Jeff Curtis

I am currently building a G50 gearbox for my 964 that will incorporate a transmission cooler setup.

I have a Mocal fluid pump and a bunch of -10 (5/8" I.D.) Aeroquip hose and fittings gallore, and a small Mocal oil cooler that I plan to setup in the tail section of the car.

I have a few questions:

1) Is the -10 line too big for what I'm doing? ...if so, would you go 3/8" (-6)??

2) Where would you (or DID you, for that matter) pickup the fluid from and discharge to? ...I was originally thinking of picking up out of the differential/bellhousing section and discharging onto the main gearshaft, near 3rd/4th gear or further up in the box towards 2nd. I have been emailing back and forth with a PCA member who has a pair of 993s with transmission cooler setups and picks up the fluid in the mid-section and discharges where the ring and pinion mesh in the carrier/bellhousing section...the REVERSE of what I had in mind.

Either way seems like it would work, I've seen it both ways...what have YOU seen or how does YOUR setup work? ...any advice on the size of the lines/fittings?

I wound up with a bunch of new -10 line/fittings but am thinking that's too large for my application.

Geoffrey

Jeff, I think the first question you need to answer is how hot is you transmission getting. I have data from mine that it takes about 30 minutes in the summer to reach 200f which is where I have my pump turn on.

I think -10 is fine, I used -8 and would not go smaller than -8. My -8 allows enough volume that the pump cycles on and off as it keeps the temps at 200f, so I know it is sufficient.

I use the drain plug with a banjo fitting to pull the oil out, and I dump it on the differential because I think that is the hottest part of the trans. You could develop a spray bar mechanism to also get the gears, however, I think that as long as you keep the temps below 200, you have made major improvements in longevity.

I mounted the cooler next to the secondary oil cooler in the front, so it doesn't get fresh air, but dirty air from the discharge of the secondary cooler. I also used quick disconnect fittings to make removal easy.

Here are some pictures:

Larry Herman

Damn, Geoffrey - could your car be any cleaner? I mean, it's cleaner than your garage!

Sean F

drool

Jeff Curtis

Yeah, OMG that's one clean car, install, trick components - WOW!! ...I give up, SCREW this whole idea after seeing that!

Yup, we have the same pump, appears that your fittings for suction/discharge are smaller, maybe mine ARE -8?? ...I haven't seen the pump in a few weeks as I'm "remodeling" my garage and drywall mess everywhere, I'll dig it out tonight (everything is under plastic at the moment) and check it out. I see that you just drilled/tapped the case for the discharge, someone suggested that I do just that, so I guess that's what I'll do then!

How is it you cycle the pump at 200 deg? A temp plug you installed in the trans. that goes to a relay?

I like your quick fitting/banjo setup, real nice...where did you find the proper threaded components to utilize the drain plug? Also, what is the red item that says "Peterson" on it, next to the pump - a screen filter for particles?

OK, a few more questions: WHY wouldn't I want to suction from the drain plug area and discharge through the fill port in the mid-section? ...seems you have a possibility of sucking up what you discharge in by using just the carrier section, but that's just idiot logic working against me there, I imagine it gets so hot it's a non-issue with the slow speed of the fluid exchange.

Lastly, where did you source the fittings for the drain plug, the banjo setup...and what kind of hose are you using?? I was thinking the steel braided stuff but it gets cut up easily and hurts to handle it after it's been in use for awhile, so the cloth covered stuff looks to be the better choice - so where'd you source that as well??

Thanks for the great pics, after seeing that I'm going for a whole redesign of my idea - yeah, THANKS A LOT!!

Jeff Curtis

Ah, after reviewing the pics again, I see your temp. sensor and wiring harness setup to cycle the pump...I assume the harness goes to a relay and you power the pump from a source up front, or the rear fuse compartment??

Sorry for all the questions, but your setup is certainly "superior" to any ideas I had...wow.

Greg Fishman

Do you do a lot of enduro's over 90 minutes? If so you shouldn't need a cooler, this is info I got from Brian Copans.

Geoffrey

Trust me, my car is not that clean anymore. These pictures were taken during my build process.

Jeff, I am running -8 fittings all around. I would not go smaller, and based on my data, you don't need anything larger. The -8 will pump a quart every 20-30 seconds, so it gives it a chance to cool in the cooler.

The red piece is a Peterson filter so the oil from the trans is filtered before reaching the pump. I believe this will help the pump to last longer.

I did not drill and tap the case for the suction, I bought a hex head drain plug from my local auto parts store, milled the head flat so an aluminum sealing ring would seal against it, drilled and tapped the inside for the banjo bolt thread. This is so I can return it to a standard drain plug if need be. The temp sensor is a standard Bosch temp sensor and the case was drilled and tapped in an area where the sensor was submerged in oil, but did not protrude into the inside of the trans. This allows the trans cover to be removed without removing the sensor. The cool return to the case is just a pipe thread to -8 fitting tapped into the case.

