Anyone else overheating their Differentials?

[Ronald So]

Does anyone have any issues overheating their diffs? I've blown one up at the track already. Yesterday, all I could smell is my rear end overheating. My last one had a case that was finned but that wasn't enough.

I've purchased a tilton pump. So looks like I have to put this thing together now.

[Matt93SE]

What diff, what tires, how much power, what fluid?

[turtl631]

Stock euro S14s have a diff cooler, I'm curious what prompted Nissan to add it. I know folks on here have had no issues with just a finned stock Nissan cover and countless track days.

Clutch diff?

[Def]

The popular thing to do in Europe that I've heard with their S14s is to ditch the stock diff pump since it never runs in most cars (comes on at some super high temp), and the lines tend to leak over time.

My HLSD 4.36 hits about 170-190 deg F on the rear cover (infrared measurement) in 100 deg F ambient temps with ~300 rwhp and RA-1s. This is a J30/NA Z32 finned cover, Redline 75W-90NS.

[Ronald So]

Def: advan A032r, v8 350tq, 4.11 clutch with redline or purple

I can only believe it was a necessity for the euro to put it In. I know the ztune r34 package includes diff and tranny coolers. I just don't believe I'm the only one suffering these issues.

I'm going to tap and put a thermostat to activate the pump and see what happens the next time I go out.

[Tower240sx]

I always figured the euro's got it because of the Autobahn potential, I know alot of the 350Z's in FD use diff coolers and pumps.

[Def]

The reason you're having a problem is the clutch type diff. They generate a ton of heat since all biasing is done via kinetic friction all of the time (a helical biases only when you're on the power).

A diff cooler might be worth it, but you could probably get away with a larger capacity cover. I've also thought a small "scoop" to duct more air across the lower fins would help as well. There's a bunch of crap on the diff ahead of the rear cover that really disturbs airflow.


The little bit of reading I've done on SXOC makes it seem like the S14 diff cooler is just a marketing gimmick, and they were removing them left and right because they never ran, just leaked oil eventually.

[Rezlo]

All our S14’s in South Africa have diff coolers (they all euro spec), they are there for high speed highway use more than anything else, I could not get it to turn on with my T04z RB25 for love or money till one day I did a long road trip (in a hurry) and was maintaining 160-170mph for 30 minutes odd, when pulling into my destination I could hear the pump running while slowing down and the cooler was so hot I could hardly touch it.

If you look at how they set the pump up it will only come on over X amount of speed and only at very high temps, it could only prove further that its for higher speed continual usage as noted earlier.

Ive never seen one leak and most of the time when I service the diff’s the oil in the cooler and pump is brand new, never been circulated.

Now that my race car has a helical diff, I converted the diff cooler to be a trans cooler, works well.

[BeerBringer]

The reason you're having a problem is the clutch type diff. They generate a ton of heat since all biasing is done via kinetic friction all of the time (a helical biases only when you're on the power).

A diff cooler might be worth it, but you could probably get away with a larger capacity cover. I've also thought a small "scoop" to duct more air across the lower fins would help as well. There's a bunch of crap on the diff ahead of the rear cover that really disturbs airflow.


The little bit of reading I've done on SXOC makes it seem like the S14 diff cooler is just a marketing gimmick, and they were removing them left and right because they never ran, just leaked oil eventually.

Euro S13's also have them.
Both me and my brother (s13 & s14) has had ours running judging by the amout of oil in the lines and cooler.

Alot of people remove them as the lines usually are dry = the pump has never been runing. I've never heard anyone having problems with leaks. And in that case it's as simple as changing two rubber hoses.

[Matt93SE]

A lot of the GT club race guys add them. There was a guy last month looking for a new OEM pump to use (which are several hundred bucks, btw.)

I don't know if there's room, but you could always do it NASCAR style and have the pump belt-driven off the driveshaft. They're a LOT cheaper than the electric pumps.

As for using the OEM cooler, my thought is to either install a thermostat or just run it to a switch + relay and you can turn it on at will.

Road racing with slicks and a clutch type diff will usually require diff fluid changes every other race or so- I've got a friend that runs a NISMO clutch type 4.6 on his ~200whp car and he's seen temps of over 300F in the past. change the fluid and everything is still happy.

he said the ONLY fluid that lasts without overheating and turning to godawful stink is Royal Purple.

Just FWIW.

[Ronald So]

A lot of the GT club race guys add them. There was a guy last month looking for a new OEM pump to use (which are several hundred bucks, btw.)

I don't know if there's room, but you could always do it NASCAR style and have the pump belt-driven off the driveshaft. They're a LOT cheaper than the electric pumps.

As for using the OEM cooler, my thought is to either install a thermostat or just run it to a switch + relay and you can turn it on at will.

Road racing with slicks and a clutch type diff will usually require diff fluid changes every other race or so- I've got a friend that runs a NISMO clutch type 4.6 on his ~200whp car and he's seen temps of over 300F in the past. change the fluid and everything is still happy.

he said the ONLY fluid that lasts without overheating and turning to godawful stink is Royal Purple.

Just FWIW.

Well its good to know that the club racers are having these issues. The belt powered stuff would be a little more complex then what I want to build. Plus I doubt there is room down there. I have a Tilton diff pump I bought a little while ago. I just need to find a decent cooler.

[Matt93SE]

Any metal cooler with slip-on hoses will do the job. the OEM one is tiny- like cigarette pack size tiny. you should be able to find a small power steering cooler with hose barb ends for like $25..

[Rezlo]

the euro diff cooler setup, about the size of most large power steering coolers, about 4"x10"