Porsche transmission oil coolers

[Paul Thompson 'Hooligan']

Hi Lynn -

Resevoir for the oil seems a cool (no pun intended) idea however I'm a bit confused re your description of how the gears work.

If you invert the transaxle, would'nt you normally get one forward and five reverse ratios?. Which you avoid by also flipping the diffeerential over too within the box. I cannot see that the mesh of the pinion is reversed... [img]/ubbthreads/images/graemlins/confused.gif[/img]

I would think that a sprayed system is also a good idea as the standard oil level will be incorrect for the gears/shafts once the box is inverted..

IMHO!! - I am no expert (or am I thinking ZF? - maybe Porsche is different)

[Lynn]

Paul,

Now I am confused. We flip the transaxle upside down (inverted) and this would give a Porsche with the engine in the rear 5 reverse and 1 forard gear. Then we rotate it 180° around the Y axis so that the engine is in front of the axle (wrt the car), so now it once again has 5 forward and 1 reverse. As I sit in my chair whirling my fingers, hoping the neighboors aren't watching as I spin my chair around and then turn upside down, it dawns on me that the direction the internals of the transaxle have not changed direction through out this exercise. I suppose I was thinking along the lines of the Corvair where the engine does indeed turn the other way round and when used in the midengine position the gears are indeed turning opposite of their normal direction. There are other cases where the engine rotates in the opposite direction of the engine in a normally rear engined car and then the new setup is used as a midengine drive train. So the Ford V8 and the Porsche 911 engines must rotate in the same direction, since my car goes in the right direction :-)

Anyone who is less spatially challanged than I am want to comment?

As to the oil level, if you were to continue to use the original oil level plug, yes that would not be right as you would have way too much oil in the thing. I have been told that the oil level needs to be at or, better, just below the shaft centerline of the lower shaft. This provides an adequate quantity of oil and the ability of the gears to sling that oil in their normal way of lubricating the system. The spraybar oiling system is not needed to insure oil is on the gears, but to provide an adequate flow of oil on the gears to remove excess heat build up from hard core usage, like all out racing in anger for extended period of time.

Regards,
Lynn

[Bill Bayard]

Eric,

Keep in mind that the photos of the G50 from PH2, show

an oil port in the rear cover (doughnut style). I'm not

sure about your car, but the newer style cover will NOT fit

in my car. Be sure to ask Roger Brown if this setup will

work for the 1987 and older rear cover, before you jump in

with both feet!

Paul,

The G50 is reversed (180 deg) and flipped (180 deg),

hence five forward and one reverse gear. Think about it's

orientation in a Porsche, then "do the math".


Bill

[Gary Gibbs]

Another way to think about the flip is to take the trans from the Porsche and flip it over forwards about the drive wheels. You will then go from a rear engine to a mid engine without the other flips and still have 5 fwd and 1 rev.

[Eric]

Hey Bill, I am actually using the 993 6spd. I took the measurements that you gave me and in the end, after milling off the doughnut, it looks like i will easily fit. Keep in mind, i moved the engine extrememly far forward,(no distributer will fit, going to use coil near plug type ignition and have the short pulley setup from the 95 mustang) and I am not using the thick adapter plate that most people use, in fact, no adapter plate at all.The only thing i am worried about is the shifter, I think i need to modify it all somehow so that the shifter sticks out the side instead. This is how the 996 box is and apparently the boxes are allmost identical internally so it must be posssible.

[Bill Bayard]

Gary,

Now you have ME confused! [img]/ubbthreads/images/graemlins/confused.gif[/img] [img]/ubbthreads/images/graemlins/wink.gif[/img]

Eric,

I recently drilled two EFI return line holes in my fuel
tanks. To avoid particles getting into the tanks, I greased the drill bit, and used a bent, grease filled serving spoon stuck through the sending unit hole, to keep any filings from falling into the tank. When held in contact with the underside of the new hole location, the spoon caught everything coming from the hole and bit. A greased finger cleaned up anything stuck to the underside of the hole, and a clean rag took care of any grease residue. Perhaps this method would work for you, when drilling your gearbox case. I was little reluctant to use a Shop Vac on my tanks, being so near fuel vapors! Imagine that! [img]/ubbthreads/images/graemlins/shocked.gif[/img]

I'm glad to hear that the doughnut(less) cover will fit!
How far forward did you move the engine, and how much clearance do you now have at the rear?

If you could, please post some photos when you get the 996 box glued together in your car. I'd be very interested to see how you accomplish the shifter mechanism. Best of luck!


