Sunday, November 16, 2014

Crosman 1400 Repair

Sears branded version of the Crosman 1400

A few months back I purchased three vintage airguns for a great price. They were a Sears branded Crosman 600 with the original box and manual, a Daisy 1894 BB gun (the original version, not the re-issue), and this Sears branded Crosman 1400. The 1400 was the only one that worked. I took it out for the first time a few weeks ago and had a blast plinking in my back yard. That is until one of the seals failed and I heard a hiss come from the rifle after I pumped it up. Look like it's time to reseal it. I ordered a reseal kit from Bryan and Associates.

nice walnut stock
someone must have dropped it, the trigger is broken and the guard is bent
much nicer all steel front sight than the 140

I want to give credit to Nick Carter of Another Airgun Blog for the helpful instructions on the tear down. I think this is an early version from the early 1970's as evidenced by the sliding breech cover. The 1400 has a blow off valve meaning that the valve is held closed by the trigger. You cannot over pump this rifle like you can with a hammer-struck valve. It is an upgraded version of the Crosman 140 and the Sears branded version were usually of even higher quality. I thought about a complete restoration but the rifle is in pretty good condition and it is going to be a shooter, not a wall hanger. I'm just going to get it working, clean it up, and go shooting!

stock screw and safety removed
First I removed the stock screw. The entire screw came out instead of just the nut. Then I drifted the the safety out with a punch. Then the action can then be removed from the stock. With the action removed, I wiped the stock down with Formby's Lemon Oil to bring some life back to the dry walnut. That stuff works miracles on old wood.

trigger group removed
looks like heavy corrosion in the trigger group

With the action out, the trigger group is removed. Keep track of the screws, they are not the same. The small one goes in the rear. An offset screwdriver helps here.

pump cup looks good

Next the front roll pin is drifted out with a punch. The end plug and the pump arm are removed from the pump tube. The pump cup looks good and had suction when I removed it. It is a pain to replace so I'm going to leave it unless I have problems.

breech cover removed
rear screw (with spacer) and bolt removed

The sliding breech cover is removed by taking out the one screw. Then the rear screw is removed. It goes though a plastic spacer which must be removed before the rear plug can be removed. One the rear plug is removed, the bolt can be pulled out the back.

breech screw removed

Next the breech screw is removed and the barrel can be removed from the pump tube. At this point the plastic spacer and transfer port can also be separated.

threaded bushing
end plug and hammer pieces

A threaded bushing has to be removed to take the end plug out of the pump tube. I drifted it out from the top with a punch. Note the orientation of the bushing. Then the hammer pieces are removed from the rear. The end plug had a little bit of rust.

orientation of valve parts
valve disassembled

The valve can then be pushed out of the front of the pump tube. The valve is unscrewed to get to the seals and spring. That's it for the disassembly. I cleaned each part with Break Free CLP, wiped them off, then coated them with Crosman Pelgun Oil. I scrubbed any rust with CLP and 0000 steel wool. The white spacer had some rust stains. Simple Green did nothing but CLP and a little elbow grease did the trick. I cleaned the barrel with CLP on a patch and jag. Maybe I'm crazy but it feels as if the barrel might be choked as the patch felt harder to push out of the end.

new seals

Match the new seals with the old. Start by replacing the valve seals. The valve then inserts from the front. Make sure the threaded hole in the valve lines up with the bottom hole in pump tube. The hole in the black part of the valve lines up with the transfer port in the top of the pump tube.

The hammer pieces then install from the rear. The orientation of the rear valve piece is wrong in the picture. The hole should line up with the top hole in the pump tube.

transfer port cutting tool
new transfer port (L) and old (R)
The new transfer port seal in the reseal kit was too short for the 1400. It looks like it was for the 140. The white spacer requires a longer transfer port seal. No worries, I made a new one from 1/4" nylon tubing. I used my transfer port cutting jig to cut the new piece. The tubing is inserted through the 1/4" hole and then a drill bit is inserted inside the tubing. Then a sharp razor blade is used to cut the tubing. The cutting jig ensures the the cuts are square and allows you to cut very small slices from the tubing for an exact fit. I measured the old transfer port seal at 5.26 mm. I cut the new one to 5.30 mm allowing some extra material for compression.

bent trigger housing
1400 trigger group

Now for the trigger group. I had a nice adjustable 160 trigger group that I thought I could swap for the broken trigger. Unfortunately the sears are not the same. Guess I need to fix this one.

removing the dent

I used a piece of aluminum rod and a plastic mallet to tap out the bent trigger guard in my vise. It turned out pretty nice.

lots of corrosion
not bad!

With the bend removed I attacked the corrosion with some CLP and a brass brush. It cleaned right up. I put the trigger group back together, adding some grease on any contact areas.

ready to rock
Lastly, I replaced the pump assembly tapping the roll pin back in. I oiled the pivot pins and greased the high wear areas. Put the action back in the stock and bolted it back together. Time to shoot.

Crosman Premiers at 10 m with 5 pumps

I headed outside on a balmy 48° day and set up my chronograph. Here are the average velocities.

Pumps     Velocity (fps)
  2                 339
  3                 412
  4                 474
  5                 520
  6                 556
  7                 586
  8                 605
  9                 628
  10               639

Ten pumps was tough and only gave a few more fps. I tested the accuracy at 5 and 6 pumps at 10 m with Crosman Premiers and JSB Exact Diablos. The Premiers edged out the Exacts. The best group of 5 was 15/16" with the Premiers at 5 pumps. Given the mediocre sights and my mediocre eyes, I'm pretty pleased. But targets be damned, this gun was made for plinking. I was able to destroy 2" Daisy Shatteblast targets without any problem at over 90 feet once I had a the elevation dialed in. The windage was spot on; pellets smacking the narrow stakes every shot. I think this may become one of my favorite airguns. Real steel, real wood, timeless style. Now to get the rest of those vintage airguns working.

1 comment:

  1. Great description. I just ordered the o-ring kit to rebuild my older brothers crosman 1400. Hope it goes well. everything on it is in mint condition. I would love to get it running again so my boys can give it a try. We have lots of pesky squirrels in the back yard!