Rear Transaxle Judder

[deskry]

I have experienced a phenomenon that may or may not be normal and would like to hear if anyone else has experienced it or has a view on what causes it. Occasionally, (about once a week) when parking up my PHEV, I have found that when coming out of Reverse into Neutral prior to "Powering Off" which also activates Park, I have experienced a noise and judder from the back of the car just as I was holding the Joystick in the "N" position (for 2 secs) to engage neutral. Normally when I do this nothing happens other than the Dash display illuminated diagram changes from R to N. My foot brake is firmly applied throughout from the moment of halting and is not released until I power off and apply the hand brake.

The first time it happened soon after taking delivery of the car it gave me a bit of a shock as I was reversed up to my Garage door to reach the Charger. I thought I might have relaxed my foot on the brake and rolled back into the garage door! So this is no minor transmission movement that you sometimes got on older auto gear boxes like the one I had on my 1994 Shogun 2.8 TD Auto. It normal only happens periodically when I park up at home where my driveway has a slight downhill slope to the garage which I usually reverse down so as to access the ROLEC Charger mounted inside the garage. It has once occurred going from R to D when maneuvering in a car park and that was on the flat with footbrake applied. On another forum I was advised not to use N neutral, just go to P or straight from R to Power Off?

 

[pheverish]

I never use neutral. Handbrake & P, or handbrake & power off as suggested. This is what I used to do in my prius as well.

 

[Grigou]

Perhaps sometimes we should read the owner manual before driving our cars

If I remember well, the manual doesn't ask to use Neutral, except for towing the car.

 

[maby]

I have not noticed anything of this nature - and I have started using neutral more often these days. I used to use Park as others have suggested, but it then occurred to me that this relies on blocking the transmission deep inside the engine and someone hitting me in the back even quite gently could do damage that would require the engine out and a significant strip down and rebuild!

 

[gwatpe]

The Parking switch is really only for parking and not stopping in traffic. The hand brake is for when the foot brake is not able to be pressed and the car is intended to be held stationery. The foot brake has the anti rollback assist and it also electrically disconnects the drive when pressed a bit harder. The neutral position allows less pressure on the brake to hold the car stationery and also disconnects the drive.

My PHEV makes a clunk sometimes if I have used the hand brake and the park switch. My auto used to have a similar trait.

I like the joystick when I have had to make a multi point turn in a tight space.

 

[jaapv]

I only use neutral when the car is dragged through the car wash (rather embarrassingly I did not even know how to engage it the first time).
So I don't have much experience with this. I do notice, however, that the use of "P" can be quite clunky from time to time.

 

[outofyorkshire]

I often use N as my general route has a busy railway crossing, so flick the car into N (+ hand brake) while waiting there.
Never had any clunks while moving D to N or N to D.
I also have to turn the car round to reverse to my charger but always just go from D to R and R to D (never use N) and have never had any clunks there.

I tend to power off directly from D or R & as others have already mentioned this can sometimes make a clunk , but so did my last 3 Land Rover autos when engaging P so have never worried about it

 

[Grigou]

I have not noticed anything of this nature - and I have started using neutral more often these days. I used to use Park as others have suggested, but it then occurred to me that this relies on blocking the transmission deep inside the engine and someone hitting me in the back even quite gently could do damage that would require the engine out and a significant strip down and rebuild!

Yes, that's true (and it concerns all automatics gearboxes for many decades).

Nevertheless, "even quite gently" could be discussed (what does "quite gently" means etc ...). But I won't discuss it because it would be too hard for my poor english

FYI I seem to remember that a Prius HSD can switch in P at 4 kph (= more than 2 mph).
At this speed the feeling is terrible for the passengers... but not for the system (if you don't play this game too often of course !). If it could damage the system, Toyota would not had allowed to switch at this speed.
Who wants to try with the Outlander ? :lol: (I will ... on snow ).

