Australian Politics Forum - Automatic transmissions

Jest Gold Member Offline Australian Politics Posts: 1399 NSW South Coast Gender:	Re: Automatic transmissions Reply #15 - Oct 5^th, 2020 at 11:01am aquascoot wrote on Oct 5^th, 2020 at 10:40am: good post valkie Yeah great clip Valkie. I even subscribed. The guy is quite the card
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Sprintcyclist

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Re: Automatic transmissions
Reply #16 - Oct 5^th, 2020 at 11:08am

Valkie wrote on Oct 5^th, 2020 at 7:27am:

All oils degrade over time.

All transmissions cop a hiding.

The biggest enemy of transmissions and oil is heat.
If you have an auto and tow anything, you need to have the tranny oil changed regularly.

I have a 4x4, recently purchased.
The working temps for trannys and the oil therein should never exceed 130 degc.
The hotter the oil, the shorter the tranny life. THIS IS A KNOWN FACT
Seals, which are critical for the tranny to function, will start breaking down the hotter they get.
The oil starts to loose its lubricity and viscosity as it gets hotter, allowing wear and damage to parts.

I fitted a scangauge to my 4x4 when I purchased it to monitor key engine and tranny paramaters.
Towing my boat from the CC to Sydney, the tranny temp hit 110 a couple of times, the ideal temp for a tranny is 80 ish degc.
Tranny temps cooled less effectively than engine coolant temps.
The coolant hit 95 deg c on one hill but cooled very quickly once the hill flattened out.
(diesels run around 85deg c, petrol around 100 deg c)
The tranny took several kilometers to cool.

Autos are generally much better for off roading, but this will be argued by those traditionalists who like manuals.
But an auto can make changes far faster and more in line with engine demands than any manual.

I have my tranny oil changed every second service and a tranny cooler will be fitted when I get my caravan.

I worked with mining machinery for 30 years and these facts are known in that industry.
I have seen tha damage when the tranny oil dies and it aint pretty

Thanks Valkie.

That is pretty much my thinking too.
A mechanic told me if an Auto has not had the fluid changed for a long time do NOT change it all at once.
Change 30ish % of it and run it as normal for 3 --> 6 months. Then give it a full change.
I did that with my old Camry and it was good.
The old fluid smelt 'burnt' and as you said, the viscosity had changed.

Someone else said, even if you have not had a lot of kms on an auto, change the fluid.
The technology of fluids have changed a lot recently. The new fluid will be a lot better than the old fluid.

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Jovial Monk

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Re: Automatic transmissions
Reply #17 - Oct 5^th, 2020 at 11:22am

I had to bring my car in for a service or repair over the Christmas/NY week. I took it to Rowell & Searle, specialists in transmissions.

They had a huge load of work, transmissions and other work for people who had towed a caravan to Adelaide obviously without checking coolant, lubricants and transmissions etc. Nuts!

There is a long steep high hill here, Willunga Hill. When I travelled it regularly in the 80s to go work on the houses me and business partner were building I always saw at least half a dozen cars waiting for their radiators to cool down so they could top them up with the containers of water the RAA positioned there. Can imagine it “Lovely day, come on, lets go for a drive to Victor Harbor.” No checking the radiator first!

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Jovial Monk Gold Member Offline Dogs not cats! Posts: 51474 Gender:	Re: Automatic transmissions Reply #18 - Oct 5^th, 2020 at 11:25am The manual for my Mazda3 stresses not to coast in neutral, that would damage the automatic axle. So I coast to a slow stop by clicking off cruise control, pretty much the same.
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Re: Automatic transmissions
Reply #19 - Oct 5^th, 2020 at 12:57pm

Valkie - I have also read to keep the 'revs' up on an Auto when it is doing heavy work.

ie, when going up a hill or towing something heavy, Lock the auto down into to a lower gear to keep the revs up.

eg - We went up to Mt Tamborine yesterday. On the way up I locked the 5 speed auto into 3rd, sometimes 2nd.
Keeping the revs above 2500 rpm. It is not changing up and down all the time and is spinning happily.

