anyone shim a selector spindle..?

[hjarvis]

Having an annoying problem with my bike. The engine is a 2003 early model LML / Stella engine (maybe a 150 but now more of a 180).

Last winter I added a shim to the gear tree to address too much slop. The shims top and bottom match pretty closely now, and the slop is below the allowance (was it .5 mm? I forget).

But this summer it developed a nasty habit of slipping out of gear, all gears, quite regularly. The cables were snug but I don't think too tight. I believe the gear slop is now within spec. And the selector arm and assembly feel tight.

So it makes me wonder if the cross was just lying too close to the TOP of each gear, and slipping up off each gear. The bikes slips UP out of gear: in 3rd, it moves between 2 and 3, in 2nd, it moves between 1 and 2, etc.

In comparison to what my friends at ScooterWest say, the spindle appears to be the right length (no washer on this model apparently). So maybe the selector box is wrong (engine was used), or maybe the selector arm is a little short ..?

So I wondered if I might try adding a thin metal shim on the spindle underneath the cross, to help the cross engage a little deeper into each gear.

Am I nuts..??? Is something else the problem..? Thanks.

[BuddyRaton]

I'm really not following what's going on but I can add that many problems attributed to a worn cruciform are actually the result of a worn or wrong selector box.

I had a bike that I was sure had a bad cross. Someone suggested checking out and changing the box. That was where the problem was. YMMV

[hjarvis]

Thanks, BuddyRaton. I may just replace the selector box and spindle on 'general principles'.

[hjarvis]

ps. I don't have tons of experience with Vespas... I rebuilt the original engine ('74 GTR) and am now partially rebuilding this Stella engine,

but my expectation was that the bike would slip out of gear more randomly. e.g. begin with a bad 2nd gear, then spread to 3rd, and 1st... and it would slip up OR down, but not consistently slip UP out of gear, and on EVERY gear all at once.

To me that sounds like an alignment issue, not too much slop in the system. Alignment issue could be the wrong selector assembly (eg. the arm is the wrong length, or the spindle).

If anything the spindle is actually a tad long (3.24" versus 3.227"... but that's awfully close).

You're right, maybe the selector box/arm is wrong. Thanks!

[BuddyRaton]

The end of the gear stack does have a shim washer. They are available in a variety of thicknesses to achieve the proper float, did you measure with two feeler gauges when installing?

Also are you sure the gears were installed properly and not backwards? That is an easy and common mistake. When I remove the gears I mark the outside of each one with a paint pen and I wire them together in the correct position.

Gears wired together in correct position


Installing the circlip over the spacer washer. Note paint marking


Then check the float. According to Haynes it should be 0.15 to 0.40 mm

[hjarvis]

Yes, fixing the gear slop was where this all started last winter. It was way over .5mm, so I swapped in an oversize and now it's in spec. Also my oversize shim looks pretty close to the second shim on the other end of the gear tree.

I did keep the gears in order. And they were already marked with paint on the top, which was helpful. I'll see if I can confirm they were actually installed correctly to begin with too...

PS. The bike shifted fine through the full range, just tended to fall off the top of the gears.

Thanks!

[BuddyRaton]

So far it sounds like you did everything right. Did you replace the cruciform, get it in the right way and remember the washer? Please don't think I'm questioning your skills but you don't want to split the cases again unless you need to! I've been there!

I would drain the gear oil and the selector box and check for wear and slop. Be sure to reuse or better yet replace the gasket.

Keep us updated!

[hjarvis]

FYI, there's no washer on this model (LML / PX). And yes, I was surprised to hear that too.

The jury is still out on the cause.

I can't feel any slop in the selector arm.

The gears USED to have too much slop, but I put in an oversize shim as mentioned above, and the shims on either end of the gear tree are now the same thickness. (Until then, the top shim was much thinner, which is intriguing...)

The gears look new and in good shape to me, but I don't have much experience with gears. This engine reportedly came from a low mileage crashed bike - a 2003 Stella 2T. The gears are made by LML. Perhaps they are just poorly designed -- do LML gears have a bad rep..?

I will replace the cross/cruciform. I also plan to try a new spindle and selector box, in case they are simply mismatched.

