Here is how to restore a U.S. military Schrader dual foot tire gage and make it fully functional.
This is a tire gage supplied with U.S trucks (Jeep’s MB GPW, Dodge …) during WWII.




Usually these old military tire gages are out of service because the rubber gaskets are dry and hard or are simply missing.
Also the leather washer and the felt washer are usually missing or badly damaged.
The long spring in my gauge was also blocked inside with rust and dust.(removed with WD-40 and a few shocks on each spring turn with a hammer and a long pin.)



I’ve scoured the web to find Schrader spare parts w/o success.
But I’ve found an interesting gage on eBay, made by Tru-Flate.(P/N 17-545)

That gage is very similar to the original Schrader gage with some minor differences:
The indicator bar has a square section in the Tru-Flate gage and is made of plastic.
The spring is slightly different with a wire dia. of 1.6mm i.o 1.5mm in the Schrader gage.

The spring turns are evenly spread in the Tru-Flate gage.
The plunger and the rubber are different but are fitting correctly in the Schrader gage.
Otherwise the other parts are a Schrader gage repro.
1- Dismantle the gage. Use WD-40 to unblock the screws and the spring if necessary.
Do not use a hammer to unblock the two screws if they are in steel. Use a large screw driver instead.
I’ve broken one of them because it’s hard steel.
2- Clean-up each part and remove rubber remainings.
3- Clean-up the spring (outside and inside). The spring must move freely in the tube and the indicator bar must move freely inside the spring with a slight friction if you reuse the original spring.
Do no use any electrolytic technique as it would destroy the spring.
4- The indicator bar tube must be straight.
5- If your gage has been used as a tire leaver , find a way to make it straight. You could carefully insert a 13mm drill bit inside to do that.
6- Thoroughly cleanup the indicator bar tube. I’ve used a 13mm drill bit to do that and finished with sand paper.
Once OK , the spring must move freely inside the tube.
7- Oil/grease the spring in order to protect it from rust.

Mounting the parts :

Dual foot head side:
Remove the gaskets (2 X), plunger and screws (brass) from the Tru-Flate gage and mount them on the Schrader gage.
Use a very large screw driver to tighten the screws.
If you want to DIY your rubber washers, here are the dimensions :
Gasket (2X) head (rubber washers): ext dia : 12mm
int dia: 5 mm
thickness : 3 mm




Indicator bar side:





Insert the indicator bar into the spring as shown on the picture.
You can make use of the Tru-Flate spring. I’ve not measured a significant pressure difference with
the Tru-Flate spring. (very slightly lower and can be adjusted with the indicator bar screw.)

Insert the steel cup on the indicator bar (open end pointing towards the exterior of the tube)
Insert the felt brake on the indicator bar and into the cup.
You can make that part yourself from a felt sticker used for chair feet. (3mm thickness – 10mm dia.)
The felt washer is used as a constraint to avoid the indicator bar to return to its rest position after measuring the tire pressure.
In some original gages, there are also two little springs (1 turn of about 8mm inside dia) placed symmetrically (spring ends in opposite directions) on each side of the felt and also used as a constraint for the indicator bar.
I’ve not found necessary to place these springs as the compressed felt is strong enough .

Insert the closure (brass) on the indicator bar.

Insert the assembly into the tube.

Insert the Tru-Flate plunger assembly in the tube, rubber pointing outwards.
If you decide to reuse the original brass plunger, you need to make a rubber washer of 13mm ext.dia with a centered hole of 2.8-3mm dia 0.5mm thickness.
Carefully remove the plunger ring with a screw driver (used as a pry - step by step around the ring until it can be removed. Insert the gasket ring and tighten the brass ring.
Insert the plunger with the tip pointing towards the indicator bar. The plunger fits exactly inside the spring.



Finally, screw the tube on the other brass part.

Test you device with another pressure gage.
If the pressure readings are lower than with a standard gage, you could unscrew the adjusting screw at the bottom of the indicator bar.

With the original spring, my refurbished gage was giving the correct pressure w/o the need to readjust the screw.

Have fun with the restoration of that very expensive vintage gage.

Here is another beautiful vintage Schrader gage made under license in the UK, likely after WWII.
That tire pressure gage, stored in an original wooden box, looks brand new with a chromed body.
It was given to a young worker starting his career in a garage in the UK between 1945 and 1950.
(found recently on eBay)

A few parts can be ordered from the Tru-Flate catalogue shown below. (chucks, rubber washers, screws)