V7 Special gearbox return spring |
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GUZZIPETE
Senior Member Joined: 29 Jul 2016 Location: Devon Status: Offline Points: 198 |
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Posted: 12 Jan 2019 at 22:22 |
Update.
After making no progress at all with this gearbox problem. I took the box over to Nigel at NBS before Christmas for some investigative surgery. After collecting it today, he found that the shaft that selector drum runs on was worn, and causing the drum to bind. Also the selector shaft that the return spring is fitted to was one tooth out of alignment on the gear teeth it meshes with. That must have been me when I changed the spring. In my feeble defence, it's not easy to see when the box is still in the bike. I will get it back in the bike over the next couple of weeks and hopefully enjoy the improvement.
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1971 Moto Guzzi V7 Special
1974 Laverda 750 SF2 1979 Laverda 3CL |
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Ogmios
Falcone Joined: 03 May 2016 Location: Dublin Status: Offline Points: 39 |
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"
... and with the four-speed box you can if you have to change the spring on
the side of the road. Pity the later gearbox doesn't have that facility." understatement of the year! ~~~ Og ~ 78k miles on a Cali 3 and twice had the gearbox out. (... and just back from a tour of Brittany. Again. Only not on the Cali this time )
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Appears bright from a distance / dim up close.
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GUZZIPETE
Senior Member Joined: 29 Jul 2016 Location: Devon Status: Offline Points: 198 |
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Ha, yes definitely!
Pete.
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1971 Moto Guzzi V7 Special
1974 Laverda 750 SF2 1979 Laverda 3CL |
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Dave P.
Senior Member Joined: 12 Jan 2015 Location: Northants Status: Offline Points: 5572 |
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Just a thought, or another straw to grasp. Is the gear lever shaft binding in the tunnel through which it passes? Is it clean and greased? And does it have end float? Ah! Greg's already asked you that.
I think we should have an emoticon on here of the little yellow chap reaching for a straw. Edited by Dave P. - 20 Sep 2018 at 17:09 |
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TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.
1971 V7 Special. 1972 850GT. 1970 T120 Bonnie. 2009 500 Bullet. |
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GUZZIPETE
Senior Member Joined: 29 Jul 2016 Location: Devon Status: Offline Points: 198 |
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The pedal was sticking intermittently and the return action was weak, which prompted the spring swap.
The doesn't do a lot of miles, as I generally tour on the 850 T and I've been using the Convert for most of the local miles this year, so I'm wondering whether it could be lack of miles that is causing the pedal to stick a bit. But I could be clutching (no pun intended) at straws? You have obviously carried out surgery on your box and survived to tell the tale? Pete.
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1971 Moto Guzzi V7 Special
1974 Laverda 750 SF2 1979 Laverda 3CL |
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Dave P.
Senior Member Joined: 12 Jan 2015 Location: Northants Status: Offline Points: 5572 |
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Hi Pete, this is a bit strange as all was apparently well before you changed the spring. Was it shifting OK before? Or did you change the spring because of poor shifting?
When I rebuilt my box I shimmed the shifting drum which made the lever return just a tad reluctant. Not wishing to strip it all again I rode it for a while and it freed up nicely. I think it just polished the surface of the shim washer which was plated. |
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TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.
1971 V7 Special. 1972 850GT. 1970 T120 Bonnie. 2009 500 Bullet. |
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GUZZIPETE
Senior Member Joined: 29 Jul 2016 Location: Devon Status: Offline Points: 198 |
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Hi Dave
Some improvement I think Dave, but still not as it should be. I contacted Greg Bender at the weekend, and he was kind enough to reply with some insightful suggestions. Apart from the obvious points like making sure the pivots and linkages are moving freely, he also responded to a question about whether there could be anything inside the box causing the issue, and he responded with this below:- External to
the transmission, I would make sure that all of the linkages and pivot bushings
are in good shape, clean, lubricated, etc. If that still does not solve the
problem, then I would look internal to the transmission. Specifically, I would
look at the shift drum and examine how it rotates on its shaft and against the
thrust washers at either end. Any of those pieces can become corroded and make
for something that doesn’t want to rotate. I'm not keen on getting into the box myself, as Dave Richardson says that they are not easy to re-assemble, and I think you need a few special tools too, so I don't see much point in ending up with a pile of parts on the bench. I guess Nigel at NBS would be the candidate for that job. I want to try it out on the road for a longer run and see how it fares. At the moment I have to nudge the lever back up slightly, so it's ready for the next up-change. One thing I did do was to mod the eccentric adjuster screw. As you know, it is only slotted on the end for means of adjustment, which makes it nigh on impossible to adjust when everything is back together. So I drilled and tapped the outer end of it and loctite'd an M6 bolt into it, so that it can be adjusted from the side rather than having to get on to the end of it. I also marked one of the flats on the bolt in line with the highers point of the eccentric on the other end for reference when adjusting it. I find a pair of ratchet spanners positioned from the side just above the UJ gaitor provide the best access. After all that, Greg mentioned that he has never found that adjusting screw makes very much difference to the lever action in his experience. I hope your bikes are behaving? ATB Pete. |
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1971 Moto Guzzi V7 Special
1974 Laverda 750 SF2 1979 Laverda 3CL |
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Dave P.
