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

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

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.

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

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

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

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!

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,

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.

Click to view attachment

Click to view attachment

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.

Continues to be a great thread! Keep posting people!


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

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

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.

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.

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

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.

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.

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.

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

Now there's some empirical data. John, what was the lash on those big R&P's and what was the diameter of the rings?

I just had my first R&P failure in the past 16 years and it was while I was pouring on the coals 120 miles from home. It acted strangely as well because up to 38 mph (GPS) it was completely quiet. Above that was very noisy. There were two broken pinion teeth adjacent to each other.

The regular noise variation told me the mesh area was moving as the speed went up, so perhaps the R&P got spread apart briefly by a broken tooth and the case got tweaked. When I put together another gear stack the diff carrier wouldn't preload with the same spacer/shim package.

I've cleaned up another case for the rebuild because although I don't see any cracks, Like you said John, I don't want to see this anymore, so the oiling system is required as far as I'm concerned. I'm convinced if I had one already this might not have happened.

Good question about the oiling of gear assemblies and it applies to both a ship's reduction gears and our transmissions. In our case we start out with the splash lubrication only and by adding the squirters we increase the "splash" of oil on the most important areas, namely the R&P and gears. A side benefit is the cooling and when I was racing, I found that when trans temps got over 240 or so that shifting would get harder and harder, even with Swepco oil. The cooler kept the temps below 210 even when racing in Tecate MX in August. The bearings we have are sloppy when compared to the ones in a Navy reduction gears and in those cases the oil is pressure fed to the bearing and also splashed on the mesh area so everything gets it's share of oil.

The clearances of the R&P can change due to the flex of the side plate and I remember seeing several transmissions that had an aftermarket one that was much stiffer but I am not sure if they are still available any longer?

Aftermarket (billet) side plates are available for the 915 but I don't remember seeing any for 914 boxes. I'm going to put on a late 915 side-plate on the early mag case diff section because it is truly stiffer with both extra webbing and made of aluminum instead of mag, but the early mag covers are just a slab.

I don't know if the billet side covers are worth the extra money for only 300hp and the associated torque. But I might want one when this engine gets tired and I tweak it a bit. I'm thinkin' 400 hp sounds nice "and will suffice" for at least an hour or two before I want more. I'm fortunate to have some extra cases (and stuff) lying about to build with so I can experiment... just need more time right?

Well, for various HP ratings, Black Forest in San Diego and their race mechanic and at two other shops used this rule of thumb:

100 to 140 HP just keep the bushings and parts tight.

140 to 220 HP use a cooler and you could get 2 years of racing if you were careful.

220 to 300 HP use a cooler and rebuild at the end of the year for sure or sooner. Note a 915 can be used but over an average of 10 years of racing the total cost is nearly the same.

300 HP and up use a Turbo transmission especially if over 350 HP with a lube system. The 914 Bonneville car that had 850 HP used a Turbo 4 speed and cooler setup and never had transmission issues although it kept spinning out when the NO2 was cut in at 185 MPH or so!

Well I'm out of the envelope by those guidelines and should have used a cooler since 1994! But after an upcoming hp upgrade on this 993 engine I do think about an inverted short-bellhousing G-50 since it bolts right up, and suck up the large axle/cv angle and the associated hp loss. But it's SO darned heavy and I have these others lying about that I already own. Regardless, I'll always have a cooler/filter system from this point on.

The 930 box is probably a smarter thing, it's just those four gears, marginal torque and technical tracks that worries me. But I suppose first gear is irrelevant anyway.

Haven't compared the two latter options but this is approaching OT for this thread. I haven't searched for the G-50/930 specific topic. On the cooler topic again...

I'll post pix of my cooler installation when I get it installed just to tidy up a bit.

The Tilton folks like to mount the pump after the cooler to keep the temps down in the pump-motor below 150F. Anyone experience priming problems using that configuration (with a check valve)? I'll be mounting my cooler with the fittings on top to keep the cooler circuit oil from going into the sump while turned off.

Thanks for all the thoughts in this thread! I've changed my design because of them.

The location of the pump will make a difference. Gear drive pumps, like these: http://www.rbracing-rsr.com/oilsystems.htm need a gravity feed- they won't "pull" oil if the pump is located above the lowest point of the oil feed. The tildon style can be mounted above the trans if needed.

