transmission oiling and cooling, Once again, my approximation Options

[michel richard]

I will be putting significant power through my 901 transmission, with the new engine I am having built (2.5 short stroke twin plug six) and I figured it might be beneficial and fun to build a cooling and oiling system for the tranny.
The factory did it on some racing cars, both 911 and 914. There are pictures on the thread below.

http://www.pbase.com/9146gt/porsche_gearbo...lubrication_kit

As usual, I don't want to go whole hog and through the trouble of sourcing factory parts, so I will machine a system to approximate what the factory did.

This is testing the limits of my abilities, though, and there is no guarantee that I will end up with a system that is good enough to install on my car.

Still, here it goes.

I was looking for a sportomatic oil pump, and Mark Garcia found one in his stash. He was kind enough to send it to me. Here's a thread with those details.

http://www.914world.com/bbs2/index.php?act=...&hl=sporto+pump

The next part I chose to tackle is the tranny drain. Here's what it's supposed to look like:

http://www.pbase.com/9146gt/image/39330791

After much thinking and experimenting, here's what I've come up with (the part is not completed, this is what I've done so far) :

[michel richard]

I managed to drill 70 holes, 1/16 inch diameter. The area is thus approximately the same as on a 1/2 inch hole. I suspect there's issues of dynamic flow that affect the equivalence (i.e. 64 small holes may not flow as much as 1 big hole, at certain fluid speeds) but this is what I will go with.
The oil lines are not going to be near 1/2 inch id in any event.
Here's a picture of the fitting, as it is now, from the inside.

[michel richard]

The threaded portion I made by removing the upper side plug on a spare tranny and machining it. I used the upper one, because there's no magnet in it and it was simpler.
Here's an end view.

I don't understand how the original part fit (it is visible in one of the links above). The portion with the strainer appears to be pretty long, and there's limited depth available at that spot inside the tranny. I'll post more pictures to illustrate that in the morning.

[michel richard]

Anyway, details to follow. Once again, I'm not sure this is going to work and I am posting as I make progress.
It's Saturday night, and my daughter asked if I would take her to the movies.
My priorities just shifted.

[ArtechnikA]

don't forget the Sporto pump transfers engine oil. also true in its later incarnation as a Turbo scavenge pump.

gear oil will have significantly higher viscosity. you gonna drive it from the camshaft?

[michel richard]

The intention is to use he sporto pump to drive the transmission oil, yes, and driven by the camshaft. I understand the factory did this.

To exit the drain fitting, I made a collar and modified a fitting that I had. The fitting is whole on the left and sawed off next to that. Then a collar I turned to make the parts fit (If I had thought this one through ahead of time, I would have made a smaller hole in the plug). Here are the parts.

[michel richard]

The parts, ready to be brazed.

[michel richard]

And then, brazed and cleaned.

[michel richard]

This is what it will look like from the inside of the tranny case.

[michel richard]

On to the next fitting. I got to work on the nozzle to spray oil on the pinion gear. First I did a quick assembly to see how the pinion and ring gears mesh. I want to be spraying oil right below the mesh point, on the ring gear:

[michel richard]

This let me figure out where to put a hole in the side cover. Once again, this requires some faith. I drilled the hole 1/2 inch because that's a tad larger thant the 12 mm thread I want to use on the fitting itself.

[michel richard]

And here's where the hole ends up on the inside of the cover:

[michel richard]

The webbing on the outside of the side cover makes it necessary to turn a fairly long fitting. The thread is 12 x 1.5 mm. I will braze or silver solder a small tube from the end of the fitting nearest the camera to reach the ring gear. Stay tuned. The part that goes into the side cover is a press fit.

[michel richard]

Here it is, pressed in. I cut the fitting a little short, unfortunately, but there's not a lot of torque on the end nut. I will use a capnut.

[michel richard]

And here's the progress so far.

[john rogers]

The system looks good so far. I started running a trans pump and cooler when we put in the higher revving six and I was told quite a few of the vintage 2L cars, both 911s and 914s have trans failures due to high heat and high RPMs. I used the "kit" that Jim Patrick sells and when the trans was out for refresh we added the spray nozzle over the R&P as you did and also one over the gear cluster. It was a bit tight to route the braided lines and AN fittings but they all fit. He also sells an aluminum bung that replaces the speedo drive so I hooked up a temp gauge and was surprised hot hot things got. I was going over 300 degrees in the Mexican road races where there was no long straights for extra cooling so I added an axial fan in the air supply line and temps stayed below 250 after that. I also switched the pump so I can let things start to warm up a little before I turn it on. For capacity, we are using just about a gallon of Swepco now.

[ArtechnikA]

QUOTE (michel richard @ Mar 26 2006, 09:43 PM)

The intention is to use he sporto pump to drive the transmission oil, yes, and driven by the camshaft. I understand the factory did this.

i could be wrong, but i don't think so,

they never really used a transmission cooler before the 915, which had one integral - first in the nose cone, later in the side cover.

the sporto oil pump is just for the torque convertor, which uses engine oil (common with the engine) rather than separate ATF like most torque convertor cars.

[michel richard]

QUOTE (ArtechnikA @ Mar 26 2006, 07:23 PM)

QUOTE (michel richard @ Mar 26 2006, 09:43 PM) The intention is to use he sporto pump to drive the transmission oil, yes, and driven by the camshaft.  I understand the factory did this. i could be wrong, but i don't think so, they never really used a transmission cooler before the 915, which had one integral - first in the nose cone, later in the side cover. the sporto oil pump is just for the torque convertor, which uses engine oil (common with the engine) rather than separate ATF like most torque convertor cars.

Not saying the "factory" did it on any production car. But there appear to be at least a few racing cars that were prepared by the factory and used a sportomatic pump as a recirculating pump for the transmission.

See this link, of a car that appears to have been restored to original condition:
http://www.pbase.com/9146gt/image/54417634

It may also have been done on a few 911s.

In any event, I agree that the different viscosity is something to keep in mind, thank you for bringing that up. Not sure how to figure out if it's something to worry about, though. Once again, it appears to have worked in at least a few cases.

[michel richard]

There will also be some oil injected into the tail housing of the transmission. I think the most important part here is to spray some oil onto the bearing for the input shaft, in the intermediate plate.
It's the ball bearings under the small gear in front of the picture:

[michel richard]

So I machined a small block of aluminum to support an oil squirter, drilled a hole through it and through the tail housing of the transmission for the squirter, as well as a couple of holes to run screws to tie everything together.
Here's the view down the hole for the squirter. It's not the clearest, but the best I could do.
The gear that can be made out is the first gear pinion on the input shaft.