Characteristics of an automatic.

jamoor

jamoor

jamoor

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Nottinghamshire
Bieng an auto newbie, I have a few questions about the 530.

When pootling along at say 40mph, and if i hit the gas a tad, the car begins gathering speed, now if i take the gas pedal down halfway, the revs surge suddenly, the car picks up speed, but it doesnt seem like its kicked down a cog, what's going on there?

I know what a kickdown feels like as i can put my foot flat to the floor and it suddenly changes gear.

Thanks for your help :D
 
At 40 in kickdown it'll knock it down to 2nd gear, but push the throttle down a little it's probably knocking it down into 3rd or 4th (if it's a 5 speed auto) or dropping out of the lock up torque converter.
 
CypherPunk said:
That will be the torque converter lockup mechanism disengaging to allow for faster acceleration.
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thought so,
I dont want to constantly kickdown the gear as surely that will wear out the box?
 
jamoor said:
thought so,
I dont want to constantly kickdown the gear as surely that will wear out the box?
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An automatic transmission's biggest enemy is heat. Changing gears a lot is what it's supposed to do, but a buildup of heat will kill your tranny quicker than anything else.

Next in line is dirty fluid. In an autobox, the fluid isn't just the lubricant, it's also the hydraulic fluid that operates the various clutches and valves, it's also the coolant. So fluid that's old is contributing to the biggest nightmare for it, heat.

Keep your fluid and filter changed often, about every four to five oil changes in the engine (somewhere around every 20,000 miles). Yes, this is a little excessive since most manufacturers suggest changing the fluid every 60,000 or more, but it's a lot cheaper to grab a couple bottles of ATF and a filter and change it out in the driveway every year than it is to have the transmission rebuilt in 5 years.....
 
my box has a sealed for life transmission with oil that apparently lasts its lifetime which is obviously bull.

The oil however is bmw spec and costs £20 a litre!
I dont really want to use non bmw spec oil as that may cause a problem. apparently the atf needs sucking out with a machine or something...
 
Well, there's an alternative to doing it the "normal" way of dropping the pan and changing it along with the filter.

You take the cooling lines off the bottom of your radiator. Have someone turn the engine over for just a second until you see fluid spurt out one of the lines.

Put that line in an empty bucket good for holding petroleum products.

Put the other line in a rather LARGE bucket full of fresh fluid. Make sure it can reach the very bottom.

Have an assistant start the car and watch VERY carefully the level in the fresh fluid bucket. Run it like that until you get clear, clean fluid coming out to the (originally) empty bucket, being sure not to let the (originally) full bucket run completely empty.

When you've got clear fluid coming out of the cooling lines, you've completely flushed your transmission fluid system. This won't help the filter at all, but it is the ONLY way to get 100% of the fluid changed.

The "normal" way is to undo the between 10 and 16 bolts on the underside pan on the bottom of the transmission, leaving the two at the high end only loose so you can tilt the pan to let all the fluid drain out, then remove those two last bolts. Remove the two or three (depending on transmission make and model) machine screws holding the filter in (normally this involves a T-15 Torx bit) and remove the filter and its gasket. Put new gasket in, new filter in, screw it back in, then bolt the pan back on after giving it a good wipe out with a clean rag. Then add 2 litres of fresh fluid, fire the car up and check the fluid levels, adding more fluid as necessary to bring it up to the correct point on the dipstick.

The disadvantage of doing it that way is you don't get the old fluid out of the torque converter. The best method is to do a combination of the two, changing the filter first, then doing the fluid flush.


I can't really see a manufacturer even suggesting that an automatic transmission can go the life of the car without a fluid and filter change. It just doesn't seem possible considering there's MANY bimmers out there with 200,000+ miles on them and still going strong. But then again, I've been out of the mechanic's loop for about 10 years now, so anything's possible.....
 
^^^^^ All good advice, but I'd add that it might be worth shifting the box through all the drive selections, to make sure you're flushing ATF from all the circuits.
 
[TW]Fox;10437807 said:
No, sealed for life is, according to BMW, sealed for life. But concencous amongst the community is that its a load of rubbish and its prudent to change it every 100k.
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Exactly the same with Audi.
 
Damn, sorry for the necropost folks, was searching for automatic transmissions and assumed it meant November 2007! :)
 
BMW recommend very long service intervals. because its good for the car or because it helps them sell them on the basis that 'its cheaper to service'?
 
Matt82 said:
BMW recommend very long service intervals. because its good for the car or because it helps them sell them on the basis that 'its cheaper to service'?
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Most of the German manufacturers persist with this 'Autobox fluid is for life' garbage. The actual servicing intervals are similar to any other car.
 
i just dont trust them, my rant will probably go slightly off topic lol. service intervals will all be similar otherwise (for example) a BMW salesman would be able to say "you should get a BMW, it only has to be serviced every XX thousand miles, the Audi needs to be serviced every X thousand miles"

so in a bid to make their brand new cars a more attractive/cheaper proposition to buy, theyll cut corners on stuff like that which wont be a problem until the car is well out of warranty and well out of dealer's hands...

not sure why the autobox fluid is meant to stay there for life, youll read loads on Merc boards about auto box issues when years ago they used to last forever, but cars arnt the same now
 
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