I switched from the tildon style to the RB gear pump for the scavenge pump on the turbo 914. Don't know if the tildon was bad or not, but liked the idea of the smaller and more powerful gear drive to be SURE there was no oil backing up into the turbo, as with the low mount of the turbo, there is no roof for a sump.

Just something to think about in the trans application.

Now that's interesting. I thought all external-gear pd pumps were self priming (by definition) up to varying heights depending on the pump design. My check valve on the pump outlet will keep oil in the circuit anyway unless it leaks down but by this example since I'm pulling the oil out of the drain plug, I'd have to install the pump down at that level. Am I understanding you right?

You are correct about the "gear" pump and they are all what we used to call positive displacement and as such as self priming. Some may have such loose clearances that they require priming to get started and they are done that way so they will not seize if the fluid is too cold or thick. One thing I found handy with the Tilton installed in the trunk was to empty the transmission I could disconnect the line at the outlet of the pump, run it through a line to a clean container. We would then filter the trans fluid and once the transmission was back in the car, use a suction line from the container through the filter back into the transmission. NO spills, puddles, etc and very handy.

How often did you filter the fluid?
Did you also have an inline filter?
If you ran a torque biased diff rather than the LSD clutches would you filter less often?

I'm definitely looking forward to not crawling under the car to drain and fill the system after I've arrived at the proper fluid level.

In the pictures I posted there is a bright red filter near the pump and it is a disk type that can be disassembled and cleaned as needed such as when a trans fails. That is the way Patrick set it up and the continuous filter may help prolong the internals life. One thing we did do was to look at the fluid with a very bright light for any microscopic "gold" which was an indication of a possible bearing failure.

I generally changed transmissions a couple times a year, short gear box (K-Q-V)for PIR, Button Willow and all the Mexico road races and long box (M-S-X) for Willow Springs and CA Speedway. This gave me a chance to check the fluid quite a lot.

I thought I'd follow up with a summary of the approximate cooling system costs. This assumes you don't have any of this stuff lying about and that , instead of a diaphragm pump, you choose a mid-range gear pump with a catch can etc.

Pricing for hose fittings from Racer Wholesale Parts:
1. Cooler $ 90
2. Fan $ 70
3. Pump $275
4. Filter $ 75
5. Chk valve (1.2lb) $ 40
6. Fittings (-8AN) $308 (mandrel-bent except the vent system)
7. Hose (-8) $ 70
8. Catch can $ 70 (unless you make your own... I did)
9. Controller $ 30

Roughed out it'll be: $ 1,028

Someone out there is going to do this. For some reason I just can't get any new system into Penelope without spending $1,000.

Did you give Patrick in Phoenix a call although the price may be higher now as I did mine a long time ago. I would imagine that the cost is 25% or more higher now now matter where you buy the stuff.

You can do some saving by installing in sections, I.E. pump, lines and nozzles first. The do the filter and cooler and it's ducting. Not sure what the "controller" is as I just wired mine to a switch and once I started rolling turned it on. I had a big blue light over it so I would see it and it was powered to run even if the engine was off. The pump can easily handle the cold Swepco so no worries. For a fan I used a small plastic housed axial boat bilge vent fan I bought at West Marine and they sell them on line. I ran when the pump did. Make sure to have a drain on the puke tank and some sort of filtered vent as race organizations want that type of setup. Remember you'll be running 4 qts of fluid instead of 3 so some will splash into the puke tank. Finally I don't think a check valve is needed as it all drains into the trans anyways so that will save a bit of $$$$ too.

But I have to say that after the setup, I never had a trans failure so it was worth it I think!

I didn't give Patrick a call because I already have a lot of this stuff around now that I've been stockpiling over the last year or so. I'll just have to buy a little more hose, some more hose fittings and a few adapters. Then fab up the catch can and fittings for that circuit.

The controller is a pulse-width unit. Simple, reliable, and I don't have to throw off as much heat as a rheostat would. I figured I'd wire it in so that if I get too much cooling (return oil <160F) I can simply slow down the pump speed rather than break open the cooler ducting to blank-off some of it. If I always run the pump at full-bore I'll install a switch and use the controller for something else, like pushing the cockpit heat from my front oil cooler in the winter time. I use a 4 in bilge fan on my front heater system too. Good value that.

I am going to install the pump motor in moving air as it doesn't have it's own fan. Whether that turns out to be in the wheel well or upstream of the cooler fan housing I don't know yet. The specs on the pump read that it's top operating temp should be 150F.

