Transmission Fan Wiring and Cooler Installation

[doublespaces]

Since my car is up on jackstands I figured I'd upgrade my transmission cooler. Previously I had been running a converted PPKv2 radiator as a cooler. I do not recommend it because you'll experience runaway temps, that core is no match for the stock system. I've dealt with it for a long time because I have not driven my car much but now I've decided to take some action.

I started by sourcing a 'Small' dual pass cooler from Mishimoto then upgraded to the Large then went to a Setrab 72 row but in the end I decided to go back to an ebay dual pass that is virtually identical to the Mishimoto unit. I bought these coolers on sale in December 2018 and they have just sat in my garage and upon looking just now, it appears they are half off the half-off price I paid before, just under $60 a pop:

Universal Small Bar and Plate Dual Pass Black Oil Cooler Core:9.5"x5.5"x1.58" | eBay

Find many great new & used options and get the best deals for Universal Small Bar and Plate Dual Pass Black Oil Cooler Core:9.5"x5.5"x1.58" at the best online prices at eBay! Free shipping for many products!

www.ebay.com

This cooler isn't a world beater but it does fit the given space with convenient side outlets unlike pretty much any other cooler I could find. Since this is not a race car and I don't like the look of deleted ducting, my constraint was an oem fitment and that meant retaining the fog lights, brake ducts and headlight washers. Ideally, I'd be able to retrofit my existing PPK duct with this new setup.

After testing fitment(and waiting a year) I pulled off the frame rail support bracket and hammered it flat. The OEM bracket comes in at an odd angle and means the task of bending metal to fit had become no longer a DIY at home sort of job. Since I don't have a welder I would have to stick to more rudimentary means to make this work.

This is what the bracket looks like before:

Used a dremel to cut off the welded bolts:

Take a heavy hammer and flatten it out to make a nice mounting surface. This picture below was not the final angle, but you'll want it to be pretty close to the frame rail when done with a slight angle forward about halfway through so the cooler fits inside the fender liner.

Next, I went an grabbed some aluminum flatbar from Home depot and hammered out a simple bracket:

Additionally I bought:
2x 10AN to 8AN 90 degree hose ends (Fragola 229009)
6x 8AN hose ends (Russell 610035)
10 FT 8AN Nylon hose (Amazon)
5.2" Paddle Blade Pusher Fan (Spal 30103013) (VA31-A101-46S)
180 Degree Farenheit fan kit (Derale 16720)
8AN adapter with 1/8 NPT Sensor port (Russell 670353)

It is also assumed you've purchased or already have the 8AN transmission fittings and the Improved Racing 160 degree thermostat with 8AN fitment.

When mounted it will look something like this:

I did start to mock up the OEM bracket since I already had it but this metal is not good for bending and broke so a custom bracket will need to be made later:

I decided to mount the thermostat below the brake duct since there is a circular flat spot on the fender liner(MSport) that it should be able to mount to pretty easily. This is the position it will have:

Be sure to run the outlet to the top cooler port. If you go back to the transmission, the 'outlet' is on top, per realoem diagrams.

Now I mounted up the thermoswitch:

And here we are a few zipties later:

WIRING:

Per the chart above, I think that says the fan will draw 4-6 amps at 13v since I have the pusher fan. The pusher fan part number ends with "S" and not "A" so I am guessing that means Soffiante vs Aspirante. Makes me wonder if the motor is actually different or if the propeller angles are just optimized for one direction or another. In any case, we will need 22-23 gauge power wires.

Spoiler: Wire Gauge Chart

This estimate is based on nick-free soft annealed Cu wire having a tensile strength of 37000 pounds per square inch.

