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2007 Smart 451 Reverse Gear issue

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Hi All,

Need your expertise and advise on Smart 451 clutch. We have a Smart 451 2007 model full automatic. We had an occasional Reverse gear issue (car did not take the reverse gear) from the beginning... (I have check the previous threads but this issue is re-occuring and quite unique...)
  • At 27000 km Mercedes replaced the clutch plate under warranty. We are using the car as second one, so not frequently, we only take 6000 km in a year. We noticed when the car is not used for a while it did not take the reverse gear at first start.
  • 3 years back at 70000 km “3 lines”, car did not take any gear, and complete clutch set and actuator change, reverse issue still occurred but quite rarely.
  • 1 year back again “3 lines”, car did not take any gear, and actuator change (as it was broken again).
  • Now 50% of the cases at cold start the car did not take the Reverse gear, but after restart it works, now 80000 km are in the car.
Anyone has such an experience, what can be the issue, or underlying issue, as this will be the 4 time that the clutch replaced.. Reprogramming of the clutch was done multiple times.

Thanks, Daniel
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I seem to recall there was a transmission firmware update for the early 451s which was to partially address this issue. I would hope that after this many visits to the dealer that it has been applied.

I think there was also an issue with some early clutch disks, but after 3 clutches I can't imagine it would still be your problem.

Have the pilot & release bearings been replaced each time? Has the clutch hub spline been lightly greased at replacement? If the transmission input shaft has any rust or damage to the splines it can prevent the clutch disk from sliding freely. Unlikely you would know if these were done properly by the shop. Possibly your repair order may list the pilot & release bearings as items.

Has the transmission fluid level been checked or replaced?

~toaster
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Hi All,

Need your expertise and advise on Smart 451 clutch. We have a Smart 451 2007 model full automatic. We had an occasional Reverse gear issue (car did not take the reverse gear) from the beginning... (I have check the previous threads but this issue is re-occuring and quite unique...)
  • At 27000 km Mercedes replaced the clutch plate under warranty. We are using the car as second one, so not frequently, we only take 6000 km in a year. We noticed when the car is not used for a while it did not take the reverse gear at first start.
  • 3 years back at 70000 km “3 lines”, car did not take any gear, and complete clutch set and actuator change, reverse issue still occurred but quite rarely.
  • 1 year back again “3 lines”, car did not take any gear, and actuator change (as it was broken again).
  • Now 50% of the cases at cold start the car did not take the Reverse gear, but after restart it works, now 80000 km are in the car.
Anyone has such an experience, what can be the issue, or underlying issue, as this will be the 4 time that the clutch replaced.. Reprogramming of the clutch was done multiple times.

Thanks, Daniel
Hi All,

Need your expertise and advise on Smart 451 clutch. We have a Smart 451 2007 model full automatic. We had an occasional Reverse gear issue (car did not take the reverse gear) from the beginning... (I have check the previous threads but this issue is re-occuring and quite unique...)
  • At 27000 km Mercedes replaced the clutch plate under warranty. We are using the car as second one, so not frequently, we only take 6000 km in a year. We noticed when the car is not used for a while it did not take the reverse gear at first start.
  • 3 years back at 70000 km “3 lines”, car did not take any gear, and complete clutch set and actuator change, reverse issue still occurred but quite rarely.
  • 1 year back again “3 lines”, car did not take any gear, and actuator change (as it was broken again).
  • Now 50% of the cases at cold start the car did not take the Reverse gear, but after restart it works, now 80000 km are in the car.
Anyone has such an experience, what can be the issue, or underlying issue, as this will be the 4 time that the clutch replaced.. Reprogramming of the clutch was done multiple times.

Thanks, Daniel
Hi Daniel,
Having owned a 2008 smart cabrio and currently a 2009 cabrio both had and still has the reverse gear issue.
Both had the computer update. I tried using the parking brake when leaving the car for an extended time, but it didn't help.
Failure to engage reverse only happens when the car is left undriven for a few days or more. Almost never when the car has been driven and the engine is hot.
Unfortunately this problem has been well documented with no real permanent solution. It's a problem that I live with.
Reverse lights and reverse gear intermittent operation...