Coming down, my wife locked it into 2nd the whole way. She hardly had to brake, it revs up to 4000 or thereabouts.

A few years ago we went up to Mt Bunya. It was very steep.
I locked it into 2nd gear on the way up and kept the revs above 3000 rpm.
It never got bogged down.

Your thoughts on that?

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John Smith

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Re: Automatic transmissions
Reply #20 - Oct 5^th, 2020 at 7:45pm

Sprintcyclist wrote on Oct 4^th, 2020 at 8:08pm:

Following from the amiable discussion on 4WDs I thought to start this thread.

Automatic transmissions, 90+ % of car sales are autos.

New Autos are great.
Some sales staff say Autos are 'sealed' and required no maintenance for the life of the car.

Well, depends on how long you want the life of your car to be !

Most cars you can't even get in a manual transmission anymore .... unless you count that clutch less triptonic thing as a manual ... which I don't.

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Bertie Gold Member Offline Posts: 785 Gender:	Re: Automatic transmissions Reply #21 - Oct 5^th, 2020 at 8:06pm Automatic is for ladies and learners.
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Valkie

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Re: Automatic transmissions
Reply #22 - Oct 6^th, 2020 at 6:36am

Sprintcyclist wrote on Oct 5^th, 2020 at 12:57pm:

Valkie - I have also read to keep the 'revs' up on an Auto when it is doing heavy work.

ie, when going up a hill or towing something heavy, Lock the auto down into to a lower gear to keep the revs up.

eg - We went up to Mt Tamborine yesterday. On the way up I locked the 5 speed auto into 3rd, sometimes 2nd.
Keeping the revs above 2500 rpm. It is not changing up and down all the time and is spinning happily.

Coming down, my wife locked it into 2nd the whole way. She hardly had to brake, it revs up to 4000 or thereabouts.

A few years ago we went up to Mt Bunya. It was very steep.
I locked it into 2nd gear on the way up and kept the revs above 3000 rpm.
It never got bogged down.

Your thoughts on that?

The revs are more about reducing the stress on the engine than the tranny.

Higher revs mean less stress on the engine(within limits) as it isnt working as hard.

But trannys are different.
The torque converter is a very simple fluid drive.
The oil is directed through a tortuous path to drive the tranny.
The harder the oil is worked, the hotter it gets.
The hotter it gets, the more the oil loses its viscosity.
which means it has to work harder......etc etc.

Many new trannys have a lock that locks the torque converter at speed, to reduce the heat build up and slippage.
The worst thing that trannys hate is continually varying speed.

Unlike engine coolant (which boils and make lots of visible steam etc)
Autos boil and have little external visible indicators.
You can smell them when they get too hot (sweet smell)
By then the damage is done and the oil should be changed.

But when the tranny dies, it is a slow and very expensive problem.
There are symptoms, rarely identified by drivers .
The smell is first
Then leaks as the seals die
Tranny does strange things, changing early or late, slipping between gears etc.
Then there are whines, noises and finally catastrophic failure.

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Valkie

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Re: Automatic transmissions
Reply #23 - Oct 6^th, 2020 at 6:39am

Bertie wrote on Oct 5^th, 2020 at 8:06pm:

Automatic is for ladies and learners.

I too love manuals.
I have had a few myself.
But autos are easier, and as my wife cannot drive a manual, we must have an auto.

Additionally.
Driving in the moving car park known as Sydney, which I occasionally have to do.
Manuals are a real pain.

Yep, give me a manual for a nice country drive or fang
But for general motoring, give me an auto.

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Sprintcyclist

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Re: Automatic transmissions
Reply #24 - Oct 6^th, 2020 at 6:18pm

Valkie wrote on Oct 6^th, 2020 at 6:39am:

Bertie wrote on Oct 5^th, 2020 at 8:06pm:

Automatic is for ladies and learners.

I too love manuals.
I have had a few myself.
But autos are easier, and as my wife cannot drive a manual, we must have an auto.

Additionally.
Driving in the moving car park known as Sydney, which I occasionally have to do.
Manuals are a real pain.

Yep, give me a manual for a nice country drive or fang
But for general motoring, give me an auto.

Absolutely.
No manual is 'better' than even a 5 speed auto.
Now 6 speed autos are about the minimum.
Autos are way ahead. that is why 90+% of sales are autos

I think rubbish trucks are autos

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Sprintcyclist

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Re: Automatic transmissions
Reply #25 - Oct 6^th, 2020 at 7:31pm

Valkie wrote on Oct 6^th, 2020 at 6:36am:

Sprintcyclist wrote on Oct 5^th, 2020 at 12:57pm:

Valkie - I have also read to keep the 'revs' up on an Auto when it is doing heavy work.

ie, when going up a hill or towing something heavy, Lock the auto down into to a lower gear to keep the revs up.

eg - We went up to Mt Tamborine yesterday. On the way up I locked the 5 speed auto into 3rd, sometimes 2nd.
Keeping the revs above 2500 rpm. It is not changing up and down all the time and is spinning happily.

Coming down, my wife locked it into 2nd the whole way. She hardly had to brake, it revs up to 4000 or thereabouts.

A few years ago we went up to Mt Bunya. It was very steep.
I locked it into 2nd gear on the way up and kept the revs above 3000 rpm.
It never got bogged down.

Your thoughts on that?

The revs are more about reducing the stress on the engine than the tranny.

Higher revs mean less stress on the engine(within limits) as it isnt working as hard.

But trannys are different.
The torque converter is a very simple fluid drive.
The oil is directed through a tortuous path to drive the tranny.
The harder the oil is worked, the hotter it gets.
The hotter it gets, the more the oil loses its viscosity.
which means it has to work harder......etc etc.

Many new trannys have a lock that locks the torque converter at speed, to reduce the heat build up and slippage.
The worst thing that trannys hate is continually varying speed.

Unlike engine coolant (which boils and make lots of visible steam etc)
Autos boil and have little external visible indicators.
You can smell them when they get too hot (sweet smell)
By then the damage is done and the oil should be changed.

But when the tranny dies, it is a slow and very expensive problem.
There are symptoms, rarely identified by drivers .
The smell is first
Then leaks as the seals die
Tranny does strange things, changing early or late, slipping between gears etc.
Then there are whines, noises and finally catastrophic failure.

Thanks Valkie, it is good to chat with someone who chats.

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Sprintcyclist Gold Member Offline OzPolitic Posts: 41827 Gender:	Re: Automatic transmissions Reply #26 - Oct 6^th, 2020 at 7:52pm Valkie - for a normal Auto, what causes the torque converter to lockup ? Is it revs or speed or does it use various sensors to decide?
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Valkie

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Re: Automatic transmissions
Reply #27 - Oct 7^th, 2020 at 7:32am

Sprintcyclist wrote on Oct 6^th, 2020 at 7:52pm:

Valkie - for a normal Auto, what causes the torque converter to lockup ?

Is it revs or speed or does it use various sensors to decide?

You are now getting above my experience in this area.
The vehicles I worked on and engineered were heavy duty mining equipment, they had no lock up option as they rarely reached 30k/hr, let alone a sustained speed.

I have however owned several autos.
The earlier ones had no lock up option (early holdens and fords)
But my later vehicles all have a drive lock up to conserve fuel and to reduce heat from slippage.

How they work?
Not my field, but as you say it would have something to do with sensors and conditions.

A torque converter is like two opposing turbines facing each other (very rough description)
one turbine is anchored to the engine, the other, the transmission.
The engine spinning directs the oil from one at the other and makes it spin, the higher the revs, the more force applied.
This also creates heat as the oil is forced through this torturous path and is under load.
The inner workings of an automatic transmission comprises of valves and sensors which read load and speed and adjust accordingly.
This is a dark science and one, even with my fluid dynamic engineering qualification, I do not fully understand, nor want to.
All the lock up does is engage a clutch type mechanism that locks the torque converter, it has little to do with the transmission pers see, but is instrumental in reducing slippage.

