Clunk when slowing down

[Tom109]

Mine has a small downshift clunk.
Small; on a side note you should drive my 60s Benz. It is normal for them to clunk harshly from new. Nobody questioned the quality of a Benz back then

When new mine had a demonstrable clunk when the transmission downshifted from 3rd to 2nd.

By 2500 miles, it shifted like any other gear. Give a little time to break in.

I can always tell when the Gren has downshifted to 2nd when slowing gently (8-15mph). Dealer aware. Not getting worse…
Petrol Trialmaster - my brother’s diesel N1 doesn’t do this. (Slightly different ZF box; very different software throughout).

Same for me - occasionally at slow speed, no throttle, clunk when it downshifts to 2nd.

 

[shiv.nandak]

For some modern transmissions an owner can improve the shift quality by going to a flat straight road and from a standing start lightly accelerate until the transmission works through all the gears then let the car slow down through the gears without the brakes. This may have to be done several times to allow the transmission to readapt. The owner can experiment with this and do the opposite, hard accelerate and slow quickly through the gears several times, add a trailer and see how the transmission quality changes when the car is empty again until the transmission re-adapts. Any further mechanical clunking will have to be investigated as it could be loose components in the drive line or steering related.

When I had Bmws you could actually follow a few steps to reset the ZF8 adaptation. I am not sure what the procedure is for the Grenadier, but it may be similar.

* Press the start button once to turn on power (Don't start the engine)
* Press the accelerator down to the floor for at least 5 sec.
* Hit start button once to turn off power
* Remove foot from accelerator
* Wait for min. 2 minutes
* Start the engine and drive

 

[Jayman1]

After 500 miles in my new Fieldmaster, I noticed a clucking sound between the right front wheel well and the steering wheel (US). It does not appear on highway driving, but side road, lower speed. Sometimes when turning or shortly after.
Intermittent, but more apparent. Curious if this sounds familiar

It stopped after 900 miles I have not heard or felt it since.

 

[AWo]

That means

a) it' totally f****d up now
b) it's lost
c) it has never been there


AWo

 

[lightning]

Or the transmission has proactively adjusted itself to smooth out the gear shifting.

 

[Ghempo]

When I had Bmws you could actually follow a few steps to reset the ZF8 adaptation. I am not sure what the procedure is for the Grenadier, but it may be similar.

* Press the start button once to turn on power (Don't start the engine)
* Press the accelerator down to the floor for at least 5 sec.
* Hit start button once to turn off power
* Remove foot from accelerator
* Wait for min. 2 minutes
* Start the engine and drive

@shiv.nandak Thanks for this very helpful information!

I tested it out on my Grenadier last night (at around 1700 miles), and it appears to have worked out my "clunking" issue.

For those of you out there that have experienced intermittent, but somewhat persistent, "clunking" from 3rd down to 2nd gear, definitely try this out!

Cheers!

 

[JackieTreehorn]

l've got a new Defender and it has the same transmission as the Grenadier l believe.
As in. ZF 8-speed.

Occasionally l get a "clunk" that l can feel rather than hear, at low speeds after slowing down then accelerating slightly.

lts when the transmission seems to shift from idle, into second gear.

lts worth checking the oil level in the transmission, as some have found it's a bit low. However it's not straightforward to check and probably something to ask your dealer to look at.

Funny you mention that..... I can's speak to the Grenadier yet because I don't have mine yet (next month), but I do have a 2021 Defender and ever since day one it has made odd clunking or popping noises in the drivetrain, always when creeping around at low speed and low loads, never under acceleration or load.........the theory on TSBs and drivers is that it is the electronic diff (center and rear) doing its thing....

I'm totally fine with a car or truck making noises (we aren't driving a lexus), as long as it is designed to sound like that!!
All I ever wanted from LR was some comfort that this would not become my $5,000 problem when outside warranty.

Vehicles today are so damn quiet, we could hear a pin drop inside the cabin, so in the case of Grenadier, I imagine that sound deadening material was not a priority, so my guess is we are going to hear things going on underneath (which tbh is a good thing, a good operator knows every sound their vehicle makes and when it sounds off)

Back to the point of this thread.......if there is some strange noises, I hope that Ineos will honestly address this and issue a TSB or statement that lets us owners know that it is within spec and totally normal.

