One method transmission manufacturers use to deliver the automatic transmission fluid from the valve body to the band servo assemblies, or to flood transmission fluid on the critical lubrication areas are called “delivery tubes”. They are not used on every transmission though. In fact the most common way to transfer fluid is through pre-machined passage ways deep inside the transmission case. Either way, a transmission with delivery tubes has to have smooth and un-smashed tubes to deliver the fluid in the correct volume and amount.
Here is what a few of the delivery tubes out of a Borg Warner T-35 look like. You can also see the front pump seal and the rear extension housing seal too:
The top delivery tube is made out of steel instead of aluminum. The bottom two tubes are aluminum. The steel tubes were an upgrade over soft aluminum tubes. Upon rebuilding on of these transmissions, the delivery tubes have to be tapped into place, many aluminum tubes were dinged and distorted after the hammer was put to them upon reassembly. Eventually Borg Warner decided to address this issue and started to use steel as the material, thus eliminating flow problems caused by flattening the aluminum tubes upon installation.
The true test of whether a rebuilt transmission has properly flowing delivery tubes is to pre-test them on a dynomometer before the rebuilt transmission is sold. All of the transmissions we sell go through a flow test while it is in the pre test mode to insure the delivery tubes and all other components are working properly. Courtesy of GotTransmissions.com @ 866-320-1182.