Rear mount auto trans cooler installed!
05-15-2003, 05:55 PM
#1
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Rear mount auto trans cooler installed!
Notes so far:
The car feels 'heavier' at take off, (less converter slip?) but if I put my foot down, it goes fast, faster. Engine braking is more pronounced.
Shifts are immediate, but surprisingly, less harsh. Downshifts are lightning quick.
I tend to leave it in D much more now as the response is so much better now. Before, the overall feeling was 'mushy' at low rpm's.
Measured with a heat-gun at 70f ambient, the pan warms up to about 150-160f. Standing still, there is about a 5-10f drop in temp across the cooler.
Still plenty of room to reach up to the reservoir.
Next up:
Remove the old metal lines.
Small sheet metal shroud with a screen(!) in front of the cooler.
New trans mounts.
Flip the radiator over and install the factory oil cooler hoses.
I may install:
A small thermostatically controlled fan?
An oil thermostat by next winter?
Synthetic ATF?
Brackets are bent, drilled, and painted 1/8" steel stock (3/4" and 1 1/4") with 6mm stainless hardware.
The blue fittings are Earl's (Holley brand) which I did not use.
The cooler is at tilted back about 45deg to fit and is no lower than the trans.
The backing plate under the passenger back seat cushion is shown in the upper right pic.
The metric adapters have a smaller internal passage after the first 5mm, so I used progressively larger drill bits and drilled them out to the initial bore diameter. I reused two old crush washers.
The old long flex hose is zip-tied temporarily in the center of the lower pic.
The new hoses are tight against the trans, not resting on the other old metal line as it may appear.
Oil Filter Service, Co. - Aeroquip SocketLess AN-6 (3/8") fittings:
5' 2556-6-IN hose $14.40
(1) FBM-1532 90deg elbow $16.11ea
(3) FBM-1542 120deg elbow $17.77ea
(2) FBM-2246 12mm/1.5 adapter $8.98ea
Race Central:
(1) SET-610 Setrab oil cooler $91.50ea
(2) SET-M22-AN6 adapter $6.90ea
Total ~$220.
*Update*
~thread~start~
The car feels 'heavier' at take off, (less converter slip?) but if I put my foot down, it goes fast, faster. Engine braking is more pronounced.
Shifts are immediate, but surprisingly, less harsh. Downshifts are lightning quick.
I tend to leave it in D much more now as the response is so much better now. Before, the overall feeling was 'mushy' at low rpm's.
Measured with a heat-gun at 70f ambient, the pan warms up to about 150-160f. Standing still, there is about a 5-10f drop in temp across the cooler.
Still plenty of room to reach up to the reservoir.
Next up:
Remove the old metal lines.
Small sheet metal shroud with a screen(!) in front of the cooler.
New trans mounts.
Flip the radiator over and install the factory oil cooler hoses.
I may install:
A small thermostatically controlled fan?
An oil thermostat by next winter?
Synthetic ATF?
Brackets are bent, drilled, and painted 1/8" steel stock (3/4" and 1 1/4") with 6mm stainless hardware.
The blue fittings are Earl's (Holley brand) which I did not use.
The cooler is at tilted back about 45deg to fit and is no lower than the trans.
The backing plate under the passenger back seat cushion is shown in the upper right pic.
The metric adapters have a smaller internal passage after the first 5mm, so I used progressively larger drill bits and drilled them out to the initial bore diameter. I reused two old crush washers.
The old long flex hose is zip-tied temporarily in the center of the lower pic.
The new hoses are tight against the trans, not resting on the other old metal line as it may appear.
Oil Filter Service, Co. - Aeroquip SocketLess AN-6 (3/8") fittings:
5' 2556-6-IN hose $14.40
(1) FBM-1532 90deg elbow $16.11ea
(3) FBM-1542 120deg elbow $17.77ea
(2) FBM-2246 12mm/1.5 adapter $8.98ea
Race Central:
(1) SET-610 Setrab oil cooler $91.50ea
(2) SET-M22-AN6 adapter $6.90ea
Total ~$220.
*Update*
~thread~start~
Last edited by PorKen; 09-19-2003 at 02:34 PM.
05-15-2003, 06:17 PM
#2
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Yup..id get on that screen ASAP. You know that man Murphy!!!
Good idea!
<img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />
Good idea!
