Questions about an automatic gearbox

[h00t_h00t]

I read on the intrawebz it's not recommended to rev the engine above 3,000 rpm in my Camry...

Thats a load of arse to be honest, if you rev the engine more you'll go faster and use more fuel. If it was going to do damage to the engine/transmission at over 3000rpm then that is where the rev limiter would be.

[zeppelin]

Thats a load of arse to be honest, if you rev the engine more you'll go faster and use more fuel. If it was going to do damage to the engine/transmission at over 3000rpm then that is where the rev limiter would be.

This.

I rarely shift at under 3000 RPM with my car, often times I take it up to 5000 for more spirited driving. It redlines at 6500 RPM, so I intend to use what it'll take.

Chiming in that the whole 'put the auto in third gear' is silly. I don't see any way how that would be better for the car, as opposed to letting the automatic do the job it was designed to do, (select the appropriate gear).

[jediali]

Thats a load of arse to be honest, if you rev the engine more you'll go faster and use more fuel. If it was going to do damage to the engine/transmission at over 3000rpm then that is where the rev limiter would be.

Its your choice! performance vs fuel consumption and accelerated wear. The redline tells you when what rpm is limited by combustion/ balance. I think that many engines (that dont use variable technologies) have a single rpm optimised intake/exhaust gemotry, valve tuning and many other aspects therefore the engine will work well at this point. anything above/below this point will be a comprimise of varying degrees depending on the engine. It usually is around peak torque rpm. you may not do damage but wear rates will be higher and oil/fuel consumption for continous high revving. Its no big deal but not all engines sound good when extended

[nota]

I see. Thank you very much.
So the final verdict is that choosing my own gear isn't any healthier for the car than letting it choose itself, in this situation?

I'll have to disagree with most answers. I think your mother & her boyfriend are right

In general terms most automatics are tuned to upshift early, eg at low to mid-throttle openings and even when the engine is already at lower engine revs before the upshift occurs. This works well under low-load conditions, helps fuel economy and reduces unnecessary engine wear etc

However there are a helluva lot of automatics that aren't as smart or as foolproof as you'd think. Once an upshift has occurred, the autos of most cars on the road today will tend to hang on grimly to the higher gear - even when the drive-situation changes into a relatively high-load condition, such a climbing hills - and only downshift to a more apppropriate gear once the throttle is opened wide enough to actuate the 'kickdown' (ie a throttle-induced downshift)

Most autos incorporate a useful part-throttle kickdown feature (PTK) although some older ones do not! For those that do not, this means that they need virtually full-throttle to actuate an on-power downshift (ie kickdown). This also means a careless or ignorant driver could find themselves struggling up a steep gradient, at innapropriate revs (say 2800-1500rpm or LESS), with the engine labouring away in top gear, even @ say an 85% throttle-opening .. and the trans would still NOT provide an automatic downshift into a more appropriate gear! Apart from excessively loading up the engine, this situation will also overload your transmission - in other words cause it to overheat

Excessive heat is the #1 enemy of all auto transmissions

Lots of autos which do incorporate the part-throttle downshift feature still tend to be reluctant to automatically provide a downshift, even when a downshift would be desirable - such as in changing conditions when encountering a steep hill eg. This is particularly true of AU cars, which are tuned for very early upshifts, due to their typically torquey motors

For example under light throttle our PTK Falcon 4sp auto will upshift to 3rd by 16km/h, and into O/D 4th by about 30km/h, which corresponds to virtual idle-speed for the engine. And once upshifted, even on steep hills @ 60km/h or 80km/h it often chooses to stay in 4th, despite a lower gear (or two) being far more appropriate for those inclines

Likewise when going up steep climbs my old V8 Benz 4sp auto will retain top gear right down to 60km/h or less (eg 1550rpm) even though the throttle might have to be be at 60% for sufficient power to keep up momentum. But if I trigger a downshift to 3rd (either manually or by kickdown) the required throttle opening (for sustaining speed) actually reduces down to 40% or 30%. This translates to using less fuel, along with taxing the engine & transmission far less - in spite of using more revs and in despite the trans incorrectly deciding the downshift was not needed

This leads to the crucible of this subject, imo. Whether manual or auto, a good driver will always strive to reduce the throttle openings (ie reduce mechanical loadings) while keeping up the required speed, with lower revs as the secondary aim

In other words, if the car tells you by a reduced throttle requirement that its engine/transmission is happiest up that hill in 3rd or 2nd, instead of 4th or 3rd, then you should active a downshift into the appropriate gear - no matter what the supposedly 'clever' auto transmission thinks is right. And of course you also want to avoid generating wasted power, through using overly high revs under low-load conditions

Obviously these guidlines are general, and you don't want to 'overshift' when driving. But what you should want to do is to strike (and keep chasing) that fair & prudent balance in engine/transmission/throttle usage between needlessly high revs vs excessively high loadings

[Quiggs]

5500 shifts everywhere I go. \m/

[Ferrer]

@nota, in other words, buy a manual.

[Fleet 500]

I agree with nota.
The '66 Dodge Dart GT I used to own (with 3-speed automatic) would not stay in 2nd gear when going up a hill unless it was going very slow, like under 20 mph. It would go up a long hill in 3rd (top gear) unless it was downshifted manually. I got into the habit of always putting it in 2nd gear when I was going up a hill.

The transmissions in my Cadillacs are more sensitive and will stay in 2nd gear when going up a hill but I put it in 2nd anyway out of force of habit and to make sure it won't upshift too early.

Going up a steep hill is much easier on an engine when using 2nd gear in a 3-speed trans and 3rd gear in a 4-speed trans.

[TVR IS KING]

It's a VS model Toyota Lexcen VXi.
Well the thing is, the car has never shown any trouble getting up hills like this. Except one instance on another hill, a particularly steep one, when I was mashing the pedal down and not getting much response...
But usually it's fine, so I figure the auto is doing a pretty good job of automating things.

[pimento]

It's a VS model Toyota Lexcen VXi.

For those not in the know, it's a Commodore with a Toyota badge on it. Legend has it that Toyota got annoyed with customers that took them to a generic service joint who just used Holden parts in them. Mainly because Toyota charged a premium for the little sticker saying 'Toyota Genuine Part' on it.

I once saw a rather beaten up example with one Toyota mudflap, and one Commodore mudflap.

[SlickHolden]

It's a VS model Toyota Lexcen VXi.
Well the thing is, the car has never shown any trouble getting up hills like this. Except one instance on another hill, a particularly steep one, when I was mashing the pedal down and not getting much response...
But usually it's fine, so I figure the auto is doing a pretty good job of automating things.

If you gun it and it doesn't drop i might need a serves... But another thing it's the Electronic controlled version of my auto, So you should have the power button at the shifter, So another thing you could flick that it will hold rev's longer and gears it more for towing but it might go great on hills... Also you could grab a corvette servo kit off ebay for it for around $40 they help them sloppy changes heaps. So i'm told.

For those not in the know, it's a Commodore with a Toyota badge on it. Legend has it that Toyota got annoyed with customers that took them to a generic service joint who just used Holden parts in them. Mainly because Toyota charged a premium for the little sticker saying 'Toyota Genuine Part' on it.

I once saw a rather beaten up example with one Toyota mudflap, and one Commodore mudflap.

And you know something funny people believe the Toyota's were faster and better built But holden built them all so maybe the badge is a mirical.

[Waugh-terfall]

My Grandfather in France has a '92 Mercedes 190D 2.5Auto, when he goes up a hill, such as the one to get out of their hamlet he shifts into 2nd or 3rd but he never tells me why, when my Dad drives that same car he slots D and mashes the throttle the revs rise and slowly, slowly the car creeps forward 90bhp, 4 people, steep hill... The car then gets to about 4,000rmp and shifts to second, then third, revs get lower, shifts to 2nd and then just holds it then it goes up, and as the hill flattens it goes back to normal.

When riding the busses I notice that when we climb hills (and boy there are lots of them!) they're in D and they change Up-Down-Up-Down-Up-Down more times than you change your underpants...

[jediali]

...more times than you change your underpants...

that will depend on the reader

[Bob]

Manual>>Auto.
For the record, I shift around 1500-2000 rpm in traffic. 300 ft-lbs ftw
When it gets exciting I shift around 4500 even though the redline is at 5000. 2 ft long runners really limit the top end