Gearbox woes

[muskrat]

Good one John (a101960). most of us have had those DOH moments. 
Cheers

[Colsbeeza]

Hi John and you gearbox experts,
Well I finally got the Flash out on the road yesterday, after fitting my Club plates. As I am on a busy road, I did not try to run it before I had the plates on. (Don't want the men in blue offside).
It rode and handled like my old A7, so very pleased sofar.
A few minor problems with the motor, but the gearbox was not minor. Whilst on the stand, I could get all gears by turning the back wheel and moving the lever by hand.
Once on the road, I could not get gears going up or down. Getting in and out of 1st was no problem.
It found the neutral between gears very easily, but fluked the other gears with a few jabs. I still haven't found 2nd. Certainly not ideal for running in a new motor.
The box was rebuilt by a friend long ago, but he is a Harley man, so may not be so familiar with BSA gearboxes.
I did rebuild the Lilac gearbox 10 years ago, but absolutely no similarity with the BSA gearbox. Otherwise I have had no experience with BSA gearboxes. I suspect that is about to change.
Reading all your views, I fear that I may have to remove the gearbox to even start on the problem. I think that means the motor removal also.
Can I begin to sort it without removing the gearbox.? Is it worth starting without removing the gearbox.? I am confident of finding neutral between 1st & 2nd, so the cam plate should be in the correct position when I dismantle it, so perhaps I don't need to go inside the inner cover.?
I cannot say yet what is inside until I start.
Thanks in anticipation
Colin

[duTch]

 Hola Col- it is possible to pull the whole guts out with the box in place, but you need to at least remove the clutch to do so.
 You may only need to remove the outer and inner covers to sort it (No clutch removal), as it may just be a selector fork issue (which I'm out of touch with for swing-arm boxes), except I'll suggest maybe the 'dots don't align properly'.
    No offence to your mate,  but I'd be having a bo-peep anyway to make sure it's all in order...  especially the thrust washer behind 1st (H gear) on layshaft

 

[orabanda]

Check that the cam plate selector plunger (accessible from underneath) has the correct adjustment (spring pre-load). If too light, then gear selection might be hit & miss.

Also drain out the oil and check for excessive contamination.

[KiwiGF]

You need to check the dots align as per dutch’s Post HOWEVER this can be a bit tricky as on many boxes the dots are slightly off alignment when in the correct position, so it becomes a bit 50/50 on Which way to try first.

With a bit of luck misaligned dots may be your only problem. There is not TOO much that can be done incorrectly inside.

As per orabandas post, it’s best to err on the side of too much spring pressure on the cam plate plunger/index, and back it off once your happy with everything else.

[chaterlea25]

Hi Colin,
If you can select the four gears when stationary , then I would say that the timing dots are correct
AS suggested check the detent plunger adjustment, 3 threads showing should be ok
Have you tried selecting the gears by hand when the bike is on the centre stand?
Make sure the rear wheel is clear of the ground when trying this
If the gear lever return spring is not bringing the lever back to the correct position then the ratchet will not pick up the next change
The ends of the spring should hold the lever shaft tightly in the centre position

John

[trevinoz]

I would suspect that the dot alignment is the problem.
I've had the same problem, works on the bench but not on the road.
The box can be removed without removing the engine if needs be.

[Colsbeeza]

Thanks Heaps,
That gives me a clear direction to follow:
First - re-check the gear change by hand with back wheel off the ground. I have done this before, but not with problem-solving in mind. Look for good spring return action.
Second - Check the tension on the cam plate selector plunger has correct tension and about the right number of threads showing. See if that fixes the problem. By this stage there is a good chance of nailing it. Failing that -
Third - Drain the oil, look for contamination and get inside. Look for dot alignment (nearly everybody) and the gear lever return spring action. Since the gearbox has done 3.7 miles since assembled, I would be rather surprised to find any contamination, but look anyway.
Fourth - Well I will get back to you.!
Cheers
Colin

[Colsbeeza]

Thanks for all the great advice chaps.! Wouldn't it have been nice if this was around years ago.? The Internet can be a curse or a blessing - a blessing as far as BSA enthusiasts go. It is a bit daunting realising how much experience you fellas have.

I've worked through the issues with the gearbox up to a Point.!!! (Images below covers the issues.) and not necessarily in order.
1st - Check the Camplate Plunger after draining oil etc - No foreign bodies.  About 2 threads showing (OK), Pull it out and check condition. Loosen lock nut and attach spanner. But No - the plunger body would not budge - rusted in well and truly.! Spanner rounded off the very short flats. The gearbox was empty of oil for most of the last 25 years, so moisture may have got in. Why did the plunger housing have to be round, with two short flats ?? - a hexagon would have been great. I cannot get a decent hold of it. Maybe that's not such a bad thing. There is a risk of shearing it off.

2nd - Checked all gear changes whilst turning the back wheel - Going down the gears (upwards pedal) was much better than going up. Gears usually slipped through to a neutral or the next gear ahead of the claws stopping point if you get what I mean.  Suggesting Camplate Plunger.? The gearbox was empty of oil for most of the last 25 years, so moisture may have got in.
So whilst awaiting for a brainsurge solution to removing the Camplate Plunger housing, I thought I'd take a look inside.