I will also get some good quality transmission oil from ScooterWest. I was using a generic Autozone 30 weight non-detergent. Also I have a tendency to overfill the crank -- is that bad..?

Thanks for the advice.

[BuddyRaton]

There is still a lot here that I'm just not following.

FYI, there's no washer on this model (LML / PX). And yes, I was surprised to hear that too.

What washer are you referring to, the selector rod washer or the gear shim?

quote="hjarvis"]I can't feel any slop in the selector arm.[/quote]

You might not feel "slop". I could be that the batwing or the ratchet arm is worn.

The gears USED to have too much slop, but I put in an oversize shim as mentioned above, and the shims on either end of the gear tree are now the same thickness. (Until then, the top shim was much thinner, which is intriguing...).

Ok..here is where I get lost. As far as I know there is no washer or shim on the clutch side of the spindle. If there is then that is probably your problem
http://vespamaintenance.com/engine/teardown/index.html

I will replace the cross/cruciform. I also plan to try a new spindle and selector box, in case they are simply mismatched.

So you split the cases pulled the gear stack and didn't check the cruciform? It's a sacrificial part. Unless I know it is new (like when I have t resplit) I always replace it no matter how it looks. It wears and is a cheap part.

I will also get some good quality transmission oil from ScooterWest. I was using a generic Autozone 30 weight non-detergent. Also I have a tendency to overfill the crank -- is that bad..?
Thanks for the advice.

Good gear oil isn't going to hurt...but I don't think using 30W ND has anything to do with your problem. Why intentionally overfilling? It isn't going to do anything but make a mess when it blows out the clutch vent.

[hjarvis]

BuddyRaton, and anyone else following this, sorry for the length. Trying to be really clear....

LAST WINTER (a year ago), replaced the cross, and added an oversize SHIM to the engine side of the gear tree. The gear slop was well over .5mm. I replaced the cross because I had intermittent issues slipping out of some gears (I think 2nd, and maybe 3rd). The cross was worn.

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Last summer, the shifting was good. I could easily engage all gears, but noticed I was beginning to slip out of gear, and noticed this was for ALL gears, and always UP (4th into space just below 3rd, 3rd into space just below 2nd, etc.). The problem went from occasional, to very regular, and I had to modify how I drove to allow me to react quickly. I assume it happened more and more as my (new) cross got more worn.

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Then in October the clutch blew up and I took the bike off the road. Yes, this is new information. The circlip popped out of the clutch and the plates all popped. Yes, a nasty event. No I wasn't hurt thanks. Fortunately I was at a good place and immediately pulled over and killed the engine. No, I don't hammer the clutch, or do fancy shifting, at least not to my knowledge. I think it was just a fluke. Apparently some clutches are badly made/assembled and I hope that was my problem here. I try to shift really gently, so there's no clunk when the cross engages, and I use the clutch gently and smoothly and bring engine speed down naturally first before shifting by releasing the throttle...

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THIS WINTER I cracked the case again, and put in a decent Corsa clutch. I cleaned out all the little bits of metal that had escaped, and I began to assess the shifting problem.

I checked the two SHIMS on the gear tree. Yes, I am told that Stellas and PXs have TWO shims, one on the bottom of the tree, and the other on top. Haynes doesn't show this, but SIP does (see their diagram), and it was repeated by ScooterWest and some other PX-experienced folk.

Interestingly, the shim I put in last year is the same thickness as the shim at the outer end of the gears, so my bike previously had mismatched shims. They now match in thickness, and the slop is well under .5mm. (I think it's about .25mm, but didn't write that down.) That seems like a good thing, but the thinner shim was on the engine side of the tree, so I don't think it will solve my problem. In my head, I think the cross was too high on the gears, which would mean the gears were too far towards the clutch side... But maybe this was the problem...

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The cross was again quite worn. (I don't recall if it was a Piaggio, but will; put in a new Piaggio cross this time.) And remember the shifting problem happened soon after I worked on the bike a year ago, and got worse as the cross worn down. The worn cross is a symptom, not the original cause.

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The gears looked ok to me, but I don't handle a lot of scooter gears. I will take another look at them just in case, but remember this problem happens for ALL gears...

