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Automatic transmission behaviour

O

old cruiser

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Location
slough
Car
honda accord
here's one for the Auto transmission boys! e.g. when stopped in traffic with engine fully warmed up there is this sort of jerkiness (kinda feel like your moving back and forth in the seat so to speak!) when I let off the brake pedal and let the car creep without touching the gas pedal, can be more noticeable if car is on a slight incline, first thoughts are that maybe it's an combination of the car trying to roll back slightly and the transmission pushing you forward as it were, would be interested to know others thoughts on this.
Cheers Pete
 
Set handbrake, select neutral or park, when able to go select drive release handbrake and accelerate, not good practice to leave in drive whilst stationary.
 
Hi mate, more often than not I apply the handbrake with it in drive when say at traffic lights, as was once told keep putting it in neutral or park then back into drive then moving off from lights can wear the gearbox more than leaving it in drive, this is an exert from a gearbox specialist that seems to confirm this.
"When stationary in traffic, even for many minutes, it is not necessary to move the gear lever into neutral because the torque converter absorbs the engine propulsion force but does not transmit it all to the gearbox as the engine revs are too low. No wear is taking place.
In fact, more wear will take place if the driver engages neutral and then engages a gear when he is able to move off.
When stationary, but in gear for any period, the hand brake should be applied and the foot kept clear of the accelerator."
Cheers Pete
 
edgeoftime I'm doing the same thing at lights as you do.... Why this is a better practice or worst than to leave it in D and just take the foot from brake pedal.
what's the real truth and logical explanation ?
 
I always leave mine in D and hold with the foot brake, usually I'm only waiting a minute or less. If I've not moved for a while I'll put the handbrake on and put it in N. Done this on the Civic as well and never had an issue.
 
As an aside, leaving the auto in D while stopped with either the foot brake or hand brake applied makes no difference (or very negligible) difference to the box. Why? From the fluid perspective, it looks no different that if the engine is under normal load (i.e. driving). As such leaving it in D and applying the brakes is generally preferred (lazy drivers). Now, moving it to N (which also makes negligible difference to the power train) takes the force off the braking systems BUT the braking systems are supposed to be able to handle this and the wear is also negligible. For laziness, some drivers prefer to move to N. In reality the hand-brake is supposed to be able to hold the load of the engine in D with no throttle.

Now, on to the OPs situation, ***uming you are not idle hunting (as you mentioned the car is warm), this is probably a situation whereby the fluid in the auto is not being chucked around the converter in an even fashion.As such you get this notchiness or uneven drive with the load of the car versus the available drive power. Hence the rocking. I would imagine applying throttle and the car pulls normally?

So what to do? Not really a big issue, the usual ATF fluid and filter change will help, but unless you are having other problems (seized caliper, vibrations, engine issues), I wouldn't sweat it.
 
As an aside, leaving the auto in D while stopped with either the foot brake or hand brake applied makes no difference (or very negligible) difference to the box. Why? From the fluid perspective, it looks no different that if the engine is under normal load (i.e. driving). As such leaving it in D and applying the brakes is generally preferred (lazy drivers). Now, moving it to N (which also makes negligible difference to the power train) takes the force off the braking systems BUT the braking systems are supposed to be able to handle this and the wear is also negligible. For laziness, some drivers prefer to move to N. In reality the hand-brake is supposed to be able to hold the load of the engine in D with no throttle.

Now, on to the OPs situation, ***uming you are not idle hunting (as you mentioned the car is warm), this is probably a situation whereby the fluid in the auto is not being chucked around the converter in an even fashion.As such you get this notchiness or uneven drive with the load of the car versus the available drive power. Hence the rocking. I would imagine applying throttle and the car pulls normally?

So what to do? Not really a big issue, the usual ATF fluid and filter change will help, but unless you are having other problems (seized caliper, vibrations, engine issues), I wouldn't sweat it.
Click to expand...
Thanks for all the explanation there mate, yeah car pulls fine when applying throttle and brakes etc seem ok no binding etc. so as you say I don't think I'll sweat it!
Cheers Pete
 
It will also pull when your foot slips off the brake pedal, or the fly by wire throttle malfunctions, Who mentioned wear and tear??? NOT ME.
 
SOMETHING HAS MALFUNCTIONED SORRY ABOUT THAT, It should read it will pull when your foot slips off the brake pedal or the throttle decides to take over on it's own, do not put in P though, for if someone back ends you it will break the parking pawl. Who mentioned wear AND TEAR not me!!
 
edgeoftime said:
Who mentioned wear AND TEAR not me!!
Click to expand...
Errr... I mentioned the wear and tear element. My point is doing so was to demonstrate that either options (N or D) have minimal impact on the wear of components. Some people believe that holding in D will increase wear, while others believe that shifting from D-N-D will increase wear. Neither options make much of a difference.
 
Just to say my Accord was rough when I got it. Jerky, not smooth at all. Checked and tranny oil changed at 71k. It was 102k when I bought it so immediately changed it (by garage who filled with wrong oil then with correct ATF-DW1).

Car is a revleation now. Not immediate but have a few miles it was so much better in all respects. It wasnt jerky at idle but selecting gears was rough.

Worth a try for £35 pounds worth of oil.
 
It doesn't feel right when stopped at lights and in D & hand/foot brake is on.
The car tries to pull forward.
The various systems seem to be under strain (albeit not by a great amount).

As above, but in N & handbrake on. It feels right, as everything seems in equilibrium.

Just a gut feeling...........don't know about the theory, as i'm not a gearbox expert.

When stopped, Can't see why moving from D to N to D would cause a problem.
 
I think when it comes down to it , it's probably the safety factor of placing in neutral when stopped, although leaving it in drive apparently causes no wear in the gearbox, I suppose it could be said that more wear could be taking place by continuously moving it to neutral in traffic, namely on the linkage and other parts with the slight surge going from neutral to drive.
Cheers Pete
 
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