 

[Red pepper]

Hi, any updates on this issue? Did someone got rid of the " clunk when slowing down " ( from second to first gear) looks like it's affecting just petrol cars ... , is resetting the gearbox can help? Is there any software fix?
Little bit annoyed of this issue, sometimes it's happening, sometimes not, but every time when slowing down waiting for that..
Thank you .

 

[Zimm]

Hm. Gonna give the reset a whirl. Downshifting is starting to feel like a transmission set in “tow/haul” mode when coming to a stop. 1600 miles.

 

[Tom109]

Hm. Gonna give the reset a whirl. Downshifting is starting to feel like a transmission set in “tow/haul” mode when coming to a stop. 1600 miles.

Post your thoughts afterwards. Mine has a good clunk into 2nd too.

 

[Zimm]

Post your thoughts afterwards. Mine has a good clunk into 2nd too.

Didn't work. I'm assuming its key on, foot down, key off. I really can't come to a smooth stop. There's really no way to modulate the input of down shifting and locking up of the transmission during the last few MPH with the grabby brakes. I did an hour of stop and go highway traffic this weekend and boy, is it irritating. I'll try it again, but, this isn't a BMW ecu/tcu so I don't really see why it would work.

The clunk very well could be the tcase, but because of the sudden on/off nature of the transmission. I'm getting the sensation of the tq converter locking up instead of allowing proper slippage for smooth shifting.

 

[Tom109]

@Zimm - Thanks for the update. It does feel like the t-case to me, just like my old '96 D1.

 

[Zimm]

@Zimm - Thanks for the update. It does feel like the t-case to me, just like my old '96 D1.

To be clear, mine will clunk but not every time. I seems speed and deceleration, need to time it right with the downshift. Kinda like committing a crappy downshift in a manual.

 

[ErnieB]

I'll go off the current line of thinking but I would check the torque on the control arm bolts. One of our members here was experiencing the same issue only to find that one of his upper control arm bolts had worked its way loose and was in fact completely missing. Remember to torque them with the vehicle on the ground NOT on a lift.

 

[grnamin]

Could it sound like a loud fart when accelerating and then quickly easing up on the throttle?

 

[Red pepper]

There are a lot of topics on the Google search about : "ZF8 transmission downshift clunk " , but there are no real solutions how to fix it....

 

[Zimm]

I tried the reset a second time. Nothing.

I did watch the temps and the tranny acted "normally" at 90deg, and the situation start to appear as the temps rose to normal operating temps. The time window is short to mess around while its still cold, so that may take a few days to be sure.

I did try slowing to stop with it shifted into manual to see what would happen, and it really appears to downshifts normal, or at least smoothly without any herky jerky back any forth . I know nothing about modern auto transmissions, but I'm guess it has a set parameter to downshift in manual mode when the driver fails to do so , and there's really no other parameters it considers. maybe it feels smooth because it stays locked? Never locks? I have no idea really. I'm just tossing shit to see what sticks.

 

[lightning]

There's a few people complained about a similar issue on the new Defender, which has the same transmission.

There's a couple of things that have been identified as a cause.
Firstly mine had the clunk but Land Rover Assist came out and updated the software in the transmission control module. After that it was a lot better.

ln addition, there have been reports of vehicles being delivered with slightly low oil level in the transmission. You could check this, although it's far from straightforward to check the oil level in the ZF 8 speed.

Thirdly, l've found that diesel engines can take 10,000 miles or more to fully loosen up, and mine has indeed become smoother over time. When new, if you slowed down nearly to a standstill and then accelerated, nothing would happen for a coupke of seconds and then the transmission would suddenly engage with a "thump" and the Defender would suddenly take off as if it had been rammed from behind.
Again this reduced over time until it stopped doing it.

And finally, it's possible to reset the "gearbox parameters" on the ZF transmission control module although l haven't any information as to whether it does any good.

Mine used to sometimes lurch when changing from second to third, in certain circumstances. Over time this improved and eventually stopped doing it.

 

[DCBNA]

I get the same thing under braking from time to time. I’ve tried to intentionally recreate it but I can’t. It sounds/feels like I’ve run over something or there is something moving around underneath the vehicle. I can’t for the life of me figure it out.

 

[Tom109]

With 1990’s LR’s, wasn’t the downshifting clunk due to the t-case intermediate shaft preload being low?