A65 Rocket gearbox

[Cmcl.1959]

Hi to all again.
I'm still trying to resolve the gearchange issues I have coming down the box.
The gearbox will go from 3rd to 2nd, but will rarely go into neutral and most of the time won't go into 1st before coming to a standstill.
I've read the service bulletins and before I go to the extent of delving into the gearbox, one mentions the two stop "plugs" for the return lever. When I was fitting a new return spring I noticed that the flats on these are facing in the wrong direction i.e. away from the return lever.
Does anyone know if these are shrunk, glued or screwed in their holes so that I can try turning them. If they are shrunk in then to avoid damage, I'll either file new flats or as the service bulletin says grind a bit of the return lever arm. I'm not sure if it's possible to grind too much off.
In the meantime I've rebuilt the clutch with new friction plates. I ended up using the old plain plates as the ones I got from Draganfly didn't fit (they were the correct part no.). Also the new springs were also the correct number but were much longer than those fitted.
Any advice gratefully received.

Thanks
Clarke.

[AdrianS]

Can't help you with the gearbox other than to say that I have trouble going down mine from 3 to 2 to 1 and often have to stop before I can get a lower gear. I was meticulous in reassembly so was surprised to have this niggling problem. Will be interesting to see what others suggest.
With regards to clutch springs I had great difficulty in getting the right sized springs. Drags supplied me some that were too long and I bought some of eBay which again were too long. A local dealer found me some that appeared to be correct and if I remember correctly he said that they were from a Triumph engine ( could be a 3TA ) but appeared to be the correct size.

[DAVE BRADY]

Hi,

Is this a new problem or one that has always been there?  If it was OK and you have removed the spring for some reason then try turning it over as it is possible that it is stronger in one direction.  This can prevent the little plungers from locating in the selector plate properly.  A give away is that the lever will have some slack movement and when lifted and depressed again will probably engage correctly. 

Dave.

[Cmcl.1959]

Hi Dave,

This has been a problem since I bought the bike in May. I've been discovering things (see previous posts) ever since. Changing the spring is just the latest attempt to solve this problem.
I've already described various issues I've found with the bike as I've gone along. I was at the point of going into the gearbox but thought I'd overhaul the clutch first to see if that would make a difference. Obviously I'd have to undo a lot of the work I've done  to go into the box do that but I thought I'd see if anyone knew about the stop pins first.
The flats being on the wrong side would limit the movement of the return lever but I didn't want to force them round and possibly crack the casing.

Clarke

[DAVE BRADY]

Hi,

Thinking back I would say that the pin is a push fit so perhaps a bit of twisting may turn it. I currently have the timing side off one of my A65s so I will have a look tomorrow and let you know.

Dave.

[DAVE BRADY]

Good morning,

Just been out to the shed to check the anchor peg.  I could turn it quite easily with mole grips so I would say a tight sliding fit.  Mine is a later model so only has one peg.  It has a flat on one side only.  Unless there is other information I would say that the flats are and attempt to tune the selector by changing the movement slightly. A flat allows more movement so turning the peg adjusts the selector. So perhaps turn the peg that restricts the lever when pushed down to give a bit more travel.

Dave.

[bikerbob]

I assume the parts you are talking about are part numbers 68-3075 gear change plungers. they should not be a tight fit in the gear change quadrant as they are spring loaded part number 68-3076 and so should be a sliding fit.

[Cmcl.1959]

Hi again,

I'm referring to advice given in Service Bulletin no. 164 and part number 68-3058 (in my 1963-65 parts list), two pegs that limit the travel of the gearshift return lever, not the shifting quadrant plungers that engage in the cam plate.
The quadrant shaft comes through the inner gearbox casing and eventually out the timing side cover where the gear change lever is attached. The return lever 68-3083 and associated spring are mounted on the shaft and the amount the quadrant plunger can move up or down when using the gear shift lever is limited by these pegs.
The advice on the service bulletin is that the flats face the return lever (in my case they don't) and if more travel is required, grind a small amount off the side of the lever (up or down) that has insufficient travel. Not enough travel and the plungers may not go into the cam plate slot for the selected gear.
I'll try turning them as Dave suggests (thanks Dave) and see if that makes a difference.

Thanks again to all that replied

Clarke

[Andy Edwards]

I think that the flats machined onto the two pegs are only there to allow air to escape when the pegs are pressed into the blind holes in the casting.  These flats do not need to be aligned with anything. I was told this by SRM.  I had the same problem with my A50 of not being able to change down from 3rd to 2nd gear. 0.0020" removed from one side of the gearchange return lever sorted out the problem.

[DAVE BRADY]

Hi,

Interestingly, the parts books do not show flats on these pegs and the one in the bike that I have the cover off only has one flat and it does not go into the hole. Flats extending in the hole could encourage movement and wear.  Also, as had been mentioned in a previous thread the last A65 models had an eccentric spring cup to facilitate minor adjustment of the spring.  I suppose taking a bit off the return lever is the same as making a bit of flat on the peg.  The important thing is that it works.

Dave.

[Bess]

Hi,
    I had the same problem, the cause was the gear change quadrant shaft end was worn enough for it to move when changing gear hence selection wasn't happening as expected. A tight primary chain will also effect gear changes as the engine heats.

Dave mentioned the eccentric spring cup for the later models which are practically impossible to source. You can open up the hole of your existing cup and silver solder an eccentric washer in the cup to mimic the original.

If I get enough interest I will make a batch up in the future.

Best wishes..

[Cmcl.1959]

Hi to all,
I seem to have caused a bit of confusion regarding these pegs or plugs as listed in the Service Bulletin no.164 (the sheet refers to BSA incorporated New Jersey) but refers to A50s and A65s and is dated 2nd June 1964.
I've tried umpteen times today to attach it to this reply without any joy so I'll just write here what the bulletin says.

Subject: Gear change mechanism on all A50-A65 models
"When difficulty is experienced in changing up and down the range it may be due to incomplete travel of the cam plate.
The movement of the gear change return lever is limited by two plugs (part no. 68-3058) in the inner case which control the travel of the cam plate.
The return lever (part no. 68-3083) stops against flats ground on the two plugs. When these plugs are assembled in the case, the flats must be located so that the top and bottom sides on the return lever strike against the stops squarely to get the maximum travel to complete the ratchet movement which is required to slide the gears from one speed to another.
When this movement is 0.20" or 0.30" lesstthan what is called for shifting difficulties will be experienced.
When difficulty is experienced in shifting down the range, grind 0.20" to 0.30" off the lower flat on the return lever. When difficulty is experienced in shifting up the range, grind 0.20" to 0.30" off the upper flat on the return lever"
It then goes onto possibly changing the return spring for one from the Super Rocket.
The return lever can be seen on the end of the cam quadrant in Bess's photos.
My Rocket is an early one (1963) so later ones may be different.
Just thought I'd post this to try and clarify what I was doing.

The plan is still to go back into the timing side and rotate these plugs so that the flats are in the correct place to see if this makes a difference. I'll see if I can take a couple of photos to show them.

Thanks to everyone who responded and hope you all have a Merry Christmas and a Happy New Year.

Clarke