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sub27
Member
Date registered: Jun 2007
Location: Kiel - Germany
Vehicle(s): ML270CDi 2003
Posts: 6
| gas pedal
I read in other foruns people who have the same problem as me with the gas pedal very hard.
I read a lot of information how to make the gas pedal to be lighter, but my car is still in the warranty, and like to have your opinion concerning this.
it's really a problem or it's normal?
did I need a new pedal or there are a solution cheaper?
thank's |
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Marcelc
Date registered: Dec 1899
Location:
Vehicle(s):
| RE: gas pedal
sub27 - 6/5/2007 3:04 PM
I read in other foruns people who have the same problem as me with the gas pedal very hard.
I read a lot of information how to make the gas pedal to be lighter, but my car is still in the warranty, and like to have your opinion concerning this.
it's really a problem or it's normal?
did I need a new pedal or there are a solution cheaper?
thank's
The gas pedal mechanism sucks. If the vehicle is still in warranty get them to replace the fulcrum pin which is a simple job.
I have replaced the useless (it's plastic and not even round!!) fulcrum pin with a well greased 10mm bolt, this works wonderfully, it is very smooth and the pedal feels as it should.
I have also carefully stretched the springs at either end of the cable which makes the action lighter; you should also check that the cable has no kinks, tight corners or tight clamps as any of these things will cause sticking and rough action.
It is not too hard to remove the cable at the potentiometer end and slowly drip light oil into it - that needs doing annually for best results.
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sub27
Member
Date registered: Jun 2007
Location: Kiel - Germany
Vehicle(s): ML270CDi 2003
Posts: 6
| Re: gas pedal
First I Like to tank's for contribution.
I would like to know if it is possivel to get drawings or projects of this system not to run the risk to lose the right at warantee in case something runs badly.
I already informed the Mercedes of this problem but the reply it was that is normal in ML classe.
I am thankful if someone be able to help me with some project or drawing.
And I'm thinking about to send a letter to Mercedes to inform of this problem in almost owner's, I think Mercedes is a big company and should solve this problem to all the customers.
Thank you very much. |
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Marcelc
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: gas pedal
sub27 - 6/6/2007 8:18 AM
First I Like to thank for contribution.
I would like to know if it is possivel to get drawings or projects of this system not to run the risk to lose the right at warantee in case something runs badly.
I already informed the Mercedes of this problem but the reply it was that is normal in ML classe.
I am thankful if someone be able to help me with some project or drawing.
And I'm thinking about to send a letter to Mercedes to inform of this problem in almost owner's, I think Mercedes is a big company and should solve this problem to all the customers.
Thank you very much.
I took some pictures of my throttle pedal / cable mods.
Apart from oiling the cable, removing the kinks, etc. I found that the return spring at the potentiometer end is mounted on a plastic mount which rotates to prevent stickiness, I removed the circlip on top, removed the grooved plastic piece, oiled it and checked it rotated freely.
I replaced both plastic pins in the pedal assembly with steel bolts, the top one is 5mm and the bottom one is 10mm; they screw into the plastic, cutting a thread as they go in, so the nut on the end is just a lock nut and is not very tight. I greased both bolts before assembly and am pleased with the result.
I took pictures of the top and bottom plastic pins from the pedal assembly, even though it is not a good picture it is obvious why the pedal functions so poorly.
Happy modding!
Edited by Marcelc 6/18/2007 12:29 PM
 (Throttle Cable Spring Mount.jpg)
 (Throttle Pedal Steel Bolts Assembled.jpg)
 (Throttle Pedal Plastic Fulcrum Pins.jpg)
Attachments
----------------
 Throttle Cable Spring Mount.jpg (581KB - 77 downloads)
Throttle Pedal Steel Bolts Assembled.jpg (219KB - 68 downloads)
Throttle Pedal Plastic Fulcrum Pins.jpg (430KB - 63 downloads)
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HarmsWay
Date registered: Dec 1899
Location:
Vehicle(s):
| RE: gas pedal
Great pics. Thanks for posting, I'll definitely do that mod. |
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roadsession
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: gas pedal
Marcelc - are you an engineer?
Your mods are extremely meaningful.
I am doing this one this weekend...
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Marcelc
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: gas pedal
roadsession - 6/21/2007 6:39 PM
Marcelc - are you an engineer?
Your mods are extremely meaningful.
I am doing this one this weekend...
No, but thanks for the compliment and good luck!
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sub27
Member
Date registered: Jun 2007
Location: Kiel - Germany
Vehicle(s): ML270CDi 2003
Posts: 6
| Re: gas pedal
Thank you very much!
That's all I need. |
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Marcelc
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: gas pedal
Just to finish this off properly I have changed the cable return spring (the one at the potentiometer end) to one with the following specs:
Outside Diameter 12.700 mm
Wire Diameter 0.863 mm
Maximum Load 13.335 N
Free Length 38.099 mm
Rate 0.16 N/mm
Maximum Length 114.300 mm
Initial Tension 1.107 N
material Stainless Steel
Total Coils 17.9
Number of Coils 17.9
finish PASSIVATE PER ASTM A967
This one has about a third of the rate (pull) of the standard one and prevents the overtension protection contraption (at the pedal end of the cable) kicking in which gives it a spongy feel - it's much nicer to drive now as the pedal has a direct action.