(ps. The gears are LML, and perhaps not high quality...?? But again, I don't know that -- just asking a question. If anyone can comment on LML gear quality from 2003, that would be helpful!)

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IMHO, my shifting problem seems to be a situation where the cross is slightly out of synch with the gear locations. e.g. it seems to be landing consistently just at the upper edge of each gear, where it can too easily fall off the gear. That sounds like the length of the spindle, or selector arm is wrong. Just speculating....

But double checking my spindle, it seems to be the right length for a Stella, based on helpful dimensions from the good people at ScooterWest. (There is no loose WASHER, but I am told that is normal for a Stella/PX even though Haynes and SIP diagrams both show a washer on the spindle...)

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The selector box looks ok to me. I don't feel any play in the selector arm. It looks in reasonable shape... but I've only handled two of these before. But who knows, maybe it's the wrong box, or arm, or some other issue unknown to me. As BuddyRaton helpfully mentions, it could be a problem with the spring or the batwings, so I plan to get a new, correct spindle and box, and swap them in, just in case.

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What else... could be cables (e.g. tension). I thought they were ok last summer -- I could change gears great -- but when I had more and more slipping out of gear, I did slacken both adjusters slightly just in case one was pulling me out of gear and that did NOT help the problem that I could tell.

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Someone mentioned I must use GOOD OIL. Ok, I will stop using the generic Autozone 30 non-detergent and will buy some genuine scooter approved transmission gear oil. Worth a shot. Also getting hard to get not-detergent oil locally anyhow.

I mentioned I like to fill my crank case above the fill hole. No, it isn't squirting out the spark plug hole... I just go a LITTLE beyond where it first starts flowing back out the hole. I just mentioned in case there is some unknown reason why the oil should never exceed that exact fill point.

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As you can see, I'm just looking for reasons why the bike is acting up.

Thanks!!!

[BuddyRaton]

I'll admit that I haven't done a PX so thanks for the info on the clutch side shim. Let me think a bit before I give bad info.

Additional gear lube will not make it to the cylinder. It will just blow out the clutch vent and make a mess but not damage anything

[hjarvis]

I believe I mentioned this bike had TWO shim washers, one below the gear stack above the outer circlip, and a second on top of the gears, immediately below the inner circlip.

My gears were quite sloppy, over the .5mm allowed. I originally had added a second overstock shim on the top of the gears, but hadn't looked at the shim below the gears (didn't know about it).

This time around, with everything apart, I discovered the lower shim was the same thickness as a second overstock size... suspicious.

There was some debate whether the shims should be upsized in tandem, but a very helpful Max at Scooterwest mentioned his manual says the outer shim should be left alone, and just the inner upsized.

So I will put my thinnest shim (I think it's the original size from the inner) into the outer spot, and am adding a much thicker new OUTER shim (4th oversize), giving me a hair over the minimum allowed .2mm gap.

Cross your fingers, this may get my shifter back in alignment as well!

[BuddyRaton]

Thanks for the update. I would go with what Max suggests, he has given me good advice more than once!

[BuddyRaton]

Thanks for the update. I would go with what Max suggests, he has given me good advice more than once!

[az_slynch]

Thanks for the update. I would go with what Max suggests, he has given me good advice more than once!

Thanks for the update. I would go with what Max suggests, he has given me good advice more than once!

And it looks like you've gone and reinforced the goodness of Max's advice more than once.

I may be missing something here, but I haven't seen a mention of the type of cruciform (other than "Piaggio") in this discussion. Doesn't the Rally/Sprint/GT/P/pre-EFL PX use a slightly stepped cruciform while the VLX/Stella use a non-stepped cruciform?

If I read right, the motor is an '03 LML 150. If it's a Piaggio cruciform, it might be the stepped type and could cause an alignment issue. The Stella should have the "flat" cruciform.

Just a hunch...I'm curious as to why your gearbox would give you so much grief. They're generally a lot less fiddly than this.

[hjarvis]

The cross is the standard flat one.

I have no idea why there's so much play in the gears. The engine came from another bike which I believe was crashed. And it was installed by a gent who seems to gave taken some short cuts in other areas of the rebuild.

But Is slop common in early Stella's..? Does LML use low quality gears..? (They look pretty cheap to me...). I don't have much experience with this issue.