Gem Piston Washer Replacement

[micky2]

I have had a Gem with a leather washer glued to the end of the piston. but what as been said above they are just a very tight fit metal to metal.

[DCL_dave]

It seems to be mostly Diana and Langenhan types of Gem pattern that may have a piston washer of some type fitted, have seen the usual cup washer types as fitted to the later Diana 6 as well as the more unusual stacked leather disc type and the greased hemp string type as well in some LZ/FLZ Gems too.

EG and Marck Gems are usually a machined fit metal to metal and they work surprising well if not too tired and worn...

If you have a lathe its quite easy to cobble something up, but if not and the seal is knackered then you have to improvise as best you can...if you want authentic then cut off the old crap off the piston, punch out some oversized leather discs, punch centre out and put a few slits in the leather radiating out from centre hole, soak it in warm water for 10 minutes or so and see of you can stretch it over the piston head, if successful repeat...once you have all the stacked discs on the piston dip it in boiling water for 30 seconds to a minute to shrink the leather back on the piston head leave it to dry and shape to final size...

[WebleyWombler]

It seems to be mostly Diana and Langenhan types of Gem pattern that may have a piston washer of some type fitted, have seen the usual cup washer types as fitted to the later Diana 6 as well as the more unusual stacked leather disc type and the greased hemp string type as well in some LZ/FLZ Gems too.

EG and Marck Gems are usually a machined fit metal to metal and they work surprising well if not too tired and worn...

If you have a lathe its quite easy to cobble something up, but if not and the seal is knackered then you have to improvise as best you can...if you want authentic then cut off the old crap off the piston, punch out some oversized leather discs, punch centre out and put a few slits in the leather radiating out from centre hole, soak it in warm water for 10 minutes or so and see of you can stretch it over the piston head, if successful repeat...once you have all the stacked discs on the piston dip it in boiling water for 30 seconds to a minute to shrink the leather back on the piston head leave it to dry and shape to final size...

Good advice from an expert!
I have a couple of FLZ gems with the stacked discs and what I have done is carefully ground the end of the riveted stub and removed the steel and leather washer stack. I then fitted the cup washer from a primus stove pump with a leather tap washer to reinforce the centre. then fitted a steel washer and re riveted the piston. All works ok

[DCL_dave]

Good advice from an expert!
I have a couple of FLZ gems with the stacked discs and what I have done is carefully ground the end of the riveted stub and removed the steel and leather washer stack. I then fitted the cup washer from a primus stove pump with a leather tap washer to reinforce the centre. then fitted a steel washer and re riveted the piston. All works ok

Sounds like a good plan if the steel on the piston stub is workable/ can be peened over again. Sometimes the steel used in some gem pistons is extremely hard and difficult to drill/machine (possibly case hardened?) if memory serves, that is usually the machine fit piston types though.

[Benelli B76]

Sounds like a good plan if the steel on the piston stub is workable/ can be peened over again. Sometimes the steel used in some gem pistons is extremely hard and difficult to drill/machine (possibly case hardened?) if memory serves, that is usually the machine fit piston types though.

Yes they are very, very hard.

Baz

[Stefran61]

Many thanks for all the responses.
Steve

[johnbaz]

Hi

I have a Gem that had a big screw holding a rotten leather cup washer when I eventually got it apart!

I've cleaned them up here, Had a hell of a job removing the screw as it was siezed in place!


The gun was a heck of a mess, Paid a tenner with the .25" spare barrel, Was going to make a stock but found one on Mel's table at Melbourne for a fiver!!




I snapped the trigger guard/cocking link whilst tring to get the piston to move, Luckily it came with a spare on the other barrel (Can't use that one as it's not a T bar Gem!)..



Plenty of emery cloth, Draw filing on the flats of the barrel and I got it shiny!!




I then messed it up trying to cold blue it!!




I should finish it really, Can't even remember where it is now


John