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markmaytum
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: gas pedal
Marcelc,
You are a god! My 2003 ML350 has had a sticky/heavy throttle since I purchased it 2 months ago. My Mercedes dealer has replaced the cable assembly, potentiometer assembly and the pedal assembly itself and claim this is as good as it gets. They even asked me to try driving in different shoes to see if that helped (morons).
Just stretching the potentiometer return spring ever-so-slightly has made all the difference in the world. I plan to visit a hardware store tomorrow to get the 5 and 10mm bolts that replace the plastic pins. I'm assuming that pedal detail picture was taken from inside the firewall, 10mm bolt is the main fulcrum, the 5mm bolt attaches to the cable itself? Is there a lot of interior trim to remove to get at it?
Thanks in advance!
-mark |
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Marcelc
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: gas pedal
markmaytum - 7/13/2007 12:16 AM
Marcelc,
You are a god! My 2003 ML350 has had a sticky/heavy throttle since I purchased it 2 months ago. My Mercedes dealer has replaced the cable assembly, potentiometer assembly and the pedal assembly itself and claim this is as good as it gets. They even asked me to try driving in different shoes to see if that helped (morons).
Just stretching the potentiometer return spring ever-so-slightly has made all the difference in the world. I plan to visit a hardware store tomorrow to get the 5 and 10mm bolts that replace the plastic pins. I'm assuming that pedal detail picture was taken from inside the firewall, 10mm bolt is the main fulcrum, the 5mm bolt attaches to the cable itself? Is there a lot of interior trim to remove to get at it?
Thanks in advance!
-mark
It is not really necessary to remove the trim but it is helpful to remove the panel which covers the pedals - easy to do although a little fiddly to refit over the heating duct.
I am pretty sure the 10mm shank diameter bolt is correct (17mm head), but the upper bolt may be 6mm as I tried several bolts from my box of 'bits', I cannot now check but I believe it had a 13mm head; there should be a table somewhere of shank sizes to DIN bolt head size.
The bolts replace the plastic pins, if you insert the bolt from the correct side (you can see it on my picture in a right hand drive ML), the bolt inserts freely through the pedal wall then screws into the other side (where the clip end of the plastic pin is), I screw it in slowly as it is cutting the thread the first time and the lock nut is not done very tight. The only disadvantage of proper bearing surfaces, instead of sloppy pins, is that the pedal no longer slops from side to side and your foot needs to be straighter over the pedal.
Let us know how you get on.
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skyline7
Date registered: Dec 1899
Location:
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| Re: gas pedal
That is really beneficial.thanks for that post Marcelc. |
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Tarydesign
Date registered: Dec 1899
Location:
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| RE: gas pedal
I had 1/2 hour spare and did this mod, for anyone who hasn't done it yet, its well worth the time!! I only replaced the bottom pin, the top one didn't seem to be a problem.
1/2 hour well spent!!  NO MORE WOBBLE WOBBLE
Thanks to all for their input.
PS, I rotated my accelerator cable, and this helped for a smoother feel untill I get to buy a new one! |
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Marcelc
Date registered: Dec 1899
Location:
Vehicle(s):
| RE: gas pedal
The top pin didn't seem to be a problem on mine, and replacing it didn't make anywhere as much difference as replacing the bottom pin, but it is, nevertheless, worth doing.
The whole accelerator assembly is now smooth which makes driving much nicer.
I'm glad others are doing this - the accelerator pedal is arguably the worst engineered bit of the ML.
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mjuu
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: gas pedal
Just came across this little gem of a mod and did the throttle pedal side on a Sat morning.....great idea & thanks !
Feedback: I put in a 6mm bolt on the top pivot and drilled out the throttle pedal so that the bolt easily passed through - and secured it with a nut.
At the bottom, I tapped the 'tight' side 10mm in situ ( using a shifter to turn the tap) and simply turned the bolt in afterwards ....btw, I used a 10x60mm , but I guess a 50mm long bolt would be perfect.
The pedal fit at the bottom still aint perfect and I think in my case 2 x 10mm x 0.25mm washer/spacers inserted between the pedal frame and the mounting on either side would stop any lateral movement on the lower pivot point completely. Another day maybe?
Cheers!
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Marcelc
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: gas pedal
Nice to know it's useful and thanks for adding the proper measurements.
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rb48901
Member
Date registered: Jun 2009
Location: Adelaide Australia
Vehicle(s): ML320 Luxury Pack
Posts: 8
| Re: gas pedal
I have the problem of the actual pedal pivot (Bottom) is broken, allowing the pedal to twist to one side, with the effect of missing the kickdown switch altogether. I can get the two bolts out, but i cannot remove the assembly from the car to repair the pedal. Any suggestions as what is stopping it?
Thanks
Bob |
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