a Foray in to the dark art of shimming
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Old douglas ..smallie with polini 115..super with nasco 177
Joined: 07 Nov 2013
Posts: 631
Location: New Zealand
Mon Feb 15, 2021 5:08 pm quote
Went to add a new selector box to a VBC cos the old was all sloppy and noticed SIP says it may need a shim due to factory tolerances being poor in some batches. I have three of the said shims.

The SIP catalogue book (love it) says there needs to be 1.5mm between mating surface and the selector rod and if not sure then "measure it"

Im not sure where to measure the Rod at....ie do they mean the rectangle block that pivots.....or the round part of the rod with a pin that carries this block

both stick out from "mating surface"

I would rather measure than trial and error.

what say ye?
Jet Eye Master
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 2602
Location: London UK
Tue Feb 16, 2021 12:10 am quote
SIP are being generous, they never line up perfectly and all need some kind of adjustment.

Wouldn't get to excited about measuring, making it fit is what's important. If you lift the rear wheel off the ground, so it spins. Fit the new selector and leave in neutral. Spin the rear wheel. If the shim is too big or too small there will be a faint clicking noise from the cruciform. Select the right size shim to spin silently. Check 1st and 4th select correctly and you're done.
Joined: 12 Mar 2018
Posts: 47
Location: Texas
Tue Feb 16, 2021 10:06 pm quote
Ran across this article a while back. Yes is says PX, but I think the logic may apply to your situation. Regardless, the Jack method is what ultimately matters.

SLUK: Pre-EFL vs EFL Selector Boxes

SLUK: Part 2 of Selector Boxes
SIP Website Description wrote:
The lever of the selector box should be parallel to the gasket face when third gear is selected in the following Vespa models: Series I - Vespa 125 VNB5-6T/GT/GTR/Super/TS/150 VBB/VGLB/VGL1/GL/Sprint/V/Rally 180/Rally 200 (similar to PX EFL).

On the models Vespa 125 GTR/Sprint 150 V/Super and the Rally 200 of the second series the lever should be 1.5mm further.
I cut out the rest of the quote bc it seemed confusing.

Maybe compare the new one to your old one assuming it isn't too trashed.
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