GEARBOX COOLER SYSTEM Installation and Review
10-04-2012, 06:57 PM
#16
Rennlist Member
Thread Starter
Knowing what I know now that I have kept an eye on the gearbox temps, a gearbox cooler would be overkill for a street driven car or someone that does 1 or 2 DEs each year. Just change the gear oil after each DE. On the street my cooler doesn't even turn on because the temps will stabilize at around 180F to 185F or so and the cooler is set up to turn on at 195F. The cooler normally turns on about half way through a 25 min session at the track. So, if you do go to the track on a regular basis and drive the car hard in the upper run groups, then a cooler is a worthwhile long term preventative measure especially if you have an LSD. Hope that helps.....
10-04-2012, 10:02 PM
#18
Rennlist Member
Thread Starter
12-31-2014, 08:58 AM
#19
Since a number of you have PM'd me about the gearbox cooling system I have decided it would be easiest to do a quick write up on it. Basically, my decision to do a gearbox cooler was a result of tracking my Rturbo and a number of conversations I had with the builders of these gearboxes like Brian Copans and Gbox. Matt Monson of Guard Transmission who supplied his Guard GT Club LSD for my gearbox also highly recommended a cooler if tracking the car. Since I knew an LSD would raise the temps of the gearbox, especially when running the car hard at the track, for longevity purposes I decided that a cooler was a must. I track my car about 15 days per year.
After doing some research, I realized there were two ways of approaching this project since the gearbox and engine were removed on my car while my coolant pipes were getting welded and while the gearbox case was drilled and tapped for the GT2 slave conversion. One way to do this was to have the gearbox shipped to Gbox or Copans to have it machined and converted to the GT2/3 cooler components utilizing an internal spray bar and an external liquid to liquid cooler that uses the engine coolant to maintain the temperature of the gearbox. This option however would have been quite expensive with many parts required to be ordered from Germany (with several weeks lead time) and price wise at an estimated $6-7K+ and it just did not make sense. The other option was to do it the cheap way and just pull off the oil from the drain hole, run it through a pump and an external air to liquid cooler and return the cooled oil through the gearbox fill hole. This option would have been fairly cheap at an estimated $1-1.5K but I did not like the AN fitting hanging below the gearbox and exposed to potential damage from road debris. As a result, upon consultation with my tech at 3zero3 Motorsports, we decided to come up with a system that falls price wise between the two cooler options but actually offers much more in many aspects.
The one thing that I wanted with my application was to retain the factory drain and fill holes on the gearbox. I did not want to have to draw and return the fluid through those locations so that I would not have to disconnect any AN fittings when doing frequent gearbox oil changes as I normally do when tracking my car. As a result, we decided to drill and tap the gearbox case on the side under the passenger side axle and draw the gearbox oil from that location. This location is very close to the LSD and thus has the hottest oil due to the friction of the clutches. From there, the oil is drawn via a MOCAL oil pump (located on the passenger side of the gearbox ahead of the drive axle) and driven though an oil filter into an external air to liquid cooler located on the driver's side of the gearbox in a location similar to where the factory GT2/3 cooler resides. After the oil passes through the oil cooler it is returned through the top of the gearbox which was drilled and tapped for that purpose. A MOCAL pump, even though it is expensive at around $400, was chosen due to the fact that it is a gear pump as opposed to a diaphragm pump like a Tilton. The advantage of a gear pump is the fact that it is much quieter and more efficient than a pump like a Tilton. When the MOCAL pump is running with the car shut off, you can barely hear it, just a faint whirr. With the car engine running, it is inaudible. The Tilton diaphragm pump by comparison is very noisy due to its diaphram design. All of the hardware like the pump and the cooler is mounted via rubber lord mounts to dampen any noise and vibration.
In addition to the cooler, I also wanted the system to be "hands off", reliable, easy to service, and to provide me some feedback in the car as to the gear oil temperature. To make the system "hands off", it was decided that we would use an adjustable OEM quality automotive thermostat switch to activate the oil pump at a preset temperature which I have set at 200F. I chose 200F since this is close to the coolant temperature that the GT2/3 uses to cool the gear oil with its respective liquid to liquid cooler. In order to use a thermostat switch we needed to insert a temperature pick up probe into the gearbox and did so by drilling and tapping a location in the side of the case near the same spot under the passenger axle where the oil pick up is tapped. Once again, this is near the LSD where the hottest oil is. As a result, when the thermostat senses a temperature of 200F it activates the pump which in turn starts to circulate the gear oil through the cooler. The pump will run continuously until the oil temperature drops to around 180F at which point it stops. There is also a small LED installed (in the lower portion of the center dash below the climate control) which lights up green when the pump is energized and running. In addition, there is also a manual override switch next to the LED that I can use to turn on the pump independent of the thermostat.