Good Luck keep us posted
  • Like
Reactions: 1
Hi All,

Need your expertise and advise on Smart 451 clutch. We have a Smart 451 2007 model full automatic. We had an occasional Reverse gear issue (car did not take the reverse gear) from the beginning... (I have check the previous threads but this issue is re-occuring and quite unique...)
  • At 27000 km Mercedes replaced the clutch plate under warranty. We are using the car as second one, so not frequently, we only take 6000 km in a year. We noticed when the car is not used for a while it did not take the reverse gear at first start.
  • 3 years back at 70000 km “3 lines”, car did not take any gear, and complete clutch set and actuator change, reverse issue still occurred but quite rarely.
  • 1 year back again “3 lines”, car did not take any gear, and actuator change (as it was broken again).
  • Now 50% of the cases at cold start the car did not take the Reverse gear, but after restart it works, now 80000 km are in the car.
Anyone has such an experience, what can be the issue, or underlying issue, as this will be the 4 time that the clutch replaced.. Reprogramming of the clutch was done multiple times.

Thanks, Daniel
I had no problem with the reverse gear but my car was kicking on start ( 1st gear and reverse ). The mechanic changed the clutch*** but the problem still existed. Re-teaching the clutch actuator has failed many times.
The clutch actuator was full of dirt and rust inside.... after changing the actuator it was easy to re-teach and works fine. Also I attached a link for you for further reading and tips: Evilution - Smart Car Encyclopaedia



***the mechanic changed clutch plate to a slightly different one so the actuator can push it easier he says. He did some retrofit as well on the clutch parts. I can ask him if you interested.
I seem to recall there was a transmission firmware update for the early 451s which was to partially address this issue. I would hope that after this many visits to the dealer that it has been applied.

I think there was also an issue with some early clutch disks, but after 3 clutches I can't imagine it would still be your problem.

Have the pilot & release bearings been replaced each time? Has the clutch hub spline been lightly greased at replacement? If the transmission input shaft has any rust or damage to the splines it can prevent the clutch disk from sliding freely. Unlikely you would know if these were done properly by the shop. Possibly your repair order may list the pilot & release bearings as items.

Has the transmission fluid level been checked or replaced?

~toaster
Hey Toaster, thank for your detailed response, appreciate it. Well I really don't know whether they did automatically transmission firmware update, I guess not! They did manual and sw clutch adjustment multiple times, and of course the replacement of the disk, set, and actuator multiple times (now 3 complete set within 80,000 km approx 50k miles, which kinda fun that we are using as a second/third car and always in automatic transmission). The car is made in June 2007, one of the early 451, bought in Germany directly. From the beginning I noticed the clutch smell (especially after hills) and reverse issue also turned up in early time. I am not sure about pilot and release bearing, I will check. Regarding the transmission input shaft you have a point, as the issue much frequently occurs in rainy days. Transmission fluid level is okay, but never been replaced, and also one point the battery was replaced in 2010 April (but the reverse issue still occured when the battery was new). Daniel
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Hi Daniel,
Having owned a 2008 smart cabrio and currently a 2009 cabrio both had and still has the reverse gear issue.
Both had the computer update. I tried using the parking brake when leaving the car for an extended time, but it didn't help.
Failure to engage reverse only happens when the car is left undriven for a few days or more. Almost never when the car has been driven and the engine is hot.
Unfortunately this problem has been well documented with no real permanent solution. It's a problem that I live with.
Reverse lights and reverse gear intermittent operation...