AWG gauge	Conductor Diameter Inches	Conductor Diameter mm	Conductor cross section in mm2	Ohms per 1000 ft.	Ohms per km	Maximum amps for chassis wiring	Maximum amps for power transmission	Maximum frequency for 100% skin depth for solid conductor copper	Breaking force Soft Annealed Cu 37000 PSI
0000	0.46	11.684	107	0.049	0.16072	380	302	125 Hz	6120 lbs
000	0.4096	10.40384	84.9	0.0618	0.202704	328	239	160 Hz	4860 lbs
00	0.3648	9.26592	67.4	0.0779	0.255512	283	190	200 Hz	3860 lbs
0	0.3249	8.25246	53.5	0.0983	0.322424	245	150	250 Hz	3060 lbs
1	0.2893	7.34822	42.4	0.1239	0.406392	211	119	325 Hz	2430 lbs
2	0.2576	6.54304	33.6	0.1563	0.512664	181	94	410 Hz	1930 lbs
3	0.2294	5.82676	26.7	0.197	0.64616	158	75	500 Hz	1530 lbs
4	0.2043	5.18922	21.1	0.2485	0.81508	135	60	650 Hz	1210 lbs
5	0.1819	4.62026	16.8	0.3133	1.027624	118	47	810 Hz	960 lbs
6	0.162	4.1148	13.3	0.3951	1.295928	101	37	1100 Hz	760 lbs
7	0.1443	3.66522	10.6	0.4982	1.634096	89	30	1300 Hz	605 lbs
8	0.1285	3.2639	8.37	0.6282	2.060496	73	24	1650 Hz	480 lbs
9	0.1144	2.90576	6.63	0.7921	2.598088	64	19	2050 Hz	380 lbs
10	0.1019	2.58826	5.26	0.9989	3.276392	55	15	2600 Hz	314 lbs
11	0.0907	2.30378	4.17	1.26	4.1328	47	12	3200 Hz	249 lbs
12	0.0808	2.05232	3.31	1.588	5.20864	41	9.3	4150 Hz	197 lbs
13	0.072	1.8288	2.63	2.003	6.56984	35	7.4	5300 Hz	150 lbs
14	0.0641	1.62814	2.08	2.525	8.282	32	5.9	6700 Hz	119 lbs
15	0.0571	1.45034	1.65	3.184	10.44352	28	4.7	8250 Hz	94 lbs
16	0.0508	1.29032	1.31	4.016	13.17248	22	3.7	11 k Hz	75 lbs
17	0.0453	1.15062	1.04	5.064	16.60992	19	2.9	13 k Hz	59 lbs
18	0.0403	1.02362	0.823	6.385	20.9428	16	2.3	17 kHz	47 lbs
19	0.0359	0.91186	0.653	8.051	26.40728	14	1.8	21 kHz	37 lbs
20	0.032	0.8128	0.519	10.15	33.292	11	1.5	27 kHz	29 lbs
21	0.0285	0.7239	0.412	12.8	41.984	9	1.2	33 kHz	23 lbs
22	0.0253	0.64516	0.327	16.14	52.9392	7	0.92	42 kHz	18 lbs
23	0.0226	0.57404	0.259	20.36	66.7808	4.7	0.729	53 kHz	14.5 lbs
24	0.0201	0.51054	0.205	25.67	84.1976	3.5	0.577	68 kHz	11.5 lbs
25	0.0179	0.45466	0.162	32.37	106.1736	2.7	0.457	85 kHz	9 lbs
26	0.0159	0.40386	0.128	40.81	133.8568	2.2	0.361	107 kHz	7.2 lbs
27	0.0142	0.36068	0.102	51.47	168.8216	1.7	0.288	130 kHz	5.5 lbs
28	0.0126	0.32004	0.080	64.9	212.872	1.4	0.226	170 kHz	4.5 lbs
29	0.0113	0.28702	0.0647	81.83	268.4024	1.2	0.182	210 kHz	3.6 lbs
30	0.01	0.254	0.0507	103.2	338.496	0.86	0.142	270 kHz	2.75 lbs
31	0.0089	0.22606	0.0401	130.1	426.728	0.7	0.113	340 kHz	2.25 lbs
32	0.008	0.2032	0.0324	164.1	538.248	0.53	0.091	430 kHz	1.8 lbs
Metric 2.0	0.00787	0.200	0.0314	169.39	555.61	0.51	0.088	440 kHz
33	0.0071	0.18034	0.0255	206.9	678.632	0.43	0.072	540 kHz	1.3 lbs
Metric 1.8	0.00709	0.180	0.0254	207.5	680.55	0.43	0.072	540 kHz
34	0.0063	0.16002	0.0201	260.9	855.752	0.33	0.056	690 kHz	1.1 lbs
Metric 1.6	0.0063	0.16002	0.0201	260.9	855.752	0.33	0.056	690 kHz
35	0.0056	0.14224	0.0159	329	1079.12	0.27	0.044	870 kHz	0.92 lbs
Metric 1.4	.00551	.140	0.0154	339	1114	0.26	0.043	900 kHz
36	0.005	0.127	0.0127	414.8	1360	0.21	0.035	1100 kHz	0.72 lbs
Metric 1.25	.00492	0.125	0.0123	428.2	1404	0.20	0.034	1150 kHz
37	0.0045	0.1143	0.0103	523.1	1715	0.17	0.0289	1350 kHz	0.57 lbs
Metric 1.12	.00441	0.112	0.00985	533.8	1750	0.163	0.0277	1400 kHz
38	0.004	0.1016	0.00811	659.6	2163	0.13	0.0228	1750 kHz	0.45 lbs
Metric 1	.00394	0.1000	0.00785	670.2	2198	0.126	0.0225	1750 kHz
39	0.0035	0.0889	0.00621	831.8	2728	0.11	0.0175	2250 kHz	0.36 lbs
40	0.0031	0.07874	0.00487	1049	3440	0.09	0.0137	2900 kHz	0.29 lbs

