Gearbox advice 2002 LeMans.

[pete roper]

OK, heres the plot.

 

2002 LeMans, 7,500Km. Bike runs fine BUT.

 

It has this weird *thing* with the gearbox. On downshifts, most noticeably 5th to 4th, it will seem to select a false neutral and then throws itself into 4th or sometimes 3rd. Now to me this would indicate that there may be a problem with the detente spring and/or plunger but I'd like to pick the brains of those more knowledgeable with the *old* six speeder as to if this is a known problem with a known cure. I've never had to have one apart, not even the plate to do the return spring, so I'm flying blind here.

 

I tend to think that maybe it will 'Ride up with wear'. I don't think the owner pushes it particularly hard, he also owns an MV and a couple of other bikes so I'd think the Guzzi is probably not the *Thrasher* bike. It did ave some horrible sort of snot in the gearbox, certainly not a top grade lube, it now has Mobil Synth 75-90. But this doesn't seem to have cured it. Engine seemed to have fermented possum piss in it, and the factory filter, so much for 'First Service' at my local dealer! Now has Mobil 1 Racing in so it will probably leak from every seal

 

Pete

[Paul Minnaert]

Pete, never heard about this downshifting problem. When you open the door behind starter engine, you get a pretty good look inside. Also the gearchanging thing is in your hands then.

 

inside you have something like this:

 

http://www.fastguzzi.nl/gallery/main.php?g..._serialNumber=2

[Bruce Reader]

Pete.

 

My 2002 Scura has the exact same symptoms at the moment. Still getting around to sorting this out. Hope you come up with some ideas.

 

Bruce

[pete roper]

Pete, never heard about this downshifting problem. When you open the door behind starter engine, you get a pretty good look inside. Also the gearchanging thing is in your hands then.

 

inside you have something like this:

 

http://www.fastguzzi.nl/gallery/main.php?g..._serialNumber=2

62621[/snapback]

 

Thanks Paul and Bruce! I am suggesting that the owner leave it for a bit, I'm not entirely sure there is a *serious* problem as the box shifts fine most of the time. The biggest issue is at lower RPM's especially if you don't try and spin up the engine to match the dogs.

 

The only other problem I can see is essentially poor cutting of the cam plates, coupled with/or a weak detente spring. We'll leave it for another 5,000 and see what eventuates.

 

Thanks again blokes.

 

Pete

[belfastguzzi]

Definitely the best thing is to get your hands into the pre / selector parts, as nothing major has to be disassembled to do that. Everything is obvious once the cover is off.

 

I found a post where I had commented on the potential for the selector to hang about between the higher gear positions, "there is a relatively big physical shift needed to move the selector mechanisms between gear positions, except for first, neutral and second which are right beside each other– so there is potential for mechanism to sit between selections"

old post here

 

So it might just need a quick disassemby, clean up (or slight tweaking) and careful reassembly.

If you are lucky and that is all that it needs, these are the (easily accessible) parts.

see left side on this picture

[dlaing]

Here are some lousy instructions on how to adjust the gearbox adjuster screw.

I did it with the box open, but doing it with the box closed should be pretty easy.

You will be flying blind, so it is important to understand what the adjuster does.

Adjusting the screw directly turns an eccentric cam that raises or lowers the rest postion of the shift lever and the rest position of ratchet lever. The rest position is created by the balance of the upshift return spring and the downshift return spring. The trick is to turn the screw until you find the balanced position.

If you mis-shift both up and down-shifts, it it probably a different problem.

But since this guy is only missing down shifts, it could indicate an imbalance.

If he shifts and then it does click right and then you can't go to the next gear, then you might want to adjust it. I am not sure about the false neutral, but I don't think it excludes adjustment as a fix.

To begin:

mark where you started.

It is possible to make it worse.

Remove the acorn nut and mark the position of the adjuster screw.

The lock nuts may be tricky to loosen.

I had to keep turning the out until the adjuster screw would go no further out, and then the nuts turned on the screw.

One half turn takes the lobe 180 degrees, so stay within a quarter turn of where the factory adjusted it. Adjust in small increments, be patient and test it every 15 degrees or fewer of the 180 degree arc, to find where it shifts well and where it shifts poorly.

Too much in one direction and it will get stuck on upshifts and too much in the other direction, and it will get stuck on downshifts.

You want to be right in between the two obvious failure points.

One can not say that turning clockwise or counter clockwise will fix a downshift problem as the cam can be on either side.

One could try going five degrees each way and see if it helps, but that is alot of trial and error.

It is better to just try and get it centered between the upshift and downshift failure points.

Once there, lock the lock nuts, put the starter back on and test ride!

 

Pulling the side case makes it easier and you could check for damage, and The Pawl Spring binding issue.

 

Oh and did we mention, stay away from the Yak fat and use RedLine ShockProof Heavy.

[pete roper]

A-HA! Thank you Mr Laing and BFG!. My V11 manual has gone walkabout, (I think I lent it to John Y. in Yass.) and going from memory I thought that the pawls were non adjustable on the six speeder! My guess is that it's the pawl adjusting eccentric which should be easy enough to find. Can I get to it without removing the starter motor, (My 'pooter is at home, not at the workshop so I can't look for myself right now so if anyone is on-line who can let me know it would save me some time.

 

Pete

[Guzzirider]

Pete

 

From memory you need to whip off the starter motor and also the remote compression adjuster.

