HW77 strip down

[brouwpa]

This is what I found:
1 it already has a kit inside with a power washer installed, I think the existing spring has slightly thicker wire than the new TBT one and the spring guide is not as snug as the new one
2 I think the piston rod is off centre, it oscillates slightly when I spin it in my drill. If I do it slowly there is a definite high and low point
3 the trigger is really mucky inside.

The problem was that it is very twangy am I correct in thinking the off centre rod could be responsible? There is some space between the spring and piston, so I was thinking a liner might be useful ?
I have a new setback trigger to install so will the trigger Need to be dismantled to fit it?

Any guidance would be greatly appreciated
Cheers Paul

 

[Bighit]

@Blackmax , @Tinbum may be able to help here .

 

[Lpgc]

Following your thread, I'll be stripping and rebuilding my HW77 again soon.

Did they come with 'power washers' as standard or has someone put one in the piston (or other end) to increase preload and power?

What's the spec of the spring (outer diameter, inner diameter, wire thickness, overall length, number of coils)?

Other than twang how did it shoot before (including power output)?

 

[Tinbum]

The rod could be pushing the spring against the side of the piston, but if it’s coming apart again you could go full “belt and braces”: Straighten the rod, fit a liner and put a little more grease on the spring.

I think you can fit a blade stripping the trigger, but @Blackmax is your man for that

 

[CTD]

Trigger is easy. Use a small cable tie and loop it around the lower sear (the one that sticks out the front - the one with the adjustment screw) and the upper main sear (the one that the latch rod hooks on to). Gently tighten it and it will take the pressure off the trigger. Drive the trigger pin out and you’re away.

 

[brouwpa]

Following your thread, I'll be stripping and rebuilding my HW77 again soon.

Did they come with 'power washers' as standard or has someone put one in the piston (or other end) to increase preload and power?

What's the spec of the spring (outer diameter, inner diameter, wire thickness, overall length, number of coils)?

Other than twang how did it shoot before (including power output)?

TBT kits come with power washers, I won’t be using them as I don’t like anything over 11 ftlbs.
It shot ok, but I don’t get on with the underlever release and it was twangy! I am hoping that this exercise will help.
The kit I am fitting is the standard TBT kit, it looks like one of his older ones or something similar was inside. Will get the measurements when I find my callipers

 

[Gummage]

I would look to be gently trueing the piston rod, fitting the full kit without power washers, and you should be golden, having said that, the piston seal looks like it is ready to become a door stop, and a Britseal would be a good upgrade whilst in there.
The trigger is, I believe, dealt with previously here, though it looks in need of a good clean which can be achieved without stripping, brake cleaner spray, or a good turbulent soak in solvent, a good blow out, and appropriate oiling.

 

[brouwpa]

I would look to be gently trueing the piston rod, fitting the full kit without power washers, and you should be golden, having said that, the piston seal looks like it is ready to become a door stop, and a Britseal would be a good upgrade whilst in there.
The trigger is, I believe, dealt with previously here, though it looks in need of a good clean which can be achieved without stripping, brake cleaner spray, or a good turbulent soak in solvent, a good blow out, and appropriate oiling.

I just happen to have a Britseal, and some brake cleaner. Will fit the new TBT kit and keep the old one in reserve.
I have taken the piston to a pal with a lathe and I think it is now running true so it will look better tomorrow when I put it in my drill.

I was surprised how easy it was to strip down, it has given me more confidence to tackle other projects! There are a few, including 2 Airsporter Mk2s!

Any idea what I can do to the underlever release on the 77 to make it a bit easier? I have relaxed the connecting bolt a little is there a spring that could be changed?

Will search for my broken vernier callipers tomorrow!

 

[brouwpa]

The rebuild will be ably assisted by the spacer that @Plinky Dave kindly sent me. I have the longer trigger bolt rather than the lug that attaches to the action! Will chuck a tenner in the kitty when I meet up at Throckmorton

 

[Gummage]

The underlever release could be disassembled and lubed with Molly grease, or the spring altered I would imagine, but I have not done this myself so take the advice of others over mine.

