Mog, I got some O rings a while ago, I made a ring removal tool from an old screwdriver - got the ring out - difficult to measure as the 'male' coupler part is 'oversize' (creates an interference fit) so I slid the ring gently up a morse taper end of a drill. Using an Aldi digital Vernier I got the 3/8 QF ring to be 17mm I.D. x 2.5mm thickness. This checks out with info I found on the net concerning gap width & dia, & % oversize of the male shaft. The nylon washer I have found should be nearest the open end.
The 1/4 QF takes as far as I can tell an 11.6mm I.D. x 2.5mm thick (no nylon washer present perhaps too small to need one). But this ring had a split through it - & I had a spare of this size coupler.
I did not have access to an 0 ring sizing gauge - it would be interesting to measure the sizes in your kit as a reference for future use of us all.
Maybe a hyds place would measure them in return for the info on what fits what.
Also would like to know where the kit can be bought in case I am wrong. I am about to start clearing junk from around the machine (it has been dry stored). So far I have re sealed a 3/8 - seems a good fit but we will se if it works when on the machine. The kit does show that the QF's can be re sealed. - I have 6 in total, & also a pair of flat faced on a hyd PTO - to run a jack hammer / wood splitter. Thanks anyway for the interest, would love to know if these kits can still be got.
