Any dry sump gear lube experts? (foam)

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Anyone have any experience with gear oil delivered via a shared oil pump to very heavy duty race gears via oil squirting from .092” orifices (5 or 6) at 100 psi gauge pressure? After doing the lube job the oil at the shared pump driven pick-up in the dry sump (bottom of the gear box) is pumped through a filter and through a cooler to the holding tank, and then the process starts over again.

The guy says the oil is foaming up……
 
How is the "shared oil pump" plumbed. Is the oil level the same after the oil change? Does the foaming go away after the lube oil reaches op temp. Is this a new oil. Can you find if the oil passes ASTM D-892 for resistance to foaming? Does the flow of oil go from the top to the bottom of the cooler to kill air pockets? Need more info.
 
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How is the "shared oil pump" plumbed. Is the oil level the same after the oil change? Does the foaming go away after the lube oil reaches op temp. Is this a new oil. Can you find if the oil passes ASTM D-892 for resistance to foaming? Does the flow of oil go from the top to the bottom of the cooler to kill air pockets? Need more info.




The dual pump shares a common shaft geared off the gear box itself. One side pumps the oil into the box, the other side pumps the oil out at the sump pick-up.

This is first time fill with new gear oil. Don't understand "after the change".

Didn't bring box up to operating temp. The oil was foaming right away.

Oil passes all antifoam testing with ZERO foam.

Don't know how the oil flows through the cooler.

Ask away - I can fill in details as I know them. THANKS!
 
Simplified: The oil travels through ¼” lines via a sump pump and pick-up, some type of filter, unknown cooler to a holding tank , then a delivery pump, proper octopus tubing, nozzles and onto the gears and back down to the pick-up.
 
Start by checking that cooler flow is cold in the bottom, hot out the top, that the pump is covered with oil and run it again.
 
pump or pressure adjustments needed for new oil??
dunno.gif
 
Bad batch of oil? It happens to some of the best at times.
Consider sending a sample or calling the tech dept. and checking on the batch.
 
It's possible that 100 psi is too high. But supposedly all the teams have this exact set up.

He told me all the teams use 75W-90, most use Royal Purple. I know their viscosity is higher at 100°C (out of spec for a 90), but viscosity simply is not the issue because it was foaming at ambient!!

I mean it could be a bad batch, but that's fairly remote.

Most likely there is something askew. I mean these guys are purely by the seat of the pants. Someone is going to get killed. The hull shape and strength was computer designed, but the mechanicals and this lube system seem to be just copy and borrow from the other teams. There is probably some critical detail left out.
 
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It's got to come down to wrong oil level, pressure way to high or something other basic problem like that.




That's where I was on Monday. I'm tired of calling him. Every time I do, he says "Who?"

Someone warned me about sponsorship.
 
I think Lonnie has hit most of the high points.

How are they viewing or know the oil in the gearbox is foaming? Through a glass, viewing port?? Where is the pump pressure being measured? Any pressure drops or pressure fluctuations found in the plumbing? Are they really seeing foaming or simply the flow of oil being turbulent?

The first thing I would look for is to make sure the oil level is sufficient to cover the pickup. If the oil is not covering the pickup, the pump is going to draw air into the lines/system and excessive foaming will result.

In my view, I would design the system with larger oil lines, larger cooler tubes, larger orifices, and lower oil pressures to accomodate a 50 weight oil.

Anytime you have pressurized oil squirting on a set of gears moving at high speeds you are going to have foaming. I would start an oil analysis to get a baseline and see if any wear metals are going higher over time rather than lower.
 
also, are they de-aerating the oil when it goes back to the catch tank ?
It needs at least a shelf, preferably a proper de-aerater designed into the tank otherwise it will be a self perpetuating problem.

Amsoil has been used for well over twenty years in open wheel dry-sump transaxles, (Ams and Neo were the recommended lubes in Reynard transaxles from the late eighties on in F3000 and Champ Car) funny a problem shows up now.
wink.gif
 
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