Author Topic: Gearbox woes  (Read 2748 times)

Online bsa-bill

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Gearbox woes
« on: 28.02. 2009 15:50 »
I was'nt happy with the way the gearbox shifted after re-assebley to the point of fixing on the inner cover, thinking it could be due to the gears and selecter being dry I squirted a good amount of oil in there but still I was'nt happy.
 So I pulled it apart on the bench, of course by now the oil I had squirted in was running out so I installed a new drain plug.
I'm not sure I had the selector forks right but can't really see how I could have assembled the box with them wrong, also checked the thrust washer on the layshaft and reasembled.
Seemed ok until I replaced the inner cover, when this was fully on the gearbox locked up solid, after an hour or two of frustration I finaly spotted the culprit.
The new drian plug - as can be seen in the pics it is too long, now I think the particuler screw may have been purchesed for some other task as it came as a pair with nuts, don't know though what else they would be for as the heads are too thick for holding on the flat plate behind the clutch.
It does pay to mark spares when you get them - definitly if your project takes five years  as has mine.

first pic is the offending plug
second is a proper plug
third is the difference
Hopefully this might be of help to someone encountering the same problem in the future.


All the best - Bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online bsa-bill

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Re: Gearbox woes
« Reply #1 on: 28.02. 2009 19:30 »
well it's back together and I can get all four gears.
I'm still not sure if it's changing properly, time will tell.
The camplate plunger/tensioner seems to get very tight to screw in long before it gets anyware near the two threads showing, I think I'll have a look at it tomorrow it feels like maybe the plunger is not sliding down into the nut/tube but possibly catching on the side.

All the best - Bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline dpaddock

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Re: Gearbox woes
« Reply #2 on: 28.02. 2009 20:53 »
The drain screw should be 13/32 inch long and fitted with a 3/32 inch thick fiber washer.

The selector plunger is screwed in until one thread is showing on the inside of the case.

Note that the plunger is installed from the bottom of the case unless the reverse footchange camplate is fitted, in which case it screws in from the top.

     David
David
'57 Spitfire


Online bsa-bill

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Re: Gearbox woes
« Reply #3 on: 28.02. 2009 22:34 »
Thanks David - I've just been down to the shed and had a look, noticed that the locknut was a little bit off true, would indicate that the adjuster was not on the right thread or ar least getting pulled off course
I took it out and tried screwing iit in without spring and plunger, ah still tight.
I have a spare adjuster - it went in easier and true, will give it more of an examination tomorrow, need to have a good look at the threads in the case *doh*
Also I have a new camplate in there as the old one looked a bit worse for wear, never thought to compare it closely to the old one, might be that it's a bit bigger around about.
Your right - one thread showing in the case equates to a couple of threads left below the locknut as per Haynes and BSA instruction
Thanks again
all the best - Bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline LJ.

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Re: Gearbox woes
« Reply #4 on: 01.03. 2009 10:16 »
Quote
Note that the plunger is installed from the bottom of the case unless the reverse footchange camplate is fitted, in which case it screws in from the top.

David... Is that how a 'genuine' goldie RRT2 gearbox is recognised? apart from the inner stamped cover.
Ride Safely Lads! LJ.
**********************
1940 BSA M20 500cc Girder/Rigid- (SOLD)
1947 BSA M21 600cc Girder/Rigid-Green
1949 BSA A7   500cc Girder/Plunger Star Twin-(SOLD)
1953 BSA B33  500cc Teles/Plunger-Maroon
1961 BSA A10  650cc Golden Flash-Blue
1961 BSA A10  650cc Golden Flash-Red

Online bsa-bill

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Re: Gearbox woes
« Reply #5 on: 01.03. 2009 14:20 »
The treads on the selector plunger are at fault, there's a mark on them about half way down, thankfully I have a spare one that's fine.
The threads in the case are a bit dazed at the outer end but the plunger does not seem slack at any point when screwed in.

Ah such is life with an A10

All the best - Bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online RichardL

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Re: Gearbox woes
« Reply #6 on: 01.03. 2009 15:07 »
Bill,

Bad threads is a topic I'm hesitant to broach here, for fear of derailing the gear-box topic, but I can't even remember how many male threads I repaired with a jeweler's file in the process of my rebuild. For female threads, I sometimes had luck tracing them with a bent awl or counting on the repaired male to (very cautiously) do the job, or both.

Richard L.
Plan on signing up for the world-wide 2017 DISTINGUISHED GENTLEMAN'S RIDE on September 30, 2018. Watch website at https://www.gentlemansride.com for details.

Offline trevinoz

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Re: Gearbox woes
« Reply #7 on: 01.03. 2009 20:37 »
LJ. The gearboxes with reverse camplate provision have a tappad hole top and bottom. The unused hole has a plug fitted.

