Use of Neutral vs Drive when temporarily stopped.

[Pielight]

3 hours ago, D Johnson said:

Hello everyone, I’m very new to Lexus (a recovering 5 series owner with all the mental trauma that entailed) but I, like the OP, am concerned about the effects on my IS 300h brake discs of sitting in D at traffic lights and whilst in queues holding on the foot pedal.  Also, I cannot find the handbrake and increasingly suspect that there may not actually be one to find!  This is most discombobulating…. Any advice will be gratefully received.   

Holding the car perfectly still with the brakes will not cause any brake wear….however it is recognised that sitting with the foot brake applied can cause disc warping. For this to be an issue I’m pretty sure  the brakes would need to be pretty hot (eg you’ve just descended long, heavy inclines etc). For this reason I’ve seen it recommended to apply the parking brake which usually just applies the rear brakes (which don’t usually get quite as hot as most brake force is applied by the front). I think that if you just lightly press the foot brake while stood (just enough to remain stationary), it is very unlikely to warp discs.

My original post was more around whether there was less wear, tear and heat effects on the transmission when stood  (D vs P) than the brakes.

[Pielight]

3 hours ago, eleveneleven said:

I've often wondered the same thing OP. I've had DSG's in the past and always kept my foot on the brake pedal at lights, stop n go traffic or short ish stops never had an issue 

with the Lexus however, I hear a slight rubbing sound when the brake is applied not sure what it is I'm guessing (and hoping) its a brake disks/pads issue and not the gearbox. For that reason I've been sticking it into neutral for any wait longer than a minute or so. 

Another thing I seem to be a little paranoid about is parking on steep incline, My driveway for example. every time I engage D from P when its on the drive there's quite a loud "clunk" sound. Doesn't sound like it's doin the gearbox any good at all. I'd get it occasionally with some of my previous cars but as they were all leased so under warranty I didn't really worry about it. 

womble72's answer makes sense though so I'll be leaving it D from now on 

 

As long as the car is held completely still, the rubbing noise can’t be coming from the brakes.

I don’t think standing in park at traffic lights etc is in contention - my post was around drive versus neutral (you shouldn’t get a clonk between neutral and drive) - the owners manual states that Neutral should be used when stopped for extended length of time. But extended time is a “how longs a piece of string?” type statement.

As regards the clonk… a good habit even with manual vehicles is to firmly apply the parking brake BEFORE releasing or easing pressure off the foot brake. In the case of an automatic, the park pawl will not then be holding the weight of the car and you will avoid the clonk. You can prove this on a gradient by taking engaging park, then taking your foot off the brake before you apply the parking brake. This will allow the engine to roll slightly u til the weight of the car is held by the pawl which puts it under tension. There will also be tension on drive shafts etc. When you next move the shift lever away  from P you will get the clonk.

In the case of a manual, ensure that the parking brake is firmly applied before engaging a gear and releasing the clutch. This will avoid the transmission, driveshafts etc being under tension while the car is parked. 
 

The principle for both auto and manual is that the parking brake is what should be holding the car still and the engine transmission is there only as a back up if the parking brake fails or is not holding the car sufficiently to prevent movement.

 

[Las Palmas]

On 9/24/2021 at 5:23 PM, Rabbers said:

An interesting but somewhat academic thread.  I really can’t think of a situation where an automatic car needs to be put in N unless it needs pushing or towing as the result of breaking down or having a dead battery.  In fact I would think it possible for a car (especially a Lexus👌!) to go its entire life without its owner(s) ever having put it in N.

When being driven through a washing hall N is needed as if in D it will move faster than the rollers pushing the car through all the different - soap spraying, brushing, waxing, drying. Lasts about 5 minutes. Then D again.

Stopping for red light leave it in D. Stopping for partner shopping, leave it in P (otherwise music stops, and with the good audio we have in the cars no reason not to listen to something good to make waiting more comfortable.

Fuel consumption: As long as there are pumps with fuel, it should be the least of problems for people that can afford a Lexus with the servicing prices we have.

[4969_LXS]

@Pielight hi mate, as others have said, leave it in D at traffic lights, it will reduce the slight wear and tear on solenoids and clutch packs within the transmission. Like my ISF, the GSF has a transmission fluid cooler, so any excess heat being inputted into the fluid from the work being done via the torque converter will be dissipated, not a lot of heat is generated at idle anyway. However, no fluid lasts forever, as an engineer myself, I had the fluid in my ISF done, not a complete flush as that can shock the system, but I had a transmission sump drain, refill, level set, and TCU reset. It did make a difference to mine, it shifted gears smoother and quicker afterwards but I don't think the fluid had been changed before so it was to be expected. Transmission fluid lives a hard life as a lubricant, coolant and a working fluid transfering energy in the torque converter when it isn't locked, it does degrade over time. The American forums are a good place to look for information on trans fluid. Whilst it's not Lexus, BMW say the ZF 8 speed is sealed for life, whilst the manufacturers of the gearbox (ZF) recommend changing it every 60k miles and you can acquire a servicing kit. For our cars with the Aisin AA80E 8 speed, in your case the updated AA81E, you can service them as well. It's on the ISF's service plan, I think it's every 6 years off the top of my head, not sure on the GSF. However, when I enquired about it, 1 Lexus dealership said it's sealed for life. But two other Lexus dealers said yeah no problem it can be done and my local dealership did it for me no problem. The American forum member recommend to do it after a few hard track days too. 

