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?

[stugray]

I was a little interested in this as well.
When inspecting the tranny case, I see a couple of places that make me wonder if there is a oil galley right under there.
One very flat spot on the top looks like it was designed to drill & tap.

Then I wondered if you could find two places (IN & OUT) that you could drill & tap and let the tranny do the pumping?

Maybe post on the garage or PM Dr Evil?

Stu

[Brett W]

Gear pumps are light years better than the diaphragm pumps. We have had issues with the diaphragm style pumps stripping out and the rubber deteriorating. I would like to try a gear style pump shortly.

On a gearbox you have to be careful about where you spray the oil. It is best to pick up through the drain plug and build a spray bar to spray on the backside of the gears after they mesh. You do not want to spray right into the gear meshing to avoid hydraulic pitting on the gear faces.

[Richard Casto]

I think this is an interesting topic as well. You can always look at how Porsche did it with the 915 as a starting point. If I remember correctly, it used a gear type pump housed in the end cover, driven off the input shaft and a spray bar in the racing versions. I don't know if the factory system used a screen/filter.

WEVO has their own solution for the 915 and it includes a particulate screen. Not sure of the details on that screen, but their solution uses a Weldon Racing pump. If you goto their website...

http://www.weldonracing.com

They list a 100 micron filter/screen for their oil pumps. Also they don't say exactly what their pump design is, but it says no plastic parts, so I am wondering if that means it is not diaphram based.

All of this is 915 related and I expect you would have to roll your own for a 901/911/914 transmission as I don't think there are many (any?) off the shelf solutions out there.

Richard

[stewteral]

How many of you are using gear pumps instead of diaphragm types and what filter element (micron) sizes are you using?

Hey pcar916,

From the photo on you Id field, I can see you have a Conversion car. Is it a V8 or something else?

My first question is: do you know you NEED a pump & oil cooler for the trans?

I'm running a 383 Chevy/930 package on-track at Willow Springs, CA where it gets very hot during the summer. I worried about trans oil temp and installed a BMW power steering pump (driven off the trans ouput flange) and a small oil cooler: Both were from eBay.

In running the car in the heat, I found that the trans oil temp would only get up to
125 deg F., while the water was at 220 & engine oil at 230! So I removed all the trans cooling hardware and found the oil temp only went up to 150 deg F.

NOT a PROBLEM! So what is your trans oil temp running?

Best,
Terry

[pcar916]

Gosh, I just typed in responses for the last 30 minutes and the battery went dead so they're gone. Thanks for the responses and I'll get back to this later today after tending to some urgent stuff. In short...

3.6L /w short-geared 914. I'm building up a 915 soon that will use the same cooling system.

1. Temps about 210 and higher in southern summers and aggressive hours through the Arkansas hills and on the track
2. Want to filter out particulates (Clutch LSD)
3. Increased fluid capacity (longer fluid life)

I think Weldon is a vaned pump. Very nice but more than I want to spend since a helical spur-gear will work just fine for $275 instead of nearly $600.

Weldon uses 100 micron, RBRacing uses 90. I've spoken to them and the Mocal 240 micron filter will be fine for a transaxle system. I'm not cooling turbocharger bearings here. More later...

[stewteral]

Gosh, I just typed in responses for the last 30 minutes and the battery went dead so they're gone. Thanks for the responses and I'll get back to this later today after tending to some urgent stuff. In short...

3.6L /w short-geared 914. I'm building up a 915 soon that will use the same cooling system.

1. Temps about 210 and higher in southern summers and aggressive hours through the Arkansas hills and on the track
2. Want to filter out particulates (Clutch LSD)
3. Increased fluid capacity (longer fluid life)

I think Weldon is a vaned pump. Very nice but more than I want to spend since a helical spur-gear will work just fine for $275 instead of nearly $600.

Weldon uses 100 micron, RBRacing uses 90. I've spoken to them and the Mocal 240 micron filter will be fine for a transaxle system. I'm not cooling turbocharger bearings here. More later...

Hey pcar916,

OK, then... you really know what's involved with your application! It seems that the oil temp is not the real issue, but keeping the oil clean is: Very Smart.

I went with a TORSEN diff in my 930 just to avoid the clutch plates in a limited slip diff. While the LSD is a better diff, those plates wear all the time and require radjusting & eplacement. I experienced this years ago with a Datsun 510 I raced with an LSD diff.

210 Deg in Southern Heat seems like NO Problem to me as conventional oil doesn't really start breaking down until above 250 Degand synthetics go much higher.

Since your goal is actually circulating and cleaning, may I suggest again the low-cost approach I used with the power steering pump? I think I paid $30 for it and $25 for the small oil cooler. Make your own "Aeroquip" lines and you're set!

