Impact Gun Chicago Pneumatic CP734

[jim662]

I've got an old model of this impact gun that works, but it certainly does not have 400 pounds of torque. I came across this forum in looking for repair advice and saw that the group has some expertise with this gun. So, I will ask any assistance that you can give.

The gun is a model CP734. I'd say its 25-35 years old. It is definitely not the model CP734K that is being sold now. I found a parts "blow-up" on CP's UK website for the CP734 "series," but it is slightly different than mine. Mine has the power controller as a dial on the bottom of the handle near where the air inlet is. The model in the diagram appears to have its controler on the back of the gun. Anyway, I just mention this to help determine the age of the model.

I took the gun apart last night to see what I could see. I think it ran without oil (or not much of it) for a while. The hammers (I think that is what they are called -- the pin part that strikes the anvil) had some chips (nothing too bad) out of them near the part where they conect onto the spring. The anvil seems to have some wear where the hammers hit. Do these parts sound like they need replacing?

I've ordered a tune up kit from an on-line vendor, but I am a bit worried as to whether the kit is the right part due to the H designation confusion. From what I could tell from the parts diagram that I have, there is one large O-ring and the blades that I will use out of the kit. There are a couple of other O-rings that I don't think I have a problem with and a couple of seals that are not leaking. I don't plan to replace parts that aren't bad, like the seals (which appear to be pressed in). Anyway, if someone knows of a source for parts for this older gun, I would appreciate a point in the right direction. Also, is there something else to look for in repairing or "refreshing" the gun that I should look for?

Thanks in advance for any help and advice.

Jim

 

[Bird]

Jim, as I've mentioned before (numerous times ), when I was in the air tool repair business, Air-Tech Tool Service was my primary parts supplier and source of advice and information when I needed it. What they don't know about air tools probably ain't worth knowing.

The CP734 is one of the oldest and most popular half inch impact wrenches around. I repaired/rebuilt quite a few of them, usually due to lack of oil and/or too much moisture in the air lines. As with all the air tools, you want to add a few drops of air tool oil to the air inlet every time you use it; preferably after use, then one short blast of air to distribute the oil and to displace any moisture. But then the front end of the tool should have 20W or 30W (I only used 30W) non-detergent motor oil in it. When you are assembling it, you can simply fill the hammer cage before setting the housing down on it. After assembly, if you need to put oil in it, remove the "oil" plug and set the tool down with the handle sticking up, rotate it so the oil fill hole is at the 3 o'clock or 9 o'clock position as viewed from the front or back; i.e., fill the front end about half full.

And yes, if the hammer pins are chipped and the anvil shows visible wear, you ought to replace them.

a couple of seals that are not leaking. I don't plan to replace parts that aren't bad, like the seals (which appear to be pressed in).

How do you know the seals don't leak? I nearly always replaced them. And yes, they're pressed in. They're pretty easy to pop out with a screwdriver and almost anything flat and straight might be used to press new ones in, but I used a 3 ton arbor press which is an essential tool for anyone in the business of repairing air tools. The tune-up kit will have the new blades or vanes, and if the interior of the cylinder is scored at all, I always used a cylinder hone on it before re-assembly.

 

[jim662]

That's exactly what I needed to know. Thanks for the information and your expertise.

Jim