 

Guy

[belfastguzzi]

Pete

 

From memory you need to whip off the starter motor and also the remote compression adjuster.

 

Guy 

62706[/snapback]

Those bits – and then the only other pain is getting at the difficult-to-access bottom left corner Allen bolt on the tranny cover.

 

As it probably hasn't been opened before, I'll be interested to hear what you find in the bottom of the box. Lots of metallic sludge, I'd say. Must be normal but what do you think? If you find ten bob, it's mine.

[richard100t]

My bike has the same false neutral but I've never had it jump from 5th to 3rd. If it was just the false neutral I'd say hey its a Guzzi after all lol. Does it do that gear skipping thing often? I've found that it does take a lot of getting used to that shifter in the higher gears with low rpm's. I'd leave it alone if it aint making bad noises but thats just my On the other hand if you like working on that sort of thing have fun & post here often lol

[pete roper]

Those bits – and then the only other pain is getting at the difficult-to-access bottom left corner Allen bolt on the tranny cover.

 

As it probably hasn't been opened before, I'll be interested to hear what you find in the bottom of the box. Lots of metallic sludge, I'd say. Must be normal  but what do you think? If you find ten bob, it's mine.

62713[/snapback]

 

At the moment I'm loath to actually pull the cover but I'll cerainly have a fiddle with the pawl adjuster this AM, I take it this is external???

 

Pete

[Guzzirider]

At the moment I'm loath to actually pull the cover but I'll cerainly have a fiddle with the pawl adjuster this AM, I take it this is external???

 

Pete

62726[/snapback]

 

 

Just had a look at the workshop manual which mentions an adjuster screw but unhelpfully does not mention its location or how it functions maybe you can work it out from this diagram I have attached.

 

From reading Dlaing's post it sounds as if he has done it externally and hopefully can elaborate.

 

As it tales about 20 mins to whip the cover off I would be tempted to do it that way so you can see what you are doing.

 

Guy

[pete roper]

Bingo!!!! Sorted!!!!!

 

Thanks blokes, not having the manual handy I thought I'd ask first and the pawl adjuster is dead easy to get at. it sits adjacent to the actual selector shaft and has a sodding great 19mm acorn nut on it. Remove the nut and you can see the end of the threaded pawl adjuster and the 19mm locknut tghat keep it locked to the case. On this bike it was as tight as buggery on the adjuster, the adjuster turned in the case OK but I had to use a BIG screwdriver, (Flat blade.) in the end of of the adjuster and push really hard to exert enough force to stop the blade slipping out as I turned the adjuster in relation to the lock-nut. I would certainly NOT recommend trying to do it without the bike on a paddock stand as there would be a good chance of pushing the bike over in your enthusiasm!

 

In this case I just had to turn the adjuster clockwise about 3/16ths of a turn and it's cured the problem completely. It took a couple of tries, I over-corrected at first then had to go back before finally finding a *sweet spot*.

 

Note that although I had to turn the adjuster clockwise this may not be the same in every case as it will be entirely dependent on what position the eccentric on the internal end of the adjuster is stitting at in relation to the selector mchanism.

 

Thank you very much all those who offered help and advice, when you're dealing with something you haven't done before it's always usefull to be able to access info from the more experienced and knowledgeable.

 

Pete

[belfastguzzi]

 

– See picture below & enlarge it –

 

Crikey. Hours of fun here. 10 quiz points to anyone who can figure this spaghetti out. It started off with a picture showing the inside, business end of the adjuster already referred to. As these pics are already floating about cyberspace, I thought I would use them again to let people, who haven't opened the box yet, see how the various bits relate. like Topsey, It sort of grew.

 

Let's see:

 

Top left shows the gearbox and the 2 shafts with the 4 selector forks. Beside it is the complete transmission cover pre-selector assembly. The green arrows show where the fork dogs locate in the toothed seeger rings when the cover is in place.

(The short red line indicates that it is important to have these rings lined up properly. This has been talked about in other threads.)

 

The gearshift lever turns the plate (black/yellow arrow). The slot in this plate (middle pictures and red arrows) is where the eccentric adjuster works. This adjuster is the bit that Pete fiddled with, from the outside. It is shown in the black circle, middle right. This plate is where the infamous SPRING and pawl arm are attached. The movement of the plate (turned by the gearlever) pulls the pawl arm backwards and forwards. The SPRING keeps the double-hooked far end of the arm engaged with the far seeger ring. So movement of the gearlever keeps pulling the seeger ring one way, or pushes it the other way. The cut-outs in the rings move the selector forks to change gears.

 

That must be about right. I'm going by memory.

 

The little wheel on the other arm and spring, bottom right, runs against an indented ring on the toothed seeger ring. It presses into detents, which 'snicks' everything neatly into gear, or not. It also finds neutral. Because there is a lot of space between the higher gears, it can sit betwen gear detents (false neutral) if the change is not positive enough.

 

There is also 'A Third Spring'. But enough is enough...

 

In sideways view you can see: hooked pawl arm; the ring it acts against and far right, middle, the gearshift lever shaft through the housing.

[belfastguzzi]

So when The Infamous SPRING breaks, the preselector arm (pawl arm) is not held in tension against the seeger ring and so can't turn it: hence the box remains stuck in one gear.

 

Anyone feeling yet?