27 replies to this topic

[belfastguzzi]

The web pages that I made a long time ago (2004) with photos of the spring fix are no longer working. I still receive regular enquiries and requests from various parts of the world regarding the infamous broken spring issue. Yesterday, I received two requests for info and photos, from opposite sides of the globe. That has prompted me to get the photos into a FAQ / How To topic on the site here.
Clearly the springs are continuing to break, so at root, it's probably a bad design and even having the correctly spec'ed parts won't always avoid the consequences.

Gearbox Pre-Selector Spring
and Pawl Arm Boss
My repair procedure as documented in 2004
including a roadside repair method.

Please see the exploded parts diagram and the detailed instructions on disassembly and fitting that are already on the site and are referenced with links in the FAQ sub-forum.

I originally posted some of these pics in 2004 discussions on the V.11 Forum in this thread
1) here
and the roadside repair one is
2) here
3) and actual roadside job is here

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[belfastguzzi]

New sized parts have been available for a long time now. The spring has a bigger coil, to allow for the oversized bosses that were on the bad batch of pawl arms. All new springs should have the wider coil, unless you buy from someone who still has very old stocks. If you get a new Pawl Arm, it should have the 15mm boss, not the 16mm boss that appeared around 2002.
>> April 2005, Moto Guzzi Technical Bulletin
Problem: broken gear change pawl spring
Solution: In case of breakage of the pawl spring A in vehicles with frame numbers before KT111435 - KS112350,
the pawl B should be changed (when asking for the spare part, you automatically receive the pawl updated version).
The change consists in the reduction of the diameter on which the spring rests from 16 mm to 15 mm.

Part nos:
04 23 51 01 for the new arm,
04 23 83 00 for the OEM spring.

Springs are still breaking, so while it is best to have the correct size of pawl arm and spring, it's not a guarantee that it won't break again. It must just be a flawed design.

Here is a summary instruction, previously provided on the Forum.
>
Box in NEUTRAL.
Detach shock reservoir from bracket.
Isolate battery.
Remove starter motor.
Detach neutral switch term.
Detach shift link from shaft.
Drain gbox oil.
Remove 11 (5mm) socket cap bolts. Remove Selector cover plate (there's no gasket, goo holds pretty firm).
Remove 2 selector gears (retained by circlips) & mechanism, to access spring.
Ensure NEUTRAL in box (check spaces between sliding dogs & gears are equidistant) & in selector before replacing plate. Move the selector forks into the neutral position before replacing the side plate (rotate the rear wheel to confirm neutral - if the plate doesn't go on you've got a false neutral). Main thing is get box in neutral with selector forks equally spaced from sliding sleeves before putting the cover back on. Also, selector wheels in Neutral.
There's no gasket on cover. Use sealant/gasket cement.


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[belfastguzzi]

How To Make Repairs if you don't have new parts.
If you do have new parts, the pics here give a guide for checking sizes, fitting and possible re-profiling.

Gearbox Pre-Selector Spring, repaired
Pawl Arm Boss, resized
Shift Plate, re-profiled

Spring Repair or Replacement
My spring broke at 1,200 miles leaving the box stuck in 4th gear.
The spring bend hooks onto and is pulled against a sharp edge. The spring coil tightens and binds on its oversize pawl-arm boss when it is operated. The resulting stress causes the spring to snap. This break may also happen on 'properly sized' parts due to the same stress, but at a higher mileage.

I did not have a spare/new spring so I made a repair by bending a hook onto the broken spring and re-shaping the spring coil accordingly. This worked fine. A new spring was fitted later. When doing this, I tried a 'roadside repair' method. This was originally posted as a separate topic. The photos are incorporated together here.

[belfastguzzi]

Photos from my old Guzzi Repairs web album.
I have incorporated the photos from the separate album, which was called, A Roadside Repair Is Possible.
A broken spring could be repaired out on the road. Lean the bike over to keep oil in gearbox.
The biggest problem is access past the support tube to bottom Allen screws, so it is best to carry a modified Allen key. Carry a spare spring, or if you don't have one, or suffer 2 breaks on a trip (!) vice grips as well as pliers will help to bend the broken spring. If you want to be totally prepared, carry a file incase you need to reduce the pawl arm boss from 16mm to 15mm! (Or pack a spare pawl arm as well as a new spring.)

(These photos were taken at 1,200 and 1,400 miles.)


1
Assemble tools appropriate for Guzzi repair.


ok... these ones...
Tools are easily carried. If no spare spring available, grips are also needed to grasp and bend the broken spring.


