LM III Clutch - flywheel question

[jerryS]

Hi, This is really an extension of the most helpful discussion https://wildguzzi.com/forum/index.php?topic=114590.0 but as the last post of that thread was 2022, I thought I'd start fresh.
I've just pulled my LMIII clutch and as expected the hub and flywheel are both ridged. After following the discussion it seems clear that the SD TEC deep splined replacement is the way to go.. I'll need a new flywheel as well. I measured mine of the kitchen scale (oops) and it comes in at 3323g.. The Stein Dinse site has 3 flywheels, 4250, 3300 & 2450.. I'ma bit confused about this.. I assume that mine is original (the bike is pretty much unmodified). . I can't imagine putting in  heavier flywheel than original.. Unfortunately the 3300 is currently unavailable (delivery time unknown).. I'm looking at maybe the 2450 option.. there seems to be more positive than negative reports on the lighter flywheel. If I went down this route, would I also need to replace the pressure plate and/or the ring-gear? Both appear to be in good condition (at least to the naked eye). I've taken on board the other comments about the dual o-ring clutch thrust doohicky.. and will replace crank seal and gearbox input & output shaft seals..
I'd be most grateful if anyone has any other wisdom on this.
While I have the box off, I'm considering popping off the cover to replace the gearshift return spring.. I've noticed some missed gearchanges which I think is due to the gearshift not always coming back to centre. Is the spring a common issue?
My Lemon has done 55k km. I've owned it for a short time and going through sorting it out and bringing it back to life.

[Dukedesmo]

Not got into the clutch/flywheel on my LM2 (it's only done around 18k miles so hopefully won't need to) but, from previous experiences with Ducatis, if I was replacing the flywheel, I'd go for a lighter rather than heavier everytime.


Obviously 1970s Guzzi engines are 'lazier' than 1990s Ducatis but, other than being a little prone to stalling when cold, I have seen no downsides to a lighter flywheel on both mine - more responsive on both revving up and down (so more engine braking) and, as such feel livelier. Plus losing weight (especially rotating) from your bike is always a good thing.


I have no idea how heavy the flywheel (or crankshaft) on my LM2 is but, it is definitely heavy and large diameter so carries a lot of stored energy. 

[BMCMOTO]

Others may differ but, internet pictures being what they are, I think your flywheel is probably fine, the hub definitely needs to be replaced. If you replace with the lighter factory flywheel you will notice some difference but not very much, after all it was issued by the factory for some bike. The custom skeletonized, lightened, flywheels that some offer, make a very noticeable difference, those are a different kettle of fish altogether. 
Good luck with this!

Brian

[wirespokes]

I'm with bmcmoto - the flywheel doesn't look bad to me either. However, cleaning up the teeth and a new photo would help a lot. It's difficult determining how notched it might be in the current state.

[jerryS]

Thanks for your responses. That gives me more confidence going for the lighter Guzzi flywheel.
Here are some more images of my flywheel.. after cleaning.. 
You can see the driving





 face of each tooth is worn. I think it would be wise to replace. What do you reckon?

[yackee]

I've had no problems at all with my lighter flywheel installed as part of a ram clutch conversion. No stalling in cold temps, engine tics over very regularly at idle, shifts are smooth. That said I also haven't sensed much impact in overall performance "feel". The lighter clutch is definitely noticeable, but the "spinning up faster" doesn't seem super-noticeable to me at least.

[Frenchfrog]

You would possibly get away with that flywheel Jerry.But if you do high mileage and are keeping the bike long term I'd swap it out because doing a clutch/flywheel job is such a pita.

[wirespokes]

Now that I see the wear, I agree it should be replaced.

[jerryS]

Thank you for all your replies.. That's great confirmation.. I'll get a new flywheel for sure.. I really don't want to be doing this again..
While I'm in there, my clutch springs are technically out of spec. .I have a range of free lengths of 27.29 to 27.84. The spec says 27.97 - 28.00 (workshop_manual_g5_ sp.pdf) . .So, I will replace those too.. watch this space 

[Antietam Classic Cycle]

I've not had good luck with aftermarket springs, especially with the S-D Tech friction plates, which are slightly thicker than stock. Some made the clutch pull super heavy, one set would coil bind before the clutch released, another set that was advertised as "wrist relief" was still heavier than stock springs. My advice: find o.e. or new-old-stock Guzzi springs, or simply reuse the originals even though they are slightly out of spec.

[jerryS]

Thanks Antietam,
I like this advice.. The original clutch was showing no signs of slipping.. and new plates will be thicker by all accounts.. I don't fancy the idea of stiffening the clutch action..

[Stevex]

I replaced my LM2 flywheel with a lightened one. To me it improves the ride and I would even think about going lighter. My lightened flywheel came with the timing marks machined off, which was an advantage, as I etched them back on using a timing wheel and piston stop, so I know they are 100% accurate now.
Use Viton replacement seals.

[jerryS]

Thanks Steve,
I did wonder about the timing marks on my original flywheel.. the stamped marks are around 6deg off.. I assumed that it had been put on wrong in the past but looking at how it goes together I can't imagine how a bad assembly could lead to such a small error.. there are 6 mounting bolts, so a bad assembly would lead to a 60deg error (360 / 6).. I can only assume that the timing marks are wrong.
.. and thanks for the tip about seals.. I see there are several brands on offer at a variety of prices.

