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#341901 - 11/07/10 4:43 pm STD T gearbox question  
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darbone85737 Offline
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Tucson, AZ
I posted this earlier on the general BSA board without success so I'm hoping someone here can help

I'm replacing the layshaft in my gearbox. It's a STD T box with needle bearings on the shaft. I have a parts book and manual but they only cover the standard box with bronze bushings.

There are 3 thrust washers or spacers that were in my gearbox but are not shown in the books. Does anyone have a diagram for the "T" box or can you tell me the location of the spacers. What is the normal end play for the layshaft at the inner cover ?

Thanks in advance

Larry


Tucson, AZ
1955 BSA Gold Star clubman
1958 BSA A10 Super Rocket
BSA Gold Star eBay items

BSA Gold Star forum This board is dedicated to BSA Gold Star motorcycles.

#341991 - 11/07/10 10:28 pm Re: STD T gearbox question [Re: darbone85737]  
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Ron - in California R.I.P. Offline
In Remembrance
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The Gold Star parts book (red cover) shows all 3 items by part number. But that book does not give you dimensions... so I just measured 2 of the 3 parts as follows...
42-3078 Layshaft thrust washer (clutch end), O.D. = 1.164" and 0.100" thick

42-3079 Layshaft washer, (cover end)

67-3203 Layshaft thrust washer -goes between 1st and 2nd gears, the bevel inner edge goes towards 2nd gear, 1.090" O.D. and 0,085" thick.

I do not have the 42-3079 handy, but should be easy to figure out from the above... please add that dimension to make the list complete..

Ron

#342058 - 11/08/10 4:39 am Re: STD T gearbox question [Re: Ron - in California R.I.P.]  
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darbone85737 Offline
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Tucson, AZ
Originally Posted By: Ron - in California
The Gold Star parts book (red cover) shows all 3 items by part number. But that book does not give you dimensions... so I just measured 2 of the 3 parts as follows...
42-3078 Layshaft thrust washer (clutch end), O.D. = 1.164" and 0.100" thick

42-3079 Layshaft washer, (cover end)

67-3203 Layshaft thrust washer -goes between 1st and 2nd gears, the bevel inner edge goes towards 2nd gear, 1.090" O.D. and 0,085" thick.

I do not have the 42-3079 handy, but should be easy to figure out from the above... please add that dimension to make the list complete..

Ron


THANK YOU RON !!! I have the parts in the shop and will measure & add the dimensions in the morning.

Best regards
Larry


Tucson, AZ
1955 BSA Gold Star clubman
1958 BSA A10 Super Rocket
#342140 - 11/08/10 5:26 pm Re: STD T gearbox question [Re: darbone85737]  
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darbone85737 Offline
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Tucson, AZ
Ron- and anyone else who may need this information in the future-

part # 42-3079 Layshaft washer (cover end) is 1.245" OD
.113 thickness

The measurement is from the part on my used gearbox so the spec may be slightly different from new but the gears now move through the range smoothly on their shafts.

On the Road Again !

Ron in CA, Muchas Gracias. If you're ever in Tucson (or at the Red Bull MotoGP next year- I'll be corner working turn 3.1) I owe you a beverage of your choice.

Best regards
Larry


Tucson, AZ
1955 BSA Gold Star clubman
1958 BSA A10 Super Rocket
#342299 - 11/09/10 2:55 pm Re: STD T gearbox question [Re: darbone85737]  
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[IMG]http://i1205.photobucket.com/albums/bb426/dpaddock_2007/Tlayshaftwashers-1.jpg[/IMG

Use this link to see John Gardner's memo re the T gearbox layshaft washers. Note the written comments; they are the dimensions of the washers in my STD T box. Some are different from John's, but they work OK.