3rd - Took off the outer cover for inspection. Red Dot alignment looks correct.? I found one of the selector claws quite worn flat. How bad is bad.?  I noticed that Julian's photo of his claw also showed flattening, but better than mine. Kickstart pawl & pinion looked great.! The claw spring very rusted. Also does the stop plate return spring look OK.? It works well!

4th - I replaced the gear lever spindle and pedal and ran it through the gears with outer cover off.
   It was very obvious when changing gears that the quadrant would run ahead of where the claw stopped. The wear on the claw did not seem to cause a problem. It seems to me VERY suggestive that the camplate plunger is not working, or so far out that the cam positions do not line up with gear positions. Given that it is rusted in, I am looking forward to getting it out for a look. I don't want to try heat whilst gearbox is in situ, so am wailing (Whaling, waling ??) into it with a large Vicegrip and hammer. Still not budging, and the vicegrip won't bite properly. Any ideas.??? Worst case is if I break a piece of aluminium out of the gearbox. Maybe I should weld a large nut onto the end of it.?? (after removing the fuel tank & carb).
  In anticipation I have ordered a new claw (Gear selector plate), all the camplate plunger parts, and a new claw spring. I'll wait for your thoughts before whal - wal- (bugger)-ing into it.
Happy Days.!!
Colin

[duTch]

......... so am wailing (Whaling, waling ??) into it with a large Vicegrip and hammer. Still not budging, and the vicegrip won't bite properly. Any ideas.???

 I'd say 'waling is close, but as 'Whack' is right above 'Whale' in my dictionary, I'm happy to go with that 

.... Maybe I should weld a large nut onto the end of it.?? (after removing the fuel tank & carb)....

 Reasonable idea, may work, and the heat generated would help, but I'd be more concerned about the Genny if doing a couple of spot welds (I know from experience), disconnect the battery ( and everything else just to be sure)

 Being a Swing Arm box, I can't offer too much more at this stage

[muskrat]

G'day Col.
I'd lay the bike over and apply a little heat to the case around the cam plunger housing (hot enough to sizzle spit) then stand her up and put a cop of turps in the box. Wait over night and give the plunger housing a tap or two with a hammer then have a go.
Cheers

[Colsbeeza]

Thanks Dutch and Muskrat,
I'll go with "Whacking" Dutch.
I hadn't thought about the Generator - that could get expensive.!
I might be best to try Muskrats idea first, and if it gets too scary - bite the bullet and remove the gearbox.

Incidentally I went through my box of bits I forgot I had and found an old camplate plunger housing with plunger still in it - all rusted in and unmoveable. I dunno whether there is a spring in it still. It must have happened to someone before.
I ordered a new selector plate (or fork) from Feked, and the image shows both fork tips are pointed the same (I hope he doesn't mind me posting a cut-down version of his image of it), so that answers my earlier question. I should have gone through the box before ordering stuff. There seems to be no end to buying stuff.
Col

[Butch (cb)]

Probably isn't, but from this distance that looks identical to the set up I was fooling with on my Bantam D14/4 Piecrust Racer I was fooling with last weekend. Could it be?

[Colsbeeza]

Hi Gents,
Following on from my Post#16, I took the bike for its first run ( 20 miles) since January. The Gearbox worked perfectly.!  I had found the following:
    1. I had changed the claw for an old one in good nick from my parts bin. The new Feked claw didn't solve the problem, and I put it down to being made from 5mm plate, not 3/16" like the originals. I advised Feked, and they replied to say that 3/16" plate (4.76mm) is not available. I am not so sure.
    2.  The camplate plunger had seized in the outer tube. As mentioned earlier, I took the gearbox out, put it in the vice and worked the plunger housing until it freed up. Damn it was tight. Rusty on the inside no doubt due to it being left dry (no oil) for 20+ years and moisture had ingressed. I replaced the 3 components of the plunger. John Chaterlea was right. That was the mainproblem. It is a little tight, so will back off the adjuster a little.
    3. The kickstart had been jamming at the top, often needing to move the bike in gear to free it. I replaced the ratchet pinion with a new one.
    4. The clutch was a non-standard Triumph 4-spring with many problems, although it had worked OK in January. I ended up replacing the entire clutch. It is working perfectly, although a little heavy. I will adjust during 5. below.
    5. Overall the bike went beautifully. First time I had ridden an BSA A-Series since I sold my A7 in 1970. The handling was just as the A7 had been - predictable and safe.! It still has an 18-tooth engine sprocket, so felt like 50mph revs at 35mph. Will obtain and try a 20 tooth.??
    Anyway, the beast is finally on the road after 35 years, so Cheering.
Col

[chaterlea25]

Hi Colin,
Good to hear you and the Flash are on the road
From memory a Flash should have a 21 tooth engine sprocket as standard
With today's traffic being so much faster that the 50's and 60's upping the engine sprocket size is a good idea
They will pull a 22 tooth easily, My SR is running a 23 tooth engine sprocket that gives a fairly relaxed 4000rpm, 70MPH

John