Modern Vespa

The old style large frame gearbox has a circlip & shim at one end only.
But the EFL style has shims & circlips at both ends.
A mate of mine had a gearbox making a racket in 3rd gear and it was found that a tooth had broken off the 3rd primary gear.
Then we noticed the main individual gears had a lot of excessive movement on the main rear spindle.
Both shims were very thin & I find this suspicious.
Are each of the shims, or both, supposed to be thicker like the single shim you find on the early style gearboxes?
I get the feeling whoever built the gearbox for him has fitted the wrong shims.

EFL shims are the same type used on Smallframes (4 teeth). Thickness is no different in my experience.

Thanks Travis.

Should both shims be the same thickness?
Should they be similar thickness to old style shims?
Its just that the shims in this gearbox are very thin & the free play on the gear cogs is way over what i'd expect.

I'll ask my mate if he has a Haynes manual for this type of gearbox so he can check shim size and what the play should be with feeler gauges.

Cheers.

To my understanding they should be fairly equal.

If they are loose, they should've been measured with 2 mm gauges prior to running.

2mm seems massive!!

2 mm is not 2mm. (2) mm [feeler] gauges.

You've lost me Travis . . .

You mean 2no 1mm feeler gauges?

Get [2] sets of mm feeler gauges. you want to find the end gap on the stack to be between .15-.45

Get 2 sets of this Neb...

That was so simple it gave me a sore head . . .

I have 2 sets because when I built my own engine from scratch I checked my own gears & bought an oversize shim to suit.
But that was an old style Rally/P200 gearbox with single shim.

But what i'm trying to get at here is that the lad who built the engine for him, in my "common sense" opinion, used the wrong shim(s) because they are very thin & theres far too much play in the gears that's caused a tooth to break off the primary 3rd gear.

So - are the 2 shims supposed to be the same size in an EFL later type gearbox, or is the one near the rear wheel supposed to be thinner & the one nearest the selector thicker?
When you check the gap in this type of gearbox, do you change the shim nearest the selector with an oversize one or do you change both?

I get the feeling the one nearest the rear wheel is a thinner shim & the lad has used this type of shim at both ends of the gears . . ??

Correct me if im wrong.

Cheers.

The later EFL gearbox should have two 4-tab spacers of equal thickness, one on each end of the gear stack, each being held in place with a separate circlip. Original factory came with 1.0mm shims.

Oversizes from 1.0mm to 1.45mm or so do exist to keep the end float within spec range of 0.15mm to 0.40mm, but they seem to be hard to find in the US.

Non-EFL gearboxes are only shimmed on one end using one circlip and use the thicker shims starting at 2.05mm that you usually see listed in reprints of older manuals, like this... If there exists even another, earlier version of EFL with more variations, I don't have any information about it.

See my post here for my experience with this...