I5 valve spring washer question.

[popdemonic]

i just had the AAN head rebuild and found the tiny washer under the lower spring retainers.what's the used for this washer?i decided to hook up another 7A head and
found none of these washers exist.checking on the ETKA,found this..
ABY,ADU,AAN has this washer on both IN/EX valves.
7A None of this washer being used.
NM Only EX valves side.

[UrS4boy]

3B, AAN, ABY and ADU intake and exhaust valve info

Designs changes experiences (failures) and proposed stresses demand.

The washer you are talking about is Item 9 in the AAN diagram below. It sits underneath the Item 13, lower valve spring seat (Item 15 is the upper valve spring seat). As you suggested Pop, Item 9, PN 034109629, was used for all 20 NM, 3B, AAN, ABY and ADU valves. Also as you suggest, only 10 were used on the 7A intake valves (not sure why). Also not sure why it doesn't show up in Dima ABY's photo (below).




Photo courtesy of Dima ABY

[popdemonic]

Dave,
none of the washer was used on 7A head and only 10 on ext. valves for NM.
This washer is located under the lower seat.this washer is not possible to
remove if the stem seals are still intact the guides that's why the photo
above didn't show the washer.one more thing this washer is very flat and
tiny.if we didn't have a closer look,we won't see them.

[s2coupe3b]

With 1 groove valve cotter you need the shims to allow the valve to rotate.
With 3 grooves valve cotter you usually don't need these shims because the valve end can rotate in the cotter.

[UrS4boy]

Dave, none of the washer was used on 7A head and only 10 on ext. valves for NM.

I am just going on what my good friend Kate, the friendly parts girl says.

[andy10v]

My 3B head had them on all the valves



Brand new one

[Dima ABY]

I have 7A head,fabrication year 89.No washers was found there.
My ABY head,fabrication year 94.No washers as you can see.
Maybe different valve spring seats were used in some moment?
Will mesure my 7A v.seats.Some one can mesure their v.seats were washers was used?

[Pirvu Eugen]

With 1 groove valve cotter you need the shims to allow the valve to rotate.
With 3 grooves valve cotter you usually don't need these shims because the valve end can rotate in the cotter.

Interesting!! Thanks for sharing!!
But...all the 20v heads i dismantled were with 1 groove cotter.
Can you elaborate please!
Thank you!

[s2coupe3b]

Hi,
the valve must have the possibility to rotate, the reason for that is to have a uniform wear on the valve seat.
there are 2 possibilities to provide that:

- By using non clamping valve cotters, this type is often seen as 3 groove style, you can recognize them as there is no play between the 2 cotters so they can prop up against each other, allowing a little play between valve end and valve cotter, so the valve can esaylly rotate in the cotters.

- By using clamping cotters, this type is often seen as 1 groove style, you can recognize them as there is a clearly visible play between the 2 cotters, so the cotters will clamp the valve end in the upper spring retainer and form a unit.
The reason of the shim under the lower spring retainer is to allow the rotation of the valve retainers, the springs, the cotters and the valve as a unit by sliding on the shim, without the shims the only possibility of rotation is between the spring retainers and the springs,what is not optimal in my opinion,
so I recommend the use of the shims in combination with the clamping cotters.

I hope it's understandable, my English is not the best, but my explanation is not to take as a reference to any engine as they are many different valvetrain configurations.

In addition, my 3B head has the clamping 1 groove cotters and shims on all valves, I also have a 10VT KG head with non clamping 3 groove cotters and without shims.

[Pirvu Eugen]

Great explanation! Thank you!
Is interesting that, on some 20v heads, which are using the same cotters, some have shims..some not. But anyhow...makes sense.

[orignalS60]

Also sometimes shims are used to correct
improper valve stem height.

[JP]

Why does everyone make life so complicated?
VAG group is lazy so instead of making lots of different spring varìations a lot of the time they add shims for pre load depending on the use of the head.

For example a 1.8t head that comes from a turbo assisted 9.5:1 engine will have no shims whereas one from a turbocharged engine like the 9:1 compression BAM engine does.
Same with I5's 7A Heads are NA and use stock springs whereas a turbo charged heads are more susceptible to float from boost pressure acting on the back of the intake valves and exhaust back pressure acting on the exh valves. So instead of making a whole new range of springs they use shims to pre load the springs simulating a stronger poundage spring where needed at a fraction of the cost.

[Dima ABY]

No.Not compicated our live.Just curiosity why same head/engine have them or not.