<img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />
05-15-2003, 08:33 PM
#3
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What prompted this - radiator cooler problems? And the trans is working better?
curious mind here...also have a 3speed, but no problems so far.
jp 83 Euro S AT
curious mind here...also have a 3speed, but no problems so far.
jp 83 Euro S AT
05-15-2003, 08:43 PM
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Pinging Steve C., any pro's and con's we are not seeing on this one?
I know it's apparent of things that could damage the cooler and spring a leak, maybe a better location is possible?. Great Idea though!
I know it's apparent of things that could damage the cooler and spring a leak, maybe a better location is possible?. Great Idea though!
05-15-2003, 10:15 PM
#5
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Here's my thinkin':
Blank spot under car.
Aeroquip fittings are bitchin'.
No additional heat input to engine coolant.
Weight savings by removal of hard steel lines, hoses, and additional oil.
The forthcoming shroud will protect the cooler from rocks/possums/wombats?
I have the hoses to hook up the engine oil cooler, but only one oil cooler in radiator.
It's not that low, the bottom of the cooler is higher than the bottom of the transmission, lower link, and rear passenger floor.
But mainly:
All 4 flex hoses need replacing.
If no thermostat/fan, then rational for synthetic ATF purchase.
Higher available line pressure/volume in trans circuit for smoother operation.
Transmission oil operates at 160f versus 200f+ of engine coolant, extending fluid/trans life.
A couple of horses run free, no longer needed to pump 30W oil 20' through 10mmID pipe, 5mmID weepy hoses, and banjo fittings.
Cons:
(2) factory-unauthorized 6mm holes.
Slower trans oil warmup even with a future oil thermostat.
I'm more worried about the connection at the trans (even though they are not lower than the pan) being snapped off by an obstacle than the cooler being damaged. I was initially going to reuse the banjo fitting ends of the hoses, but was lured by the increased flow of the straight through fittings.
Blank spot under car.
Aeroquip fittings are bitchin'.
No additional heat input to engine coolant.
Weight savings by removal of hard steel lines, hoses, and additional oil.
The forthcoming shroud will protect the cooler from rocks/possums/wombats?
I have the hoses to hook up the engine oil cooler, but only one oil cooler in radiator.
It's not that low, the bottom of the cooler is higher than the bottom of the transmission, lower link, and rear passenger floor.
But mainly:
All 4 flex hoses need replacing.
If no thermostat/fan, then rational for synthetic ATF purchase.
Higher available line pressure/volume in trans circuit for smoother operation.
Transmission oil operates at 160f versus 200f+ of engine coolant, extending fluid/trans life.
A couple of horses run free, no longer needed to pump 30W oil 20' through 10mmID pipe, 5mmID weepy hoses, and banjo fittings.
Cons:
(2) factory-unauthorized 6mm holes.
Slower trans oil warmup even with a future oil thermostat.
I'm more worried about the connection at the trans (even though they are not lower than the pan) being snapped off by an obstacle than the cooler being damaged. I was initially going to reuse the banjo fitting ends of the hoses, but was lured by the increased flow of the straight through fittings.
Last edited by PorKen; 07-15-2003 at 12:26 AM.
05-16-2003, 08:27 PM
#7
Burning Brakes
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Hi Porken,
The use of a conforming synthetic ATF will produce benefits at both ends of the temperature extremes - and in between.
Most benefits are missed when thinking about Syn. ATFs. It will usually make the mechanical components in the transmission operate with less frictional loss ( smoother )but the hydraulic function of the ATF is where the extreme temperature benefits really occur along with better valve/component cleanliness ( less residue )
An earlier post of mine "Oil Condition Report No2 " give some ATF temps read at the oil cooler inlet/outlet points on my S4. In most cases the synthetic ATF I use - Castrol Transmax Z - runs VERY cool as you can see
An "original equipment" benefit ( not S4 )is in warm up
I would be very wary of stone damage and fit a screen in front of the cooler pictured. It may also be prone to trash build up in the core
One question though - why was it needed?
Regards
The use of a conforming synthetic ATF will produce benefits at both ends of the temperature extremes - and in between.