Below are the specs of the fan, on the graph it is the red line, VA31-A101-46S:

It uses connector SUMITOMO Code 6010-2802, terminal code 1800-2093.

The female connector we need is 6110-4623 with terminal 1800-2094. You can find in various places including Amazon but I ended up ordering from https://www.corsa-technic.com since they provide the contacts with the housing in addition to listed documentation and a decent price. Truth be told, you should just depin/cut/splice but I'm weird.

FYI, regular female terminals actually fit inside of this connector so I'll be doing this temporarily until the actual connector shows up:

Possible Wires of interest:

B3Xa are the front PDC sensors but only have access to 5 amps if I am reading the diagrams correctly(probably not). E26 is the left fog light which is interesting as a manual switch. E126 is the left headlight. B42b (not shown) is the ride height sensor but I'm unsure if there is usable power
B43a TPM RDC Transmitter is also in this area, but the wire gauge is small.

Headlight:

Spoiler

This seems to be what people first gravitate to.

Connector	Pin	Description	Color
X13420	1		Grey / Brown Stripe	??
	2	Ground	Brown
	3	Signal, low beam	Yellow /Green Stripe	Left headlight
	4	Ground	Brown
	5	Activation, bi-xenon shutters	Brown/ Yellow Stripe	Left headlight Right headlight
	6	Signal, high beam	White / Green Stripe	Left headlight
	7	Signal, parking light	Black / Green Stripe	Left headlight
	8	Signal, headlight vertical aim control	Yellow / Red Stripe	Left headlight
	9	Supply, stepper motors	Yellow / Brown Stripe	Left headlight Right headlight
	10	Signal, LIN bus	Blue / Red Stripe	Left headlight
	11	Signal, headlight vertical aim control	Blue / Brown Stripe	Left headlight
	12	Signal, front left direction indicator	Blue / Green Stripe	Left headlight

What I don't like about these wires is primarily the gauge thickness. All of these wires appear to be aprox 27 gauge

=======================


Foglight:

Spoiler

Connector	Pin	Description	Color
X768	1	Ground	Brown
X768	2	Signal, fog light	Yellow / Brown Stripe	Left fog light

==========================


Ride height Sensor:

Spoiler

Connector	Pin	Description	Color	Connector
X18032	1	Ground Ride height sensor, front	Grey / White Stripe	Ride height sensor, front
	2
	3
X18032	4	Signal, front level sensor	Grey / Green Stripe	Ride height sensor, front
X18032	5	Supply, level sensor	Grey / Brown Stripe	Ride height sensor, front

TPM RDC Transmitter:

Spoiler

Power wire seems thin so it may be able to act as a switched trigger wire.