 

[CTD]

Trigger is easy. Use a small cable tie and loop it around the lower sear (the one that sticks out the front - the one with the adjustment screw) and the upper main sear (the one that the latch rod hooks on to). Gently tighten it and it will take the pressure off the trigger. Drive the trigger pin out and you’re away.

I think I might have over simplified this. Cock the big latching sear first, then pop a pin (small nail will do) through the 2mm cross hole above the sear. Then pull the trigger. The previously inserted pin will stop the big sear flying right up which is important to avoid damage. Now you can move on to using the cable tie as above.

 

[Blackmax]

Trigger is easy. Use a small cable tie and loop it around the lower sear (the one that sticks out the front - the one with the adjustment screw) and the upper main sear (the one that the latch rod hooks on to). Gently tighten it and it will take the pressure off the trigger. Drive the trigger pin out and you’re away.

Or simply remove the tension screw behind the trigger blade, compress the upper sear and pop a bit of copper wire through the hole at the top.

 

[brouwpa]

Or send the whole thing off to someone cleverer than me and not scared of triggers

 

[Blackmax]

Glad to see you’re fitting a Britseal Paul, I hope you’re pleased with it.

Regarding the trigger, I don’t want to steal his thunder, but I recall @Lightning22 did a guide on how to strip and rebuild the Rekord unit.

I just happen to have a Britseal, and some brake cleaner. Will fit the new TBT kit and keep the old one in reserve.
I have taken the piston to a pal with a lathe and I think it is now running true so it will look better tomorrow when I put it in my drill.

I was surprised how easy it was to strip down, it has given me more confidence to tackle other projects! There are a few, including 2 Airsporter Mk2s!

Any idea what I can do to the underlever release on the 77 to make it a bit easier? I have relaxed the connecting bolt a little is there a spring that could be changed?

Will search for my broken vernier callipers tomorrow!

 

[Lightning22]

Glad to see you’re fitting a Britseal Paul, I hope you’re pleased with it.

Regarding the trigger, I don’t want to steal his thunder, but I recall @Lightning22 did a guide on how to strip and rebuild the Rekord unit.

The link to it is in my signature..

Please don't just spray it with cleaner and blast it through, it will improve it over the clagged up state it's in at the moment, but you'll wind up with some of the dirt on your bearing surfaces.

 

[brouwpa]

The link to it is in my signature..

Please don't just spray it with cleaner and blast it through, it will improve it over the clagged up state it's in at the moment, but you'll wind up with some of the dirt on your bearing surfaces.

Bug*er that's exactly what I planned to do! So back to the drawing board. Will study your guide with trepidation!!!

Will let you know how I get on, or send you a box of bits!!!

 

[CWC Matelot]

Bug*er that's exactly what I planned to do! So back to the drawing board. Will study your guide with trepidation!!!

Will let you know how I get on, or send you a box of bits!!!

It's very simple to do yaself... just done mine recently... minimal tools required.

 

[brouwpa]

Well I haven't got to the trigger yet except to give it a bit of a clean! Have degreased everything, made a piston sleeve, centred the piston rod, fitted the new seal and will put it back together today! If everything works and I think it needs it I will return to the trigger!!!

 

[CWC Matelot]

Well I haven't got to the trigger yet except to give it a bit of a clean! Have degreased everything, made a piston sleeve, centred the piston rod, fitted the new seal and will put it back together today! If everything works and I think it needs it I will return to the trigger!!!

Top tip, pop the piston in a drill and polish the death out of it with Autosol

 

[brouwpa]

That is a very pretty piston! Mine needs more polishing time!!!

Anyway getting serious now - I have rebuilt it, all went together as it should, cocked it, but the safety won't release to fire it! Have taken it out of the stock, but don't want to do anything else until someone tells me what to do!!! Please help!