MTFCA Forum

I just replaced a bad rubber stem on a model A tube with a new metal stem. My question is, do you need to put cement on the stem base ? I aired up the tube partially and did not see any bubbles around the washer. Was not sure how it would be with the proper air pressure.

it is not a good idea to use anything that might act as a lubricant when installing a metal valve stem, other than water which will dry off quickly. Modern tubes have no fabric reinforcement around the valve stem hole like the old time tubes had. If too much tension is applied when tightening the nuts on the bridge washer the tube rubber can be squished out if there is lubricant there to help it do so. On the old time tubes this could not happen due to the fabric reinforcement.
Just run the nut up tight enough to stop leaks, without applying too much crush on the tube.

Allan from down under.