For anyone unfamiliar with the bi-directional wheel electronics (not everyone has it):

They are mounted on the fender liners. I had to move their mountijng point because I put the cooler exhaust vent here:

Connector	Pin	Color	Signal Type	Description
X18040	1	Brown / Yellow Stripe	RDC_VL-	Ground
X18040	2	Black / Yellow Stripe	RDC_VL+	Positive supply RDS transmitter, front left
X18040	3	Grey / Yellow Stripe	RDC_BUS	Signal, RDC receive antenna

======


===

So it looks like I'll be looking for:

Yellow with Brown stripe fog light override
Black with Green Stripe headlight remote wire for thermoswitch
Dedicated 12v battery wire[/SPOILER]

 

[matreyia]

I used headlight, left. and I leave it on permanently since it turns off when engine is shut off. Add red wire to constant ON connection with inline fuse.

 

[doublespaces]

I used headlight, left. and I leave it on permanently since it turns off when engine is shut off. Add red wire to constant ON connection with inline fuse.

Based on my latest documentation of the RDC Transmitter, I am hoping to find a positive remote wire on Pin 2. Then I'll likely run a dedicated wire to the battery post using a proper gauge power wire. The only power wire I've seen so far that looks sufficient is the fog light and I intend to use it as a manual thermoswitch over-ride instead. The parking/daytime lights wire you are using is only 0.5mm which shouldn't be used for more than 3.7 amps per the chart I listed above. I don't know how many amps your fan uses but mine could see as many as 5.8+ if the fan were to get stuck or seize somehow and go under load.

 

[doublespaces]

Connected the fan directly to the fog light wires for testing:

 

[matreyia]

Based on my latest documentation of the RDC Transmitter, I am hoping to find a positive remote wire on Pin 2. Then I'll likely run a dedicated wire to the battery post using a proper gauge power wire. The only power wire I've seen so far that looks sufficient is the fog light and I intend to use it as a manual thermoswitch over-ride instead. The parking/daytime lights wire you are using is only 0.5mm which shouldn't be used for more than 3.7 amps per the chart I listed above. I don't know how many amps your fan uses but mine could see as many as 5.8+ if the fan were to get stuck or seize somehow and go under load.

I run two fans off the headlight and never had any problem. Not daytime lights...headlights you must turn on to activate fans when temps are reached.

 

[iminhell1]

Based on my latest documentation of the RDC Transmitter, I am hoping to find a positive remote wire on Pin 2. Then I'll likely run a dedicated wire to the battery post using a proper gauge power wire. The only power wire I've seen so far that looks sufficient is the fog light and I intend to use it as a manual thermoswitch over-ride instead. The parking/daytime lights wire you are using is only 0.5mm which shouldn't be used for more than 3.7 amps per the chart I listed above. I don't know how many amps your fan uses but mine could see as many as 5.8+ if the fan were to get stuck or seize somehow and go under load.

If you're using a relay (which you should be), the trigger wire size won't matter ...

 

[doublespaces]

If you're using a relay (which you should be), the trigger wire size won't matter ...

Right, I was trying to avoid running a dedicated power wire. None of them are sufficient besides the xenon and fog lights. Both of which are poor choices as they must be switched on or depend on the sunlight sensor.

The remote wire was a different topic, also I thought he was using a switchable wire as his main power source. Which he is but he's cleared that up as well.

 

[iminhell1]

Suggestion for switch, the help call button in the overhead. It's not good for anything else.

 

[doublespaces]

Suggestion for switch, the help call button in the overhead. It's not good for anything else.