Most benefits are missed when thinking about Syn. ATFs. It will usually make the mechanical components in the transmission operate with less frictional loss ( smoother )but the hydraulic function of the ATF is where the extreme temperature benefits really occur along with better valve/component cleanliness ( less residue )
An earlier post of mine "Oil Condition Report No2 " give some ATF temps read at the oil cooler inlet/outlet points on my S4. In most cases the synthetic ATF I use - Castrol Transmax Z - runs VERY cool as you can see
An "original equipment" benefit ( not S4 )is in warm up
I would be very wary of stone damage and fit a screen in front of the cooler pictured. It may also be prone to trash build up in the core
One question though - why was it needed?
Regards
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05-16-2003, 11:49 PM
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Please, everyone, I'm gonna put a shroud around it, with a trash screen, OK! Jeez 
Doug - thanks for the oil write up, I'm definitely going to go with synthetic ATF.
(See two posts up for previous reasoning.)
The main reason for all this was the thought of pumping ATF 20 feet or so, the horsepower required, and the inevitable pressure drop.
Previously I would drive most of the time in 2 for pickup and engine braking, because my slush box, was so, slushy. There was fractional delay between pedal down and launch forward.
After this conversion, I drive in D because there is a lot more 'pull', if pressed, shift-downs are instant, and the car doesn't run on so far when you let off the throttle.
Today I backed off the vacuum modulator one turn, to smooth slightly the 2-3 shift. I had cranked it down quite far to give at least bearable shifting performance.
Doug - thanks for the oil write up, I'm definitely going to go with synthetic ATF.
(See two posts up for previous reasoning.)
The main reason for all this was the thought of pumping ATF 20 feet or so, the horsepower required, and the inevitable pressure drop.
Previously I would drive most of the time in 2 for pickup and engine braking, because my slush box, was so, slushy. There was fractional delay between pedal down and launch forward.
After this conversion, I drive in D because there is a lot more 'pull', if pressed, shift-downs are instant, and the car doesn't run on so far when you let off the throttle.
Today I backed off the vacuum modulator one turn, to smooth slightly the 2-3 shift. I had cranked it down quite far to give at least bearable shifting performance.
Last edited by PorKen; 06-02-2004 at 01:26 AM.
05-18-2003, 04:47 PM
#9
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Proken,
The oil feed thru the cooler lines is not line pressure oil (working pressure); the oil used to operate the inner workings of a transmission, like bands and clutches. Cooler line oil is super heated oil from the torque converter and gear train lubrication oil. Since the torque converter generates 95% of the heat in the transmission it must be cooled before being introduced into the transmission and gear train lube oil circuit.
There could be an explanation for your performance claim of “The car feels 'heavier' at take off”
Here is a simplified description on how a torque converter works. The engine drives the impeller; it puts the transmission fluid into a circular motion creating a fluid force, that fluid force turns the turbine blades. The turbine turns the transmission planetary gears; driving the wheels. The medium used to transfer the engine torque to the wheels, is transmission fluid.
By lowering the transmission fluid temperature the torque converter is more efficient at multiplying engine torque. The colder THICKER transmission fluid with its higher viscosity has more potential energy than hot THIN transmission fluid. That greater potential energy when from, mechanical (engine) to fluid (oil) to mechanical (transmission)
Cons
You do not want to over cool, especially in colder climate areas were the temperatures can drop below 20 degrees. The flow of the fluid thru the cooler can be restricted; if it happens there is a possibility for planetary damage due to no or low lubrication oil. For this reason some cars have a cooler bypass valve. This is when synthetic oil would be extremely beneficial for its low temperature lubrication protection.
By having it mounted closer to the Trans even with its larger surface area with extreme use or on a hot summer day there is not enough time for the cooler to extract the heat from the oil. So the transmission is circulating hot oil.
Pros
The stand alone cooler isolates the radiator coolant from the transmission fluid eliminating a potential transmission failure when the radiator transmission cooler fails allowing water and oil to mix.
A bigger cooler extends the life of a transmission by lowering the transmissions operating temperature. The worst enemy of a transmission is heat. At 220 degrees oil starts to break down, at 260 degrees the rubber parts start to harden.
There are duel function coolers available, were you can cool transmission and engine oil, and you might what to consider one mounted in the front of the car as a stand alone system.
Nordskog makes a nice digital Trans temp gauge, I installed one on the ash tray cover of my car since I don’t smoke I have no use for it.
You did a great job, thanks for the AN fitting number, I was looking for them
<img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />
The oil feed thru the cooler lines is not line pressure oil (working pressure); the oil used to operate the inner workings of a transmission, like bands and clutches. Cooler line oil is super heated oil from the torque converter and gear train lubrication oil. Since the torque converter generates 95% of the heat in the transmission it must be cooled before being introduced into the transmission and gear train lube oil circuit.
