Crosman Town & Country 107

[DT Fletcher]

"I used silicone grease on the seals. And a tiny bit of moly grease on the metal parts of the pump rod that make contact with the tube wall. Do you think that this would cause issues? I have Pellgun oil, no "secret sauce". "

Silicone grease is going to attract dirt and grit, I'm assuming. Moly grease? No idea. The question is: is it compatible with hydraulic systems?

The problem is that the lubes used will invariably end up on the seals, so, that lube needs to be fully compatible. MAC-1 did their work in finding a better lube than Crosman (which tends to gum up) and they came up with Secret Sauce. I've let out the "secret" a number of times so no big deal; it's heavy weight motorcycle fork oil. 50 wt, if memory serves. Can't recall the brand they used but might have been Bel-Ray. It's pretty certain that any high quality fork oil is going to be okay.

I made the effort to use the flat washer for the exhaust valve, instead of an O-ring. As I recall, the flat washer made it easier to get the exhaust port properly aligned with the barrel inlet.

If you go for a replacement pump rod, again as best as I can recall, the 101 pump rod is the same thing. Pretty wild how the previous repair actually welded the new pump head on the old one. Pretty sure it's a first for me. Your rebuilding the previously unrebuildable pump head being another first.... for me anyways.

These guns are great fun to work on and even more fun to shoot.

[DT Fletcher]

Had to think a bit about precisely why o-rings aren't the best choice to replace the stock square-section seal. Note the positioning indent on the exhaust valve body; this is the shallow hole in the body that can be seen through the hole in the compression tube. These holes when perfectly aligned mean that the exhaust port is perfectly aligned at the same time. So, when installing the exhaust body, you want to place a rod of the precise diameter that fits these holes, then, with that positioning rod in place, fully tighten the exhaust nut, without the exhaust body moving at all. This usually doesn't work with an o-ring... as I recall.

[jirushi]

Had to think a bit about precisely why o-rings aren't the best choice to replace the stock square-section seal. Note the positioning indent on the exhaust valve body; this is the shallow hole in the body that can be seen through the hole in the compression tube. These holes when perfectly aligned mean that the exhaust port is perfectly aligned at the same time. So, when installing the exhaust body, you want to place a rod of the precise diameter that fits these holes, then, with that positioning rod in place, fully tighten the exhaust nut, without the exhaust body moving at all. This usually doesn't work with an o-ring... as I recall.

Good tips, thank you. I might have some time to do some further testing later today, and then I'll report later.
I'm confident I'll get this 107 to work better.
The extactly-fitting-rod-in-the-indent technique is a good one. Until now I've lined the hole up, and then tightened the exhaust nut, which does make the exhaust body move slightly. And could cause the transfer port to work less efficiently.
@ Ped, valve grinding paste it is.
I will also order some parts from JG Airguns. My sister is in Santa Barbara, so she can take some parts back with her

[--ped--]

works fine if you have the right section o ring and yes you need the rod to align plus it holds the valve body against the valve spring pressure making it easier to tighten up the locking collar
if you can easily and cheaply get the correct seals then yes use original but over here they need shipping from the US and postage is often very dear or suppliers won't ship so I often have to think outside the box to repair the ones I have and often have to make new parts or alter a part to accept a new type of seal that is easy to get

[DT Fletcher]

works fine if you have the right section o ring and yes you need the rod to align plus it holds the valve body against the valve spring pressure making it easier to tighten up the locking collar
if you can easily and cheaply get the correct seals then yes use original but over here they need shipping from the US and postage is often very dear or suppliers won't ship so I often have to think outside the box to repair the ones I have and often have to make new parts or alter a part to accept a new type of seal that is easy to get

The proper square section seal is a standard off-the-shelf part here in the US and costs very little... but it does take some effort to track it down with industrial suppliers.

Having to scrounge for parts is part of the fun. I clearly remember how happy I was to find that #2 faucet washers worked perfectly for the exhaust valve seal of a Crosman model 101. Used the faucet washers for probably the first dozen or so old Crosman rifles I repaired. At the time, I was one of only a small handful of people able to work on them at all. No Crosman Service Station would, because no parts were available. Today, fortunately, some great folks have stepped up and made the critical parts available with the modern replacements being better than the originals.

[--ped--]

tap washers are handy things and I use them for some seals

[jirushi]

Some improvement:

545 ft/s with 8 pumps, 584 ft/s with 12 pumps (6,4 ft/lbs).
I'm not sure what 107's are capable of? And if they're meant to be used with more than 8 pumps.
I think .177 is going to be less efficient in a pump gun anyway?

Here are the adjustments I've made, following the advice I received from DT Fletcher and ped:

1. align blind hole in exhaust valve body perfectly with hole in tube

2. weaker check valve spring

3. pump rod is now "longer", the pump cup leaves a tiny gap for air to be sucked in through the breathing hole.

Not sure which adjustment made the biggest difference: it would have been best to try one at a time, but I feel that disassembling and reassembling the 107 causes a bit of wear, which I want to keep to a minimum of course.

By the way when there's no pressure in the gun, the forearm drops down. So I guess my pump arm adjustment isn't right yet.
Any ideas how to adjust in order to get it right?
Looking at my 108, the pump cup clears the breathing hole more than my current 107 setup. Hmmm.