The last part of the gearbox cooling system I wanted to employ was some type of an indicator in the car that would give me a temperature readout of the gearbox oil. I looked at many options but one of my requirements was that the install must be very OEM looking. I just did not want to have some gauge stuck in the dash that would look out of place in the car. After much research I decided to employ the Brockway Dgauge with its 996 specific console mount as it is a direct drop in to the 996 console and looks perfectly OEM. The Dgauge has an option to plug in an external sensor for numerous items with oil temperature being one of them. You can purchase the various sensors directly from Brockway and they are OEM automotive quality parts. The side benefit of the Dgauge is the fact that you get a display of countless user selectable data that the unit pulls up through the OBDII port. You have a choice to select up to 4 parameters on the Dgauge display and I chose to have the gearbox oil temp in the upper left, IAT in the upper right, and AFRs for both banks of the motor in the lower left and right. Display colors are also user selectable. The Dgauge is a self contained unit that is powered through the OBDII port and required no wiring besides plugging in the flat connector to the OBD. The final step was to insert one more temperature probe in the gear box and again this was done in a similar fashion as with the thermostat probe by drilling and tapping the case in the location under the passenger axle. If you decide to go with a Dgauge on the 996tt, ask Eric at Brockway to download software V1.24 to ensure the unit Auto shutdown and startup sequence functions correctly in our cars. I sent mine in to Eric at Brockway and we came up with this update for the 996tt since our ECU functions a little differently from other cars.
To wrap everything up, some of the factory coolant hoses that run under the car near the transmission have to be rerouted to make room for the various components of the transmission cooler system like the radiator. This was all pretty straight forward. A few custom brackets had to be made and welded to the crossbar to mount everything up. The last item to complete everything was to add a NACA duct to the bottom of the plastic belly pan cover that is under the transmission. This NACA duct directs air flow over the oil cooler radiator making the system work efficiently. For clarity purposes, the attached pictures do not show the belly pan with the NACA duct installed.
So, how does this whole ball of wax work in the real world? Well, I have to say very well now that I have had a chance to play with it for a couple of weeks including 3 days at the track. During my testing, I discovered that during regular driving which includes stop and go traffic, normal roads, and driving on the interstate, the gearbox oil temp will climb up into the 180s. This is about the same number that I have observed during an hour long drive on the interstate at a constant 80mph. To test the effectiveness of the cooler, I switched it on using the over ride switch and within 2 minutes I saw the temperatures drop 12-15 degrees. This is quite substantial. When running at the track in 85F ambient temperatures I saw the oil temp climb to 200F in about 10 minutes at which point the cooler automatically switched on and maintained that temperature. 200-205F is where I'm seeing the temps generally stabilize at the end of a 25 min track session. The highest temp I ever saw was 221F and that was at the end of the 3rd 25 minute session during mid afternoon when the temps were close to 90F with ambient track temps probably over 100F. When I spoke with Matt of Guard Transmission he told me that you don't want to see temps over 240F or so (if I recall correctly) as this is where the synchros start to swell and the lubricating properties of the oil rapidly decline. Prior to having the cooler, I could definitely tell the gearbox oil was getting hot as it felt quite "watery" from the oil getting so hot and thin when I would come into the pits at the end of the session. BTW, I am running Mobil 1 Delvac 75w90 gear oil.
