Spring is sprung

[belfastguzzi]

The gearbox pre-selector arm spring broke at 1,200 miles.

After disassembling, I measured the boss that spring coil locates on. Sure enough, it was over 16mm.

Baldini reckons it should be 15mm. I confirm that the coil does bind on the oversize boss.

 

The spring hook bend pulls against a sharp edge. This makes a rough gouge.

 

The two stresses probably both contribute to the spring's early demise.

 

I re-profiled this edge where the spring bend seats, to make it a better, more positive, less stressed fit for the spring hook.

 

Now the spring:–

 

I bent the broken end to make a new hook and slightly reshaped the rest of the spring.

.

 

The ratchet boss was filed down to just under 15mm and offset so it is shorter to the rear. (I forgot to photograph this.) The spring coil now moves freely on this.

 

More pictures on here.

 

When disassembling, the box was still in gear: when it was apart I worked out that it was fourth. I don't think that the gear number has any significance to the break happening. Neutral was then selected by sliding the forks. For re-assembly, toothed wheels were set in neutral position and the cover then fitted easily back on to gearbox.

 

On a short test run, the spring has worked fine – gear change works. Changing could possibly be improved by re-setting the adjustment screw (given the different size & tension of my repaired spring). Has anyone used this adjustment screw to good effect?

 

Could a spring change be done at the roadside? I think it could but you would need to have the right tools and of course lack of tools is a likely problem. Better to check this out and make modifications before a break happens.

 

Update on roadside repair: see website page here

[al_roethlisberger]

Excellent detailed report

 

 

I've added this to the FAQ

 

 

al

[Martin Barrett]

Glad to see that you sorted it without the long delay for parts to arrive or finding a dealer to do under warantee. Your detailed report gives me confidence that if mine goes I might beable to rectify it as easily.

I loved the "tools required" style of your link, There are some gaps in my tool box, but I might be able to adapt what I have.I did learn the hard way (new clutch basket for my XJ550) that some times the correct tool is required

On my FJ I had to reseat the spring on the selector quadrant, couldn't find any breakages or reason for it to have sprung off. But worked okay afterwards.But haven't done too many miles since.

[Baldini]

Belfastguzzi,

 

Blimey! Can we fix it ??? .............

Great report, esp pictures.

 

KB

 

PS.I wondered about reprofiling the edge of the shift plate, but was worried it would cause spring to slip off edge, course now it doesn't bind, it wouldn't, so I wish I had . Presumably you cut the plate back cos you shortened spring? as well as to locate spring in a 'v'? I'm not sure about the wear on that edge contributing to spring failure, spring is harder than plate & moves across edge in use anyhow...once it's worn a groove...I dunno. I know nothing about metalurgy but will the new bend on the spring not weaken it...or work itself out in use? Are springs not heat treated after forming? What do you think about setting a pin or something into the shift plate to locate bottom of spring & doing away with the 90degree bend altogether?

[belfastguzzi]

Belfastguzzi,

 

Blimey! Can we fix it ??? .............

Great report, esp pictures. 

 

KB

 

PS.I wondered about reprofiling the edge of the shift plate, but was worried it would cause spring to slip off edge, course now it doesn't bind, it wouldn't, so I wish I had . Presumably you cut the plate back cos you shortened spring? as well as to locate spring in a 'v'? I'm not sure about the wear on that edge contributing to spring failure, spring is harder than plate & moves across edge in use anyhow...once it's worn a groove...I dunno. I know nothing about metalurgy but will the new bend on the spring not weaken it...or work itself out in use? Are springs not heat treated after forming? What do you think about setting a pin or something into the shift plate to locate bottom of spring & doing away with the 90degree bend altogether?

Re Martin's comments –

Tools: yeah, that's the problem about roadside repair, I don't usually carry those particular tools (as illustrated) with me.

