What are the ideal temps for our differentials. I am starting to build an diff cooler for my car, I have the nismo diff and finned cover. I want to install a temp. switch to turn the pump on once it gets warm. Just curious what temps do I want the pump to kick on. Thanks again.

 

The ideal temp for a gear oil would be between 90-110 degrees C. If you trigger it to come on at 200 degrees F you'll be good.

Typically my pump/fans turn on after about 7-8 hard minutes of lapping. This is with a 1.5way clutch type diff and racing tires.

 

Thanks, what setup do you have. You own or a kit and do you have pics. I want to start piecing this together doing the winter and put it on in the spring for the track, appreciate all the help.

 

That sounds way too high. Gear oils break down at temps over 200ºF. I'd think you want it to come on around 150ºF.

 

200 F they break down? They are that much weaker than engine oil?

It does seem unnecessary to let the diff get that hot though.

 

Yeah, when you consider that engine oil coolers start off at 180 in most systems, and the fact that diffs like to be at slight lower temps I would say use the 165-180 range. I would guess with cooling starting at that point max normal operation temps should be in the 190-210 range (and spiking to 220+ under tough and high load operation) with proper air flow.

 

I live in California so a temperature switch is not needed. This is also a deticated track car. We run 30 minute sessioins also. I had a Borla Exhaust and plan to cut out the the rear canister. I plan to build a frame to mount the heat exchanger, pump, oil filter and monitor. This will then be hung from the mounting points the heat shield was mounted under the tire caring area.
I am in the process of getting the mounting frame built by a local fabricator.
$1000 so far for all hoses fittings and parts.

Plane to have temp guage then the filter, next the heat exchange then pump.

By the way the threads to attach to the case is 18mm.

good luck with your build. We should compare notes. I will take pictures.

 

Keep us updated, I want start working on mine for at least a month or 2. It was 15 degrees today. I will get some pics up when I start my build

 

Guys,

For a good synthetic gear oil, that is no trouble at all. If you're using mineral based oil based on your limited slip manufacturers recommendations, then I could see you having some problems - but even at that point I doubt it.

I've got my motec opened up so I can tell you EXACTLY what my diff oil temps look like. here we go:

In the middle of a 3hr endurance race (on a rather cool day actually) the diff temp stabilizes at 108 degrees C, which is 226 degrees F.

During qualifying or a sprints race, the differential temp climbs up from 50 degrees C (122F) to 85 degrees C (185F) over the course of about 8 minutes - at which point the session ended.

So basically, if you're only running 10 minute sessions you don't need a diff cooler. If you're running longer than that it would be a good idea!

Our diff cooler setup is custom and very easy to make. A setrab core, a tilton oil pump or similar, some lines and welded -6 bungs to the fill and drain plugs is all you need!

The process to fill the system is as follows:

Fill the diff until fluid comes out of the inlet fitting (which is the return line from the cooler system).

Run the pump with this line off (the return from the pump/cooler) until fluid flows consistently - now cap the line so it doesn't siphon out.

Re fill the differential through its the fill port until fluid comes out and re-install the line quickly, avoiding a big mess!

Now the fluid level at the diff is the same as OE, while the cooler, lines and pumps are all full with fluid.

 

I run 30 minute sessions and as the afternoon temperatures build I start spitting out and fluid. I have found that I burn the Mutol systhetic 75-90 oil as with Royal Purple,and Red line. I am just forced to go to this cooler. I run a Nimo rear diff. This problem has gotten worse as my times have reduced.

 

For sure, as grip increases and power increases (and driver improves) diff temps will go up up up!

If you want to avoid the cooler you can install the nismo diff cover and install a vented overflow bottle on the breather. It keeps the mess off the back of the car

Of course, a diff cooler is the right way to do it!

 

Having a hard time finding a switch for those temps. Anyone have any other ideas for a good way to kick the pump on or switch ideas

 

I have a touring with heated seats so I am planning to use one as the switch for the diff pump. I will also have a temperature sensor on the drain side of the diff to monitor temperatures. Adding a dual guage pod on the "A" pillar. I will also monitor engine oil temperature.

 

M18x1.5 to be exact...

C Ray Z - please post up some pics.......even now of your car, thing sounds like a beast....would definitely love to see pics of this pump set up and mounting....

-J

 

So you don't have a temperature switch kicking the pump on? You are physically watching the temps and manual turning the pump on. I was looking for a temperature switch to put in line with the pump and once it reached the correct temperature it would kick the pump on itself. A regular switch I can find, just not the correct temperature switch

 

I have the benifit of living in Claifornia so our minimum temperatures are maybe 50 degrees in the fall and spring so I don't have to be real careful for low temp starts. I do plan to run one session of warm up then ingague the pump for each session after that because we only have an hour between sessions and a race on our last session.

 

I wonder if an HKS Fan controller would do the trick for you guys.

You could use a coolant temp sensor in the differential, so the fan controller would act as a temperature display as well as a switching mechanism.

Hookup the pump (and fans if you have any) to the fan control output and you have a really clean install that works with a mostly stock car.

If you have an aftermarket ECU you should be able to easily do it through an input for diff temp and an output for a ground switch that would be used to trigger a relay.

It's funny this thread came up because I'm actually re-doing the diff cooler in my racecar now, mounting it inside the trunk to vent out of the license plate area - reasoning being I'm working on a flat bottom that would eliminate all the flow under the car.

I'll get some photos up shortly

 

heck ya! pics or ban dammn it............LOL j/k....

no but for real

-J

 

I dont think they make the fan controller anymore though

 

That's a shame! Perhaps there are still some floating around. Anything else that displays temp and has a switching mechanism would do though!

Here's a picture of the new cooler mounting, it's not all done but should be ready in a few days. The aluminum welding came out really nice, I'm happy with that. My aluminum welding skills a few months ago absolutely sucked!



Here's a photo of the old diff cooler setup. It's a simple clean design where the cooler was mounted under the floor, and the pump attached to the subframe. Two bilge fans (used on boats to clear exhaust gas) are used to promote flow through the core, since it's not getting much from under the car (very turbulent back there)



The new system will be fed from naca ducts through the rear quarter windows as well and I will start with the fans still in place just to be totally sure there is more than enough airflow through the core. Hopefully they will be more of a restriction than a help and I'll be able to remove them shortly after testing!