David

#352150 - 01/09/11 4:54 am Re: STD T gearbox question [Re: darbone85737]  
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SEATTLE GS Online content
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SEATTLE WA
I spent several months last year std gears and shafts into a SC T box. Shimming the lay shaft was the big headache. After much trial and error I discovered the best arrangement was keeping the three spacers in place as per BSA spec, and adding the extras on the clutch end to achieve about .010 end float. The really peculiar problem that no one in 100 years has had is the box shifting positivly but requiring quite an effort with the foot to make the change. I had been slavishly using the stock gaskets on both sides of the sandwich plate, figuring BSA knew best. Finally, I experimented with different thicknesses and finally ended up with homemade gaskets about .025 thick. Of course, this new distance must be taken up on the layshaft. Since thin spacers are IMPOSSIBLE to find, I had them made up by "THE SHIM SHACK", $20 for about 10 nicely cut out of stainless with a laser. Finally!! Now it shifts quite easily and has withstood several rides. This process took about 7 months.

#352337 - 01/10/11 3:53 am Re: STD T gearbox question [Re: SEATTLE GS]  
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Ron - in California R.I.P. Offline
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California
The BSA gear box design has a LOT of slop built in to it... and for the most part it does not matter...

But I have found that the tolerance on some of the middle cases are out too much... this causes the shift arm to bind on the shift cam. Usually you just use two gaskets and all is well..

Ron

#352341 - 01/10/11 4:35 am Re: STD T gearbox question [Re: darbone85737]  
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SEATTLE GS Online content
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SEATTLE WA
Saying "it's British" explains a lot of things.

I did discover that .050 slop on the layshaft was too much....010 produced good results. My GS is a Sunday bike so it doesn't get really pounded.

#354312 - 01/22/11 7:58 pm Re: STD T gearbox question [Re: darbone85737]  
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db133 Offline
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Will someone be kind and clarify the thrust washers or spacers on a STD Gearbox please ? I have the BSA Service sheet no 311 is it correct ?

#354417 - 01/23/11 11:30 am Re: STD T gearbox question [Re: db133]  
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Peter R Online content
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There should be a spacer on the layshaft between first and second gear, this spacer is 3/32 inch thick, and must be fitted with the chamfered side towards the splines on the layshaft.
On the mainshaft there is a spacer that goes between the kickstart ratchet and the bearing in the outer cover( I am not sure of the dimentions, I believe approx 1/16 inch thick).
furthermore, there are circlips fitted between mainshaft first and second gear, and the layshaft third and fourth gear.
hope this helps.


Peter.
1974 Commando 850
1972 Trident T150T
1961 Goldie DBD34
1969 Benelli 250 sport special
#354643 - 01/24/11 8:51 pm Re: STD T gearbox question [Re: darbone85737]  
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dave - NV Online content
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Here are the dims for the tranny spacers taken from my copies of the data sheets compiled for the "Goldie", GSOC UK years ago by John Gardener for the BSA "T" transmissions. Perhaps worth printing a copy of these numbers for reference.

For those who are not familiar with BSA's letter ident for the gears, here's the way it's done. It's easy to become familiar with the system and it will eliminate any confusion.
A - 'sleeve' gear, the reduction gear on the mainshaft
B - pressed on layshaft, the reduction gear
C - mainshaft 2nd gear that engages the A gear in 4th
D - layshaft 2nd gear that engages the B gear for 2nd
E - mainshaft 3rd gear that engages mainshaft G for 3rd
F - layshaft 3rd gear that engages H for 1st
G - pressed on mainshaft 1st gear

shim washers:
43-3078 between shell and layshaft 'B' gear.
1 5/32" - 1.156" OD, 11/16" - 0.687" ID, 0.108" thick

67-3203 between the 'F' and 'H' gears
1 3/32" - 1.094" OD, 3/4" ID, 0.093" thick

42-3079 between the 'H' gear and middle cover
1 1/4" OD, 3/4" ID, 0.113" thick

67-3161 behind the kicker ratchet pinion bush
1.1625" OD, 3/4" ID, 0.075" thick

Note: the 67-3203 shim between the F and H gears on the layshaft should be fitted with the chamfer against the spline to allow for the slight radius in the shaft.

I would guess if you run into shimming problems it's because there may be some non standard pieces installed. An issue easily overlooked, is the 'bushing' box pressed on 'B' layshaft reduction gear is narrower then the 'T' box gear. If this gear is fitted in a T box there will be excessive layshaft end. I've had BI suppliers send the wrong gear. Be careful.
Or perhaps the tranny was converted at one time from a 'bushing' box to 'T' configuation by fitting Torrington layshaft bearings. This will change the shimming requirements.

