How much oil to run in an inverted Porsche 930?

Ron Earp

Admin
First off, who on the board is using a Porsche 930 in the inverted configuration? I'd just like a head count so that I might share information and learn a thing or two from you guys.

I'm running a 930 inverted in the Lola. Thus far things have been fine with it and it seems happy. It was rebuilt a couple of years ago and probably has less than 500 miles on it, mostly track miles.

I have asked around to a number of transaxle companies as to how much oil should be in a Porsche 930 box when it runs inverted. The answers have been all over the board - two gallons, four quarts, six quarts, and "fill it up til oil comes out of the half shaft seal". Clearly, all of these answers are not correct. According to a couple of sources I found a Porsche 930 box when run normally has a factory capacity of 3.7 quarts. But I have not found a definitive answer for an inverted box.

I don't really know how much oil is in mine at the moment but I think it is "too much". Mine seems to spit oil out the breather and catch can at speed until it throws enough out to be happy. I'm worried that "happy" might be low on oil. My breather is attached to a short metal tube that is above the gear section of the box. The setup I run does have a cooler and the feed for the pump/cooler is taken from the bottom of the diff area and it is returned in the side of the case in the differential/ring gear area.
 
Ron,

I've forgotten the level of oil I used - still looking for my notes and will advise you when I find them.

I do remember reading somewhere that Swepco 210 gear lube is recommended!

John
:thumbsup:
 
930 LSD, inverted mated to an LS engine. Looking for the same answers here too.
Pump, filter and cooler is ready to go. Similar set-up as yours Ron.
 
Ron,
Haven't filled mine yet but am about to. Engine and trans are ready to go in(again). When I was setting my cooler and pump up I noticed that it would take more than 4 liters. One jug of the 210 would not reach the pump for circulation. Now that doesnot include the cooler which will have to be brought into consideration. I am spraying the individual gears 2-4 and the ring and pinion. I will have to add a bit more. I would suspect that when mine sits after circulation, it will show a little higher with one or more spray head above the fluid level line. May have to fill and dirculate with the cooler below the final level line to get all the air out. May even have to put a one way valve inline. I have one but will have to see if it is needed.

Bill
 
Russ Nobles box is inverted.
Your 'breather fitting', any possibility that its directly in line with one of the gears and having oil thrown at it giving a false impression of over full.
Russ has spray bar & pump so might not have level info that suits splash feed setup.
 

flatchat(Chris)

Supporter
I run Castrol syntrax (synthetic) 75 / 90 of 4 Litres (~ 4 Quarts) --no coolers etc

I used this in the G50 (in a gt40) which I used to drive flat out in the rain with bald tyres in the dark :laugh: --just change the oil once a year --that gear box has out lasted 7 W302 POS
 
Seems to be confusion as to how much oil if the box is inverted.
If the oil comes up to a particular height on the lower gear set, would you not be filling back to that height their abouts on the now lower gear set that was the upper.


Jim
 

Ron Earp

Admin
Russ Nobles box is inverted.
Your 'breather fitting', any possibility that its directly in line with one of the gears and having oil thrown at it giving a false impression of over full.
.

Well of course there is, you know me!

I've thought about that too and I don't know the answer. The tube is pressed into the casing and I bet it doesn't have a baffle. But, I could certainly make one for it. I'll check and let you know.

I used this in the G50 (in a gt40) which I used to drive flat out in the rain with bald tyres in the dark :laugh: --just change the oil once a year --that gear box has out lasted 7 W302 POS

I'm a bit concerned with the comparisons with the G50 as they not quite the same are they? Flat out, that is how I drive, flat out.

Seems to be confusion as to how much oil if the box is inverted.
If the oil comes up to a particular height on the lower gear set, would you not be filling back to that height their abouts on the now lower gear set that was the upper.


Jim

I'd think that okay too. But not easily determined.
 

Russ Noble

GT40s Supporter
Lifetime Supporter
Ron,

I am running a heat exchanger in the bottom hose along with pump and filter and as Jac Mac noted a spray bar also.

Personally it is my view with a cooled trans that the amount of oil is not that critical unless it is grossly excessive, because when the trans is running the oil is raining, splashing and lubricating everywhere inside.

I decided to have my dynamic minimum oil level at the height of the top of the crown wheel teeth at the bottom of the c/w so the c/w was always running in an oil bath. I achieved this by having the pickup port for the pump set into the sideplate at that height. Thus the pump can never lower the level below this, even if there is an external oil leak. Coincidentally this level is probably not far off Jim C's thoughts of centreline input shaft. More details and photos in posts #155 and #162 in my build thread. http://www.gt40s.com/forum/gt40-build-logs/16138-kiwi-scratchbuilt-6.html

Dimi was good enough to establish for me, and post on here, that the difference in level between static and dynamic equated to approx one litre. G50 not 930 but result will be similar IMO. So I fill and bleed my entire system to the level of the pickup port and then add one litre.

There is hardly any work in fitting a spray bar so I figured I might as well return the oil that way through the rear of the trans. Conventional wisdom has it that a spray bar is largely redundant, but I figure it can't do any harm. That is unless it disintegrates and gets caught up in everything:furious: So far the only failure we have had documented of a 930 has been a 3rd gear fail. See http://www.gt40s.com/forum/gt40-tech-powertrain-transaxles/19746-930-failure-4.html . So I'll go with the spraybar on the theory that every little bit helps......

I will be pulling my trans in a couple of weeks to fit my custom ratios, so it will be interesting to see how everything has held up, particularly the syncros with the instantaneous 'rifle bolt' shifter which I am sure must beat the crap out of them. No ill effects so far though.....