Bill

[Paul Thompson 'Hooligan']

Thanks Guys

It all becomes clear now (I think) - I had'nt thought it through - considering the Porsche Engine/Gearbox lay out to be similar to a 40, but obviously it is not. I have in my mind always considered a 40 to be rear engined but in comparison to a Porsche - I suppose it is in fact Mid engined. -

My mistake, although I still cannot get my head around the forces on the gears being reversed [img]/ubbthreads/images/graemlins/confused.gif[/img]

[Eric]

Lynn was thinking about the old corvair transaxle (engine turns counterclockwise). With the porsche, the engine still turns clockwise the same as the ford so the gears are actually loaded up the way they are supposed to be. Invertiing the tranny only changes what side the pinion gear mates to the ring gear, but it still loads it up the exact same, as the motor is still turning the same direction.

[Lynn]

Yeah, what he said [img]/ubbthreads/images/graemlins/grin.gif[/img] - Lynn

[Des]

Hi Eric
Do you have dimensions for your box handy,
ie overall length, engine face to axle centres.
I am trying to decide on box I will use.
Regards Des

[Eric]

Bill, I cant remember how far forward it is, but if i remember right, i went forwarde about 1.5"-2" compared to yours. I am not 100% sure on the clearance yet as the body is not fitted, but given the dimensions you gave me earlier, i should be almost exactly the same as you. It looks like i will need to ditch the waterpump though, not sure, but it looks like it will be in the cab quite a bit, even though i am using the short pulley setup.
Des
I cant give you exact measurements if that is what you need as the box is all in peices and the bellhousing is on my milling machine right now. And that is stalled due to the fact i stuck my finger into the rotating end mill (dont ask, but it hurts). I can measure all the peices and give you a guess but if you are in no hurry, wait a month and i can give you exactly what you want. Or see this thread for starters http://www.gt40s.com/ubbthreads/show...true#Post31491
It is the 5speed but i think the stuff like axle width and engine face to axle centers is the same, (except i dont use an adapter plate) let me know.

[Lynn]

Des,

Here are the measurement I took off of a G50/50 ('89 911 Turbo)

[*]Overall length with shifter extended to its max 28 5/16" [*]Overall to max of case (includes cones for shafts)26 3/4" [*]Front to flat surface of nose cover 25 1/2 " [*]Front to Diff/gerbox case split 14" [*]Front to gearbox/nose piece split 22 14" [*]Front to CV Flange Center 8 5/8"[*]Front to rear of Bell Housing 3 3/8"[*]Nose piece overall (as above w/ shifter) 6 1/16" [*]Nose piece overall (as above w/ cones) 4 1/2" [*]Nose piece overall (as above to flat) 3 1/4" [/list]

[Tim Kay]

[ QUOTE ]
As I sit in my chair whirling my fingers, hoping the neighboors aren't watching as I spin my chair around and then turn upside down, it dawns on me that the direction the internals of the transaxle have not changed direction through out this exercise.

[/ QUOTE ]
Lynn,

Hate to "beat a dead horse" but I now am sitting hear doing the rotating chair and finger exercise to only to get a head rush and confuse myself [img]/ubbthreads/images/graemlins/crazy.gif[/img]

Question is: when “inverting” the G50, i.e. the trans case now upside down and in the mid-engine position, is it then necessary to flop the ring & pinion to the other side?

In this question “inverting” defined as simply flipping the tranny from rear-engine to mid-engine configuration with the output shaft\cv’s above the input shaft instead of below. Leaving the internals untouched.

In my pathetic mind, even though the trans is upside down the input shaft remains turning clockwise whether standard or inverted wherein axle rotation remains the same, no internal changes necessary.

Tim

[Lynn]

LOL, and I can since I have been there and done that. Here is my G50 mounted to the SBF. I have overlain an X, Y and Z axis to give us a frame of reference. So this is in the inverted position and has 5 speeds forward and 1 speed in reverse. Now lets take it back to its "normal" Porsche position. First lets flip it 180º about the X axis. It still in mid engine position, but we have just made it run with 5 speeds in reverse and 1 speed foward, right? Do the twirly finger thing :-). Now if we flip it 180º about the Y axis, it is sitting in the normal Porsch position and again has 5 spds forward and 1 in reverse. Now if we had left it in the second position,it would have been upright with respect to the way it runs in a Porsche, with the input shaft above the half shafts, BUT to make it have 5 speeds the right way, we could flip the ring gear in the diff to accomplish in another way than flipping the whole box.

Does this help?

Lynn

[Tim Kay]

Lynn,

Thank you, I can stop spinning now [img]/ubbthreads/images/graemlins/grin.gif[/img]

A picture is a 1000 words [img]/ubbthreads/images/graemlins/wink.gif[/img]