Senior Member Joined: 12 Jan 2015 Location: Northants Status: Offline Points: 5572 |
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Any progress Pete?
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TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.
1971 V7 Special. 1972 850GT. 1970 T120 Bonnie. 2009 500 Bullet. |
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Dave P.
Senior Member Joined: 12 Jan 2015 Location: Northants Status: Offline Points: 5572 |
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Pete, just thank your lucky stars it's not a five-speed box!
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TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.
1971 V7 Special. 1972 850GT. 1970 T120 Bonnie. 2009 500 Bullet. |
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GUZZIPETE
Senior Member Joined: 29 Jul 2016 Location: Devon Status: Offline Points: 198 |
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Road tested the bike tonight, but it's still not right. The gear lever is still biased to the rear, so that when I change up a gear, the pedal is not springing back up ready for the next gear without some help. This also means that it will easily jump out of first. I will have another go at moving the adjuster, but this time I will try to adjust it so that the bias is the other way, rather than setting it for what felt like an equal loading in either direction.
I don't know about changing it on the roadside Dave, but I will be able to do it in my sleep soon!
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1971 Moto Guzzi V7 Special
1974 Laverda 750 SF2 1979 Laverda 3CL |
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Dave P.
Senior Member Joined: 12 Jan 2015 Location: Northants Status: Offline Points: 5572 |
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Hmm, that puts a different perspective on things. I'll leave the five-speed spring in there but if it fails I'll go back to the original four-speed. I carry one on the bike anyway and with the four-speed box you can if you have to change the spring on the side of the road. Pity the later gearbox doesn't have that facility. Every day's a school day.
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TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.
1971 V7 Special. 1972 850GT. 1970 T120 Bonnie. 2009 500 Bullet. |
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GUZZIPETE
Senior Member Joined: 29 Jul 2016 Location: Devon Status: Offline Points: 198 |
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I can see your logic there Charlie. I'll see how I get on with the 5 speed, now that it's in there, but might revert to the 4 speed if I don't have success in sorting the initial issue.
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1971 Moto Guzzi V7 Special
1974 Laverda 750 SF2 1979 Laverda 3CL |
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Amboman
Senior Member Joined: 05 Dec 2015 Location: Maryland, USA Status: Offline Points: 383 |
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The only reason I went with the 5 spd. spring in the first place was due to due to a period of unavailability of the 4 spd. spring. I always disliked having to trim and bend the 5 spd. spring to make it work, the 4 spd. spring was a direct fit, so when they became available again I went back to using it. How many 4 spds. have suffered a broken return spring? In my 35 years of owning Guzzis, I can't say I've heard of one. How many 5 spd. springs have broken? Dozens! It took Guzzi three tries to make a spring that didn't break.
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Charlie
'69 Ambassador,'71 Ambassador,'73 Eldorado,'75 Eldorado police,'76 Convert,'77 Morini 3 1/2 Strada,'81 Ducati 500SL Pantah http://www.AntietamClassicCycle.com |
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Dave P.
Senior Member Joined: 12 Jan 2015 Location: Northants Status: Offline Points: 5572 |
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The trimming of the "progs" was what I was referring to when I mentioned modifying the five-speed spring, they are too long. I thought that the later spring felt stronger so I'm also interested in why Charlie reverted to the four-speed version.
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TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.
1971 V7 Special. 1972 850GT. 1970 T120 Bonnie. 2009 500 Bullet. |
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GUZZIPETE
Senior Member Joined: 29 Jul 2016 Location: Devon Status: Offline Points: 198 |
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Fitted the 5 speed spring and worked on 'tuning-in' the selection with the adjuster tonight. It feels more positive at this stage, but always difficult to tell on the bench.
Will finish re-assembly and road test it tomorrow. Charlie, why did you revert to the 4 speed spring I wonder?
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1971 Moto Guzzi V7 Special
1974 Laverda 750 SF2 1979 Laverda 3CL |
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