HW 55 ratchet feel

[EdSIII]

Instead of struggling how about setting the spring before you try installing it.

Get some threaded bar with an O/D close to the inner diameter of the spring and longer than the spring, add a nut and washer at one end, insert into spring and with a nut and washer at the other end compress the spring fully and leave it to set to its working length.

Doing it this way saves struggling and getting a velocity drop.

That's a good idea! I have several unset springs so it will be worth buying the threaded rod, nuts and washers to set them.

[EdSIII]

Well I replaced the cocking arm with a new version with the delrin bar I got from Chambers as well as a new leather piston seal. I also replaced the mainspring and spring guide with one fro ARH and am happy to say the gun seems to be shooting very nice with no ratchet feel at all. going to run 30 or so pellets through and check with the chrony to see what the power level is and will report back. A satisfying rebuild on a gun well worth the effort!

[TonyL]

Excellent; result.

[mrgeoff]

Are we sure the cocking linkage is the same as a HW35?

Mine had a hw35 link fitted, and it was too long, causing the piston to slam into the link on firing, made a right mess of everything.

I had to fettle the slot in the piston a few mm longer to get it to work.

It’s all had a totally modern makeover now, synthetic piston seal, piston liner etc and it’s a joy to shoot.

[T 20]

Are we sure the cocking linkage is the same as a HW35?

Mine had a hw35 link fitted, and it was too long, causing the piston to slam into the link on firing, made a right mess of everything.

I had to fettle the slot in the piston a few mm longer to get it to work.

It’s all had a totally modern makeover now, synthetic piston seal, piston liner etc and it’s a joy to shoot.

Ah, the cocking linkage of the HW35/50/55 have the same part number on both Chambers and Knibbs.

I swapped a knackered HW55 linkage for a good HW35 linkage with Neil Price for an article he was writing for Airgunner and the two measured up the same.

As your gun was slamming with the leather seal fitted it could be a case of your leather piston head being too short, so instead of taking metal out of the slot you could have just packed the seal forward.




All the best Mick

[mrgeoff]

I removed quite a lot of material from the slot, but i guess my piston could have been wrong too!

Dosnt matter now, the internals are now far from standard.

[EdSIII]

Finally had a chance to chrono the HW55 today as we have had a break in the constant snow and rain. Using Hobbys I was getting regular velocities @ 650 fps, pretty happy with that, clearly the new seal and Maccari spring are working well.

[MDriskill]

I have found that the cocking shoe can wear a bit over time, and develop a tiny “lip” of displaced material on its top rear edge, if that makes sense. That can cause the slight “ratcheting” against the mainspring that you describe. The good news is, it can be cured by 30 seconds’ work with a fine round file.

And yes, I believe the cocking linkage is the same on HW 35’s, 50’s, and 55’s of similar vintage. All three models have the very same receiver tube length, though the HW 35’s is of course 5 mm larger in diameter than the other two.

[harry mac]

I have found that the cocking shoe can wear a bit over time, and develop a tiny “lip” of displaced material on its top rear edge, if that makes sense. That can cause the slight “ratcheting” against the mainspring that you describe. The good news is, it can be cured by 30 seconds’ work with a fine round file.

I stripped my 50 down a couple of weeks ago and found exactly what you describe on the cocking shoe. My round file must be cheap rubbish because the cocking shoe was evidently harder than it, so I just gave it a couple of light touches with the Dremmel. Sorted.