hw 35 leaking breech fix

[bigtoe01]

capillary action works best under vacuum...the loctite seeks out holes etc.

a modification to the method would be create a vacuum for 30 mins, release the piston, withdraw the TP plug, withdraw the piston, replace the TP plug but this time from the inside of the action, then push the piston back in to pressurise the cylinder.


I have done one 35 this way and 2 35's with just vacuum , and all 3 had the issue cured

[Big Seth]

capillary action works best under vacuum...the loctite seeks out holes etc.

a modification to the method would be create a vacuum for 30 mins, release the piston, withdraw the TP plug, withdraw the piston, replace the TP plug but this time from the inside of the action, then push the piston back in to pressurise the cylinder.


I have done one 35 this way and 2 35's with just vacuum , and all 3 had the issue cured

I am quite sure you got the results you were after but how can you maintain any vacuum by withdrawing the piston if the breech weld is porous? Sorry for my pedantry

[bigtoe01]

I am quite sure you got the results you were after but how can you maintain any vacuum by withdrawing the piston if the breech weld is porous? Sorry for my pedantry

the loctite seals it up

[T 20]

I am quite sure you got the results you were after but how can you maintain any vacuum by withdrawing the piston if the breech weld is porous? Sorry for my pedantry

The cylinder doesn't leak to outside through the braze --- what you are doing is filling a void within the braze on the inside of the cylinder.

If the braze is porous inside the cylinder between the breech plug and cylinder tube then the pressurised air can pass through the porous braze into the voids in the breech plug.

Here's a debrazed cylinder showing the voids :-

image.jpeg

The voids are machined into the breech plug to hold a mix of brass and flux, this is then pushed into the tube and then heated up to form the brazed joint.

A slight cockup on heating and a porous braze can form allowing air from the cylinder side to enter the void left by the brass and flux.


Hope this helps




All the best Mick

[Big Seth]

The cylinder doesn't leak to outside through the braze --- what you are doing is filling a void within the braze on the inside of the cylinder.

If the braze is porous inside the cylinder between the breech plug and cylinder tube then the pressurised air can pass through the porous braze into the voids in the breech plug.

Here's a debrazed cylinder showing the voids :-

http://i1138.photobucket.com/albums/...12006666-1.jpg

The voids are machined into the breech plug to hold a mix of brass and flux, this is then pushed into the tube and then heated up to form the brazed joint.

A slight cockup on heating and a porous braze can form allowing air from the cylinder side to enter the void left by the brass and flux.


Hope this helps




All the best Mick

Thanks, now I understand. Regards Ian

[forks]

thanks guys for the info, feel a lot more confident taking this on now, seems fairly straight forwards...but before i do...quick question, which 35's does this affect?? upto what serial number/year or is it just all 35' with a leather seal, mine is 1980's one of the later ones to be made with leather piston seal as i understand, had the problem been sorted by the 80's?? anyone know? or is it best to do the fix as a precaution anyway whilst fitting new spring an top hat etc, also the conversion parts for changing to a synthetic seal...worth doing? my leather seal looks like new after 24 hours in neats oil.... thanks again fellas

[forks]

does anyone know up to what year / serial number this problem affected? or is it all hw35's with the leather piston seal? thanks again for the great info

[TonyL]

Revived for contemporary assistance.