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-   -   diff & geaqr box temps (https://www.rx7club.com/race-car-tech-103/diff-geaqr-box-temps-561816/)

dgeesaman 09-15-06 11:14 AM

I would contact KAAZ and see what they recommend.

It's possible that the oil in there now is too thin, causing scuffing wear that a thicker oil may prevent. The tradeoff is the thicker oil will eat a bit of power and it may run hotter. Cooling the oil wouldn't fix this situation.

Ideally, I would pull the axles, remove the diff, and evaluate which gear surfaces are doing the wearing.

Dave

KevinK2 09-15-06 11:45 AM

It's all the rubbing contact, vs just rolling teeth contact, that shear the diff oil, create heat, and blacken the oil. And it's more than just the worm gear friction.

http://www.sonic.net/garyg/zonc/Tech...ferential.html

With no friction, a manual trans will work great (except syncros), but a torsen would act like an open differential.

An open spiral bevel gear runs hotter than a trans ... that's why GL4+ gear oil is used to control sliding mesh friction and take the heat. But a Torsen, on a track will create more frictional heat.

sdminus 09-15-06 12:21 PM

The KAAZ is new. I have only just ran it in. The oil look good when it came out but i had only done figure 8's with it and a little driving about to run it in.
The whole set up weighs very little i would guess at maybe 5 kgs max

Scott

KevinK2 09-15-06 04:20 PM


Originally Posted by DamonB
.... I also wouldn't bother to worry about cooling either until I knew I needed to cool them.

Good point. I have used temp-lables in the past on IC piping. Just need a smooth surface on the diff (or trans).

http://www.mcmaster.com/ctlg/DisplCt...RelatedCtlgPgs

Tke Kaaz diff is also friction based. No heat issue when locked on a drag strip, but powering through long fast corners will really heat em up. Open diff's on other cars I tracked never blackened synthetic oil like the Torsen did.

sdminus ... that oil cooler looks a bit small. I recall a local nissan race team that used a diaphram type pump on the rear differential.

sdminus 09-15-06 04:24 PM

I am now looking to make a transistion from drag strip to circuits I want the car in the best shape to combat this. I will measure the cooler after the weekend to see what you think. The pump is a piston pump.

I opted for the whole thing becasue it was as cheap as a thermo couple. £20 delivered.

Thanks for the commets etc. Its much easier with more input.

gnx7 09-17-06 01:21 PM

How long will the typical road race session be? If it is under 30 minutes I don't think it is as critical to cool down the diff or even the trans. For endurance racing that is another story.

sdminus 09-17-06 02:24 PM


Originally Posted by gnx7
How long will the typical road race session be? If it is under 30 minutes I don't think it is as critical to cool down the diff or even the trans. For endurance racing that is another story.


ITs gonna be less than 30mins, howeva i plan to do lots of suspension/aero development with the help of a GT3 driver and some good contacts. So the car could be getting lots of abuse for sustained periods.

This is going to be a good experiment. I guess it will give a good inication of its nescesity.

Scott


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