Overall, I am very pleased how this project turned out and it has exceeded my expectation in every way. My hats off must go to my incredibly competent tech Emery at 3zero3 Motorsports for working out the design and bringing this to fruition. I believe this type of air to liquid cooling system has a greater cooling capacity than the liquid to liquid cooler employed on the GT2/3 as they are using 185F liquid to cool the gear oil. The advantage of the factory system however is that it does bring the gearbox up to temperature quicker especially in the winter. Would I do this project for a street car? No. Would I do it for a car that does one or two track days per year in the lower run groups? No. However, I would absolutely install a gearbox cooler on any car that is taken to the track on a regular basis and is run hard in any of the upper run groups like black or orange. The addition of an LSD will add 15-20 degrees to your gearbox temps due to the friction of the clutches and at that point the cooler will definitely prolong the life of your internal components and make your gearbox more bullet proof and last longer between rebuilds. Couple things of note. While I had my gear box out and taken apart I had the Gbox detent installed and also the 2nd gear synchros replaced as they showed a bit of wear. There was no issue with shifting but since everything was out I figured why not. The one thing I found interesting was the fact that all the synchros in the gearbox were steel. My car is a 2002. There was a rumor floating around that the X50 or GT2 gearboxes came with steel synchros while the normal 996tt had brass synchros but evidently this is false. Additionally, looking at the PET catalogue, all the gears and synchros are the same part number for the Turbo and GT2 so outside of the GT2 cooler the gearboxes are the same.
I believe this gearbox cooler kit is now available in kit form. Hope that helps…….
http://
Gear box cooler system by pwdrhound1, on Flickr
Looking at the transmission from the passenger side of the car. Note the MOCAL pump mounted in the center at the top of the picture. The oil filter is the red "tube" visible just to the right of the pump
http://
Gear box cooler (radiator view) by pwdrhound1, on Flickr
Looking at the transmission from the front of the car. Note the thermostat mounted in the upper left of the picture next to the transmission mount
http://
Temp probes and AN fitting oil pick up by pwdrhound1, on Flickr
AN fitting for oil pick up and the temp probes for the thermostat and Dgauge
http://
Gearbox cooler (oil return close up) by pwdrhound1, on Flickr
Oil return via AN fitting at the top of the gear box
http://
Gearbox cooler (Dgauge:LED
verride switch) by pwdrhound1, on Flickr
Dgauge installed in the console. Note the manual override switch and LED in the batwings
Cooler scoop by pwdrhound1, on Flickr
Rubber air scoop that is located at the aft end of the belly pan behind the NACA duct and directs air over the air to liquid cooler. The rubber scoop is a Porsche Boxster part.
After doing some research, I realized there were two ways of approaching this project since the gearbox and engine were removed on my car while my coolant pipes were getting welded and while the gearbox case was drilled and tapped for the GT2 slave conversion. One way to do this was to have the gearbox shipped to Gbox or Copans to have it machined and converted to the GT2/3 cooler components utilizing an internal spray bar and an external liquid to liquid cooler that uses the engine coolant to maintain the temperature of the gearbox. This option however would have been quite expensive with many parts required to be ordered from Germany (with several weeks lead time) and price wise at an estimated $6-7K+ and it just did not make sense. The other option was to do it the cheap way and just pull off the oil from the drain hole, run it through a pump and an external air to liquid cooler and return the cooled oil through the gearbox fill hole. This option would have been fairly cheap at an estimated $1-1.5K but I did not like the AN fitting hanging below the gearbox and exposed to potential damage from road debris. As a result, upon consultation with my tech at 3zero3 Motorsports, we decided to come up with a system that falls price wise between the two cooler options but actually offers much more in many aspects.
The one thing that I wanted with my application was to retain the factory drain and fill holes on the gearbox. I did not want to have to draw and return the fluid through those locations so that I would not have to disconnect any AN fittings when doing frequent gearbox oil changes as I normally do when tracking my car. As a result, we decided to drill and tap the gearbox case on the side under the passenger side axle and draw the gearbox oil from that location. This location is very close to the LSD and thus has the hottest oil due to the friction of the clutches. From there, the oil is drawn via a MOCAL oil pump (located on the passenger side of the gearbox ahead of the drive axle) and driven though an oil filter into an external air to liquid cooler located on the driver's side of the gearbox in a location similar to where the factory GT2/3 cooler resides. After the oil passes through the oil cooler it is returned through the top of the gearbox which was drilled and tapped for that purpose. A MOCAL pump, even though it is expensive at around $400, was chosen due to the fact that it is a gear pump as opposed to a diaphragm pump like a Tilton. The advantage of a gear pump is the fact that it is much quieter and more efficient than a pump like a Tilton. When the MOCAL pump is running with the car shut off, you can barely hear it, just a faint whirr. With the car engine running, it is inaudible. The Tilton diaphragm pump by comparison is very noisy due to its diaphram design. All of the hardware like the pump and the cooler is mounted via rubber lord mounts to dampen any noise and vibration.
