Can't get 1st Gear

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Can't get 1st Gear

Post by Terryb » Sun Aug 21, 2016 9:53 am

Sorry Guy's, but this is a non B50 question, humble apologies.

1970 TR25W (B25 rebadged) - this has been a complete rebuild, the gear cluster was part assembled and the guy I brought the bike from informed me that it needed a main shaft shim/spacer. I'm having trouble trying to select 1st gear, either when the engine is stationary or running. I can get it to select it when I do it manually with the box stripped. I've checked that all the pieces are there and they check out, but my first question is:-
Is the thrust washer 57-2678 between the sleeve gear and second gear on the main shaft, retained in the second gear?

I've read some where that the thickness of these shims/spacers can effect the selection.

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Re: Can't get 1st Gear

Post by minetymenace » Sun Aug 21, 2016 12:14 pm

Terryb wrote:Sorry Guy's, but this is a non B50 question, humble apologies.
The site may be B50.org, but all BSA unit singles are catered for here, no need to apologise.

Have you seen this? Anyway the great and the good will be along shortly and will point you in the right direction.
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Re: Can't get 1st Gear

Post by midgie » Sun Aug 21, 2016 1:34 pm

thrust washer correct position is between the mainshaft sleeve gear and mainshaft 2nd gear. check your gearchange quadrant is not a pattern part, as these are at best a joke.

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Re: Can't get 1st Gear

Post by Terryb » Mon Aug 22, 2016 9:08 am

Hi, Thanks for the replies.

I think I have all of the thrust washers/shims, but one of them appears to be attached to one of the gears and not loose. Is this normal?

Today I will strip the box and check the operation of the cam plate, it is quite possible that this could be the problem. Again, I'm not sure if all of the parts where assembled before and I'm afraid that it could be a bitsa.

Terryb

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Re: Can't get 1st Gear

Post by minetymenace » Mon Aug 22, 2016 11:06 am

Terryb wrote:I'm afraid that it could be a bitsa
45 years on they are all bitsas, don't worry, the forum members are here to guide you and will hold your hand (just beware of holding hands with mlb50 :oops: ).
There is no evidence to support the notion that life is serious.
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Re: Can't get 1st Gear

Post by kommando » Mon Aug 22, 2016 3:36 pm

I can get it to select it when I do it manually with the box stripped.
How stripped is stripped, is the inner cover on and you are using the quadrant or is the inner cover off and you are moving the camplate manually.

Former suggests the outer cover is not aligned and affecting the quadrant, 2nd suggest the quadrant is not working correctly or the camplate is hitting the crankcase and not allowing it to get to 1st, had that with a camplate before except it was 4th that was the problem.

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Re: Can't get 1st Gear

Post by Terryb » Mon Aug 22, 2016 4:38 pm

Test - Quadrant with spring and cam plate attached to inner cover. Layshaft + gears removed and inner cover assembly attached with top and bottom bolts. Gear leaver operated and inspection light.

Result - cam plate stopping halfway to 1st gear, but will not go any further, looks like all other gears reach their rightful slot. I need to check again because I was more concerned with 1st gear. Index spring is new, so can't see if it's rubbing due to under use.

Compared the TR's with a C15 cam plate to see if profile matches. The TR's cam plate has more meat on it than the C15, especially at the 1st gear end, but not sure if this is a good comparison?

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Re: Can't get 1st Gear

Post by Terryb » Mon Aug 22, 2016 6:06 pm

Hi Gerry1, I sent you some pictures via your email address. I hope you don't mind. Not sure how to load them onto the Forum.

Terryb

Edit by MM: No Worries, I have a few pictures to post....I'll be onto it after tea.

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Re: Can't get 1st Gear

Post by kommando » Mon Aug 22, 2016 6:09 pm

Something is either stopping the camplate from moving or the quadrant is not moving it far enough, you are going to need to look hard and long at it. Take the quadrant out and see if you can move the camplate into first or assemble it in first and see if you can get it out of first to second and then back again.