Apologies if I digressed a little.

Our tranny's are pretty much bullet proof.

Hope this helps shed some light and eases your mind.

[D Johnson]

On 9/27/2021 at 4:26 PM, Womble72 said:

On 9/27/2021 at 4:06 PM, D Johnson said:

Think the handbrake is a footbrake, check for a high level foot pedal next to your left leg, push down to engage, push down and release to dis engage, or it’s possibly an electronic one which would be illustrated (P) somewhere on the dash……. You won’t miss that BM I can assure you 

Thank you Womble72 - I have now found the handbrake and it is indeed a footbrake!  I am assuming that I can now safely leave the shift lever in D and apply the handbrake with my foot when stopped at lights or in queues.  

 

[Pielight]

On 9/27/2021 at 10:21 PM, 4969_LXS said:

@Pielight hi mate, as others have said, leave it in D at traffic lights, it will reduce the slight wear and tear on solenoids and clutch packs within the transmission. Like my ISF, the GSF has a transmission fluid cooler, so any excess heat being inputted into the fluid from the work being done via the torque converter will be dissipated, not a lot of heat is generated at idle anyway. However, no fluid lasts forever, as an engineer myself, I had the fluid in my ISF done, not a complete flush as that can shock the system, but I had a transmission sump drain, refill, level set, and TCU reset. It did make a difference to mine, it shifted gears smoother and quicker afterwards but I don't think the fluid had been changed before so it was to be expected. Transmission fluid lives a hard life as a lubricant, coolant and a working fluid transfering energy in the torque converter when it isn't locked, it does degrade over time. The American forums are a good place to look for information on trans fluid. Whilst it's not Lexus, BMW say the ZF 8 speed is sealed for life, whilst the manufacturers of the gearbox (ZF) recommend changing it every 60k miles and you can acquire a servicing kit. For our cars with the Aisin AA80E 8 speed, in your case the updated AA81E, you can service them as well. It's on the ISF's service plan, I think it's every 6 years off the top of my head, not sure on the GSF. However, when I enquired about it, 1 Lexus dealership said it's sealed for life. But two other Lexus dealers said yeah no problem it can be done and my local dealership did it for me no problem. The American forum member recommend to do it after a few hard track days too. 

Apologies if I digressed a little.

Our tranny's are pretty much bullet proof.

Hope this helps shed some light and eases your mind.

Hi Nathan - thanks for your reply. Lots of interesting points which make sense there. I am now keeping the shift lever at D now.

Its reassuring to learn that the transmission is well proven having been around in several models for a long time now - and I will get the oil changed at some point - your experience shows that periodic replacement is very beneficial (life does not mean appear to mean life in this instance!!). Thanks again - very useful.

[Herbie]

1 hour ago, Pielight said:

(life does not mean appear to mean life in this instance!!). Thanks again - very useful.

I believe that it's based on what the manufacturers consider to be the 'end of life' of the car but maybe someone could expand on that?

[4969_LXS]

@Herbie That's what I take it as. If a transmission has an expected service life of 100k miles for example. Also, most modern cars are on PCP, so you could say it only has to last 4-5 years. It also lowers the price of PCP plans as you don't have to service the gearbox if it's "sealed for life". 

[DAW]

I always put the car in N at the lights in case someone hits me from behind. Possibility of transmission damage if in D or P I was told.

[Zotto]

In hybrid cars N has to be absolutely NOT used as in this mode  HV Battery can't be charged, so the choice is between D or P.

Besides, in some models it's possible to set "hold" button to avoid keeping brake pedal depressed leavin  gear selector in D that disengages brakes  just decing to move car with pedal.

 

[Arnett]

16 hours ago, Zotto said:

In hybrid cars N has to be absolutely NOT used as in this mode  HV battery can't be charged, so the choice is between D or P.

Besides, in some models it's possible to set "hold" button to avoid keeping brake pedal depressed leavin  gear selector in D that disengages brakes  just decing to move car with pedal.

 

😅 I mean it being the F forum the whole hybrid thing is semi-irrelevant 😉 

[Zotto]

Just "pour parler" 🙂

[Arnett]

2 hours ago, Zotto said:

Just "pour parler" 🙂

I know, just playing 🙂

[Pielight]

On 12/3/2021 at 11:27 AM, Arnett said:

I know, just playing 🙂

Ou plus précis….”Je blague”