daj

Posts: 15

Country:

Thanks: 0

Thanked 0 Times in 0 Posts

Has anyone had an issue with a jerky 7G gearbox when slowing down giving you a jolting action, it happens when the car is coming to a stop probably shifting to 2nd or 1st gear, intermittent, sometimes small jolt, other times a more violent jolt. I have had my gearbox software flashed twice in two weeks with the latest software, but still have the issue. Just got my car back again today and the dealer has run all the diagnostics on the box and says no fault is showing up. Anyone have any ideas about what this could be???

nmslk

Posts: 207

Country:

Thanks: 1

Thanked 9 Times in 7 Posts

It sounds like the normal downshifting that the car does as a part of slowing down. Do you notice any difference if you are in S, C or M tranny mode?

-Michael

daj

Posts: 15

Country:

Thanks: 0

Thanked 0 Times in 0 Posts

Have the same issue in S and C (so possibly only issue with 2nd gear, as I do not think C engages 1st gear), going to try M over the weekend. Never had the issue with the box until recently, used to be a very nice smooth gear change. Took out an E-class with a 7G box and that is perfect, in fact every other Auto I have driven is smooth. This feels as if you have slammed your foot on the brake very hard for a split second when the gear goes into 2nd but with different variations in force (depending on the jolt given). Sometimes it occurs whilst pulling away too, as if it gets the wrong gear.

Dean

etyu

Posts: 5,281

Country:

Thanks: 377

Thanked 277 Times in 168 Posts

I had something similar but it was short-lived (2-3days) during the break-in period. After driving at varied speeds for a day or two, I think the adaptive software "learned" and the jerky downshift disappeared.

IIRC, some old threads in other forums mentioned that it may be related to a faulty throttle valve body (?) at the transmission. I believe there was a TSB on this.

__________________
Eddy

To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts.

Pewter/Beige, PIII package, Airscarf, Hands-Free Communication System, Lighting package
Designo Black Leather Cover on e-brake handle, (
To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts.
Bill T), SmartTop v1.0, Kleyman 3BFM (NoRegret Custom), Green Air Filters, Mod. R170 ant., EuroClear sidemarkers w/PIAA PlasmaIon lamps, chromed front & rear turn indicator lamps, PIAA SuperPlasmaGTX front parking lamps, bilateral rear fog lamps enabled.

etyu

Posts: 5,281

Country:

Thanks: 377

Thanked 277 Times in 168 Posts

Here's TSB no.: Auto Trans - Rough Shift Quality _ P-27-60-61F _ 27-Nov-06

__________________
Eddy

To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts.

Pewter/Beige, PIII package, Airscarf, Hands-Free Communication System, Lighting package
Designo Black Leather Cover on e-brake handle, (
To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts.
Bill T), SmartTop v1.0, Kleyman 3BFM (NoRegret Custom), Green Air Filters, Mod. R170 ant., EuroClear sidemarkers w/PIAA PlasmaIon lamps, chromed front & rear turn indicator lamps, PIAA SuperPlasmaGTX front parking lamps, bilateral rear fog lamps enabled.

DansSlk

Posts: 6,756

Country:

Thanks: 96

Thanked 221 Times in 173 Posts

What year is your car mate?

Like Eddy said sounds like valve issues, the dealer should check the filling time using SDS

__________________

leelk

Posts: 135

Country:

Thanks: 0

Thanked 0 Times in 0 Posts

I have the exact same problem with my 06 slk55.
However, the problem seems to happen during the break-in period in the first thousand miles. I think the computer is learning the way you drive as well. So just get used to it and wait to see you still have that problem or not.

jliu

or it could be you just need to reset the adaptations.

Duo-Art

I also had this problem when my car was new but it disappeared after a few thousand miles.

daj

Posts: 15

Country:

Thanks: 0

Thanked 0 Times in 0 Posts

Sorry Dan, just updated my profile to reflect age of car. It's a 2004 (one of the first batch). The dealer showed me some printouts yesterday saying there was nothing wrong with the box, but they could have showed me anything really. From the diagnostics they ran on the box would the filling time be one of the standard checks made, if so I can get the results from them. And just so that I sound like I know what I am talking about, is it the filling time of the valves they should be checking, thanks?

daj

Posts: 15

Country:

Thanks: 0

Thanked 0 Times in 0 Posts

I really wish it was just a running in problem, but i have had my car 3 years now and it's only just appeared and progressively getting more noticeable.