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Re: Can't get 1st Gear

Post by crankbuster » Mon Aug 22, 2016 7:22 pm

You can series the three loose shims here:
https://youtu.be/7Q6R-C4z86o

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Re: Can't get 1st Gear

Post by Terryb » Tue Aug 23, 2016 10:16 am

Hi Guy's.

Here is my progress report.

Dug out the old Alpha spring and there was previous sign's of interference, so did a small amount of filing and general clean-up of the cam plate. Still not reaching 1st gear slot, using Quadrant.

Managed to assemble cam plate minus quadrant and it slots into all gears manually, as long as I pull the cover off slightly to release the spring pressure.

I guess, this leaves the option of filing off some of the quadrant stop on the case side. Do you think I should file off both the top and bottom stops or just the top stop? Alternatively try a new quadrant?

Terryb

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Re: Can't get 1st Gear

Post by kommando » Tue Aug 23, 2016 3:05 pm

Short term only the side that is needed to get more travel for first eg downshifts, go carefully and only do enough to get first and no more or you risk downshifts 4 to 3 etc to be over travelled and give you false neutrals, check the plungers first as replacing worn ones may stop the need to file the quadrant. Long term get a better quadrant if the plungers are ok.

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Re: Can't get 1st Gear

Post by minetymenace » Tue Aug 23, 2016 7:39 pm

Terryb wrote:I guess, this leaves the option of filing off some of the quadrant stop on the case side
Try searching the forum, I recall something about this...
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Re: Can't get 1st Gear

Post by Terryb » Tue Aug 23, 2016 8:12 pm

OK Guy's some success.

I've managed to select 4 gears + neutral, several times with just the cam plate and quadrant fitted. I achieved this by filing the cam plate as per HPSTAN's article. I've bottled out of filing material off of the casing.

Only problem is that I can get 1st gear, Neutral, 2nd, 3rd and then 4th. I can then change all the way down to Neutral, but it won't go into 1st gear unless I go from 2nd through to 1st and then back to Neutral. Should I file a bit more off closer to the 1st gear?

Terryb

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Re: Can't get 1st Gear

Post by kommando » Tue Aug 23, 2016 8:19 pm

but it won't go into 1st gear unless I go from 2nd through to 1st and then back to Neutral.
Yes take some more off, the second to 1st shift is stronger, as you get more speed up, than neutral to 1st so it needs just a bit more off.

That is how I got 4th to select on my problem gearbox, took some metal off the camplate but at the opposite end.

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Re: Can't get 1st Gear

Post by beat » Tue Aug 23, 2016 8:24 pm

I have had something like once .
my problem was , there was still some oil left in the gearbox ( in the pouch where the drain plug is and the camplate shifts )
inside this oil was a pice of metal ( M6 nut ) stoping the camplate for going all the way to shift 1. in totally .
moron me was not cleaning nicely....
:oops: :oops:

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Re: Can't get 1st Gear

Post by Terryb » Thu Aug 25, 2016 10:15 am

Hi Guy's,

Just successfully selected all gears, including Neutral to 1st. So I will do a dry run with all the bits in and try my luck. :ban

Just like to thank you all for the good advice, keep up the good work.

Cheers Terryb

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Re: Can't get 1st Gear

Post by midgie » Thu Aug 25, 2016 4:56 pm

what was it then terry?

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Re: Can't get 1st Gear

Post by Terryb » Thu Aug 25, 2016 8:40 pm

Just re-assembled the gearbox and found all 4 gears + neutral. Not easily, but a great improvement from before, hopefully it will be easier when the wheels/engine is running.

Basically, with the filing of the cam plate between neutral and 1st and general de-burring of the tracks and selector slots, this did the trick. Hopefully repetitive use will make it get easier.

So thanks again Guy's
Terryb :thumb

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