[moto-uno]

  Those slight wear marks on your flywheel are of minor concern (think my LeMans2 with a flywheel lightened over 30 years ago) . I had a machinist resurface them after
about 100,000 kms and that flywheel (now with over 1/4 million kilometers) is being replaced as we speak . I got the lightened one (not the alloy one) . Before you install the assembly ,
verify the the pressure plate fits easily ! This is no joke , I'm on my third re & re of the clutch this month . I used the wire wheel on my bench grinder to smooth the pressure plate splines , clutch grab was awful.
Then took the dremel to every tooth and removed a very slight amount of material from every tooth (patience please) and the next road test was better but it still sucked .
That flywheel cost me over $800 Canadian and I was going to be damned if I was going to be beat by it ! Before removing more material from the pressure plate teeth , I checked another
old T-3 clutch assembly I had and found the pressure plate teeth were in fact significantly deeper the those on my original LeMans2 . The plate slipped into the flywheel with no drag at all
and was easily moved about . I'm doing another road test in a couple of days , if this is the magic bullet , I'm sending pictures to MG Cycle to make them aware of this !
Just a heads up .

[pehayes]

+1 on replacing the flywheel and hub.  Probably can keep the forward pressure plate, but I would swap the intermediate floater plate as well.  Notorious for warping under heat stress.  Make sure you understand the marked alignment of the flywheel and its multiple springs.  Can easily be assembled incorrectly.

As to the shift return spring.  I think you're barking up the wrong tree.  The spring is a binary function.  It either returns to center or it snaps and fails to return at all.  Your casual description of occasional slow or missed shifts might point to internal gear or bushing wear or lubrication quality.  You might wish to dig into the transmission, but not for the solution you proposed.

Patrick Hayes
Fremont CA

[Turin]

in regards to lighter flywheels, I'm a fan. Here are a few I'm running going from mild to wild. Don't go heavier.

mildly lightened 850 lemans flywheel (my favorite)




Extremely lightened lemans 1000 flywheel (done locally in the early 90's)




Transkontinental (Royal pain in the ass)




I have a Ram Clutch in my Call 3 (love it and bought a used spare)




I also have a couple of alloy flywheels I'm hoarding for a future project. Haven't tried these yet
Stucchi






Ergal

[g5guzzi]

why is the transkontinental a pain in the arse?

[jerryS]

thanks for all your wisdom guys..
I'm currently waiting on parts.. I decided to go with:
2450g lightened flywheel, new friction plates and intermediate plate, new hub with 4mm splines
Viton g'box and crank seals.
I'm keeping the original springs as they are only slightly out of spec.
I'm not going to open the gearbox this time round and will just monitor the gearshift situation.
I'll let you know how I get on.

[moto-uno]

So here's a pic of my original LeMans2 pressure plate (on the left) and an old T-3 pressure plate . Notice the T-3 plate has longer teeth , exactly the opposite
of what I thought might work . Turns out this plate fit in the new lightened flywheel just fine . Been out on 2 roadtests since and can say that it is finally an
acceptable engagement ( not perfect , but close enough for now ) . I'm using some Stein-Dinse friction plates and as "Antietam" has remarked not the best
friction plates . I'm searching for an as new (or new) old style clutch hub with the 2mm splines . I've an old set of Sureflex bronze friction plates that were my
absolute favourite , they are only about 1/2" wide friction surfce and would leave noticeable grooves where they touched ( but at 3/4 of a century old ) I'm not too concerned 
Get in touch if anyone knows where that old style clutch hub can be had ! Thanks

[Antietam Classic Cycle]

I'm using some Stein-Dinse friction plates and as "Antietam" has remarked not the best
friction plates .

Hold on there... I never said that at all! Just the opposite - they are the best currently available! Yes, the engagement is a bit abrupt, yes they are slightly thicker than original factory plates. But, they don't shear off their rivets (like Newfren), don't wear the hub, change thickness when hot/cold, or engage super grabby (like Sureflex), or notch the hub all to heck in less than 10k miles (like Barnett plates). Nor do the "spokes" fracture like any of them made that way.

[wirespokes]

I'll second what Charlie said.

It's funny, but I come from the airhead side of life and I rarely had any issues with clutches, and if I did (I don't remember - that's how seldom it was an issue) it was probably to replace because it was worn out. And then I get into Guzzis, and practically every one (like 8 or 9)has needed some sort of clutch work - grabby, notchy splines, and other issues like plates frozen to the friction discs due to water (probably hurricane Sandy),  and don't recall what all else. I've become a master at crabbing Guzzis.

So listen to Charlie - there's a path - follow it exactly. Going astray has penalties.

[pehayes]

Viton g'box and crank seals.

Inspect the parts manual for your specific model.  IIRC there may be one or perhaps two o-rings on the transmission input shaft which get compressed for sealing when the spline hub is installed.  You are changing the OD seal and it would be wise to change ID rings as well if they are called for.

Patrick Hayes
Fremont CA

[moto-uno]

  Okay Charlie , gotcha , but for me in particular , that slightly grabby engagement has lost it's appeal to me when riding around town !
Finding neutral at a light or shifting is fine with the Stein-Dinse plates I'll admit , plus they don't slip under power . And would you happen
to have a good old shallow splined clutch hub ?

[Turin]

g5guzzi wrote - why is the transkontinental a pain in the arse?

It needs adjusting as the bike warms up. Maybe great for racing, not so much on a road bike.

[Antietam Classic Cycle]

  Okay Charlie , gotcha , but for me in particular , that slightly grabby engagement has lost it's appeal to me when riding around town !
Finding neutral at a light or shifting is fine with the Stein-Dinse plates I'll admit , plus they don't slip under power . And would you happen
to have a good old shallow splined clutch hub ?

I'll have to check to see if I have a good shallow spline hub.