The fittings are standard A/N fittings I probably used Goodridge. The quick disconnect are Jiffy tite fittings. The hose is Aeroquip kevlar braided hose. I won't use the stainless braided stuff because it is nasty to work with and it is heavy.

I have a MoTeC dash and I used an analog temp input to read the temp sensor and used one of the outputs to turn a relay on. I set it for 200F(I can set it to any temp I need), so the MoTeC can cylce the pump as required. I also provided an override switch so I can turn the pump on manually if I so choose.

I don't disagree with you that there are better ways to plumb the inlet and suction lines than I did it. I chose an easy method and for what we are doing, I don't think it matters much. My temp sensor is in the mid case so the data I'm getting shows that that part of the fluid is maintained at 200f, or cooler if I turn the pump on earlier. I feel confident that what I've done is sufficient. You could always make a spraybar for the inside, but that added a level of complexity I didn't feel I need at this time.

Yes, Brian Copans says that unless you are running over 90 minute duration you do not need a trans cooler. However, the data I have shows my trans temp reaching 200f on a hot summer day in about 30 minutes, so I might disagree with him. I feel that 200F is a good temp to maintain. I believe that in a 90 minute enduro, the temps will see 300F. I know when I ran my 930, my G50/50 case, as measured by an IR temp gun would be 285F after running it 45 minutes.

I can only speak to the data that I have collected and feel that it is accurate. My decisions and therefore, recommendations are based off of that data. YMMV.

Jeff Curtis

Wow Geoffrey, every time you post some pics of what you've done with the car, I'm left in awe...VERY VERY nice work indeed.

OK, so I don't do 90min. enduros with the car, but I do have a few issues that might be resolved with a cooler, not sure though.

1st of all, let me add that this pump/Aeroquip accessories setup cost me NOTHING out of pocket, and I do have one of my transmissions disassembled at the moment, so it's a "why not" type scenario...I have to carry ballast in the car anyway, might as well take up 7-12 lbs of it with something useful?

I have the upshift/downshift "notchiness" when the gearbox gets good and warm, not present during the 1st 5 laps or so, but real prevelant later in the race, especially when having to go to 2nd entering a turn if I'm battling with a car in front or having to go at a slower pace, then upshifting to 3rd is notchy as well.

Some say the clutch disengagement (or lack thereof) is to blame for this, but with a hydraulic system, what more can I do?? ...I can't "adjust" the throw of the clutch pedal except for the stop and it pretty much gets bumped off a few times a year (rubber bumper that limits clutch pedal travel) - I have replaced the slave cylinder, but not the master cylinder for the clutch...I'm thinking maybe the clutch gets hot and drags a bit...but is it possible internal heat within the gearbox is causing this??

SO, my logic is to install a cooler setup, manually operated (via a dashboard switch) and after a few good hot laps, or viewing a trans. temp gauge up towards 200deg. I can throw the switch and get things cooled down, and maybe that will kill my issues with the notchy shifting, possibly make it better??

Any thoughts on this issue?? ...I know that several people have encountered this. I have NEW synchros and selectors...still get that problem.

On the -10 -vs.- -8 quandry, I measure the aluminum connectors at 1/2" I.D. yet some #s I find on the connectors have a -10 in them?? I have the wrenches, maybe that'll tell me, again, haven't fiddled with the setup too much.

Geoffrey, if you don't mind, and you have a few minutes, let's get together via email and I would like assistance on getting that banjo setup you have for the drainplug end of the system, I like that setup A LOT as it provides maximum clearance between curbing, etc. at the track.

Geoffrey

You can call me. Contact information via my website link in my sig. Just for kicks, here is the datalogging from a summer day at WGI. It took 20 minutes to reach 200F.

BC

What is the part number of the mocal pump please?

Geoffrey

The Mocal part number is 17-522HT. It appears to be identical to the Tilton pump as well as a third one I've seen. I think they are made by someone else who supplies it to people like Tilton and Mocal.

BC

Thanks!

BC

Is there any info WRT the spray bar being positioned so as to not to add liquid compression problems between the gear teeth? You know, when you drop a thick, uncompressable fluid inbetween teeth of a gear meshing it may actually push the gears apart?

Just a wierd memory from somebody speaking about it.

JasonAndreas

There are a few technical papers by Southwest Research Institute and Ricardo that measure transmission efficiency and the effect of lube temperature. I've posted the numbers somewhere here on Rennlist but I can't find them and don't have access to the papers anymore without paying more $$$. It was somewhere around 6% every X degrees. Overall not a lot in terms of what gets put to the ground but more than you could ever hope to receive from a chip upgrade.