Since the oil going through it will be hotter than that, there will be heat conducted from the pump housing into at least the output bearing and the lower half of the motor. Maybe that's overkill but I'm starting with a clean slate so it's easy to avoid that potential problem.

The reason for the valve was to avoid letting the pump lose it's prime. Even though it's self priming it makes me feel better. As to the extra oil, I thought it would be a potential leakage problem (i.e. output flange seals) if a lot of oil went back into the case.

Generally those pumps can handle the gear oil temps we have with no issues. The extra quart of oil will not cause any leaks unless the input shaft seal is worn a lot and/or you park on a very steep downhill grade all the time. I never experienced any leaks or weeps during the years the system was installed. I would not worry about getting the temp too low unless you are racing in snow as the exhaust will keep everything back there toasty warm!

Patrick does sell a couple of handy transmission related items, one is an aluminum adapter that replaces the speedo drive and has a VDO sender matched to a temp guage. Another is an hi temp reversing wheel for the clutch cable which will never get soft or wear out. I used both items and they were very handy. I did have one of the factory wheels get smoochy in a race in Mexico and the cable came off and scared the hell out me as I thought I'd broke a trans or clutch!

Funny you should mention the grade. My driveway is extremely steep. But the input seal has never given me a problem.

That exhaust is always an issue. It's so close to my oil return hose that I'm sure I get a significant engine-oil heat jump. I put in an additional cooler (sandwich adapter) at the oil filter console behind number six.

I turned an aluminum, double o-ring plug to block off the speedo drive hole and considered putting a temp sender in it. But I though it might not give me the temp I really wanted which was in the R&P or main gear chambers. You think it would be close enough? It's an elegant place for one and easy to drill and tap.

The temp setup Patrick sells uses the speedo hole. It seems the case transfers the heat pretty well and I have seen temps get to close to 300 degrees and that is when you have to be very careful with shifting as it gets harder.

Thanks for the bill of materials!

What is the breakdown of the $308 and do you have any PICTURES of something similar?

It always blows me away what it takes in materials to put together racing stuff.

Here's a pic below, but some of the fittings, the Spal fan, and a catch-can and it's breather aren't shown. The breakdown is roughly this.

Hose fittings, hose, and adapters:
- 6 -8 mandrel-bent 90's
- 8 or 10 straight's
- 8 -8 adapters to 3/8 NPT
- 1 8 ft section of -8 hose
- 2 -6 straights
- 2 -6 mandrel-bent 90's
- 2 -6 adapters to 1/4 NPT

I'll probably add a couple of -8AN couplers since I found some other fittings I already have out there and the filter housing is already -8AN.

Notice that there is a -8 to 3/8NPT adapter fitted into the drain plug, which means there isn't a magnet in this system unless I want to attach one or two to the filter housing. I'm relying on the oil to carry the crud into the filter element. But I might also epoxy some strong neodymium magnets onto the case as well.

Everyone's gonna route their systems differently and the equipment will be different, so I wouldn't put to much stock in this list since it'll be specifically my install, but you're right. It's expensive, but it saves gearboxes.
Good luck.

Click to view attachment

Hey Pcar916,

I see that you have been working over the whole issue of trans cooling very diligently, but am left with ONE basic question: do you have empirical DATA so you KNOW your trans oil temp will run TOO HOT and that you MUST have an oil cooling system?

You could find, as I did, that all that extra hardware is just NOT necessary.

Best,
Terry

I'm planning on installing a trans cooler in my 1.8L race car if I ever resume racing at the National level.
I have no empirical data on which to base my decision - only experience.
What I do know is that shifting becomes more difficult the longer I'm on track.
To me, the most logical cause is transmission temperature.

I MUST. As I put in an earlier post temps on the track can never be less than 210 because that's the temp measured on the street in the early summer in relatively cool weather (for here). It's never going to be lower than that at the track but will certainly be higher, especially in the late summer. It's true I haven't measured it on the track, but this transaxle will never see hp and torque lower than this 3.6L delivers.

Since I'm building a filtration system anyway the extra cost is for a cooler, fan and the associated hose and fittings. I'm willing to go there knowing I'm squirting cooler oil on my R&P. I like 180-200 for an operating temp. If I could get the return oil to the 150 you see in your machine I'd be delighted. How are you measuring it?

Now, if I lived in Alaska we probably wouldn't be having this conversation...

