lfire.com/

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sunny
Norfolk
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March 7, 2021 - 5:32 pm
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fully     service  the  cluch   mechanism    check   and size   the    endfloat  [ 7 1/2 thow ]  donot  fit  new  cork  plates  

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chickensoup
Bolton, Greater Manchester
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April 2, 2021 - 7:35 am
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Hi Paul,

I am experiencing the exact same problem as yourself with my D7, it will just not go into 2nd gear from 1st. Last year my D7 had the problem of jumping out of 2nd gear, which just made the bike impossible to ride with any enjoyment. After reading many posts I came to the conclusion that the gearbox from the D7 and D5 models were basically useless after about 1000miles, due to minimal amounts of wear.

I found some information somewhere that the gearboxes from the D1 and D3 were much better due to the layshafts being of a different design, this held the second gear better whilst under load. Great I thought, so like a fool, I rushed out and swapped over the layshafts and a gears from D7 to D1.

This totally cured the problem of my D7 jumping out of second gear, the only problem is, as you know, you cant get it in to second gear. I suspect it is a selector issue. I will look into it in the future. I feel the trade off is better as you can set off in second gear no problem unless on a very steep hill. Its certainly a better riding experience than before. I guess you just have to make allowances, after all it is 75 year old technology.

Today I start work on my other bantam, the D1 hybrid which has a D5 engine with the same jumping out of second gear problem. It is also going to get the D1 layshaft treatment. I will give the selector components a good coat of looking at before re-assembly this time, but if the out come is the same as the D7 I will be happy..

1950 BSA D1 Plunger   242 UYW

1966 BSA D7  LBF 62 D

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Sponge
Lancashire (A chip shop somewhere near Preston)
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April 2, 2021 - 9:55 am
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I am convinced that the solution lies with the selector mechanism itself. The semicircular cam plate spring and swivel pin are also critical to being able to get it into gear and keeping it in gear. 

I have 2 x 3 speed bantams and both were cured by paying close attention to the selector mechanism. I removed the slop but kept a little play to aid rotation of the camplate. Both are running their original gearset.

I have a theory that if you swap the gearset you should also swap out the selector as well because there are subtle differences.

I suspect that a 3 speed gearbox that does not want to select up to 2nd will be related to the detent ball, the socket and the spring inside it. Ad well as the ramp on the selector camplate.  After market detent springs can have a higher rating on the mistaken premise that more is better and this will make things very stiff. Unless there is a compelling reason I therefore re-use the original spring, a new ball and ensure that all is working well. Crud can get trapped in there and make it stiff as well. 

I might take some photographs to illustrate the point.

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GlenAnderson
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April 2, 2021 - 12:06 pm
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The top of the socket can get very worn too - which doesn't help matters - although it's more likely to cause jumping out than prevent going in...

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cocorico
Central France
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April 2, 2021 - 12:25 pm
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Said the Actress to the Bishop?...

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Sponge
Lancashire (A chip shop somewhere near Preston)
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April 2, 2021 - 1:52 pm
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A good analogy Coco. A new pin and a little bit of gentle dressing with a file can work wonders with all this jumping out and refusing to go in business. 

Unfortunately it all has to be taken to pieces every time you try an adjustment. It becomes tedious. 

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Sponge
Lancashire (A chip shop somewhere near Preston)
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April 2, 2021 - 5:34 pm
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This is how bad it has to be before it starts to jump out of gear. I learned about thsi many years ago when working on my D1 engine with a friend who was a well known Yamaha racing engine tuner. We replaced the whole gear cluster with a brand new genuine BSA one, we line reamed the layshaft bushes and fitted new bearings whilst measuring up and adjusting all the end floats etc. Upon re-assembly it still jumped out of 2nd gear. My friend, being as logical as Mr Spock the Vulcan said.......if its still doing it then it must be something we have not changed yet.....let sopen it up and look at everything in there that we have not replaced......so we did and discovered this selector swivel pin problem.  A new selector mechanism, a ball socket and spring with a shiney new ball was sourced from Jack Bottomleys in Salford for less than a Tenner and the problem was resolved. 

The pin in the picture came out of my current D1 with about 40K miles on it.  Previously fine, I stripped my engine down because it started to jump out of second gear on uphill stretches and on hard acceleration as I was returning home from a ride out about 9 years ago.   I could not see anything wrong with the gear cluster but as I expected,  I did discover a lot of up and down play in the selector mechanism.   A quick strip down revealed the problem which was easily fixed with a spare pin and a good clean up. ( I keep a slack handful of spare pins which I got from Sids Place in Radcliffe many years ago).  I also deepened and re-profiled the 2nd gear notch by a few thou with a file.  A good inspection revealed no wear anywhere else so I re-assembled the engine and it has been fine ever since.  In fact I was out on it yesterday.  

......it did not need a new gear cluster.   

Unfortunately you cannot buy these 'pins' as an individual spare part - they come as part of an assembly and that is why they often get overlooked...... but I reckon they would be fairly easy to make.   Rex ....are you listening in ?

My theory is that an owner gets gear jumping around and puts new gears and shafts in, and perhaps the odd shim, and it is OK for a while until that little pin wears a bit more then the problem starts up again.  How many 3 speed engines are sitting on shelves because they jump out of gear and the owner is unable to fix it so consigns the engine to the parts bin ??  

Anyway that's my theory........I am just waiting for a forum member with a 3 speed jumper to replace a pin and confirm this back to me ?

20210402_gear_selector_pin.jpg   

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Number6
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April 2, 2021 - 8:36 pm
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Very interesting!

Mike H --

Murphy's 4th law of motion states that any small object that is accidentally dropped will immediately hide itself under a larger object.

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chickensoup
Bolton, Greater Manchester
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April 3, 2021 - 6:43 am
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Hi all,

Will certainly look in to the worn pin, when I strip down the D7 engine. Yesterday, I stripped down and swapped over my D5 engines layshafts and gears. All the selector components and spring seemed in good order. I have not put the engine back together yet, but did carry out a dry run of the gearbox and crank case halves. All the gears and neutral selected very well, much better than I remember last time, and I will take a look at that pesky pin.

To get back to Pauls original post, I hope our experiences have helped you.

1950 BSA D1 Plunger   242 UYW

1966 BSA D7  LBF 62 D

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Sponge
Lancashire (A chip shop somewhere near Preston)
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April 3, 2021 - 8:10 am
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Hi Soup Mate, it is really worth checking that pin whilst the engine is on the bench. Good luck with it. 

Sponge

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