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American Triumph
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After fitting the inner gearbox cover on my '58 T110 following a repair to the cover, I noticed approximately .050" of endplay on the layshaft. Seeming excessive, I removed the layshaft for inspection. I have questions about what I found.

It appears that the layshaft endplay is determined by the thickness of the flanges of the two T1367 bushings (see photo below). The bushings I have installed have flanges that are about I took about .100” in thickness.

In 1961, the GB case layshaft bearing was changed to T1606, a caged needle bearing and also added a thrust washer T1607. Also changed was the inner cover layshaft bushing to T1614 and added thrust washer T1607. The layshaft changed from T1063 to T1608.


My questions are;

Is .050” layshaft endplay is excessive?
Is the earlier layshaft endplay determined by the thickness of the layshaft bushing T1367 flange?
What is the nominal thickness of the layshaft bushing T1367 flange?
What is the nominal thickness of the inner cover layshaft T1614 bushing?
What is the nominal thickness of the thrust washer T1607?

------------------------------------------------------------

I also found that when comparing the layshaft I used in this gearbox with other layshafts I have, the GB case bearing end of the shaft was .140” shorter than some others (see photo below).

My question here;

Is the difference between the earlier layshaft T1603 and the later layshaft T1608 the length of the GB case end of the layshaft?
If so, which one is which?

I know there are a lot of questions to answer here but I believe that somewhere here is the answer to my suspected problem.

Thanks! gp

IMG_5456a.jpg IMG_5455a.jpg

Geoff Patrick
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geoff,
Bruce Baker will probably know.
Scott

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Mr Patrick -
Several ideas for you....

• IMHO .050" axial play is not excessive, and may have steered you from measuring the REALLY important dimension... namely the diameter of the end journals of the layshaft. The bronze layshaft bushes are worthless. They absorb grit, which then act like grinding stones reducing the journal diameter (basically grinding it down as you ride).

• I believe that journal is supposed to be 11/16 (.6875) inches diameter on both ends. It's not unusual for pre-unit layshafts to loose .030" or more using old plain bronze bushes. That goes on to affect the shifting.

• If there is any way possible, you should convert your layshaft bearings (both ends) to the needle roller type used from ~1963 on. If your journal diameter is reduced, you may have to find a layshaft from a 1963-65 model (such as in your photo) that still used the speedo drive off the layshaft end.

• Conversion will require that you fit the shaft with the 0.66" long journals that you show in your photo. That's the difference in those 2 shafts in your photo: pre-unit plain bush vs. unit construction with Torrington needle roller bearing journal lengths. Once you have the shorter layshaft, conversion is easy. You simply tap the needle rollers into place with THIS TOOL. No machining of the cases is required.

• Let me urge you to further reduce your gearbox wear by converting over to 90W or 80/90W gear oil. Your Manual may suggest 50W engine oil, but that is so far outdated as to be laughable. OTOH you don't need expensive synthetic, just plain old EP gear oil will do fine. Synthetic is simply too expensive to change every 6 months like you should be doing.

• If you have evidence of a lot of water collecting in the outer g/b cover then you may want to consider drilling an extra drain hole as I did on my 1966...
[Linked Image]
This allows all the water to drain out during a regular oil change. Without the lower hole the water is simply trapped.

Hope this helps! :bigt


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RF Whatley
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Thanks for all of the info RF!

Cheers!


Geoff Patrick
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Since oil doesn't normally circulate in the outer g/b cover, you either have to get the g/b hot enough to vaporize any water present (not a huge issue on unit engines), or change the g/b oil often enough to keep it from building up. The constant oil changes are the best reasons not to use expensive oils.



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RF Whatley
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Originally Posted by RF Whatley
Mr Patrick -
...
� I believe that journal is supposed to be 11/16 (.6875) inches diameter on both ends. It's not unusual for pre-unit layshafts to loose .030" or more using old plain bronze bushes. That goes on to affect the shifting.

� If there is any way possible, you should convert your layshaft bearings (both ends) to the needle roller type used from ~1963 on. If your journal diameter is reduced, you may have to find a layshaft from a 1963-65 model (such as in your photo) that still used the speedo drive off the layshaft end.

... :bigt


I'm currently re-building a 6T gearbox and found this thread. I realize it's an old one but addresses a topic I'm working on. The bushings in my box are shot and I'm looking to replace them. However, I just measured the layshaft diameter where it rides in the bushing and the diameter is .6810. Is that diameter within tolerance to use the new needle bearings? If not, will a layshaft from a later model work?

If it is within spec will part number 57-1614 work (650 unit layshaft bearings)?

Last edited by SteveM; 11/23/17 12:48 am.
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http://americantriumph.tv/holiday-stuffed-gearbox-recipe/

Doesn't answer your question, but kinda cool....

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I found a part number change for the layshaft when they went to needle bearings. I could see no difference between the two shafts, so I assumed that a different hardness was required in order to be compatible with the new bearings.

Just precautionary. I know I couldn't use the later available layshafts because they weren't drilled for the speedo gear. However, there is a couple of years (63-65) when the gears were used in the unit bikes and those shafts would probably be what you want.

Cheers,
Bill

Last edited by HawaiianTiger; 11/23/17 3:58 am.

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Originally Posted by HawaiianTiger
I found a part number change for the layshaft when they went to needle bearings. I could see no difference between the two shafts, so I assumed that a different hardness was required in order to be compatible with the new bearings.

Just precautionary. I know I couldn't use the later available layshafts because they weren't drilled for the speedo gear. However, there is a couple of years (63-65) when the gears were used in the unit bikes and those shafts would probably be what you want.

Cheers,
Bill


Thanks Bill. At this point I'm thinking I'm going to use the old-fashioned bushings. If I can find them slightly under-size I can ream them to match the shafts.


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