 

[jaapv]

You can do it to the Outlander as well, I once hit P with the car still moving. My passenger did not like it... Anyway, there is no danger of mechanical transmissions or engines having to be replaced as the engine is not connected directly to the drive train and the electric motors use a simple reduction gear, however, I can well imagine the locking mechanism being damaged by overloading it

 

[maby]

You can do it to the Outlander as well, I once hit P with the car still moving. My passenger did not like it... Anyway, there is no danger of mechanical transmissions or engines having to be replaced as the engine is not connected directly to the drive train and the electric motors use a simple reduction gear, however, I can well imagine the locking mechanism being damaged by overloading it

I know that it is not going to damage the engine in the sense of the pistons, cylinders, crankshaft etc. but the exploded diagram of the power unit shows the transmission brake deep inside the power unit with no obvious access that does not involve breaking it down. It looks to me like an engine-out job and then splitting the ICE from the generator and transmission casing - not a fast or cheap job.

 

[Regulo]

Not had anything like the original poster's problem - that doesn't sound right.

Re: Engaging P while anything other than stationary, I wouldn't do it. You have 2 tons of inertia moving against a small mechanical lock in the depths of the transmission. Recipe for disaster, if ever there was one!

 

[jaapv]

Yep. But it is nice to know that it doesn't break immediately if you do so by mistake. I find it strange that Mitsubishi did not disable the possibility of engaging the lock when moving.
Btw: which transmission?? I do not know where the lock is located, but it would be surprising if it were so designed that it would put an extra strain on the reduction gears of the electric motor.

 

[maby]

Yep. But it is nice to know that it doesn't break immediately if you do so by mistake. I find it strange that Mitsubishi did not disable the possibility of engaging the lock when moving.
Btw: which transmission?? I do not know where the lock is located, but it would be surprising if it were so designed that it would put an extra strain on the reduction gears of the electric motor.

There was a cutaway picture posted here some months ago that showed it apparently on the parallel hybrid transmission to the front wheels inside the power unit. It seemed to engage with a gear wheel on the output side of the clutch that connects the ICE to the front wheels when the car goes into parallel mode.

 

[maby]

Yep. But it is nice to know that it doesn't break immediately if you do so by mistake. I find it strange that Mitsubishi did not disable the possibility of engaging the lock when moving.
Btw: which transmission?? I do not know where the lock is located, but it would be surprising if it were so designed that it would put an extra strain on the reduction gears of the electric motor.

OK - I think it is in Anko's post in this thread : http://www.myoutlanderphev.com/forum/viewtopic.php?f=10&t=1064 - I can't view it at the moment because I'm logged into the company network and the firewalls block most inline images on this forum.

 

[jaapv]

Thanks -the actuator is visible there. But it is hard to see whether the brake itself actuates before or after the drive gears. That breaking it would be serious damage is clear.

 

[Grigou]

Go here too http://www.myoutlanderphev.com/forum/viewtopic.php?f=9&t=1756

Page 58 (or 60/198 in Acrobat Reader) of the Technical Highlights Manual.

The parking lock locks the second motor speed reduction shaft

 

[greendwarf]

To go back to the OP - he seems to be describing the effect you get from have the hand brake on i.e. motors still trying to move the car (forwards or back) but physically restrained when you go to Neutral. The result is the car is "released" and rocks backwards or forwards on the suspension. Whereas, of course, as described, if you are holding the car on the foot brake then Drive is already disconnected and nothing happens when you go into N.

I get this quite a lot when I put the handbrake on first (e.g. at traffic lights etc.) before disengaging D - which is how I would have driven geared cars for the last 50 years. :lol:

 

[jaapv]

And the car has an anti-rollback feature as well. It will hold the car for one or two seconds after releasing the footbrake, more than enough to drive off smoothly.
With this and P the handbrake is rather redundant.

 

[Neverfuel]

Unless there is a problem with the electronics!

 

[gwatpe]

The handbrake is also required in the sequence to change user settings in the menu. Go figure.. :?