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Preemptive Shift Return Spring and Pawl Arm Replacement


sp838

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Really? You think it's just a matter of adjustments? That would be great if no new parts were needed. I had no idea there were two eccentrics in there to fine tune the shaft positions and ratchet. I guess you gotta be a Swiss watch maker to own a Guzzi too!

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I also had no idea about that other eccentric apdjustment until about my second coffee! I'd been sitting there scratching my head and thinking the pawl shaft needed moving when I noticed the locking nut near the gearchange that wasn't in any of the pics on this forum ( or any manual I could find online) . Theoretically, you could adjust this without even removing the cover - say 1/8 th turn at a time? I already had the cover off so have no idea if it's viable this way.

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I think this is explained also in the Workshop Manual, later "update" addition?
"
36 GEARBOX
Contrary to the previous model, the gearbox is equipped with a special adjusting eccentric “A” used to adjust gear selector hook “B” position. Gear selection will thus be improved and more accurate. To check wheels correct operation, adjust hook position on right wheel; Position hook “B” upwards and then turn eccentric “A” counter-clockwise with a screwdriver to move it towards hook “B’;  Check that the area between eccentric “A” and hook “B” – marked on the drawing – is free.
"

Exx.jpg

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Wow this is great stuff guys, looking forward to playing around with this. I will take a close look at see if it is possible without removing the clockwork cover. Thanks for the info guys!

 

P.s. Harpers called me today, and they are going to email me a copy of the service bulletin for the spring/cover kit. It sounds like my issue is not related to the pawl spring, but I will still post the bulletin here, just for completeness.

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Cam, that adjuster is only one of the eccentric screws on the post 03 box, the other is item 9 in the harper exploded view. I'll be interested to see if their service update advises how to best adjust screw 9.

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that adjuster is only one of the eccentric screws on the post 03 box

OK. I understood that there is only one eccentric, which is the "Nr.9", only the pictures (Harpers/Guzzimanual) were drawn differently. Guzzimanual as seen from inside (eccentric on the left), Harpers as seen from outside (eccentric on the right).
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No update from Harpers yet on the service bulletin.... but I think we've nailed down the two adjustment eccentrics - thanks for the drawings and info guys!

 

It certainly looks as if #9 is easily adjustable from the outside (with flathead after unlocking the jamb-nut), but it isn't as clear for #32. If I can see a flathead screw tip on the #32 threaded rod, I will report back.

 

After that, it's just a matter of figuring out a methodology!

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just a matter of figuring out a methodology

Who am I to give any suggestions, but this is how I would try to do it first (as the Beatles said: ”number nine, number nine, number nine” - Revolution 9, White Album)…

I adjusted the ”main eccentric” (Nr.9) which the Guzzi manual also describes, when I had the gear changer cover in my hand (all parts assembled). I moved the gears up and down (1-6) and searched the right position for the eccentric. My conclusion was that if it is too tight, the gear change pawl sticks to the eccentric and the movement stops, "gears stick" (test with all gears). When you give a bit more room (by turning the eccentric to the opposite direction) so that the gear change pawl moves (klick, and it is released from the "stuck" position by itself) , the adjustement is now OK.

So I would try to adjust the eccentric Nr. 9 with the gear change cover bolted to the gear box so:

1. Mark the eccentric adjustment head position accurately (to be right back where you started from if needed)

2. Loosen the lock nut

3. Turn the eccentric to different positions and find the position where the gear change pawl sticks

4. Give a bit play for the gear change pawl (eccentric a bit more away from the pawl) and tighten the lock nut.

5. Test many times back and forth (1-6) that all gears change cheerfully

 

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No 9 made the most difference to my bike. The other eccentric ( lets call him 32) was the icing on the cake - think of it as limitting the stroke of the gearlever. Effectively, once I got a reliable change using no 9 , I then adjusted 32 until I had the shortest stroke to reliably change gears. You have to remove the cover to get to 32.

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So much for me making any adjustment today... can't loosen the jamb nut unless I remove the QUAT-D exhaust... Oh well. Maybe I'll look around further from the top later on and see if I can get access.

 

Here's a shot of the acorn nut cover, and the actual eccentric adjust and (flanged!) jambnut.

 

2014-11-22100417_zps102c537b.jpg

2014-11-22100436_zpsce9d72c9.jpg
 

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