There could be an explanation for your performance claim of “The car feels 'heavier' at take off”
Here is a simplified description on how a torque converter works. The engine drives the impeller; it puts the transmission fluid into a circular motion creating a fluid force, that fluid force turns the turbine blades. The turbine turns the transmission planetary gears; driving the wheels. The medium used to transfer the engine torque to the wheels, is transmission fluid.
By lowering the transmission fluid temperature the torque converter is more efficient at multiplying engine torque. The colder THICKER transmission fluid with its higher viscosity has more potential energy than hot THIN transmission fluid. That greater potential energy when from, mechanical (engine) to fluid (oil) to mechanical (transmission)
Cons
You do not want to over cool, especially in colder climate areas were the temperatures can drop below 20 degrees. The flow of the fluid thru the cooler can be restricted; if it happens there is a possibility for planetary damage due to no or low lubrication oil. For this reason some cars have a cooler bypass valve. This is when synthetic oil would be extremely beneficial for its low temperature lubrication protection.
By having it mounted closer to the Trans even with its larger surface area with extreme use or on a hot summer day there is not enough time for the cooler to extract the heat from the oil. So the transmission is circulating hot oil.
Pros
The stand alone cooler isolates the radiator coolant from the transmission fluid eliminating a potential transmission failure when the radiator transmission cooler fails allowing water and oil to mix.
A bigger cooler extends the life of a transmission by lowering the transmissions operating temperature. The worst enemy of a transmission is heat. At 220 degrees oil starts to break down, at 260 degrees the rubber parts start to harden.
There are duel function coolers available, were you can cool transmission and engine oil, and you might what to consider one mounted in the front of the car as a stand alone system.
Nordskog makes a nice digital Trans temp gauge, I installed one on the ash tray cover of my car since I don’t smoke I have no use for it.
You did a great job, thanks for the AN fitting number, I was looking for them
<img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />
05-18-2003, 09:05 PM
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Steve Cattaneo - thanks for the feedback!
I remember vaguely reading about the cooler lines coming direct from the converter, but was unsure on this, thanks for the clarification.
I can't believe I didn't mention the 'coolant + clutches/bands = bad' reasoning. I figure engine oil with coolant is less dangerous.
Although...when I was a 928 'noob' and went to the dealer for my first parts, I overheard a conversion from the service guy to a customer with a newer Porsche, who had suffered a coolant breach into the engine oil system. The service guy said that Herr Porsche requires new rod bearings be installed if coolant mixes with engine oil. The customer did not seem happy with the repair price!
I am going to go with synthetic ATF and no oil thermostat or fan. When I convert, I am going to put a virgin (undrilled) metric adapter on the return line to slow the coolant flow, slightly, through the cooler.
I was eyeing a dual cooler with fan when I was spec'ing this project. I thought 'I could get a pump and have a differential cooler as well!'. More for C factor* than I'm going to be racing. Maybe after I have my Ebay LSD installed...
There will definitely be room for the dually+fan after I remove the gas tank and install dual fuel cells in place of the back seats!
*(cool factor)
I remember vaguely reading about the cooler lines coming direct from the converter, but was unsure on this, thanks for the clarification.
I can't believe I didn't mention the 'coolant + clutches/bands = bad' reasoning. I figure engine oil with coolant is less dangerous.
Although...when I was a 928 'noob' and went to the dealer for my first parts, I overheard a conversion from the service guy to a customer with a newer Porsche, who had suffered a coolant breach into the engine oil system. The service guy said that Herr Porsche requires new rod bearings be installed if coolant mixes with engine oil. The customer did not seem happy with the repair price!
I am going to go with synthetic ATF and no oil thermostat or fan. When I convert, I am going to put a virgin (undrilled) metric adapter on the return line to slow the coolant flow, slightly, through the cooler.
I was eyeing a dual cooler with fan when I was spec'ing this project. I thought 'I could get a pump and have a differential cooler as well!'. More for C factor* than I'm going to be racing. Maybe after I have my Ebay LSD installed...
There will definitely be room for the dually+fan after I remove the gas tank and install dual fuel cells in place of the back seats!
*(cool factor)
Last edited by PorKen; 07-15-2003 at 12:27 AM.
