trans temp

Kev · Post by **Kev** » Tue Nov 20, 07 4:58 pm

In the back of the sump

Blue · Post by **Blue** » Tue Nov 20, 07 5:21 pm

Err, the Trans. sump that is...

MrNorm · Post by **MrNorm** » Tue Nov 20, 07 7:42 pm

I would say you want to measure the hottest it gets, which not knowing the internals of a 727 I'm thinking would mean either the output line or the sump (assuming the fluid drains there once out of the torque converter??). Some people say on the input side (say after the cooler) to check it's doing it's job, but my rationale says you don't care how cool it is going in, you need to make sure that when it is inside the TC it is not getting too hot - so on the output side seems logical to me.
If the input line feeds the sump that would count against putting it there according to that logic.

Having said that, lots of things seem logical to me that might not be

- so I would be inclined to listen to the transmission master (Blue) or maybe even Kev

(just kidding Kev - you rock). In which case.....is there a flaw in my logic or is the sump the hottest part??

Dave-R · Post by **Dave-R** » Tue Nov 20, 07 7:50 pm

The temp of a sender in the pan tends to reflect the overall temp of the transmission. Not just because of the oil temp in there but also because the actual metal of the pan is heating the sender body.

Trying to second guess what the max temp is in the oil at any particular point is pointless. You still have no idea what the temp is, for example, on the friction surface of the clutch plates.

The best temp for a trans is as cool as possible. Simple as that. The cooler you can make it the better. If you can hold it down to 180 degrees (same as the engine) then you are doing alright.

MrNorm · Post by **MrNorm** » Tue Nov 20, 07 8:00 pm

My point is that knowing how well the cooler is doing or what the fluid temp going in is tells you nothing about how hot it's getting inside the trans - and THAT is what kills a transmission. I'm assuming the hottest fluid is out of the converter, but maybe it is out of the clutches, depends on the fluid flow about which I am ignorant

So to my logic, ideally the peak fluid temperature is what you want to measure, as beyond a certain temp it breaks down and that spells trouble, below that it's OK. What I don't know is how practical it is to measure that hottest temp. If it's impractical then it could certainly be that the sump is the best shot you get, in which case that is where I will put mine!

Sure, if the fluid going in is cool you could probably infer that the temp rise will be acceptable, esp if you don't have a radical converter, but given a choice I'd rather measure than infer.
Without a choice......well you don't have a choice

Kev · Post by **Kev** » Tue Nov 20, 07 8:26 pm

My theory;
Stick it in the sump then do normal driving duties, up and down, all around and observe the temp of the trans. Race and check temp, before and after. Use your readings as a comparitor. If your temp after a run is high, you've got some slippage etc etc. Blue was telling me some mad figures about the temps involved with transbrake applications. I'm sure he will be along anon!!

Kev · Post by **Kev** » Tue Nov 20, 07 8:28 pm

Gavin wrote:so I would be inclined to listen to the transmission master (Blue) or maybe even Kev (just kidding Kev - you rock).

Thanks Gav! But I'd rather have the top tech at QuikFit do me exhaust than the apprentice!!!!

Anonymous · Post by **Anonymous** » Tue Nov 20, 07 11:39 pm

Kev wrote:
Gavin wrote:so I would be inclined to listen to the transmission master (Blue) or maybe even Kev (just kidding Kev - you rock).
Thanks Gav! But I'd rather have the top tech at QuikFit do me exhaust than the apprentice!!!!

Don't be so hard on yerself Kev.

BTW , Gasser is reffereing to a power glide.

Kev · Post by **Kev** » Wed Nov 21, 07 12:03 am

So he needs a Neanderthal Trans, they still get hot

Dave-R · Post by **Dave-R** » Wed Nov 21, 07 9:26 am

I don't know why you guys think the trans temp is so critical?

Trans oil can take a lot of punishment.

The issue here is longtivity.

A colder trans will last a lot longer. A hotter will wear out quicker.

But even a hot trans (220F) will last a very long time.

As long as you get the trans temp down to below 200 (colder the better) it will be fine.

What you need to look for is changes in the regular temp over time. That is an indication of things not working right. The actual temp is neither here no there.

No need to be a fanny about it. Just stick a sender in the pan and be done with it. I can tell you from experience that any changes in the trans WILL effect the temp with the sender there.

Kev · Post by **Kev** » Wed Nov 21, 07 9:40 am

What you need to look for is changes in the regular temp over time. That is an indication of things not working right. The actual temp is neither here no there.

Precisely!

Cannonball · Post by **Cannonball** » Wed Nov 21, 07 12:11 pm

Dave wrote:I don't know why you guys think the trans temp is so critical?

Trans oil can take a lot of punishment.

The issue here is longtivity.

A colder trans will last a lot longer. A hotter will wear out quicker.

But even a hot trans (220F) will last a very long time.

As long as you get the trans temp down to below 200 (colder the better) it will be fine.

What you need to look for is changes in the regular temp over time. That is an indication of things not working right. The actual temp is neither here no there.

No need to be a fanny about it. Just stick a sender in the pan and be done with it. I can tell you from experience that any changes in the trans WILL effect the temp with the sender there.

perfect answer dave, people get to confused by all the differing thoughts on transmissions, most transmissions fail because off a breakage or it being badley set up in the first place , not through heat