Although my 500x 4x4 auto transmission is smooth when changing gears - I do notice an annoying "jerk" when first moving off ( in 1st gear when in sport AND in 2nd gear when in auto )

When I take my foot off the brake and apply pressure on the accelerator, no matter how carefully I apply that pressure, it jerks. Almost like the initial take up on the clutch is an "on-off" switch.

Any ideas ?

Is this after releasing the electronic park brake manually or when using the accelerator to release it? I notice something similar when using the latter.

Nothing at all to do with the parking brake.

Most noticeable in stop start traffic. Sitting in traffic, transmission in drive, foot on brake. Ready to move off - move foot over to acclerator and no matter how gently I depress it, it seems to jerk rather than smoothly move away.

A thought occurred to me.............

Its very close to needing its first spark plugs change. I am wondering if old plugs might mean a slight lag in acceleration causing the jerk when they "catch up" ?

theshootist said:

A thought occurred to me.............

Its very close to needing its first spark plugs change. I am wondering if old plugs might mean a slight lag in acceleration causing the jerk when they "catch up" ?

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I have the 2.0 MJ variant and I definitely do not get that unless it selects 1st gear for any strange reason, second is smoother than a smooth thing

I also get occasional jerking in lower gears on my 9-speed auto, but I can't really put my finger on what could be causing it. Nothing major, but it's there and yes, it can be annoying sometimes.

Goodcoin said:

I also get occasional jerking in lower gears on my 9-speed auto, but I can't really put my finger on what could be causing it. Nothing major, but it's there and yes, it can be annoying sometimes.

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9 speed? Blimey things have moved on since I last had a 3 speed auto [emoji50]

typecastboy said:

9 speed? Blimey things have moved on since I last had a 3 speed auto [emoji50]

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Yep. I get 130 kph (80 mph) @ 2000 RPM in the 9th gear, which I find rather amazing.

Don't know 100% about this auto transmission but on my old Stilo Aparth Selespeed auto box there is/was a "clutch learning" procedure that can be carried out by a suitably equipped technician.

I had a similar issue on my Stilo and the dealer "re-learned" the clutch pickup and it greatly improved the situation. Still had the occasional not so smooth pickup though depending on conditions.

All these modern auto boxes have one ore more calibration procedures that can be carried out. I note that MultiECUScan currenty support 3 procedures for the 500X auto boxes. On this point if your vehicle is still under warranty then do not be tempted to "have a go/play". Let the dealer check the issue etc.

typecastboy said:

9 speed? Blimey things have moved on since I last had a 3 speed auto [emoji50]

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Conventional torque converter autoboxes sap power and guzzle fuel. The torque converter would traditionally multiply torque up to about 3:1 or sometimes 3.5:1.
With more gears, the torque multiplication can be reduced, back to 1:1 or just over. This allows a little slip for moving away and shunting, then effectively locks up to eliminate further power loss or fuel wastage.
Also, more gears can allow the engine to remain nearer its most efficient more of the time. We currently have 6-speed manuals, but any more gearchanging than that and most owners would complain, but an auto can have more without bothering the driver. With smaller gaps between ratios, changes are smoother and less noticeable.

Twin-clutch transmissions reduce power loss further, and as above can have lots of gears. Not heard of one with more than 9 yet though. Anyone got more than 9?

portland_bill said:

Conventional torque converter autoboxes sap power and guzzle fuel. The torque converter would traditionally multiply torque up to about 3:1 or sometimes 3.5:1.

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Not wanting to stray too far from the original post but I've yet to find/drive a modern auto box that does not have a torque converter (ie. one or more dry clutch plates) that is *perfect* for towing. I would just love a dual system with both engagable/disengable torgue converter and the rapid dry plate system.

I loved towing with the Stilo 6 speed selespeed box EXCEPT when reversing or stuck in start/stop/crawl traffic jams. This is when human fine clutch control is required.

In reverse the selespeed would over rev and slip like mad. Very smelly and damaging.

When in traffic jam crawls you could not (like in a traditional manual clutch) get rolling and then just go feet off all pedals and just idle along. The selespeed would drop the clutch when you lift off the throttle. So a traffic crawl became a "slip" / "slip" / "slip" journey. Also with the trailed load the selespeed wanted to over rev the engine.

With a torque converter there are no such issues. All slip is just fluid dynamics till the converter locks up.

And getting back to the original post "jerky" takeoff then the computers and systems have removed the operators "feel and control" and I guess what is jerky or slack or lethargic etc will vary from one driver to another.

When we are all forced to go electric then these issues will mostly be eliminated.

theshootist said:

Although my 500x 4x4 auto transmission is smooth when changing gears - I do notice an annoying "jerk" when first moving off ( in 1st gear when in sport AND in 2nd gear when in auto )

When I take my foot off the brake and apply pressure on the accelerator, no matter how carefully I apply that pressure, it jerks. Almost like the initial take up on the clutch is an "on-off" switch.

Any ideas ?

Click to expand...

I wonder if this could not be the clutch but the brake release?

It's just that the clutch wouldnt necessarily activate from standstill, with s/s off the braking would be against the clutch, and once you release the brake I don't think the clutch is engaged. What im trying to say in a roundabout way is I don't believe that releasing the brake necessarily activates the clutch.

Are the brakes just sticking a bit? Maybe the pads dont fully release from the disc's or something? Or maybe the parking brake sticks a bit (This would be my guess).