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Slavia · Moderator

I tore into the G1's guts this morning. For the future reference of G1 (and Quest/Phantom) owners, here is what I found:

The end cap is plastic, so put a block of wood against it when using a spring compressor. It is held by the same pin that holds the rear spring guide assembly.

I used a compressor to take the spring out, but I can push it in by hand. It has 1.215" of pre-load until it goes slack, and takes 41.4 pounds to push it in by my bathroom scale.

The rear spring support is also plastic. Not only is it the wrong material to bear the force of the spring, but the spring end gouges into it like a lock washer and will not turn.

The rear spring guide fits snug, but it is rough.

I measure the spring at I.D.=0.494," O.D.=0.741," 34 coils, about 9.75" long.

There was some lubricant in there, but not much. The metal looks shiny, but feels sticky. I can handle the parts without getting any visible stuff on my fingers.

Benchmark performance (with RWS 8.3 grain Superdomes) was Mean (10 shots)=925 FPS, S.D=8.500, Min.=915 FPS, Max.=938 FPS.

cw · Banned

Ouch! Some metal replacement parts and a thrust bearing
at each end might help.

What is the trigger group like?

AirGunEric · Site Admin

cw · Banned

Yeah, using a roller bearing type thrust washer would probably not last
very long.

But, a trust bearing doesn't always have to be a roller bearing.
A thust washer stack is a thrust bearing, a plain bearing.

AirGunEric · Site Admin

I'm half pulling your chain CW- "thrust bearing" always brings connotations of the deluxe needle/roller bearing setup that people tried a few years back and often ended up with a tube full of metal shavings.

Slavia · Moderator

AirGunEric · Site Admin

I've never seen an alternating rubber-steel spacer in anything- but that's not to say it wouldn't work- perhaps use something like urethane that isn't going to come apart in a petroleum-based lubricant environment.

The mass added by a few washers (usually done up top because it's an easy job to install a couple 1/4" washer there- no machining other than making sure the washers do not have any burrs) is negligible when compared to the spring and piston weight (maybe a 5% increase in overall mass- probably even less than that really).

As for the ears on the trigger assembly hitting the piston and the whole trigger group moving under it's hold-down bolt- file the ears on the piston side a bit and tighten the hold-down bolt better- I have come across more than one gun where the bolt was not tight enough, allowing movement.

Slavia · Moderator

AirGunEric · Site Admin

If you come up with a good solution for that spacer/thrust washer- be sure to post it up- people are always looking for a better "mousetrap" (at least I hope they are)...

kanyon · Silver Status Member

Hi guys The cfx and geox have these only had the Geox apart the second land on that plastic spacer ingages with the piston and holds the back of the piston in centre so it can't move to let the trigger grab it . It may work like the Geox one!!!???
Just my two cents worth

k

Slavia · Moderator

Thanks, kanyon - I'll take another look before I cut.

Slavia · Moderator

I've been staring at that plastic thing for a while now, and here's what I think: It's a spacer/thrust bearing. The first (smallest) land clears the inside of the piston, but does not touch the piston. Neither does it touch the primary sear, which rests on the outside of the compression tube. The middle land is much too big to go inside the piston, which doesn't travel that far back anyway. I think it just provides clearance for the trigger housing. The third (and largest) land is smaller than the compression tube by a lot - so I'm guessing it was meant to spin on the spring guide as a thrust bearing.

Except - the factory finish is pretty rough, so it's not going to spin very well. The sharp end of the spring gouged into mine like a lock washer (and also scratched the spring guide). The thin end looks like it is being mushroomed out from spring pressure. Since I wanted to experiment with thick rubber washers (to absorb vibration), and since I wanted to support the spring with the thicker walled middle land - I cut it off by an amount equal to the washers I added. I think small stacks of steel will make better bearings anyway.

I used two neoprene washers. If it turns out that they disintegrate, I'll just replace them with an equal thickness of steel. The stack under the top hat was easy. Getting washers to fit between the spring guide and piston I.D. took a little more time, but it's not that difficult.

I deburred and polished anything that rubs against another part (the cocking arm slots were especially rough). As you can see with the tophat, the materials in this gun aren't the greatest. My advice for anyone contemplating this for their own G1 is to forget an even, polished finish. Just knock off the high spots and call it good.

When I went to the State Fair a few weeks ago, I spent $4.00 on a set of diamond files. They are wonderful!

I anticipate getting it back together tomorrow. I can then determine if I accomplished anything or not. Keep you posted.

AirGunEric · Site Admin

I don't believe the spacer/thrust washer was designed to turn- I have yet to hit a Crosman where there is any hope of this happening due to the tight fitment of the two together, even with a brand new rear guide and thrust washer from the parts bin (i.e. virgin/unmolested/never installed) the washer would never turn on the guide. If you also look at the front guide- nothing much there to allow rotation either. Now, throw in that I've seen more than one nearly brand-new Crosman with this powerplant in it with it's nearly brand-new spring (100 shots or less most times) and the spring is starting to bend/cock a bit in the middle. The only two causes for it I can really determine are that a) the spring is a POS right out of the box- but this doesn't seem to really hold true, or b) because it cannot rotate much, if at all, the spring is winding up and getting damaged.

Slavia · Moderator

I would differ with you regarding the fit of that "spacer" (or whatever it's called) - except for the rough finish on the ends, mine moves freely. In fact, you can see from the gouge on the rear guide (shown in my previous post after smoothing) that there has been some rotation.

That single exception aside, your general point that there just isn't enough rotation is well taken and accurate. That's why I spent 1/2 hour each enlarging the I.D. of those stupid metal washers, and then even more time on the O.D. - I agree with you.

My son says this gun will shoot so fast I'll be hitting the target with melted lead blobs. That may be an overstatement, but it's not overstated to say I'm having fun tinkering. Thanks for your input.

Slavia · Moderator

Back together after a thorough cleaning and Macarri moly paste. I think this will qualify as a success.

With RWS 8.3 grain Superdomes, same as before:

Mean velocity for a 10-shot string = 919 FPS (Before = 925 FPS)
Standard Deviation = 3.915 (Before = 8.500)
Maximum velocity = 926 FPS (Before = 938 FPS)
Minimum velocity = 912 FPS (Before = 915 FPS)

So slightly less velocity, but more consistent. Plus, it is much, much smoother. No more clunk, clunk, clunk as the cocking arm bounces over the spring coils when cocking. No more grinding sound when cocking. No more enraged bumblebee when you pull the trigger - just a nice thunk.

These graphs were made by holding a microphone against the compression tube and recording the sound with Windows Sound Recorder. Same microphone position, same gain settings, etc. For one thing, the "after" graph is cleaner. The "before" graph spikes out to 100 db (where they are clipped by the software). The "after" graph peaks at about 35 db. The main event lasts about 35 ms in both cases, but the tail-end vibrations are damped more quickly in the "after" graph. Before modification there was buzzing going on past 100 ms; after modification things became pretty quiet after 70 ms.

So next I've got a trigger that needs attention, compression tube forks that are a little loose, a breech seal that looks suspect, and a barrel latch that isn't as tight as I would like. And don't forget the Broomaster custom stock design.