Richard, you need a thread file and a set of taps and dies.
    Trev.

Online bsa-bill

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Re: Gearbox woes
« Reply #8 on: 01.03. 2009 21:33 »
Thanks guys, I had visions of having to Helicoil the case but I think there are enough good threads in there, I don't want to start trying to improve the threads that are in there as the spare plunger screws in fairly well and is not slack at any point.
Looking at Unithreads site I see they only supply up to 1/2 inch in BSCY, I'm asuming the plunger is cycle thread although I have'nt counted the threads might be twenty
The plunger measures .614 of an inch in width which probably is 5/8 inch.
Of course there is always Locktite, I am a bit reluctant to use it though ( thinking of future removal )

I do have a spare case, it had a bit of butchery to remove the screw that holds the selector rod, this would be easier to helicoil though

All the best - Bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online RichardL

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Re: Gearbox woes
« Reply #9 on: 02.03. 2009 00:50 »
Trev,

Back in the early part of my rebuild, maybe 2004, some dealer told me BSA owners are cheap. I haven't set out to prove it, but I may be doing so by accident or, as the man said, by nature. I forgot who it was, but I don't resent it. I thought it was funny. Anyway, I don't own a complete set of British taps and dies, though, I do have a couple of taps.

Richard L.
Plan on signing up for the world-wide 2017 DISTINGUISHED GENTLEMAN'S RIDE on September 30, 2018. Watch website at https://www.gentlemansride.com for details.

Online groily

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Re: Gearbox woes
« Reply #10 on: 02.03. 2009 07:33 »
Can't remember whether that thread is 26 or 20, which is an alternate Cycle pitch - but Tracy Tools in Devon would almost certainly have a tap, at a sensible price if you need it. They always seem to have everything, however improbable.
Bill

Online bsa-bill

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Re: Gearbox woes
« Reply #11 on: 02.03. 2009 09:55 »
the thread is 20 tpi.
I had a good look down the threaded hole this morning with the aid of strong morning sunlight and a torch.
There is a parch about 1/4 inch round on the outer half of the drilling where the thread has been pulled and mostly gone, same thing on the other side.
The rest of the threads are good and the plunger seems to screw in securely.

I'll see if I can get a decent pic

I don't think I need a tap, I think if I need anything it's an insert kit but can't see one for sale.
Alterantive way forward is to repair the other case I have ( I have a helicoil kit for this I think)

All the best - Bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online BSA_54A10

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Re: Gearbox woes
« Reply #12 on: 03.03. 2009 10:53 »
If you cut out a "flute" from a bolt with a tangential cut in the undoing direction and a radial cut at the other side then you can use a standard bolt as a thread chaser if you can not afford ( or find) a proper tap to do the job.
Similarly if you cut a nut in 1/2  then clamp the 2 halves together and run it up & down the threads it will clean up the threads on the  bolt.
Better if you use high tensile nuts & bolts.
An old bodge but dose the job well enough particularly if you are repairing a thread in alloy.
Bike Beesa
Trevor

Online bsa-bill

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Re: Gearbox woes
« Reply #13 on: 03.03. 2009 13:10 »
The Photos not that good but should show damage to threads, there is a similar area damaged on the opposite side.
I have ordered a tap ( set of three ) from RDG tools for just over £5 ( 5.5 euro?) plus vat and postage
I will try the tap and see what the threads look like after but I don't know that I want to trust the threads after taking any more metal off them.
But some good news - I managed to sort the thread in my spare gearbox case for the selector fork rod fixing screw with a helicoil, that is now sound.
the plunger hole in this case is good, I will need to change over the mainshaft bearing and the layshaft blind bush, but that not a problem.
So one way or another I can sort this

Thanks for all your siggestion

All the best - Bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online bsa-bill

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Re: Gearbox woes
« Reply #14 on: 03.03. 2009 21:28 »
Taps I ordered yesterday arrived this afternoon, three taps £5.08 + £3.00 for delivery  (next day) + the proverbial VAT.
How good they are long term I don't know but a good price for something I may never use again.
RDG can be found at www.rdgtools.co.uk
I used the second tap as the first one might I thought get cross threaded very easily, this proved a good choice as the second one went through true .
I then tried the plunger in and it screwed in fully with fingers, also I did not remove much metal so now I have to decide wether the threads are good enough to hold the plunger, I think the depth of good thread should be enough really.
so three choices
1. swap the cases. 2. use existing case as it is. 3. use existing case and make some sort of bracket that would support the plunger in use as insurance.

I find it so hard to make decisions like this these days  *dunno - is it an age thing?

suggestions would be welcome

All the best - Bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco