Transmission cooler-manual
 

Is there any reason for a tranny cooler on a manual transmission? Just wondering because I always see them for autos, recommended for towing, etc, but never see them tailored to manuals. Just curious, really.

I was wondering too.. this being my first manual transmission vehicle.

No, manual trannies don't get nearly as hot as automatics do.

CTB, et al:

Yes, this is definitely a good question that I've wondered about too.

CTB, just based on my gut reaction, I would agree with you. However, but I think it would also be safe to say that both trannies get overheated when towing or hauling large people.

Would there be any harm though if you did install one in a 5 speed? I think for the minimal investment, its a good mod to slow heat/wear and tear on the tranny.

Bob

Bob,

If I remember right, I actually posted this question a while back on the Outdoorwire forum. I think Gadget responded and told me that there was no need to put one on a manual tranny. I do agree with you, too, that it would seem that during heavy towing/hauling the tranny would benefit from being cooled. However, I'm not even sure how you would hook one up on a manual tranny. Maybe someone else will be able to chime in on this one??? Then you and I will know for sure.:D

CTB

Ever try to move cold gear oil through a narrow passage? It takes a lot of force. Much more than auto tranny fluid which flows as easily as water, especially before it gets to operating temp.

Its really not practical to try to cool gear oil with a radiator type oil cooler the way automatics are. Gear oil is very thick and sticky and dosen't flow freely like auto tranny fluid. If you look at your manual tranny, it has fins on the outside to increase surface area and dissipate the excess heat into the air. This is all you need to keep your gear oil at proper operating temp, not too hot, not too cool. The oil has to be hot to work effectivly.

Most of the heat in auto tranny fluid comes from the tourque converter which a manual does not have. Towing increases this heat dramaticly but still, it comes from the tourque converter which is really just like a fan 'blowing' fluid onto a windmill that drives the gears and driveshaft. The tremendous friction in this process is what cooks auto tranny fluid. Unless you always drive with the clutch half engagued this friction and heat does not occur in a manual transmition.

In order to fit a radiator type cooler to a manual tranny you would have to come up with some sort of pump that is strong enough to push the thick sticky oil through a bunch of skinny hoses to a cooler where it will get even thicker and stickier before it returns to the tranny. Such a pump would rob a lot of power from your driveline. Also you would have to drill and tap holes in your tranny or drain and fill plugs to fit the hoses. There are too many ways for such a system to leak or fail and it will over-cool and thicken the oil reducing efficentcy.

FYI NASCAR teams use manual tranny and differential coolers and pulley driven pumps but run free flowing oil in them that is more like motor oil than normal 75w-90 or similar gear oil. Also they change trannys and diffs and the oils every week. It won't work.

hallo mates :

yes - trying to revive an old post .....

anyone further this investigation - as I am about to replace an LT77 Gearbox on a Land Rover due to heat - desert heat - will replace with an updated R380 that comes with ( in Military /WOLF ) cooler hookup

I do have a BJ60 with H55F - like to look into cooling this as well

and a RN67 /85 pickup 2LT - all desert dwellers - especially now that money is tight - like to know my rebuilds will last long time - lots of hills and mountains to climb

cheers:

Ok guys ... let's think about this one again...

Automatic transmission is Hydromatic (powered by moving fluid)

A pump shoots fluid around in there, and spun by torque converter so with constant moving (friction) it heats up.

Manual Transmission is stationary and rotational. Air cooling is more than sufficient even towing because there are moving parts, but not the same as automatic.

If you installed a cooler on a manual transmission EVEN if the fluid was light weight enough like water, you'd need a pump also to move it through the cooler.
Hope that makes sense to some people. ask questions on more specifics if you want.

The only manual tranmission coolers I've ever seen were on rally (Alltrac Celica) cars, which see much higher speeds than our trucks.

Auto transmissions by their very design make the fluid very hot. All automatic transmission vehicles have a heat exchanger/cooler.

Manual transmissions on our trucks are simple gearboxes, and when they're in 4th the torque doesn't even run through any gears, so there isn't much heat generated in the unit at all.

If you're really curious, simply put a temp gun on the transmission case after climbing a big hill in 4th gear. If it doesn't go over 200F you have nothing to worry about.

I put a cooler on my 5 speed, together with the internal combobulator it keeps it almost ICE cold even in the hottest temperatures with the steepest hills.

hallo mates :

Good points all - yet I will bring your attention to the temps I am getting here in the Desert - The heat off the pavement is enough to cook Bio Diesel in my tank to tacky goo ( over weeks )

Just taking from Land Rover Military R380 gearbox - the cooler is just an escape for high temp oil too cool -
and considered

Say XJdubber :

tell me more of your combobulator - and which gearbox you have - how you thread the lines

the R380 from Rover has these in the case - not sure of Toyota Gearboxes

cheers:

I cannot discuss the combobulator at this time as it is in it final pattending process.

On a serious note. Under almost all conditions manual gearboxes do not have to be cooled. Yours being a bit unique with high desert temps, i would look into diffrent oils to run in you tranny. you might want to go to a higher viscosity and take a look at the temperature the oil can take.

They make oil coolers for rear ends........if you needed one, why wouldn't you put one on........it can be done

xjdubber :

I hope we get to see the final patented version soon

and Right On TubedYota- extreme conditions warrant extreme measures

I figure on the Rover - full time 4wheel drive - small gearbox - always under load - why not look to see if I can do this with my Toyota's -

cheers;

Combobulater? My 145k 5-Speed w/ 75-90 Weight Synthetic shifts like crap when its cold and like a dream when it warms up, which I think is primarily from being connected to the clutch and engine.

I wouldn't want it any colder but if you were to cool a manual I would think you need to look at cooling the clutch, especially in off-road stop and go situations. I don't think there is anyway to cool a clutch other than driving habits.

Say mpavolka :

Have you thought maybe try synthetic slushbox ( automatic ) fluid instead of such a heavy weight gear oil - may save your syncro's

Agree with you on the clutch heat - so far no warpage that I can tell - or seen - until I drop gear and tranfer box to repair rear main and install new clutch - but does not feel like - I will say shifting is odd at times - for me its more about the summer months with the extreme's - pavement temps can breach 60º c and the truck is parked for days

cheers:

Manual transmission cooler
 

If you think about it, the concept is no different than that of a dry sump system on a race car for engine oil. The system has a oil heater on the holding tank, you set it up to keep the oil at a safe opperating temp at the holding tank, but the air flow takes the additional heat out. Parts needed: oil lines, a good 3 stage oil pump, holding tank, oil heater, AN fitting:welder:

Manual transmission cooler
 

pump.:welder:

Good way to add a new failure point (or multiple failure points) on a system that doesn't require cooling.