XK / XKR ( X150 ) 2006 - 2014

Noise and slight jerk when downshifting from 2nd to 1st

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Old 01-05-2019, 08:15 PM
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Default Noise and slight jerk when downshifting from 2nd to 1st

47k miles 2010 XK,
when downshifting from 2nd to first especially when going down hill,
and especially when the car is hot and been driven aggressively,

I can hear and feel a clunk almost like somethings loose suspension or a loose transmission mount,
any advice on what to look at first?
 

Last edited by trkyam; 01-05-2019 at 08:22 PM.
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Old 01-05-2019, 08:26 PM
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Universal joints. <--- easiest
Transmission mounts.
Engine mounts.
Rear suspension bushes.
 
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Old 01-05-2019, 08:30 PM
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Drive train comes to mind 1st....see how much lash is present with it jacked then rotate a wheel.
 
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Old 01-05-2019, 08:52 PM
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How much lash is acceptable?
Should this be checked while in P?

When i push my car I can roll it a couple inches while in Park back and fourth
 

Last edited by trkyam; 01-05-2019 at 08:54 PM.
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Old 01-05-2019, 09:13 PM
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While in park and one rear wheel off the ground, slowly turn it back/forth look for diff motion but no drive shaft motion. You might also hear unusual clunk/grind sounds from the U-joints if they are at fault.
As CeeJay suggests it could also be mounts or bushings as well.
 
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Old 01-06-2019, 01:50 AM
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I live in and work in mountaneous terrain, and I have never had to downshift into 1st. Just curious about why youre shifting down that low while at speed?
 
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Old 01-06-2019, 01:52 AM
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Sometimes in my condo garage the trans automatically goes to 1st in sport mode.
also the lovely pops and cracks when coming to a stop light
 
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Old 01-06-2019, 02:06 AM
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For example coming down my garage which is quite steep while im braking the trans goes into 1st and i feel and hear a clunk.
 
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Old 01-06-2019, 01:10 PM
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ZF transmission lurch???
 
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Old 01-06-2019, 02:48 PM
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ZF lurch? Please explain
 
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Old 01-06-2019, 03:29 PM
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Old 01-06-2019, 03:45 PM
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Funny as I don't ever recall my car being in 1st gear.
 
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Old 01-06-2019, 03:47 PM
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As you come to a stop in first gear going going downhill in sport mode, i assure you, your car does downshift to 1st. But you probably dont notice.
 
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Old 01-06-2019, 05:03 PM
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Originally Posted by tarokyama
As you come to a stop in first gear going going downhill in sport mode, i assure you, your car does downshift to 1st. But you probably dont notice.
it does, but not til Im at near standstill. And thats for take off purposes. In manual mode you have to drop it to 1st when at a complete stop. It will only go as low as 2nd. The reason is 1st is too short, and if I have to make a left or right from a standstill, I dont have to shift into 2nd mid turn, because the paddles are stuck to the upside down or spinning steering wheel. 2nd can handle take offs just fine, but if you want to launch, 1st is your friend. I dont use Sport mode because it downshifts too aggressively too often. I use manual mode, and I do mostly upshifts. If Im going to stop, I slow down and the computer will drop gears without downshifting(nicer on the Viscous clutch) once I stop, I will downshift to 1st for take offs, but never if Im going to turn. I will drop into 2nd if Im going to make a turn at an intersection, while at speed. Dropping into first while at speed is just too much wear and tear.
 

Last edited by Brewtech; 01-06-2019 at 05:11 PM.
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Old 01-06-2019, 07:39 PM
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Originally Posted by tarokyama
For example coming down my garage which is quite steep while im braking the trans goes into 1st and i feel and hear a clunk.
Ahhh, easy fix. Dont use Sport mode while doing non sporty driving such as exiting your garage. If you need 1st, select it manually and ride the way down. Shift up around 2k rpm, or switch to auto, and warm things up. The real challenge is to learn to shift and think ahead, when using paddles, and you can avoid needing to shift while the steering wheel is spinning. Ive gotten real good at it because sport mode doesnt do it for me. The shift points dont match what my mind is thinking, and the downshifts, as fun as they may sound, theyre simply at the wrong time. Use the paddles instead. Im going out on a limb here, but 1st is not for engine braking, unless youre tracking it, and are prepared to lose it all. Thats my approach to aggresive shifting and/or racing, and its what kept me sane when I money shifted my cup car. Live and learn.
 

Last edited by Brewtech; 01-07-2019 at 05:45 PM.
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Old 01-06-2019, 08:06 PM
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Originally Posted by tarokyama
As you come to a stop in first gear going going downhill in sport mode, i assure you, your car does downshift to 1st. But you probably dont notice.
I'll have to try it as I don't ever remember using sport mode.
 
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Old 01-07-2019, 07:34 AM
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Transmission fluid has a life, and how it is used decreases that life.

Its hard to know for sure based on what you say.

The fact that it is "when hot and driven hard" inclines me to believe it is fluid related.

Wear in driveshaft's would be evident when cold.
 
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Old 01-08-2019, 03:08 PM
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☝🏻Yup
 
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Old 01-09-2019, 10:08 AM
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It seems to be a misconception that the car defaults to starting in 2nd gear. I can assure you, at least on my 2007 model, whether in D or S mode, it always starts from 1st at a stop. All you have to do is count the shifts to 6 to realize it!

To the OP, when you say clunk do you mean like a clicking/popping sound? I have had this noise ever since I bought my XKR, most evident when lurching slightly when paddle shifting and/or getting on and off the gas in manual mode while at mid to upper RPMs. Nobody seems to have figured it out.
 
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Old 01-09-2019, 10:34 AM
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Originally Posted by amcdonal86
It seems to be a misconception that the car defaults to starting in 2nd gear. I can assure you, at least on my 2007 model, whether in D or S mode, it always starts from 1st at a stop. All you have to do is count the shifts to 6 to realize it!
So yours is not going into 7th gear?

On my 5.0 XKR, always going to 1st would be unpleasant and unnecessary.
I have found it depends on how much throttle I apply. In other words I have to request the 1st gear.
 

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