But if you want to really get into some fun stuff, try having a look at CVT transmissions.
A brilliant idea and in most cases well used in many cars today.
But prone to failure if taken beyond their design parameters.
These are often touted as "sealed for life" with the oil.
But this is mainly because people would freak at the cost of the oil, its special oil and very expensive.

If you own one of these gearboxes, they will happily perform well for many years and miles.
But dont believe the "sealed for life" crap.
I had an X trail with this gearbox and towed a 1.5 ton boat everywhere. Did nearly 300000k on it.
I changed the oil in the gearbox every year and had no issues.
Others have failed because they didnt change the oil, Nissan got a poor rep for X trail gearbox failures for a while.

Fun stuff eh?

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A DREAM OF A WORLD FREE FROM THE HORRORS OF ISLAM.

SUCH A WONDERFUL DREAM
O HOW I WISH IT WERE TRU

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Belgarion Gold Member Offline Australian Politics Posts: 6147 Gender:	Re: Automatic transmissions Reply #28 - Oct 7^th, 2020 at 9:57am Bertie wrote on Oct 5^th, 2020 at 8:06pm: Automatic is for ladies and learners. Do you still have someone walking ahead of you with a red flag as well?
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Sprintcyclist

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Re: Automatic transmissions
Reply #29 - Oct 7^th, 2020 at 5:58pm

Valkie wrote on Oct 7^th, 2020 at 7:32am:

Sprintcyclist wrote on Oct 6^th, 2020 at 7:52pm:

Valkie - for a normal Auto, what causes the torque converter to lockup ?

Is it revs or speed or does it use various sensors to decide?

You are now getting above my experience in this area.
The vehicles I worked on and engineered were heavy duty mining equipment, they had no lock up option as they rarely reached 30k/hr, let alone a sustained speed.

I have however owned several autos.
The earlier ones had no lock up option (early holdens and fords)
But my later vehicles all have a drive lock up to conserve fuel and to reduce heat from slippage.

How they work?
Not my field, but as you say it would have something to do with sensors and conditions.

A torque converter is like two opposing turbines facing each other (very rough description)
one turbine is anchored to the engine, the other, the transmission.
The engine spinning directs the oil from one at the other and makes it spin, the higher the revs, the more force applied.
This also creates heat as the oil is forced through this torturous path and is under load.
The inner workings of an automatic transmission comprises of valves and sensors which read load and speed and adjust accordingly.
This is a dark science and one, even with my fluid dynamic engineering qualification, I do not fully understand, nor want to.
All the lock up does is engage a clutch type mechanism that locks the torque converter, it has little to do with the transmission pers see, but is instrumental in reducing slippage.

But if you want to really get into some fun stuff, try having a look at CVT transmissions.
A brilliant idea and in most cases well used in many cars today.
But prone to failure if taken beyond their design parameters.
These are often touted as "sealed for life" with the oil.
But this is mainly because people would freak at the cost of the oil, its special oil and very expensive.

If you own one of these gearboxes, they will happily perform well for many years and miles.
But dont believe the "sealed for life" crap.
I had an X trail with this gearbox and towed a 1.5 ton boat everywhere. Did nearly 300000k on it.
I changed the oil in the gearbox every year and had no issues.
Others have failed because they didnt change the oil, Nissan got a poor rep for X trail gearbox failures for a while.

Fun stuff eh?

Gosh I love an honest answer.
Thanks muchly.

' ............ But dont believe the "sealed for life" crap.
I had an X trail with this gearbox and towed a 1.5 ton boat everywhere. Did nearly 300000k on it.
I changed the oil in the gearbox every year and had no issues. ............. '

I agree with that 100%

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