In addition to the cooler, I also wanted the system to be "hands off", reliable, easy to service, and to provide me some feedback in the car as to the gear oil temperature. To make the system "hands off", it was decided that we would use an adjustable OEM quality automotive thermostat switch to activate the oil pump at a preset temperature which I have set at 200F. I chose 200F since this is close to the coolant temperature that the GT2/3 uses to cool the gear oil with its respective liquid to liquid cooler. In order to use a thermostat switch we needed to insert a temperature pick up probe into the gearbox and did so by drilling and tapping a location in the side of the case near the same spot under the passenger axle where the oil pick up is tapped. Once again, this is near the LSD where the hottest oil is. As a result, when the thermostat senses a temperature of 200F it activates the pump which in turn starts to circulate the gear oil through the cooler. The pump will run continuously until the oil temperature drops to around 180F at which point it stops. There is also a small LED installed (in the lower portion of the center dash below the climate control) which lights up green when the pump is energized and running. In addition, there is also a manual override switch next to the LED that I can use to turn on the pump independent of the thermostat.
The last part of the gearbox cooling system I wanted to employ was some type of an indicator in the car that would give me a temperature readout of the gearbox oil. I looked at many options but one of my requirements was that the install must be very OEM looking. I just did not want to have some gauge stuck in the dash that would look out of place in the car. After much research I decided to employ the Brockway Dgauge with its 996 specific console mount as it is a direct drop in to the 996 console and looks perfectly OEM. The Dgauge has an option to plug in an external sensor for numerous items with oil temperature being one of them. You can purchase the various sensors directly from Brockway and they are OEM automotive quality parts. The side benefit of the Dgauge is the fact that you get a display of countless user selectable data that the unit pulls up through the OBDII port. You have a choice to select up to 4 parameters on the Dgauge display and I chose to have the gearbox oil temp in the upper left, IAT in the upper right, and AFRs for both banks of the motor in the lower left and right. Display colors are also user selectable. The Dgauge is a self contained unit that is powered through the OBDII port and required no wiring besides plugging in the flat connector to the OBD. The final step was to insert one more temperature probe in the gear box and again this was done in a similar fashion as with the thermostat probe by drilling and tapping the case in the location under the passenger axle. If you decide to go with a Dgauge on the 996tt, ask Eric at Brockway to download software V1.24 to ensure the unit Auto shutdown and startup sequence functions correctly in our cars. I sent mine in to Eric at Brockway and we came up with this update for the 996tt since our ECU functions a little differently from other cars.
To wrap everything up, some of the factory coolant hoses that run under the car near the transmission have to be rerouted to make room for the various components of the transmission cooler system like the radiator. This was all pretty straight forward. A few custom brackets had to be made and welded to the crossbar to mount everything up. The last item to complete everything was to add a NACA duct to the bottom of the plastic belly pan cover that is under the transmission. This NACA duct directs air flow over the oil cooler radiator making the system work efficiently. For clarity purposes, the attached pictures do not show the belly pan with the NACA duct installed.
So, how does this whole ball of wax work in the real world? Well, I have to say very well now that I have had a chance to play with it for a couple of weeks including 3 days at the track. During my testing, I discovered that during regular driving which includes stop and go traffic, normal roads, and driving on the interstate, the gearbox oil temp will climb up into the 180s. This is about the same number that I have observed during an hour long drive on the interstate at a constant 80mph. To test the effectiveness of the cooler, I switched it on using the over ride switch and within 2 minutes I saw the temperatures drop 12-15 degrees. This is quite substantial. When running at the track in 85F ambient temperatures I saw the oil temp climb to 200F in about 10 minutes at which point the cooler automatically switched on and maintained that temperature. 200-205F is where I'm seeing the temps generally stabilize at the end of a 25 min track session. The highest temp I ever saw was 221F and that was at the end of the 3rd 25 minute session during mid afternoon when the temps were close to 90F with ambient track temps probably over 100F. When I spoke with Matt of Guard Transmission he told me that you don't want to see temps over 240F or so (if I recall correctly) as this is where the synchros start to swell and the lubricating properties of the oil rapidly decline. Prior to having the cooler, I could definitely tell the gearbox oil was getting hot as it felt quite "watery" from the oil getting so hot and thin when I would come into the pits at the end of the session. BTW, I am running Mobil 1 Delvac 75w90 gear oil.