Cheers,

Russ
 

Ron Earp

Admin
Thanks for all the replies. This is a great picture Russ:

attachment.php


So where is your fill hole level in relation to the side plate? On these trannies, how does the oil move from the R&P area back to the gear section? Is there a channel down there at the bottom? I think filling the tranny until "oil comes out of the stub axle seal hole" would be dead wrong. All the gears, everything, would be completely under oil.

So we really don't have a volume established yet that everyone agrees with but it is sounding like 4 quarts plus a bit for the cooler, correct? I can easily measure my cooler and lines to get that part right.

Russ - what sort of half shaft angle to you achieve at ride height?
 

Terry Oxandale

Skinny Man
Ron, I'm planning on using the inverted 930 as well per your original request.

Here is a photo of my application with a 5" ride height (square tubing), 26" tires (315/35R17), and a 4" bellhousing clearance (dry sumped motor).

standard.jpg
 
I will be pulling my trans in a couple of weeks to fit my custom ratios, so it will be interesting to see how everything has held up, particularly the syncros with the instantaneous 'rifle bolt' shifter which I am sure must beat the crap out of them. No ill effects so far though.....

I plan on pinching your shifter design for use with the 930 in the back of my GDT70, so I'll be very interested to see what you find. Fingers crossed.... :)
 
Gentlemen

I have had experience with oil loss from breather on my 911 track car - filled with the correct amount of oil - just over 3 litres. This is a little difficult to expalain and comprehend but it is related to the position where the tightned breather cap stops. If you look at the angle on the bottom of the breather it is possible (beleive me) to throw oil off the gears and straight into the breather (if the angled section is facing in the right place) and out of the gewrbox. If you get the angle perfect you can almost loose all of the oil. There is a reason why porsche says do not fill the gearbox from the breater hole. Have a good look at the breateher unit and you should be able to figure out what i am saying. Breather needs to face away from where gears are throwing oil, that is why the angle is on the bottom of breateher stem - get it wrong and you will have a problem.

In relation to the amount of oil, following Dimmi's plan which is logical = 5 litres - due to shape of casing on inverted box you need more oil. The gears need to be emersed in enough oil to throw / lubricate the contents of box. To much will result in power loss only, to little - i dont need to tell you. Porsche used spray bar and cooler in cars of this era to run less oil - picked up thoeretical 5 horsepower.

Regards
Jason
 

Russ Noble

GT40s Supporter
Lifetime Supporter
So where is your fill hole level in relation to the side plate?

If you look at my build log, post #162 photos, there are two ports on the sideplate. The lower is the scavenge to the pump, upper is the return from the filter housing oil relief. The oil level is approx midpoint between.


On these trannies, how does the oil move from the R&P area back to the gear section? Is there a channel down there at the bottom?

There is a hole about an inch square cast into the very bottom of the case (top in Porsche orientation) that will allow free movement of oil between diff and g/box

Russ - what sort of half shaft angle to you achieve at ride height?

Half shafts are off my car at present as the trans is about to come out so I can convert to close ratio. But if you look at my build log, post #483, you will see the angles. Ride height under the rear chassis is 4" but my engine/trans is set relatively low in the chassis and clearance under the Porsche bellhousing is 2½" at ride height.

Hope that helps.

Cheers,

Russ
 

Dimi Terleckyj

Lifetime Supporter
Hi Ron and others

I think the easiest way to solve this dilemma is to use a standard 930 transaxle in the original orientation and fit a hosetail to the drain plug, connect a clear hose to that and have the other end up higher that the top of the transaxle and leave it open to the air.

Fill the transaxle with the correct amount of oil as per Porsche specs and see where the level comes up to in the tube and mark this level on the side of the case.

This will show how deep the gears and shafts are immersed in the oil at the Porsche specified amount.

When the transaxle is inverted use the same method but with the breather hole (which is now the drain hole when inverted) and this will give you the level with the Porsche specified amount of oil and can be compared to how much of the inverted shafts and gears are immersed and allow a decision to be made as to how much more oil needs to be added to allow the gears to be immersed to the required depth as per the original orientation and specified amount.

I hope this is clear.

This is the design behind the addition of the same tube I have fitted to my 40 with the G50 on a permanent basis. (pictures are in my build thread).

Dimi
 

Ron Earp

Admin
A bit more info for you 930 gurus.

I drained the oil out of the tranny and it looks like it had between 4.7 - 5.7 quarts in it. A little mishap with oil spillage is the reason for the range. Anyhow, the "drain" is in the bottom of the diff housing so the lowest point in on the tranny. Given the fact it has a cooler on it, pump, and some lines I'd figure 5 qts is about right. Porsche essentially calls for one gallon in the normal configuration.

My vent is located on this little tube that is under the black vent hose that I've shown in the picture. Anyone know what is under that little tube inside the tranny? I think I'm going to make a new vent like Russ suggested in another thread using that plate on to the left of my vent in the picture. What is that little plate?

Ron
 

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Terry Oxandale

Skinny Man
If you're writing about the one with the three little rounded nubs, that's the fulcrum plate, which allows the internal shifting mechanism and rods to operate properly.
 

Ron Earp

Admin
I think the easiest way to solve this dilemma is to use a standard 930 transaxle in the original orientation and fit a hosetail to the drain plug, connect a clear hose to that and have the other end up higher that the top of the transaxle and leave it open to the air.

And that is happening this evening. You'd think all these companies that work with 930s for "our" applications would have the value needed, but they don't.

How high up on the side of the transaxle do I need to hit? Enough to submerge the lower shaft, or do I need to submerge both shafts?

R
 
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