When did MK10 get spring alignment washer (10-500-118) and why?

[mr_v]

I noticed that earlier diagrams do not include 10500118 but later ones do. That is a spring alignment washer that is placed prior the shims:

Here is the pic from Rev M, 02/01 specs.

Also, why the change? Thank you!

 

[Mobulai]

The when I can’t answer (probably after the 99 rev);
the why I can speculate (badly) about: could it be something to do with vibrations of the spring and whistle noises- but could be just me projecting my pain dealing with a whistling mk19 at the moment

But I’m no SP whisperer

Edit: Funny, the last reg I opened was an mk10 and I totally missed that thid piece os for spring alignment — thanks for today’s knowledge

 

[Tanks A Lot]

The centering washer was there on the MK10 Plus in 1996. The original MK10 did not have this washer up until at least revision G in 1993. That means the washer got added somewhere in between those dates, or more likely, in 1996 with the plus upgrade.

I don't think that the washer had anything to do with whistling. Seeing as this was introduced alongside the stuff for the plus upgrade, I suspect it has something to do with it. As only the piston, seat and seat retainer changed, I'm not entirely sure why this centering washer was used, but apparently someone felt it was necessary.

 

[mr_v]

I put the centering washer in an MK10 and removed one of the shims. As expected, IP went up and and I have a spare shim. Win-win.

 

[axxel57]

My guess about the implementation of the centering washer is that it had been added because at the same time when the Mk10Plus was introduced on the market, SP also changed the recommendation of the lube for their piston 1sts from Silicone Grease to Christo Lube, which lowered automatically a bit the IP.
So starting the IP adjustment with the quite thick Centering Washer they wanted to 'neutralize' a bit that effect.......