By all means 'dry fit' and check for layshaft end play when building up a box on the bench. The spec isn't specified but I've "been told", 10-20 thou is OK, which is typical.

I've cured the problem of the tranny jumping out of 2nd under power by increasing the depth of the shaft wire ring relief in the B gear by 20-30 thou. This allows the B gear to be pressed further on the layshaft, thus increasing the D to B dog 2nd gear engagement. It's then required to add a 30 thou shim between the case and the shim against the B gear. Make sense? But of course replacing th B gear with a new one would be best.

There were a large variety of BSA gearsets and ratios made. I count 17 different boxes listed and 6 basic ratios. There were 4 different mainshafts made. And 2 different layshafts, for either the bushing box or the 'T' box. Caution: the layshafts look much the same, but the shaft's bearing size are different by 2.5 thou larger on the 'T' shaft. Good grief!

You can do a bit of mix/match playing with gears from different boxes but with the same p/n.
I seriously believe it was an expensive mistake with no reason for BSA to build both 'bushing' and 'T' gearboxes for all those years.

And speaking of Goldie tranys, it's up to 45F this afternoon and in just a bit I'm going to be diddling the DAY T box in my GS up in the fast swoopies for our 1st ride in awhile. yeah ...

Last edited by dave - NV; 01/25/11 5:47 pm.

dave - NV
#355669 - 01/30/11 7:45 pm Re: STD T gearbox question [Re: darbone85737]  
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db133 Offline
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Thanks for the info much appreciated that will keep me quiet for a while. Kind regards.

#355690 - 01/30/11 9:36 pm Re: STD T gearbox question [Re: darbone85737]  
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limeyrider Offline
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Has anyone assembled the gearbox casings without using "paper type" gaskets,i.e using only "Wellseal" or "Yamabond" type materials? .
Thank you.
James.

#356186 - 02/02/11 4:46 pm Re: STD T gearbox question [Re: darbone85737]  
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db133 Offline
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East Sussex UK
Good Question James.

Put my box together without paper gasket (on order) and it all jamed up. Slackened off nuts and screws and all ok again.

I have noticed some gaskets look to have a different thickness.

Looking for the part numbers for nuts on mainshaft clutch ends 'A' Type Box and the Plunger box................

Regards

Last edited by db133; 02/02/11 4:51 pm.
#356238 - 02/02/11 8:39 pm Re: STD T gearbox question [Re: darbone85737]  
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db; The A box clutch nut is 66-3787 and on the plunger box it is the same according to the BMS book and my 49-53 spares book.

Gordo


Without frequent roadside repairs there is no fun in riding!
#356323 - 02/03/11 9:07 am Re: STD T gearbox question [Re: darbone85737]  
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db133 Offline
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66-3787 = 11.13 thats a lot of money for a nut.

Anyone know what the thread is ?

#356426 - 02/03/11 8:00 pm Re: STD T gearbox question [Re: darbone85737]  
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db; If this is the nut we are talking about, I would gladly pay 11 pounds for it. It would not be a quick fabrication in my shop.

Gordo





Without frequent roadside repairs there is no fun in riding!
#356512 - 02/04/11 10:16 am Re: STD T gearbox question [Re: darbone85737]  
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db133 Offline
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Ref:db; If this is the nut we are talking about, I would gladly pay 11 pounds for it. It would not be a quick fabrication in my shop.

Yes I agree to make one nut but to make ..... and to charge the same price as to make one is a bit excessive methinks.

I've been looking and found the following mainshaft-clutch nuts:

40-3227
12571-54
67-3252
57=2730
68-3309
66-3787
68-3300
70-9795
42-3171
68-3300
67-3257
66-3787

Confused I am. Still like to know what is the correct one and the thread.


Pictures removed.

In anyevent kind regards.

Last edited by db133; 02/05/11 12:37 pm.
#356603 - 02/04/11 6:58 pm Re: STD T gearbox question [Re: darbone85737]  
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I would have to agree with Gordo. The nut he shows, made correctly to specs and of the correct material would certainly be worth 11 pounds to me. If there are as many different nuts as it seems there are I can't imagine that thousands of any nut would be made......and maybe I'll have a Goldie one day too.....Cheers, Wilf.


