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?

[pcar916]

Now in order of the questions.

I considered posting in the garage but thought this group more likely to have a higher ratio of oil coolers per car. I still might if questions linger.

1. I don't know where to drill to get the transaxle to pump itself enough to get the oil through a cooling system but that would be... cool.

2. Figuring out where to drill for fittings is always an interesting task. Often the best places have webbing there. so building up an epoxy boss is always a solution. I just don't like the eventual leak that will form there.

2. I'm sure the temps go much higher in summer but I wasn't tracking them then. I've noticed that on pix of existing systems my cooler is larger than most of them (15,000 BTU IIRC) so I may slow the pump down with a pulse-width controller if the cooling is too aggressive. I could use a thermostat but I like simple and once this is dialed in it'll likely be a transparent system outside of filter maintenance.

3. I've been using synthetic hypoid since 1998,.. no synchro problems and I'm sure my R&P's are happier with the synthetic EP package. The added detergents will get more of the particulates into the filter as well.

4. I'd really like to install a complete squirter system in both boxes, and started this project with that in mind. but most of the advantages are gotten by simply filtering and cooling the sump load. I really do like the cooling effect of the squirters but don't think the added BTU removal would be worth the increased aeration that would reduce the efficiency of the external cooler. I like cooling fluid better than foam. It carries more heat and won't cavitate the pump.

5. I haven't seen the inside of the factory 915's with the housing pump to know where the pickup (and maybe a screen) is either. That certainly is an elegant solution and the boss in the casting (for that pump) just sits there and taunts me... yeah.

6. I have the power steering pump that came on the 3.6 and thought about that too. But I don't know the specs of the pump and thought that, since it's job is to make really high pressure at a low flow rate, that the volume might be too low. I was gonna run it from a pulley mounted between the inboard CV and the output flange.

But the electrics give me control over the pump speed and I may be able to do my lube changes by reversing the pump if I put in a T-fitting between the pump outlet and the check valve. I wouldn't be able to do that with a diaphragm pump and I want to change out the filter element and lube from above the car.

OT: To the strength of the 915 over the 914 boxes... I'm not near my machines but the mainshaft of the 915 is slightly larger than the 914 but that's not the main reason I like 'em. I'm running 7:31 R&P's in both and that's a very stressed pair of gears. The 915 ring gear has a bigger diameter than the 914 and the pinion is larger as well. So there is more meat at the mesh surfaces to take the load as well as a slightly longer lever arm to the diff-axis. That said the 915 is definitely heavier.

I'm going to do as much as I can to make the 915 shift as sweetly as the 914. Just wish they had Borg Warner synchros without the extra weight of a G-50... but that's off topic in this thread!

[Richard Casto]

Continues to be a great thread! Keep posting people!

5. I haven't seen the inside of the factory 915's with the housing pump to know where the pickup (and maybe a screen) is either. That certainly is an elegant solution and the boss in the casting (for that pump) just sits there and taunts me... yeah.

I have not seen one in person, but the diagram in the factory manual shows that the pickup tube routes straight down from the pump with a slight bend forward at the bottom. The pickup point looks to be almost directly below 5th gear or the neighboring shaft bearings. There is no mention in the diagram about a screen. It could be that a screen is integrated into the tube, but just not mentioned in the diagram.

Richard