The on Project84 posted above is for a GSL-SE (13B).

It's also extremely similar to 12A cars that had the front mount oil cooler. (79-82)

 

Ok, I found the pressure in the automatic tranny for a 2nd gen slug-o-matic.


pressure (psi)

Range Idle stall

D,1 43-57 129-157

2 114-171 114-171

R 57-100 229-272

So tranny pressure is higher than engine oil pressure.

 

Air doesn't even contact the trans cooler. The trans cooler is entirely encased in the lower radiator tank.

 

Okay so tranny pressure is greater than engine oil pressure.. but still, the water-oil cooler for the 12A is a pile of crap in itself.. what do you think a small *** thing inside the end tank of a radiator will improve on it?

 

I thought the ATF came in contact with air. Perhaps a real oil cooler (air/oil type) would be better.

 

I thought the ATF came in contact with air. Perhaps a real oil cooler (air/oil type) would be better, kinda like the one in the pic I posted above.

 

double post

 

Actually, it's not unless you have a thermostat. Cold tranny fluid doesn't work too well.

That's why when you plumb in an aux tranny cooler (air-oil) you plumb it in BEFORE the radiator's cooler. That way you don't risk overcooling.

 

Go Away.

 

who are you talking to there alex??

 

okay wait...im confused i think.......why is the oil filter on the back of the engine better than the top of the oil cooler?

 

Ah... a moderator who knows what he is doing, and doing it well.

It's not.

 

Acctually ATF is a pretty "stable" fluid. It's pour point is way lower than any oil you would put in your engine. At 0 deg F ATF has a SUS of 650 while a straight 10W has a SUS of 10,000 @ 0 deg F. For those that don't know SUS = Saybolt Universal Seconds. SUS is the amount of time it takes for a set amount of fluid to pass a set size orifice. So basicaly don't even worry about your transmission temp (unless it gets over 140 because thats when ATF starts to break down and varnish).

Back when I was in school for fluid power my instructer told me that his 1982 S-10 had the same ATF in it that it had when it left the factory and has never had any transmission problems in the 260,000 miles that he put on it. He sold the truck to his neighbor back in 94 when he bought a new truck, the old S-10 is still running around he says with god knows how many miles on it. The trick to making a auto trans live is to keep it clean and to keep it cool, thats it. After he drove it home from the lot back in 81 when he bought it he installed a small 10 micron oil filter inline with a cooler that was not run through the radiator. The cooler was mounted under the truck with a small fan mounted on it to turn on at 120deg F.

 

ATF isn't just a lubricant, it's also (mainly) a hydraulic fluid for the valve body (which is really a hydraulic computer) and it also has to either assist, or ar least not hinder, the clutch packs and bands.

Too hot is definitely bad but cold fluid isn't too "hot" either

 

considering the radiator cap is ~13psi-15psi..I think 70psi oil would damage your radiator. ......

The ATF pressure from the tranny is much lower pressure the engines oil I believe.

If this was such a good idea, there would be many cars out there aready with this mod...

 

haha, you ever do stand up?

True, very cold transmission oil isn't the best (nothing likes to work well when it's -30 outside). I guess my point was that you shoulden't have to "warm" up your transmission because by the time your engine is warm the transmission is more than ready to get to work.

 

lol, where did this come from?

Time to take cars 101

 

I'm not quite sure how to repond to this...

 

Is somebody still thinking you run atf through the part of the radiator that uses the 15psi cap?

 

I stand corrected, what pressure do those cooler lines allow?

 

Not sure how the JATCO tranny operates, but normally (aka American automatics) the tranny fluid that goes through the cooler isn't under much pressure at all. The pressure bled off of the pump is routed through the cooler - it's not like the oil cooler where ALL oil flow from the pump goes through the oil cooler before it even gets to the engine.

 

Okay:

In a manual transmission, there's just gear oil. This is sealed in the tranny and doesn't touch the clutch, etc (if it did the clutch wouldn't work, as it relies on friction) The purpose of the gear oil is to cool the gears and keep them lubricated on their respective shafts.

When you press in on the clutch on a standard tranny, you're disconnecting the engine from the rest of the car. The gears in the tranny aren't moving at all.

When you let the clutch out, but the tranny is in neutral, none of the gears in the tranny are engaged so the shaft connected to the clutch spins, and the gears on it spin, but don't touch anything else so there's nothing moving the car.

An automatic transmission isn't simply a manual transmission gearbox with an automatic clutch (though there are a few "semi-automatics" that work that way on high dollar cars, we'll discount those from this discussion so as not to confuse things)

An automatic tranny is connected to the engine not by a clutch but by a torque converter. Inside the torque converter is something resembling a boat propeller (some say 'fan' but we're dealing with liquid, not air) on one side and blades attached to the inside of the torque converter on the other. When you're on the brake, not the gas, one side of the torque converter is whirling around pushing the automatic transmission fluid
(ATF), and the fluid moving around tries to turn the blades on the other side, but the pressure you're putting on the brakes of the car prevent the weak pressure from the blades moved by the idling engine from succeeding.

This is why, in a standard transmission if you let off the brakes on a flat surface the car stays still, but if you let off the brakes in an automatic it creeps ahead at about 4 MPH - the torque converter is trying to drive the car with the idling engine.

When you step on the throttle and increase the engine RPMs, you increase the speed of the torque converter revolutions. This increases the pressure of the ATF and makes it push harder on the other propeller blades, making the car go.

Pressure keeps increasing as the ATF flows through the transmission. When the pressure reaches a set level it 'shifts' by disengaging a clutch band around one set of planetary gears, and engaging a clutch band around another set.

They're called planetary gears because a group of them (usually 3 or 4) circle around a central, or sun, gear like planets orbiting a sun. There's one set of sun/planetary gears per 'gear' in your automatic tranny - 3 in a 3 speed, etc.



so as you go faster and faster it 'shifts' by engaging one set and disengaging the other, then at the next preset pressure threshold it'll do this again until maximum gear is reached.

All this increasing pressure of the ATF, which, as mentioned in another post is acting as pressurized hydraulic fluid, makes it get very hot. So the fluid is them pumped into a cooler and back into the tranny.

I've simplified it somewhat, but I hope that at least gives you an idea of what's going on in there and why pressurized ATF gets so much hotter than non-pressurized gear oil in a standard tranny.

 

Now THAT is technical!

 

my god , if i could cry i would....that was perfect i understand so much more now.....it makes sense!!! haha manntis, once again your up on my cool list

 

okay ... manntis, i actually got the stuff you said in the last post, and it make the automatic clearer to me now (still wouldn't want one, but i don't mind knowing how it works)

one question though, what is the stall speed? what does that describe?