Question: I have have heard a general belief that the 915 is not much, if any, stronger than the 901. Is this another erroneous "Legend?"

Best,
Terry

[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!

[Downunderman]

On my 2.7 I am using a sportomatic pump driven off the end of the right cam shaft. It sucks from the drain hole, then pumps through a spin on filter mounted to the side of the bell housing, into a manifold and from there lines go to spray the crownwheel and pinion, spray bar on the gear stack and pressure feed the input shaft bearing through the top of the intermediate plate. The car has a clutch type LSD.

The filter keeps the oil (Motul synthetic) really clean, and I recently cut the filter open after a few years compettion use and stretched out the paper. Very insructive, and not many big bits. The box runs at about 100C.

It was a lot of trouble to go to, buts its very reliable. If heat was just the issue I would just do the filter and cooler. Indeed, the filter is a must, when you see the crap it picks up.

Cheers,

[john rogers]

When I added the pump and cooler setup to the race car years ago, I used a complete setup from Jim Patrick in Phoenix AZ and while costing a bit more than working a bunch to find the parts, everything was in the box and it took a weekend to do the install. The longest part is pulling the trans, opening it up and then drill/tap for the spray nozzles on top, then cleaning everything and putting it back together. We used Earl's braided hose, AN fittings and ran one from the regular atmospheric vent to the puke tank so there would not be an vapors escaping which happens when you have an extra quart of fluid (4 instead of 3). The pump is a gear or positive displacement unit and worked fine and saved my transmissions for sure! I used a spare drain plug and tapped it for the suction and the filter was in the pump suction line but we never found anything after many many races. Here is a pict. of how it is installed in the rear trunk.

[pcar916]

Looks nice. Is the Tilton constant duty?

I talked to the Mocal people last week and apparently they've come out with a constant duty pump in this form-factor (dimensions are the same). It's not on their website yet but has been in development for the last 18 months. I'm in another state from my notes (no part number) but a call to them would be in order for anyone who wants a diaphragm pump. Sugg. retail $230. I couldn't get an idea of what they did to turn it into constant duty.

I also didn't like the idea of having to turn off the pump every two hours (Mocal recommendation) to cool down. I did like that the Tilton pumps have an internal check valve.

[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

[pcar916]

... and pressure feed the input shaft bearing through the top of the intermediate plate.

Hmmm, then a hole is drilled through even the bearing race or onto the spacer in front of the bearing?

[john rogers]

Most of the sprayers I saw installed had one nozzle right over top of the ring and pinion mesh position and at least one other right over the gear stack, better is to use two on the gear stack. As I mentioned, it is a very good idea to use a replacement for the case vent and run a line to the puke tank. This is because the trans will now need 4 quarts instead of 3 and on initial start off some will spatter out and even a few drops of Swepco really stinks and those corner workers will black flag you......

There were some posts years ago by a few "experts" who said never to spray the oil into the R/P mesh as it will cause the whole thing to seize but that has never been the case and all the vintage cars I raced with had a nozzle for this. The gear stack squirter(s) will also take care of the bearing that everyone worries about since it is such a loose and sloppy made bearing, having a dedicated oil supply servers little purpose. If it was a very tight and precision assembly, then yes it might.

[pcar916]

... never to spray the oil into the R/P mesh as it will cause the whole thing to seize

I forgot about the catch-can and you're right, I'll install one. Too bad my engine catch-can is too far away to Y into it, unless... hmmm.

I always understood the mesh squirter was a bad idea when injected into the pinch side rather than the opening side, and that the problem is that at high rpm (>6500) it forced the teeth apart putting stress on both the pinion and carrier bearings as well as the case. First I've heard about seizing.

[Richard Casto]

I always understood the mesh squirter was a bad idea when injected into the pinch side rather than the opening side, and that the problem is that at high rpm (>6500) it forced the teeth apart putting stress on both the pinion and carrier bearings as well as the case. First I've heard about seizing.

I have no empirical evidence to support, but I also agree that injecting directly into the pinch is probably not a good idea from a pure engineering point of view. Especially if the action of squirting it in, makes it hard for the gears to evacuate oil during the process of meshing.

However, I suspect it is probably a moot point because the area of actual gear mesh is pretty well hidden and hard to reach due to surrounding teeth and other components and I also suspect the pressure levels (from the squinter) are not high enough to cause problems. With that said, I probably still wouldn't aim directly for the mesh!

