Manual Transmission Cooler

[Howdy]

Just wondering if anyone has set up a manual transmission cooler or other cooling options for the nissan boxes. Mine is getting to 250F (121C) so I need to try and lower the temp somehow. I have already lagged the exhaust where it runs beside the gearbox which made a difference to how fast it gets there but I reckon it is still too high. I use Nulon 85w140 which is a GL-5 oil and the box is an SR20 with PPG helical dog set 1-4 and std syncro 5th. Any advice / experience regarding cooling set ups or additives to reduce friction is welcome. Thought some of you Guys with under trays might have temp issues?

[260DET]

Tried a lighter weight full synthetic oil?  Talk to Penrite, see what they say.

[Howdy]

Thanks Richard. I have used several good brands in the past but seemed to blow more boxes (Z, SR, FJ, RB-na), mostly the counter shaft drive gear, and 3rd gear. I think part of the issue is that if it is too thin it pools at the back end too easily even using center plates with the one way trap door. It would also blow out the breather when hot. I have been using this oil for some time now with much (and I mean a huge MUCH) better results, especially trying to keep the std syncros from snatching when the oil is hot and revs are high. In saying that, I might try the Motule competition 75w140 as synthetic might be happier at the higher temps.

 

Do you think lighter oil would not get so hot?

[260DET]

Heavier oil takes more energy to move around and most of the extra energy used is converted to heat. Definately use synthetic, gearbox and diff, 120* is OK for synthetic but getting a bit hot for seals etc and comfort, problem with the Zed is you sit right along side the hot gearbox and they get hot even in ordinary use. 

 

Last time I spoke with tech at Penrite I got a proper tech bloke who was involved in formulating their oils, great info from him. 

[dat2kman]

Richo, the racing expert!

When we ran the rally Z in mid '80's, we welded a second threaded boss below the stock fill to this level boss, as the bottom drain outlet was pitentially able to be broken or bashed flat, used hi temp 1/2" id hose, into a Jabsco brand hi-temp capable pump,then into a cooler up front.

It was manually controlled once it got hot, as coolish oil was very slow moving and the pump strained.

Did a diff cooler setup the same, that pump really struggled, until hot.

Had theooler core tucked up on LHS behind halfshaft, with mesh guards.

Car was used in Rally Australia, and then went on to win the NSW State Rally champs

We also ran long breather tube up into engine bay, with a basic plastic fuel filter to stop sucking in dirt/water etc at creek crossings.

Diff breather, a hose up through floor pan, a pladtic filter, and vented to fuel filler door.

 

We basically copied what the Nissan Group A race cars were doing, but no need to use expensive Aero type hoses, as it was all protected by bash plates.

Gearbox didn't really seem to benefit, but the diff especially on long 40-60 km dirt sections, very much helped, as the LSD would go "loose"

[Howdy]

Yep it really gets hot inside my car like a sauna, having no insulation probably doesn't help. Will definitely go to the Synthetic but higher viscosity this time.

 

Great info thanks Dat2kman, I too run the breathers up high and use a fuel filters to separate the oil and filter the incoming air when it cools down. So you returned the oil to the top filler hole in the front of the box? One of my concerns was returning to the front might starve the back but I suppose it is coming from the front anyway. I'll have to look into that Jabsco pump. I was considering returning the oil to the top over 3rd & 4th gears. The diff does get incredibly hot and I have avoided measuring the temperature because I'd need to do something about it then. It's a CIG locker so none of those issues with the plates slipping but I know what you mean as I used to run one.

[260DET]

I've thought a few times about if it was possible to catch oil thrown high inside the box/diff and then have it drain by gravity through a radiator back into the box/diff. Be a lot of messing around though to try it, a lot of messing around, much simpler to use a temp switch operated pump. Running the pump cold would delay warming up the oil.

 

Just got a Euro spec finned diff cover for the project car, it has two sensors, one for a gauge and one to switch a pump. I'll run the gauge first to see what temps the diff gets up to before doing more. But as I'm not a fair dinkum racer it will probably be OK

Edited March 28, 2017 by 260DET

[Howdy]

If you have decent power it will get hot during a 15 or 20 minute track session, but so far (touch wood) I have never had issues with diffs except the spider gear pin drifting out and seals leaking which I guess could possibly be heat related.