Overall, I am very pleased how this project turned out and it has exceeded my expectation in every way. My hats off must go to my incredibly competent tech Emery at 3zero3 Motorsports for working out the design and bringing this to fruition. I believe this type of air to liquid cooling system has a greater cooling capacity than the liquid to liquid cooler employed on the GT2/3 as they are using 185F liquid to cool the gear oil. The advantage of the factory system however is that it does bring the gearbox up to temperature quicker especially in the winter. Would I do this project for a street car? No. Would I do it for a car that does one or two track days per year in the lower run groups? No. However, I would absolutely install a gearbox cooler on any car that is taken to the track on a regular basis and is run hard in any of the upper run groups like black or orange. The addition of an LSD will add 15-20 degrees to your gearbox temps due to the friction of the clutches and at that point the cooler will definitely prolong the life of your internal components and make your gearbox more bullet proof and last longer between rebuilds. Couple things of note. While I had my gear box out and taken apart I had the Gbox detent installed and also the 2nd gear synchros replaced as they showed a bit of wear. There was no issue with shifting but since everything was out I figured why not. The one thing I found interesting was the fact that all the synchros in the gearbox were steel. My car is a 2002. There was a rumor floating around that the X50 or GT2 gearboxes came with steel synchros while the normal 996tt had brass synchros but evidently this is false. Additionally, looking at the PET catalogue, all the gears and synchros are the same part number for the Turbo and GT2 so outside of the GT2 cooler the gearboxes are the same.
I believe this gearbox cooler kit is now available in kit form. Hope that helps…….
http://
Gear box cooler system by pwdrhound1, on Flickr
Looking at the transmission from the passenger side of the car. Note the MOCAL pump mounted in the center at the top of the picture. The oil filter is the red "tube" visible just to the right of the pump
http://
Gear box cooler (radiator view) by pwdrhound1, on Flickr
Looking at the transmission from the front of the car. Note the thermostat mounted in the upper left of the picture next to the transmission mount
http://
Temp probes and AN fitting oil pick up by pwdrhound1, on Flickr
AN fitting for oil pick up and the temp probes for the thermostat and Dgauge
http://
Gearbox cooler (oil return close up) by pwdrhound1, on Flickr
Oil return via AN fitting at the top of the gear box
http://
Gearbox cooler (Dgauge:LED
verride switch) by pwdrhound1, on FlickrDgauge installed in the console. Note the manual override switch and LED in the batwings
Cooler scoop by pwdrhound1, on Flickr
Rubber air scoop that is located at the aft end of the belly pan behind the NACA duct and directs air over the air to liquid cooler. The rubber scoop is a Porsche Boxster part.
This is precisely the kind of true tech postings I appreciate in the "Turbo Technical Discussion Areas"!
Slalom996T
01-02-2015, 07:00 PM
#20
Rennlist Member
Thats a nice setup!
01-04-2015, 02:57 PM
#23
Rennlist Member
Thread Starter
Agree 100%. I now have over 2years and 70 hard track hours on this gearbox / cooler set up and both have been without any issues whatsoever. I think the cooler is the key for longevity. Gearbox will be opened in the next two weeks to swap in a 997GT2 1-3 mainshaft. I'll report on the condition of it.
Last edited by powdrhound; 01-05-2015 at 03:25 PM.
06-12-2015, 01:25 PM
#28
Racer
Join Date: Jun 2007
Location: Atlanta area
Posts: 281
Likes: 0
Received 0 Likes
on
0 Posts
Cooler
Agree 100%. I now have over 2years and 70 hard track hours on this gearbox / cooler set up and both have been without any issues whatsoever. I think the cooler is the key for longevity. Gearbox will be opened in the next two weeks to swap in a 997GT2 1-3 mainshaft. I'll report on the condition of it.
I've recently gone to late model GT2 gears 1 through 4. With the additional speed capabilities of 2nd gear, I now go through that corner in 2nd instead of 3rd. No problems yet but not many track days on the new setup. Probably losing some time with extra gear shift but that doesn't bother me.