One thing to keep in mind is the direction of travel of the ring gear. The bottom is sitting in a bath of fluid and when car is moving in a forward direction, there is a short path between the bottom and the pinion gear. So it already should be pulling up a lot of oil into the mesh anyhow? Is any R&P sprayer really for the R&P or the neighboring bearings? Or if it is sprayed directly onto the R&P is it mostly for extra lubrication, or cooling (on the assumption at what is being sprayed is the return oil from the cooler)? I would love to see what it looks like inside a transmission at speed from an oil flow/lubrication perspective.

Richard

[pcar916]

I would love to see what it looks like inside a transmission at speed from an oil flow/lubrication perspective.
Richard

I would too. I've thought that nearly as important as the lubrication gain from squirters is the extra heat that the oil would carry away. That said it's not in as captive an area like the underneath of the pistons when the case-squirters are working properly, and it is into the sump rather than whisked off to a cooler immediately like in a dry-sump system.

About all we can do with this wet sump is to have a reasonable coolant flow-rate. The pump I just ordered from RB Racing will flow at 2.6 gpm, which should be enough without shooting it through the cooler too fast. As long as it's not below 180F I'll be a happy camper.

Now to try and find a surface mounted temp sender... It's more fun to over-engineer stuff in the winter.

[Downunderman]

The oil feed for the input shaft bearing is through a drilling in the intermediate plate which intersects with the groove in the outside of the bearing. I haven't chewed one out for a long time. I put that down to the oil feed, and more critically getting rid of the flipped gears out of the box with the attendant thrust reversal on selecting the flipped gear.

[john rogers]

Well the R&P question pops up again as I suspected. In the 20+ years I worked in the Navy as a Nuclear machinist, I baby sat quite a few gear stacks, the largest was on the USS Enterprise (64,000 HP) and the smallest was on an old FRAM WW2 destroyer. Anyways, in all those cases the oil supply squirted right into the gear mesh and provided three basic things: shock absorbing ability, cooling and lubricating the metal surface. We want the same thing in these 40+ year old designed transmissions and the R&P is the weak point. When the oil come into the contact area, any excess is squeezed out the sides of the mesh and some sneaks into the clearance at the bottom of the teeth engagement area. In the 10 years I vintage raced, there were 4 or 5 R&P failures/seizes until all the high RPM 911s and 914s started running pump and cooler setups. This made a 901 last 3 and possibly 4 years with a 2L engine and 2 years with a 3.3L engine before a rebuild would be necessary. Funny thing about the failure was most times the car would be making a grinding noise and once back into the pits and cooled off, it would not move!!

[Richard Casto]

Well the R&P question pops up again as I suspected. In the 20+ years I worked in the Navy as a Nuclear machinist, I baby sat quite a few gear stacks, the largest was on the USS Enterprise (64,000 HP) and the smallest was on an old FRAM WW2 destroyer. Anyways, in all those cases the oil supply squirted right into the gear mesh and provided three basic things: shock absorbing ability, cooling and lubricating the metal surface. We want the same thing in these 40+ year old designed transmissions and the R&P is the weak point. When the oil come into the contact area, any excess is squeezed out the sides of the mesh and some sneaks into the clearance at the bottom of the teeth engagement area. In the 10 years I vintage raced, there were 4 or 5 R&P failures/seizes until all the high RPM 911s and 914s started running pump and cooler setups. This made a 901 last 3 and possibly 4 years with a 2L engine and 2 years with a 3.3L engine before a rebuild would be necessary. Funny thing about the failure was most times the car would be making a grinding noise and once back into the pits and cooled off, it would not move!!

I suspect we are mostly on the same page. I am a big fan of empirical evidence, so if it worked for you and others, I am willing to listen. I do have an open mind. (IMG:style_emoticons/default/wink.gif)

Out of curiosity, I have some questions regarding your Navy experience as well as what you have done with your 914. It sounds like on the Navy solution included some planned shock absorption via the evacuation of oil from the mesh, but in general, I am thinking that this type of spray lubrication system is NOT trying to do the same thing as what we would see with a high pressure oil pump, oil galleries and ultimately hydrodynamic lubrication of bearings (oil under pressure acting as a wedge).

Rather, at least for our Porsche transmission, it relies upon a low/zero pressure splash lubrication system in a stock configuration and that the addition of a sprayer is just an enhancement of that concept? In short, the sprayer is providing additional volume at a targeted location, but at the same time NOT trying to accomplish this extra lubrication via "high pressure induced" hydro-static films (wedge via pressure)? So my question would be for both the Navy ships and in the 914, did the solutions rely more on relatively high volume, but low pressure, or lower volume and high pressure? And a related question is if the "spray" in either (Navy ship or 914) was a "stream" (such as a single jet) or a "spray" (such as a conical spray pattern)?

Richard