1377 pump arm replacement

Moonray13 · January 17, 2014, 07:55:14 PM

I know there are a number of options for replacing the pump arm on the 1377. I really don't like the looks of the brown plastic stock item, and since I've replaced the grips with the Crosman shoulder stock, the contrast really stands out. When buying a replacement pump arm (whichever one I end up with), do I need any other hardware to make the switch or just the arm itself? I've noticed on eBay that the Backpacker pump arm is sold with or without the lever assembly. As I'm not familiar yet with how everything goes together, I'm wondering exactly what I need for this mod.

Thanks for the help.
Ray

T191032 · January 17, 2014, 08:07:52 PM

You can call Crosman and get just the Backpacker Pump (1389-010) or the older, squared off type the 760 used (C760P-010), yes. Tap out the two roll pins, remove, install new forearm pump arm with the issue roll pins.

bgmcgee · January 17, 2014, 08:16:08 PM

Quote from: T191032 on January 17, 2014, 08:07:52 PM
You can call Crosman and get just the Backpacker Pump (1389-010) or the older, squared off type the 760 used (C760P-010), yes. Tap out the two roll pins, remove, install new forearm pump arm with the issue roll pins.

Yup. Much better than that skinny pump handle. Do a search here about getting those roll pins out as there is a proper way on the direction you should knock them out.
http://www.crosman-air-pistol-owners-forum.com/board/index.php?topic=9206.5;wap2

donn · January 17, 2014, 08:36:45 PM

You'll need a 1/8" punch to remove and reinstall the roll pins.

BDS · January 17, 2014, 08:38:16 PM

And chamfer and polish the roll pin ends and lube e'm before you install, you'll be grateful when it's time to take e'm out again later

Moonray13 · January 17, 2014, 09:07:32 PM

Chamfer??? You're giving me way too much credit. I don't even know what that means.

donn · January 17, 2014, 09:17:24 PM

It means to put a slight bevel on the outer edge of each end of the pin.

That, and polishing will make the pin easier to start on reinstallation.

mudduck48 · January 17, 2014, 09:24:31 PM

Quote from: Moonray13 on January 17, 2014, 07:55:14 PM
I know there are a number of options for replacing the pump arm on the 1377. I really don't like the looks of the brown plastic stock item, and since I've replaced the grips with the Crosman shoulder stock, the contrast really stands out. When buying a replacement pump arm (whichever one I end up with), do I need any other hardware to make the switch or just the arm itself? I've noticed on eBay that the Backpacker pump arm is sold with or without the lever assembly. As I'm not familiar yet with how everything goes together, I'm wondering exactly what I need for this mod.

Thanks for the help.
Ray

Are you talking about the pumparm linkage or the forearm. If you want the backpacker forearm the number you want is 1389-025. They were $8.75 last time I bought one.

BDS · January 17, 2014, 09:24:57 PM

Quote from: Moonray13 on January 17, 2014, 09:07:32 PM
Chamfer??? You're giving me way too much credit. I don't even know what that means.

Ya... what he said, a slight angle, that's all

We'll baffle you some more with techno-talk when we discuss the poly-truncated design of a modified transfer port into a barrel. (a series of tubes that takes a 90 degree turn)

donn · January 17, 2014, 09:25:14 PM

I just looked at a pair I removed from a 1377 this morning, and they already have a slight chamfer on each end. I imagine they'll be easy to reinstall with slight compression from a pair of pliers to start them.

BDS · January 17, 2014, 09:38:48 PM

donn... the idea with polishing the angle or chamfer is to take the "bite" out of the sharp edges on the ends and let the pin get started in the hole in easy manner and straight in-line with the hole, a drop of oil helps too. The sharp edges of the rolled ends on the shank of the pin should be (mostly) left as is, they bite into the plastic of the arm to a slight degree which keeps the pins in place.

Keep in mind that Crosman sees these pins as "one and done" at assy and doesn't care about taking them out and re-using them or, how much bite they have in the plastic arm. (shaved plastic)

donn · January 17, 2014, 10:46:06 PM

These are pretty cheezy roll pins. Are there viable alternatives, like coiled SS roll pins?

BDS · January 17, 2014, 11:08:33 PM

Roll pins are supposed to be "cheezy" (sorta) they have to be somewhat anti-rotational and stay in place in the length of the hole. The spring steel and the cheezy surfaces help to do that. A super slick, polshed roll pin kinda defeats it's purpose.

If you really want stainless (you can't see it when installed) just ask around on here or check the web. If you buy them at McMaster Carr or a fastener supply, you will have to buy a bag of 50 or so, that's a down side unless you can sell them to get some money back.

T191032 · January 17, 2014, 11:20:53 PM

Quote from: donn on January 17, 2014, 09:17:24 PM
It means to put a slight bevel on the outer edge of each end of the pin.

That, and polishing will make the pin easier to start on reinstallation.

That's a bit fancy for some of us.

BillK · January 18, 2014, 12:14:31 AM

Ray, a while ago I got a bunch of stainless roll pins off Ebay. They are perfect replacement to the Crosman pins but longer. So you can cut to the length you want. (longer for backpacker type or shorter for wood type)
I've got 10x more than I'll ever use. PM me your address and I'll send you some. Offer open to all....Free

Oh, the front pin should be put in first. The hole for the rear pin is more oval and is easier to line up. Consequently if you do the rear pin first getting the front pin to line up can be a bear.