If my car wasn't a convertible then perhaps I'd consider that

 

[BoostedE90]

How much transmission fluid did you add?
Also link to 8AN transmission fittings would be helpful thx!

 

[doublespaces]

How much transmission fluid did you add?
Also link to 8AN transmission fittings would be helpful thx!

I had done a partial flush which involved about 4 liters of Pentosin ATF1. The fittings you can buy from BMP:

Precision Raceworks, LLC

www.bm-parts.com

Their fitting may save you from needing the 1/8 NPT sensor fitting.

 

[doublespaces]

Finished the install today.

The RDC Transmitter lines have varying voltages so they won't work. There is no front PDC on this car but even if there was I suspect the wires are only energized when needed. So I tapped the Parking light wire for a remote source then wrapped it with black tape so it looks part of the loom:


I ran a dedicated 12v source from the battery post terminal up the passenger side, across the radiator carrier, up the driver fender then followed the existing head light harness down to an inline 30a fuse and then to the thermoswitch:


The other thermoswitch wire goes to the relay. I also hooked the fog light wire to the relay as a secondary activation method.

Then I used black tape and cleaned up the rats nest of resulting wires:




Put it back together:


I need a duct still:

 

[Jeffman]

Your transmission radiator cooler and fan setup looks great, Tyler.
But your last photo showing the thermoswitch wiring sticking up inside the fog light grill concerns me just a little. It looks somewhat vulnerable to rock bits, sand, and water etc. You may want to wrap it up as well with a suitable weather-resistant rubbery adhesive tape.

 

[doublespaces]

Your transmission radiator cooler and fan setup looks great, Tyler.
But your last photo showing the thermoswitch wiring sticking up inside the fog light grill concerns me just a little. It looks somewhat vulnerable to rock bits, sand, and water etc. You may want to wrap it up as well with a suitable weather-resistant rubbery adhesive tape.

It hurts me on the visual factor as well. The idea is to re-use part of my existing duct and combine it with some aluminum/sheet metal to ensure the fan is blowing through the fins.

Speaking of the thermoswitch, it never activated so I'll have to double check that I've got it wired correctly. Touching a wire to both of the thermoswitch's pins activates the fan, so the circuit is just not activating at 180 like it's supposed to even at 200 degrees. So after a bit of driving I went and found a parking lot and idled there for some time with the fan enabled. The cooling isn't quick and I'm going to need some ducting/shroud to ensure the fan is blowing air through the fins and not around the side.

Here is 'proof' at a minimum it can stave off 91 degree ambient temps while parked. It started at 198, went up to 199 and fell down to 194. This took quite some time actually but at least I can park the car and not worry about the temps rising continuously.

I'll work on the efficiency of the setup and also test how it performs without the fan on open-road. Theres multiple things I would like to do to improve it's performance but at least it works, more than I can say about my last setup.

 

[Stokes]

@doublespaces couple questions...

1. Are you DCT?
2. Did you remove the factory cooler (not use it in conjunction with the dedicated one in the wheel well) and is that why the fan is required?

I'm looking to reduce DCT Temps on track days and it looks like the non M cars utilize the same setup for dct and auto.

 

[doublespaces]

@doublespaces couple questions...

1. Are you DCT?

Not yet, still 6AT

2. Did you remove the factory cooler (not use it in conjunction with the dedicated one in the wheel well) and is that why the fan is required?

I'm looking to reduce DCT Temps on track days and it looks like the non M cars utilize the same setup for dct and auto.

I have a 6MT CSF radiator and 6MT heater core return pipe (Plastic thing that runs across the subframe) and 6MT coolant fittings for my ADE ST kit. The old transmission cooling system is completely deleted, nothing vestigial.

 

[doublespaces]

The connectors came in the mail:

I also went back in and cinched down the thermal switch as I felt a little bit of oil on the bottom of the fittings. The switch is supposed activate at 180F however in my previous outing it never turned on by the time 199F rolled around so I figured seating it down further should help it give a more accurate reading:

I had a photo of the fan connector all hooked up, however it has managed to disappear although it looks as you can imagine. Fits well.

