Spline dimensions

[jar]

Hi
I know this will be a stupid question but can someone tell me which part of a tap valve the spline actually is ?

I need to replace the cartridge valve in my kitchen sink tap but, since the replacement valves I have seen (in a certain DIY chain) have sizes based on splines, I don't know what to measure on the old one ?

Thanks
John

 

[denso13]

The bit at the top

 

[jar]

Hi
Thanks for the quick reply. So it's the length of the part in the picture, and not the diameter ? And it's just the part with the teeth, not the part below this which then meets the main body ?

The packs I have seen have 8mm, 9mm & 10.5mm splines listed but all of these seem slightly longer (part with the teeth) than the one I've taken off.

So I'm assuming mine might be a 6mm or 7mm. Is it likely using an 8mm one would still fit or is it too risky to try ? I've not opened the packs yet so can still return. I didn't see anything smaller that 8mm in the store.

Thanks
John

 

[Burnerman]

You must use the exact size spline - if the tap is even a fraction slack, the top will spin after a while.
You need to measure the spline diameter, the spline length, and then count how many splines there are around the circumference.
Lunns.net is an excellent store to sort you out.
John