Hey Racer Chris,

I'm running a 930 behind a 383 Chevy and simply installed a VDO sender in the bottom of the trans with the gauge in the dash. I started out with a trans cooler driven off the 1/2 shaft flange and after running Streets of Willow Springs
in 100+ abient got oil temps of 150F. So I removed all the hardware and found the oil temps only went up to 175F.

I DON'T NEED NO STINKIN' TRANS COOLER!

Best of luck,
Terry

OK so what makes it shift harder is the higher oil temperature which cause metal to expand. Wonder if there is a rule of thumb for how much machined metal (like gears/shafts) expands for each XX degrees of temperature increase?

It would be hard to believe that the transmission fluid is breaking down, providing less lubricantion, resulting in harder shifting.

Why is that ( oil breakdown) hard to believe? Run your motor 50 deg over temp see what happens. At the only track day I ever ran (5 30 minute sessions-2 drivers), I could not believe how hot my trans got. I made the mistake of touching it......yowza!....that's enuff of that shit.

I guess because companies like SWEPCO have been around for some time, their products seem to work well and one would think they work well and have been tested at the highest temperature that could show up within a transmission. But then I don't have a clue on this one.

So is it the fluid losing capability or the metal expanding JP, or a combination of both?

Even if the gear oil isn't breaking down, it loses viscosity as the temperature climbs.
Also, expansion of the case may affect alignment of components.
So its probably a combination.
I wouldn't want the temp to exceed 220F anyway.

I'm with Chris on this.

Porsche's syncro system of brake bands would seem particularly sensitive to the lube thinning out. The brake band/slider is basically metal to metal less the oil film.
I've seen several brake bands worn flat on the outside.....slider & dog teeth don't live long under these circumstances. Normal wear becomes catastrophic. There would seem to be an ideal temperature range for these bits to work against each other. I also think that heat expansion has little effect on shifting, but gear to gear may be another story......then the different rates of expansion between the Mag case & the steel gears/shafts may well come into play. Of course, when the oil thins, the gears come closer together (less oil film) generating more heat, then I can see the thing cascade on you. Get the sumbitch hot enough and you have no film.......the ring & pinion begin shedding metal and loose their finish surface....more heat....well, you get the idea....

I've torn down a couple trans that had reached the metal shedding point on the R & P......into the recycle bin with those. The pinion shafts were heat discolored about 1/4 of the way up the shaft. Since those trans were from low powered cars, I think they were run out of lube.....thus the neglect.

For the temps question, I found with my trans temp gauge that until temps got to about 140 to 150 the trans seemed to be sluggish but then it was setup with tight clearances and ran a limited slip. Once temps got to over 275 or so the shifting got bulky and you had to shift slowly and very deliberate. This only happened at the street circuit races in Mexico where the straights were short and there was not enough time for some cooling and that is why I added an axial fan in the ducting line with a water mister from JC Whitney and Co that was actually meant to be an add on windshield washer reservoir and pump. The pump went to a garden mister and was switched with the fan and would drop trans temps by about 20 degrees when running which helped. The little bit of water lasted about 15 minutes which was sufficient for a sprint race. I was too old to do any of those enduros!!! The type of limited slip did not seem to make a difference as I used both a Guard and a "Q" which are different designs I think? I also had a pretty good shift setup with one of James' first Rennshifts and an aerospace coupler in place of the middle flex coupler.

It is the high RPM that gets the parts, especially the racing with high RPM motors and the revving with each shift, especially with engines that routinely rev to 8,000 RPM like my 2L six did. When I moved to a 2.8L six later on, the temps dropped slightly but only a little as the engine rarely went over 7,000 RPM. The HSR, VARA, HSR-West and other Porsche 2L class cars that bilders like Wayne Baker, Frank Beck and Jim Patriack on the west coast started using the pump and cooler setups after the 1st year and several transmission failures.Hope these ideas help some what?

The simplest plumb... in, out, and a vent to the catch can.

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Finally time for an update. I forced myself off of the road because two weeks of consecutive 100+ temperatures reminded me that I hadn't installed this cooling system into the car. Attached are photos of the installation. I'm running the wire for the temperature sending unit after lunch today but everything works with no leaks.

Total system capacity worked out to be 3.75 quarts.

I have a 7in. Spal fan in the engine lid above the pump to help move more air into that side of the engine compartment. If the cooler can't move enough heat out of the fluid in the right rear fender well, I'll cut a hole into the engine compartment next to the cooler and force air out over the cooler. But I suspect the cooler will shed enough heat for me not to worry about it... unless it starts to bake my paint!

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