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#628683 12/03/15 11:58 pm
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A question about setting up the gearbox ... I have a STD "T" gearbox on my project DBD34. Working on the 'box today, in the instruction included with Eddie Dow's " Goldstarlets" on setting up the gear shifting, he states to turn the cam plate to set the gearbox in bottom gear before replacing the centre casing and positioning the swinging fork to the top of the slot. If I have a reverse cam plate in my box, is the procedure reversed ? ... i.e. instead of using bottom gear, should I use top gear to position the swinging fork ?.

Thanks,

James.

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Originally Posted by limeyrider
A question about setting up the gearbox ...
That's an interesting question. Rather than trying to remember the answer, in the hopes that it helps, I'll quote from an article in 'Classic Mechanics' that's in my homemade Gold Star shop Manual:

Fit the camplate ... Gold Star gearbox fitted with the reverse camplate ... if it is a standard box, set the camplate in the neutral notch which is the shallow notch second from the end. In the case of the Goldie, set it in the first gear notch which is the end one next to neutral.

The gear cluster can now be fitted. Assemble the layshaft sliding pinions together with the selector fork. Slide the assembly into the shell making sure the peg on the selector fork fits in the groove in the camplate nearest to the sleeve gear.


Further on this topic, an article in the April 2011 issue of Classic Bike Guide says:

...be aware that the punch mark on the gear selector is to be ignored on a RRT2 box. On a standard gearbox the punch mark should line up with an equivalent punch mark on the case, this tallies with the neutral position on the cam plate and synchronises the gears so the one up, three down pattern can be found. Line up the punch marks on a RRT2 box and you'll get two gears if you're lucky. ... the reverse cam plate is a mirror image so it makes sense to mirror the punch mark to the other side of the gear selector's centre line.

Last edited by Magnetoman; 12/04/15 11:32 am.
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Thanks MM, that does clear things up a bit, I set up the gearbox according to the standard instruction ...and could only get two gears, I have not as yet counted the gear teeth to determine if this gearbox is something other than the stamped " STD T "....it seems that it may well be.
Thanks again.

James.

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James ... When a reverse cam plate is fitted, the 'red dots' alignment on the selector obviously have no bearing. Here's the drill as I vagerly remember that has worked for me. Handily the size of the 'window' in the center case limits the travel of the selector arm aka rocking lever.

Using a large straight slot screw driver and observing the cam plate detent, rotate the shift cam into 4th gear. This is the end notch opposite the 1st gear notch adjacent to the neutral shallow notch. backing off the tension on the detent plunger spring makes this easier. Don't forget you've done this!

Now slide the center cover home holding the selector arm just clear of the edge of the 'window'. Secure the cover with the one screw in it's recess.

Gripping with a large slip joint plier across the notched end of the selector arm, shift the tranny through the gears, natch wiggle the shafts to allow dog engagements.

If all is well again remove the inner cover and fit the composition (not a POS paper) gasket and reassemble again noting the clearance of the selector in the window. Recheck shifting and finish reassembly of the mainshaft kicker hardware and outer cover.
Do Not forget to tighten the grub screw securing the shift fork shaft/rod! BTDT, got to do a road side fix. aargh.
With the clutch arm stuck out through the hole in the outer cover it will hold the kicker arm while replacing the cover.

Make sense? BTW, I hope you have the 3 different shim washers properly sorted. A common screw up ...

BTW, this procedure will also work with a conventional cam plate. The parallax when aligning the 'red dots' with neutral selected can screw you up.

Last edited by dave - NV; 12/04/15 1:51 pm.

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Thanks for the walk through Dave .... gearbox shifts just fine ....now!. The internal ratios are std, just the reverse cam plate plate fitted.
I have a sheet of instructions produced by John Gardner which details the correct washer fitment....very useful.

Thanks again.

James.

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Having re-read your walk through, and the instruction sheet from John Gardner, I went back over the layshaft assembly .... the inner most thrust washer, part number 42-3078 is listed by John as .017" thick ...the same washer in my gearbox is .109" thick ... the thrust washer at the outboard end ..part number 42-3079 ..listed by John as .113" thick is missing ?. Could this be a BSA modification ...eliminating a washer....or is it some mysterious "mod" by a PO ?.

The only difficulty shifting now is due ...I think .. to badly worn teeth on the shifting fork.

Thanks.

James.

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James ... I believe we are referring to the same tranny discussion by John Gardener in 'The Goldie'.
Here's my understanding of the shim issue that's worked for me many times. I'm repeating what you know, but perhaps some useful info for others.
I'll quote:
A total of 4 shim washers are fitted. 3 on the layshaft and 1 behind the kicker ratchet.
p/n 42-3078, 0.108" thick -- fit between the outer case and the layshaft 'B' gear.
p/n 67-3203, 0.093" thick -- fit between the lay shaft 'F' and 'H' gears.
p/n 42-3079, 0.113" thick -- fit between the lay shaft 'H' gear and the middle cover.
p/n 67-3161, 0.075" (or 0.068") thick -- fit behind the kicker ratchet pinion bush.

If you are missing the washer between the 'H' gear and the cover, your lay shaft end play must be way out of the norm 0.005"-0.020" dim. ??

If you are dealing with a 'bushing' tranny cases converted to a 'T' box things are changed. hmmm?

BTW, I still remember my 'adventure' last winter fitting a Nova 5 speed gear set in a 'T' box. A whole different but doable deal with jewel like pieces. Nice.

Last edited by dave - NV; 12/05/15 4:33 pm.

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Dave...it appears that I am missing the 42-3079 thrust washer. The gearbox is stamped STD T .. I am assuming that it was originally a needle bearing gearbox and not converted from bushing.I have the 'box apart now, I will reassemble and check the lay shaft end float,probably going to need a new washer.

Thanks for the info.

James.



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