Banned

I´m sorry to say but just up to 2007 the 7g is free of mistakes, the former models have had problems, but with the new software* it should be gone. If not there´s something wrong with the gearbox itself.

* - some dealers don´t know which version is the newest...

alroumi

Posts: 6,271

Country:

Thanks: 288

Thanked 231 Times in 145 Posts

no rough shifting here might be an earlier recall when they first produced the r171 slk generation.

DansSlk

Posts: 6,756

Country:

Thanks: 96

Thanked 221 Times in 173 Posts

Hey mate,

Do you have the copies of the DAS reports?

I would expect them to just run a short test on the box, you have to request the filling times be displayed.

And yes i mean the filling time of the valves that control the flow of hydraulic fluid around the unit.

__________________

daj

Posts: 15

Country:

Thanks: 0

Thanked 0 Times in 0 Posts

Didn't even think to ask for them. I will ask for them on Monday and see if they will let me have a copy.

Just been tearing around in M and definitely only notice the problem in 2nd. Been upping and downing gears and letting is shift down itself on a level road. In M it tends to auto-shift from 3rd to 2nd at around 11-12 mph and each time their is a noticeable jolt, sometimes soft other times hard.

Another interesting factor is that if I park my car on a hill facing downwards, turn the engine off and return to it later, when I shift the gear selector into R, there is a very loud clunk of it getting into gear, again didn't notice this on the E or B class I borrowed recently.

DansSlk

Posts: 6,756

Country:

Thanks: 96

Thanked 221 Times in 173 Posts

Is the jolt as bad when you shift? If you imagine driving a manual car and shift when you feel is best do you still get the jolt as bad / at all?

That clunk could be the parking prawl if parked nose up/down it takes the weight of the car and can release with a bang, does the car squirm when it happens?

A good test is start to park the car in a spot you have confirmed you get the noise but when you come to stop the car first shift into N then engage the hand brake and release the brakes, the parking brake should take the weight of the car and you can then shift into P without the park prawl engaging into the shaft then when you come to drive off shift into R before releasing the park brake and see if you get the noise (remember to keep your foot on the brake pedal for this so the car does not try and overcome the park brakes)

__________________

suntan

Posts: 41

Country:

Thanks: 0

Thanked 0 Times in 0 Posts

Hi! I think I have the same problem too. I'm experiencing some "lumpy" shifting when downshifting from 2-1 (in auto mode). It's really odd and hard to describe, but basically the car slows down, slows down, slows down, and then all of a sudden, it surges forward! A little bit of a "nonlinear" feel, if you know what I mean? This happens in both C and S mode.

I haven't tried manually shifting yet; I'm not sure how that would allow me to diagnose the nature of the problem further. From what I understand, this could either be a mechanical problem (something to do with a valve?) or a software/adaptive problem? Is there anyway to tell between the two without bringing it to the dealer? For example, from what I understand, if the problem is adaptive, then within a few thousand miles, it will go away, but if it is mechanical, it should get worse with time? If so, I should probably just wait and see, right?

Thanks so much!

cheers,
suntan

daj

Posts: 15

Country:

Thanks: 0

Thanked 0 Times in 0 Posts

Yep, get the jolt when in Manual Mode, but only when shifting down to 2nd, manual shifting through others gears is seemless, hardly noticeable at all. I think the jolt is about the same strength, but do find the jolt is more pronounced when I am braking to slow down coming to a junction etc, than letting the car roll to a stop.

I will test out the Parking prawl issue soon, thanks.

daj

Posts: 15

Country:

Thanks: 0

Thanked 0 Times in 0 Posts

That sounds just like the same issue. One of the reasons for testing in M mode is to determine which gear is causing the issue. I originally thought it was when mine went from 2 to 1, but in M mode you can see the gear the car is in when slowing down and it has turned out to be from 3 to 2 on mine, then again not sure that is much of a help .

Mine appears to be getting worse with time, initially the jolts were minimal, happening once in a while, but now I seem to get the jolts every time the car comes to a stop.

DansSlk

Posts: 6,756

Country:

Thanks: 96

Thanked 221 Times in 173 Posts

Basically in the UK Merc offer a proper M mode on all SLK models and its useful for diagnosis because as daj says it allows you to pick out the bad gear but also try shifts at various rev ranges and force the car to hold the selected gear.

No way to tell the difference between a mechanical problem and a software problem without visiting a dealer sorry mate even we can't tell exactly but if we reset the adaptions and the problem is still present then its going to be mechanical.

If i where you i would get it looked at asap not trying to say your gearbox will go bang if you don't but it will be noted as a visit with this problem.

__________________