Allen key. I filed the edges off and cut the short end shorter, to get at lower cover screws.


2
For a roadside repair, the bike would be leaned over to save oil in box. It should be a bit more, but garage space here is too narrow.


Actual roadside repair procedure, side of motorway a long way from home (2006 photos)

[belfastguzzi]

3
Selector plate off.


4
Original gear oil (1,200 miles). Metallic paste residue that lies in bottom of box after oil is drained off.


5
Oil saved in leant-over box. This is the later 'roadside repair procedure' photo at 1,400 miles. There were a lot of metallic filings in oil again.


6
Broken spring. Hooked end has snapped off.


Broken spring end on edge of plate.


Spring break at hook bend.


7
Sharp edge of shift plate that spring hook pulls against on downshift.


8
I re-profiled this area of shift plate. Left side cut in to make better seat for spring hook.




9
Broken spring, end bent to form a new hook.




10
Later: a new, full-size spring on my re-shaped plate. It now doesn't seat in the corner.


11
A bit more work was done to better accommodate the new, full-size spring.

[belfastguzzi]

12
The original pawl arm boss that I think caused the failure: it's over 16mm diameter. It should be 15mm.
The ratchet arm boss holds the spring coil.


I filed down the ratchet boss to just under 15mm,
with the boss offset so it is shorter at rear. I forgot to photograph the ratchet arm/boss.

New pawl arm boss (15mm) and my filed-down, re-profiled from previously oversized (16mm) boss.


13
Inside coil diameter.


14
Repaired spring.


I bent a new hook on broken end and reshaped rest of spring.




15
This is the repaired broken spring on re-profiled shift plate. It worked fine.




16
Spring coil no longer binds. I am confident that the repaired spring would have continued to work fine.


17
Back together and ready to replace.

[belfastguzzi]

18
When I later got a new spring, I compared it with the repaired, re-bent spring.

Old broken spring, repaired.


New spring.


Repaired broken spring beside a new spring.






19
New spring and new pawl arm, with correct size boss on the other side.




New pawl arm boss (15mm) and my filed-down, re-profiled from previously oversized (16mm) boss.


20
View of all the spring contact points.


21 The three gearbox selector springs.

[belfastguzzi]

I found this pic that I made once, showing how the parts relate. It's a bit messy!


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I'm still sorting these pics / this topic post.

I should probably do a condensed version which just deals with doing the repair, as people have said that it's useful for printing as a worksheet for taking on trips – just in case!

[docc]

I remember 2002 saying to MGNA and my dealer, "My gearbox doesn't shift right." 81 emails later, and with my dealer's support (Ben Curlin of Jackson, TN), the gearbox was replaced. In that time, I was directed to this forum , the early units were recalled, and , as I said in those days: if there is an expert on the six speed Guzzi gearbox - it are us.

Almost ten years on, it turns out, it is us; if "us" is belfastguzzi.

Thanks, David, for the persistent support and dedication that can be found no where else!

[fotoguzzi]

thanks a lot for re posting these photos.. I never had a problem but I carry a spare spring.. now I'll print the directions so I will know what to do roadside if it happens to me.

[fotoguzzi]

on the roadside shot, why did you remove the header, does it have to come off?

[belfastguzzi]

on the roadside shot, why did you remove the header, does it have to come off?

Good observation.
I must have needed the clearance to get something off: the starter?
It's the Quat header, which has a different bend than the stock V11 pipe.
The standard MG header doesn't have to be removed.

[sctt2525]

Mine went today...at least assume so. Ballabio is stuck in second gear (and of course a LONG way from home); will get her home tomorrow. Confused if I need just the spring or the entire arm- Is there a way to tell before cracking open the gearbox case? (ie. frame #)

[Baldini]

... Is there a way to tell before cracking open the gearbox case? (ie. frame #)

No.

But I thought it was just 2002 bikes had wrong size post?

[belfastguzzi]

... Is there a way to tell before cracking open the gearbox case? (ie. frame #)

No.

But I thought it was just 2002 bikes had wrong size post?

The springs break anyway. Seems to me that it just happens a lot quicker on the 2002 bikes that have the wrong sized parts (mine went after only 1k miles from new).

Chances are that the Ballabio spring has gone the natural way of all the other broken springs (if that's what has indeed happened).

Sctt, you'll most likely only need a new spring, not the arm. As Baldini says, the arm/boss is probably the correct size. A new spring will (should) have a bigger coil anyway, to work with the bad arm as well as a good one.