 

Baldini –

 

I cut into the 'shift plate' partly because of the short spring, but I thought it would be a better shape anyway: and I still want it to work with a normal spring. Although the spring is harder than the plate and so cuts into it, by doing that, it does create rough, jagged edges. It seems better to start with a good shape that both locates the spring and lets it slide smoothly, rather than make the spring wear its channel through a chisel point. The objective is to spread the load on the spring bend instead of stress being on a very small point of the bent spring section. However I can't give any measure of how important this is. It must have some importance as this is the exact point where the spring breaks.

 

Are springs heat treated after forming? I wondered about that and of course, if needed, it could be done as part of the repair. I don't think so. I would say they are just bent up. *It would be good if someone who knows could tell us.*

I don't think that this repair will pull out, but it might break again. As well as reshaping the plate, I reshaped the whole spring slightly so that it would sit in a better position and the hook would keep in a good position.

 

Put a pin in plate? Do you mean that that the spring would then have a hook or eyelet bent into the end to locate around the pin?

It's worth thinking about, next time the bits are out again. However, if that's what you mean, the spring would still need a sharp bend in it. The current factory design should be fine. It does look like the oversize boss was the main problem as it did stop full spring movement and caused an abnormal pull on the bend when down shifting. There's not much in it, it's only a small movement.

 

**Do we know if springs are breaking on 15mm bosses anyway?**

 

It would be easier to thrash these things out and come up with ideas and solutions if it was possible to get together. As we can't, the internet/forum is a fantastic second best. If this had happened and I hadn't seen the info on here, I wouldn't have had a clue about what had gone wrong.

 

[stupidly, I didn't measure the dimensions of my repaired spring. A new, normal spring is in the post from John O'S in Cork.]

[docc]

Adjusting the throw on the pawl is easy. It just never solved any of my shifting problems. (New gearbox did that).

 

I don't think your spring changes will affect the movement of the pawl. The adjuster should probably still be centered. If it is not engaging fully in either upshifts or downshifts , the movement of the pawl can be adjusted with the external adjuster.

 

First, remove the acorn cap nut. Note the postion of the screw slot in the end of the shaft. Hold this with a blade screwdriver and release the locknut. ( A 19mm "crow's foot" works well. Rotate the shaft with the screwdriver one way then the other noting the travel oy the shift arm. As I recall it only moves 1/2 turn so adjustments of 1/8 turn may change engagement.

 

Both nuts are sealed with normal crush washers. Either renew them or expect to if the box drips there after you mess with them.

 

 

Belfastguzzi and Baldini should be given The Golden Sparkplug for sharing this with the world. Carlo would be proud! :!:

[Baldini]

Put a pin in plate? Do you mean that that the spring would then have a hook or eyelet bent into the end to locate around the pin?

No. I was thinking a stop could be put on the plate & the 90degree bend cut off the spring. The short straight part of the spring would be held against this stop, which could be perhaps a pin or plate (w/ raised end/edge to stop spring sliding off side) welded to the shift plate ( machined location in plate & piece brazed?). The spring would slide against it in use.

 

Re the 15mm boss/still breaking springs: I've pm'd sweep re his 15mm boss/7th broken spring, see if I can speak with his mechanic.

 

Cheers, KB

[belfastguzzi]

a stop could be put on the plate & the 90degree bend cut off the spring.

mmm.. can't wait til mine breaks again so that I can try this * *

 

Thanks for the note about the adjuster, Docc. I've been wishing that I had looked closer at it when the cover was off. Going by what you say, I'll leave it alone, as, so far, the thing is changing ok.

[Bill Hagan]

a stop could be put on the plate & the 90degree bend cut off the spring.

mmm.. can't wait til mine breaks again so that I can try this * *

 

Thanks for the note about the adjuster, Docc. I've been wishing that I had looked closer at it when the cover was off. Going by what you say, I'll leave it alone, as, so far, the thing is changing ok.

 

I just emailed this url to my dealer where my Ballabio sits forlornly awaiting its turn in the queue.

 

Thanks for the info.

 

Bill

[belfastguzzi]

my Ballabio sits forlornly awaiting its turn in the queue.

Have you any idea when it will be looked at, Bill?

 

Definitely get them to measure the diameter of that boss for the spring coil and let us know.

