Transaxle oil cooler pumps Options

[pcar916]

How many of you are using gear pumps instead of diaphragm types and what filter element (micron) sizes are you using?

[john rogers]

Well the R&P question pops up again as I suspected. In the 20+ years I worked in the Navy as a Nuclear machinist, I baby sat quite a few gear stacks, the largest was on the USS Enterprise (64,000 HP) and the smallest was on an old FRAM WW2 destroyer. Anyways, in all those cases the oil supply squirted right into the gear mesh and provided three basic things: shock absorbing ability, cooling and lubricating the metal surface. We want the same thing in these 40+ year old designed transmissions and the R&P is the weak point. When the oil come into the contact area, any excess is squeezed out the sides of the mesh and some sneaks into the clearance at the bottom of the teeth engagement area. In the 10 years I vintage raced, there were 4 or 5 R&P failures/seizes until all the high RPM 911s and 914s started running pump and cooler setups. This made a 901 last 3 and possibly 4 years with a 2L engine and 2 years with a 3.3L engine before a rebuild would be necessary. Funny thing about the failure was most times the car would be making a grinding noise and once back into the pits and cooled off, it would not move!!