I needed to burn off some fuel to make working in the tank easier so I went on a cruise and got a chance to do some testing of the cooling system in what my car reported as 91F ambient temps. On the freeway cruising around 70 MPH the cooler works fairly well and cooled the transmission fluid down to 76F without any ducting. The thermostat cracks at 160F and is fully open at 180F so I'm very happy with the result. I'm sure the temps could drop faster with proper ducts despite running into traffic once, here is a graph:

I also did some surface street stop light driving and this time the fan did kick on at about 200F when I was pulling into a drive through and it was off again by the time I got home. I think the trigger point was around 198-200F, which will vary for you depending on installation. While parked without airflow it is capable of halting the temperature from creeping up and it will slowly turn the temps back down.

When I was parking back in my garage it had turned back on and there was quite a lot of very hot air coming from my wheel well. I grabbed a temp gun and a napkin to give an idea of how much hot air was being pushed out:

 

[Jeffman]

Looks like you nailed it, Tyler. Is 176F while cruising your goal?
(And just wondering out loud what is an ideal transmission fluid temp?)

 

[doublespaces]

Looks like you nailed it, Tyler. Is 176F while cruising your goal?

Considering my Tstat doesn't open until 160, anything under 180 and closer to 160 is acceptable. I have not tested this in the 110-115F temps we get every year so I'll have to wait until next year to find out how it handles that.

I'm not done with it yet as I think there are a few things which can be improved.

• Ducting/shroud, since it is just a hole in the bumper there is likely tons of turbulence. The addition of some duct work that also fits around the fan and makes a moderate seal should help cooldown times at all speeds.
• Replace 180F thermal switch with 150F
• Try and find a more efficient core that will fit the given space
• Secondary cooler - I am moving my engine oil cooler in front of the radiator and will be using my 72 row setrab for this purpose. This free's up the driver side location and allows me to add a second cooler in this area. Here is something overly complicated I had thought up:

(And just wondering out loud what is an ideal transmission fluid temp?)

According to a bobistheoilguy thread, they are saying 150-180. Here is a quote from another website:

The ideal fluid temperature is under 175 degrees, but as fluid ages it starts to break down and lose its capacity to cool down the transmission. This is when transmission overheating occurs. At 220 degrees, varnish forms. At 240 degrees, seals start to harden. At 260 degrees, you’ll often experience transmission slipping as plates slip. At 295 degrees, seals and clutches start to burn and fluid forms carbon, at which point transmission failure might happen soon. But with every 20 degree drop in fluid temperature, your transmission’s lifespan can approximately double!

Seems to me once the fluid hits 160-170 there really is no reason to allow it to go higher than this. Personally, I could probably just delete the thermostat but I like to retain full functionality and that includes the reduced warmup times a thermostat allows.

The last test is how the cooler performs while under load and in extended stop and go situations. I don't expect it to keep up simply due to the cooler efficiency and size. This is my primary motivation to add a second one. Some people stick them in front of the radiator since you can easily put one large cooler up there, however I just do not see the point in sending your transmission heat into your engine coolant and oil circuits.

 

[Jeffman]

Thanks for the info, Tyler. I regularly monitor my coolant and transmission temps using MHD. (I have stock 6HP21 / stock coolant setup.). In ~80F dry weather my coolant temps reach steady state 210F in about 10-15 minutes, but I’ve observed the transmission temps take about about twice as long to reach steady while highway cruising, about 20-30 minutes. Then transmission temps equal coolant temps, about 210F...

Based on your bobistheoilguy data, I think one key takeaway is if you have a stock AT Cooling setup like I do, then you should plan to regularly change your transmission fluid (and filter). Mike Miller of BMWCCA tech guru fame recommends ATF changes every 30K miles for the average BMW/driver. I suspect Spoolstreeters like us who “work” our transmissions more than average should probably change the ATF more frequently, like every 15K miles, especially if we have stock AT Cooling. With your setup reaching 180F max your ATF changes can probably be longer.