 

Edit: *another thought – can you get them to measure the inside diameter of the coil too?

 

> Has EVERY year of bike been affected by this spring break problem?

 

 

 

*-> Another thought – could there be a variation in the diameter of the spring coils? This would be worth checking as a smaller, tighter coil on 15mm boss will give the same binding problem as 'normal' coil on big boss.

 

There could be more variations, e.g. with boss size: if there was one period of bad production when 16+mm bosses were made, couldn't there have been others? It would be useful to build up data on the size variations of these parts. It may sound obsessive, but this really is a serious problem as it potentailly means that a bike becomes disabled every 600 or 1,200 or 1,500 miles and creates a mood of uncertainty when contemplating traveling away from home.

 

Until we have definitive sizes for these items, I think I'll take the view that the boss is better smaller than bigger and there's no harm in making it smaller, to give some peace of mind.

[Bill Hagan]

my Ballabio sits forlornly awaiting its turn in the queue.

Have you any idea when it will be looked at, Bill?

 

Definitely get them to measure the diameter of that boss for the spring coil and let us know.

 

Edit: *another thought – can you get them to measure the inside diameter of the coil too?

 

> Has EVERY year of bike been affected by this spring break problem?

 

 

 

*-> Another thought – could there be a variation in the diameter of the spring coils? This would be worth checking as a smaller, tighter coil on 15mm boss will give the same binding problem as 'normal' coil on big boss.

 

There could be more variations, e.g. with boss size: if there was one period of bad production when 16+mm bosses were made, couldn't there have been others? It would be useful to build up data on the size variations of these parts. It may sound obsessive, but this really is a serious problem as it potentailly means that a bike becomes disabled every 600 or 1,200 or 1,500 miles and creates a mood of uncertainty when contemplating traveling away from home.

 

Until we have definitive sizes for these items, I think I'll take the view that the boss is better smaller than bigger and there's no harm in making it smaller, to give some peace of mind.

 

 

Hey, Michael, et al, at Atlanta Triumph Ducati (& Moto Guzzi!), note, especially, the "please measure" request of boss & inside diameter of coil.

 

Thanks.

 

So ... is it ready yet?

[Baldini]

It may sound obsessive, but this really is a serious problem ...creates a mood of uncertainty when contemplating traveling away from home.

 

Aye...That's how it starts...pretty soon you'll not be able to sleep, then you'll take to checking the gearchange at odd hours in the nightime to see the spring is still in one piece...I think of little else for most of my waking hours now....

[jrt]

I cannot sleep, but still the dreams come.

[Bill Hagan]

my Ballabio sits forlornly awaiting its turn in the queue.

Have you any idea when it will be looked at, Bill?

 

Definitely get them to measure the diameter of that boss for the spring coil and let us know.

 

Edit: *another thought – can you get them to measure the inside diameter of the coil too?

 

****

 

Tried to post this at your website as a TY, but got "text too long" msg. Fine.

 

Very, very grateful for the trouble you went to for these pics. I am as green as Irish grass about things mechanical, but am building a garage and hope soon to get my fingernails black and the air blue with curses. :-)

 

BTW, dealer has Ballabio and "thinks" they'll get to it next week. We shall see. I did buy an extra spring for the road!

 

One add-on for the board. At the dealer, I had to endure the staff telling me what a Guzzi god docc is. Puhleeze.

 

Bill Hagan

[belfastguzzi]

At the dealer, I had to endure the staff telling me what a Guzzi god docc is.

Bill, how's your hearing? Did they say god, or dog?

 

 

 

What's a TY?

Did you try to send a message and couldn't ? I'll have to investigate.

 

Another week – commiserations.

 

At least you've got a dealer though. I have just come home, dead tired, splitting headache, stopped the bike and

I'm sure I kicked my foot out and

I thought I put the sidestand down

but you've guessed it...

I got off the bike and... there was no sidestand and over she went.

Now I've got to try glueing all the little bits of indicator back together again, 'cos there's no shop to buy a new one from.