"It's about the ride..."
#356608 - 02/04/11 7:27 pm Re: STD T gearbox question [Re: Wilfred]  
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Peter R Online content
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DB133, this is a Norton mainshaft/clutch you are showing on these pictures, I happen to have a AMC/Norton gearbox mainshaft, and checked the thread size, it is 5/8 x 20tpi cycle thread (as opposed to the more common 26tpi).
The BSA maishaft has a tapered end as opposed to the splined end of the Norton, although the thread size on both shafts is identical.


Peter.
1974 Commando 850
1972 Trident T150T
1961 Goldie DBD34
1969 Benelli 250 sport special
#356696 - 02/05/11 12:13 pm Re: STD T gearbox question [Re: Peter R]  
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db133 Offline
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Originally Posted By: Peter R
DB133, this is a Norton mainshaft/clutch you are showing on these pictures, I happen to have a AMC/Norton gearbox mainshaft, and checked the thread size, it is 5/8 x 20tpi cycle thread (as opposed to the more common 26tpi).
The BSA maishaft has a tapered end as opposed to the splined end of the Norton, although the thread size on both shafts is identical.


Thanks for the info #67-3252/67-3257 at 1.82.

#356697 - 02/05/11 12:35 pm Re: STD T gearbox question [Re: Wilfred]  
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db133 Offline
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Originally Posted By: Wilfred
I would have to agree with Gordo. The nut he shows, made correctly to specs and of the correct material would certainly be worth 11 pounds to me. If there are as many different nuts as it seems there are I can't imagine that thousands of any nut would be made......and maybe I'll have a Goldie one day too.....Cheers, Wilf.


Yes I agree but with respect......what something is worth is a very subjective subject is it not ? Anyone earning the minimum wage in the UK will feel two hours work for a single nut a little confusing. On the other hand as you state its a bargin. What I do find confusing and fascinating is the price of the bikes compared to the price of the individial components. Also the prices in UK compaired to USA etc. In any event kind regards

#356730 - 02/05/11 4:02 pm Re: STD T gearbox question [Re: darbone85737]  
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darbone85737 Offline
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Tucson, AZ
Thought I'd come back to report the layshaft was assembled with the thrust washers in size/order as indicated earlier and all is well. The gearbox now shifts as it should. The coolest part of it was I found a NOS layshaft wrapped in oiled paper in the original blue and white box. I love stuff like that.

Now the magneto started acting up, sparking intermittently. But that's a story for another day


Tucson, AZ
1955 BSA Gold Star clubman
1958 BSA A10 Super Rocket
#356785 - 02/05/11 11:29 pm Re: STD T gearbox question [Re: darbone85737]  
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Wilfred Offline
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db...I think I understand as almost all of it is confusing to me, including the difference in price of the complete bikes. I think part of it has to be the export first part of it after the war but it is enough difference for British folk to come to North America and fill containers with motorcycles and cars to ship back to the UK. My thoughts on the nut were partly influenced by the difficulty experienced in getting parts that are up to spec rather than just looking like they might work. Anyway, back to the shop. Cheers, Wilf.


"It's about the ride..."
#359224 - 02/20/11 8:10 pm Re: STD T gearbox question [Re: Peter R]  
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db133 Offline
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Originally Posted By: Peter R
DB133, this is a Norton mainshaft/clutch you are showing on these pictures, I happen to have a AMC/Norton gearbox mainshaft, and checked the thread size, it is 5/8 x 20tpi cycle thread (as opposed to the more common 26tpi).
The BSA maishaft has a tapered end as opposed to the splined end of the Norton, although the thread size on both shafts is identical.


Hi Peter

Sorry just found your information thanks.

Ref the other post :
BSC thread has a thread angle of 60deg, same as UNF.
1/2 UNF also has 20tpi, so this size happens to be identical to 1/2 bsc-20.
The UNF die will probably be easier to find than a BSC die of this size.

Is there a UNF thread/nut that will fit the 5/8 x 20tpi cycle thread on my mainshaft ?

Do you know what the thread is on the other end of my mainshaft ?

Sorry about mix up and hope my questions make sense.

Kind regards.


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