Drive sprocket locking plate

[sean_rfi]

Hello all,
I thought I would post this in case it might be useful to anyone else who has run into this problem.
As part of my build I decided to fit a 530 chain set to my Z900 A4 but I couldn't find any satisfactory method of locking the nut in position.
The 530 sprocket has two m6 tapped holes on 42mm centres and I spent ages looking for something of the shelf I could adapt without much luck.
In the end I decided to make my own. I found a suitable starting washer on metalpartsdirect.co.uk -
Stainless Steel 316 Washer 54mm X 20mm X 0.9mm Thick M18
I then marked on the washer with my design and used an angle grinder with a 1.0mm metal cutting disc and then a Dremel to finish.
When installing I used two short M6 grub screws to hold the plate and stop it rotating when torquing up the main nut.
I had to use grub screws instead of bolts to allow clearance for the 27mm socket. I then swapped the grub screws for two dome head hex screws.

[chrisNI]

Good idea

[r3sc]

Nice work!

[sean_rfi]

It was all all going well with my new sprocket locking plate until yesterday evening when I came to fit the sprocket cover...
Inside the sprocket cover casting there is a raised cylindrical feature approximately 50mm in diameter that centers on the sprocket.
When the sprocket cover is fitted this cylindrical feature sits up very close to the face of the drive sprocket and just my luck fouls on the heads of the two M6 screws retaining my lock plate.
How essential is this cylindrical feature - is there to keep the sprocket on the drive shaft if the nut becomes loose/undone?
I only need approximately 3mm of additional clearance. Would I be ok to skim 3mm of the height of this cylinder so I could retain my lock plate or should I ditch the lock plate and go back to the drawing board....

[Gus]

Can you not use this?

https://www.ebay.co.uk/itm/274997810761

Or manufacture something similar.

Gus

[zed1015]

I only need approximately 3mm of additional clearance. Would I be ok to skim 3mm of the height of this cylinder so I could retain my lock plate or should I ditch the lock plate and go back to the drawing board....

Yes! That cylindrical casting only acted as a guard for the oil pump drive if fitted.
Chop away .

[sean_rfi]

Thank you for the reply Gus but that's the lock tab washer for the original 630 sprocket.
The 530 sprocket on comes with the 2 x M6 holes and it's as hard as granite son very difficult to drill.

[sean_rfi]

Thanks Rob - I've just looked on Ebay and found some versions of the sprocket cover without this feature at all - just the shell.
So this along with your go ahead I feel confident to go and pick a slot drill form the cabinet!

[Gus]

The little tang only has to go into the M6 hole and bend the rest of the washer up the side of the nut.

Saves cutting into the cover

Gus