Good Luck keep us posted
Hi Jo e Lefors, thanks wow, really appreciated. Will keep you Guys posted.
I had no problem with the reverse gear but my car was kicking on start ( 1st gear and reverse ). The mechanic changed the clutch*** but the problem still existed. Re-teaching the clutch actuator has failed many times.
The clutch actuator was full of dirt and rust inside.... after changing the actuator it was easy to re-teach and works fine. Also I attached a link for you for further reading and tips: Evilution - Smart Car Encyclopaedia



***the mechanic changed clutch plate to a slightly different one so the actuator can push it easier he says. He did some retrofit as well on the clutch parts. I can ask him if you interested.
Hi Bence, thanks for response, the world is small i am also originally Hungarian. So this is not just a Smart generic issue, this is a "Hungarian issue" hahaha.
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Hey Toaster, thank for your detailed response, appreciate it. Well I really don't know whether they did automatically transmission firmware update, I guess not! They did manual and sw clutch adjustment multiple times, and of course the replacement of the disk, set, and actuator multiple times (now 3 complete set within 80,000 km approx 50k miles, which kinda fun that we are using as a second/third car and always in automatic transmission). The car is made in June 2017, one of the early 451, bought in Germany directly. From the beginning I noticed the clutch smell (especially after hills) and reverse issue also turned up in early time. I am not sure about pilot and release bearing, I will check. Regarding the transmission input shaft you have a point, as the issue much frequently occurs in rainy days. Transmission fluid level is okay, but never been replaced, and also one point the battery was replaced in 2010 April (but the reverse issue still occured when the battery was new). Daniel
I assume you mean 2007, not 2017.

If you are having "clutch smell" that indicates it is slipping. Was it just the 1st clutch that did this or do the replacement ones do so as well?

If you are still having the clutch smell then something is dramatically wrong. In a car with a clutch pedal it normally means the clutch freeplay is insufficient or the driver is riding the clutch. Has the clutch actuator been misadjusted?

When the 1st slipping clutch was initially replaced the flywheel should have been resurfaced or replaced. If the machine shop resurfaced only the friction surface and not the pressure plate mating surface this could contribute to a replacement clutch also slipping. Has the pressure plate been replaced with each clutch?

A slipping clutch is not rocket science...I wonder if your shop is just incompetent. :(

~toaster
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Hi Toaster, yes it is 2007, mistakenly wrote 2017, yes clutch "smell" is still there, not that much, but after hill rides definietly.
I assume you mean 2007, not 2017.

If you are having "clutch smell" that indicates it is slipping. Was it just the 1st clutch that did this or do the replacement ones do so as well?

If you are still having the clutch smell then something is dramatically wrong. In a car with a clutch pedal it normally means the clutch freeplay is insufficient or the driver is riding the clutch. Has the clutch actuator been misadjusted?

When the 1st slipping clutch was initially replaced the flywheel should have been resurfaced or replaced. If the machine shop resurfaced only the friction surface and not the pressure plate mating surface this could contribute to a replacement clutch also slipping. Has the pressure plate been replaced with each clutch?

A slipping clutch is not rocket science...I wonder if your shop is just incompetent. :(

~toaster
You are totally right, it is really hard to check it was in 2010, but the first replacement (clutch disk) was done by Mercedes, next ones in the past years. But i have concerns also, and i am sure there is an underlying issue which cause all this. We are planning to visit the local Mercedes, get the records and do an sw update on the clutch.
You are totally right, it is really hard to check it was in 2010, but the first replacement (clutch disk) was done by Mercedes, next ones in the past years. But i have concerns also, and i am sure there is an underlying issue which cause all this. We are planning to visit the local Mercedes, get the records and do an sw update on the clutch.

If you are still having the hot clutch smell, the clutch is still slipping.

No wonder clutches are not lasting as long as they should. It seems the original repair did not fix the issue and it is continuing to this day. This is not a simple SW update, this is a mechanical issue. I'd be really pissed at the shop which performed the work and demand that they make it right.

I think at this point you are looking at replacing the flywheel, clutch, pressure plate, release & pilot bearings...by a competent shop.

~toaster
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