PTFE Washers for Spring gun. Click on model on check out.
PTFE stands for polytetrafluoroethylene which has the lowest coefficient of friction of any solid. It is used for coating non stick cooking vessels, and is used for low friction bearings.
The correct lubrication is very important so don't forget the MS 40 Silicon oil. I have put the MS 40 on this site under Lubrication.
Photo also shows our washers with the Stainless Steel or steel insert.
Relums do not have a Stainless Steel insert but has a Stainless Steel Screw instead of the standard rivet which is very poor. You can order a Relum washer under the options, as this comes with a screw conversion and nut. Just use locktite or similar when assembling.
Some guns just clip on or in so do not have any Steel inserts. See photos.
Our washers are designed for low friction and a higher swept volume if possible. In most cases they are as easy to fit as the standard washer.
PTFE Washers (Beware of Copies).
* Advance design features
* Designed for more swept volume
* High Quality PTFE materials
* Very low friction
* Requires virtually no lubrication after assembly
* Normally uses the standard washer fixture, with no modification.
* Eliminates Dieseling, if lubricated correctly
Fitting a PTFE washer, Please read carefully.
If the piston washer has a screw or nut fixing do not over tighten the retaining nut or screw, instead Locktite or similar thread locking product should be used. Aim to get the screw or nut slightly recessed into the face of the washer. This will allow for bedding in.
The washers are normally made a couple of thou under size and a perfect air seal is achieved after a short "running in" period (usually within 500 shots) when the washer has sized to the bore of the cylinder.
This method is preferable to dry firing which can cause over expansion and frictional problems.
Never dry fire a spring air gun.
If on rare occasions the washer is a tight fit, you can benefit by wrapping 400 wet and dry around the washer, and with a back and forth motion while rotating, take a little PTFE off until a smooth fit is obtained.
For extra swept volume, PTFE washers are in some cases thinner than the standard washers to obtain more swept volume. And on some models protruding studs or screws may need to be shortened accordingly.
With the new washer in place, the gun should be inspected to make sure a small clearance remains between the rear of cocking arm and the rear of the piston slot. This is rarely a problem.
Degrease the cylinder completely before assembly. Follow the lube instructions sheet which is supplied when any of the Robb lubes are purchased, or see the Airgun Tuning Manual.
Fibre backing washers, if fitted with the original washer, should be used if the piston is a poor fit in the cylinder.
Finally, PTFE washers require one drop of MS 40 Silicon oil smeared around the piston head before assembly. But do not reapply until the next overhaul.
The HW 35 used to be fitted with a leather washer which was held on by a large nut. The Later HW35s are fitted with a polypropylene washer, the same as the HW 80 and 90. This type just clips over a lip, after peeling the old one off.
The Original Diana model 5 and 6 pistols have a dovetail type fitting to hold the washer on which makes it harder to fit a PTFE one, but I have fitted lots of them by stretching them over after forcing them into the lower edge of the dovetail. Rounding the front sharp edge helps. Then push the washer back into the groove and roll to get it to fit in the cylinder. The washer will size itself to the bore when the gun is fired a few times.
The PTFE washer will last a lot longer than the standard ones that turn to soft cheese or break up to dust.
The last photo shows our PTFE washer on the left and the standard one on the right. Our design also reduces drag as well as the low friction material of PTFE.
Made to fit 99% of all airguns.
The second photo shows our washers with the steel insert. The third washer shows a Very Old BSA Meteor washer that replaces the old Leather type washer.
Always check the power to make sure the gun does not exceed your limit, after changing any parts.