Hard Accelerator Pedal fix? - PeachParts Mercedes-Benz Forum

dieseldan44 · #1 04-19-2010, 11:00 AM

I've gone though and adjusted / lubed all the pushrods to FSM specs.

The pedal is still fairly stiff and takes a lot of force to push through the entire travel range - sticking though - just stiff.

This is on the '85. The 82's pedal is much easier. The '82 is in storage so a side by side comparison is not easy at the moment.

What can I check / lube / change to make it easier? Have a 6k-mile road trip coming up and my gf cant drive the car with the pedal in it's current condition :-(

Thanks, dd

vstech · #2 04-19-2010, 11:04 AM

start at the pedal itself. carpeting can sometimes jam itself under things, causing issues.
then look at the pivot bushing on the firewall, see if it's disintegrated and causing binding.
if you have already cleaned and lubed all the connections on the linkage, take each one apart and see if the individual parts are seized.

Diesel911 · #3 04-19-2010, 12:12 PM

The below pick item is attached to the Fire Wall. When Old the Plastic Ball/Bushing on the back falls apart and cracks. I believe it is also supposed to be able to swivel a little like a Ball Joint.

I pulled one from the Junk Yard just to have an extra but I found thaw while the Ball was mostly intact there is a Groove worn in the front that would prevent it form swiveling around.

Also I do not recall you saying if this problem showed up by itself or if it happend after you did some work on your car?

dieseldan44 · #4 04-19-2010, 12:36 PM

The problem has always existed on the car.

vstech, I'll check the other parts out.

thank 911 I'll check that part out.

I was wondering if people have been replacing the spring for a lighter one. Ive seen others complain about the pedal stiffness on 617952 setups before.

MBeige · #5 04-19-2010, 08:50 PM

Not sure but I think there are two holes on the firewall for the spring mount. Maybe the higher one will give it a better (softer) feel.

leathermang · #6 04-19-2010, 11:27 PM

That spring has a safety aspect to it I would guess...
Think about these Recalls lately where the throttle stayed engaged...

That spring MUST be able to return that string of rods and friction spots back to idle...no matter how stiff they get from lack of lube OR ANYTHING ELSE.. ..... or something bad might happen in an unexpected flash....

So I would not be changing the spot it is hooked and decrease the pressure RETURNING the throttle towards OFF... ( I know we have no 'throttle'....but you get the point).

dieseldan44 · #7 04-19-2010, 11:44 PM

Quote:

Originally Posted by leathermang

That spring has a safety aspect to it I would guess...
Think about these Recalls lately where the throttle stayed engaged...

That spring MUST be able to return that string of rods and friction spots back to idle...no matter how stiff they get from lack of lube OR ANYTHING ELSE.. ..... or something bad might happen in an unexpected flash....

So I would not be changing the spot it is hooked and decrease the pressure RETURNING the throttle towards OFF... ( I know we have no 'throttle'....but you get the point).

leathermang,

point taken. good spot to use a great deal of caution for sure.

dd

bustedbenz · #8 04-19-2010, 11:53 PM

The accelerator pedal, made of some rubbery material, attaches to the metal portion of the accelerator rod right at the pedal through a round hole that's built onto the back side of the pedal in a little frame thing. This rubber has a TERRIBLY frequent tendency to tear, break, come off, twist off, and otherwise shred itself. When this happens, the early symptom is that the pedal feels like you're forcing it through a bind. Then you stomp it a little harder, it finally tears in half, and you're left with a pedal that is attached at the floor but not to its shaft. The shaft lodges in another part of the pedal back, thus making the angle of travel wrong, and it quits pressing at all. To get out of traffic you have to remove the pedal and just accelerate by pressing the metal rod.

Point is: get on your hands and knees and inspect the pedal where it is attached to the rod it pushes. See if it's ready to fall off in your hand and therefore in need of replacement.

I know this is how my 1986 pedal works. I BELIEVE yours is the same, but if it is not, then nothing I said is valid.

dieseldan44 · #9 04-22-2010, 01:19 PM

anyone ever remove the accelerator?

i see the FSM article on it, whats the trick to compressing the clip? it seems like the kind if thing that doesnt want to move.

i think my bushing is OK - its hard plastic, right?

LUVMBDiesels · #10 04-22-2010, 02:28 PM

Quote:

Originally Posted by bustedbenz

The accelerator pedal, made of some rubbery material, attaches to the metal portion of the accelerator rod right at the pedal through a round hole that's built onto the back side of the pedal in a little frame thing. This rubber has a TERRIBLY frequent tendency to tear, break, come off, twist off, and otherwise shred itself. When this happens, the early symptom is that the pedal feels like you're forcing it through a bind. Then you stomp it a little harder, it finally tears in half, and you're left with a pedal that is attached at the floor but not to its shaft. The shaft lodges in another part of the pedal back, thus making the angle of travel wrong, and it quits pressing at all. To get out of traffic you have to remove the pedal and just accelerate by pressing the metal rod.

Point is: get on your hands and knees and inspect the pedal where it is attached to the rod it pushes. See if it's ready to fall off in your hand and therefore in need of replacement.

I know this is how my 1986 pedal works. I BELIEVE yours is the same, but if it is not, then nothing I said is valid.

Beat me to it! I just replaced the 2nd pedal in the SDL

To compress the clip simply reach in the back of the pedal and squeeze it together. It helps to have needle nose pliers to pull the clip out of the pedal and metal fitting.

The replacement takes literally 2 minutes.

MBeige · #11 04-22-2010, 03:24 PM

I took the clip or bushing from behind the pedal once to clean it, the process was quick and easy. However, I still have the same feeling of stiffness on the pedal. I merely cleaned it up. Did not have any need to replace it.

dieseldan44 · #12 04-23-2010, 12:18 AM

RE: the bottom piece - I tried pushing mine together....and then prying it with pliers. The thing is held in with black magic. Ill give it another go tomorrow.

BTW - I changed out my firewall bushing near the oil filter canister - no real difference in pedal feel. The original one did have a lot of play and was pretty far gone.

andrewjtx · #13 04-23-2010, 12:31 AM

Quote:

Originally Posted by dieseldan44

BTW - I changed out my firewall bushing near the oil filter canister - no real difference in pedal feel. The original one did have a lot of play and was pretty far gone.

Pretty far gone is when that nylon ball has disintegrated and it's barely staying together. Been there. Done that.

rhodes2010 · #14 04-23-2010, 12:54 AM

Funny that this would come up tonight.

After years of thinking my 1983 300SD was just too darn tight.
I removed the spring on top of the valve cover that is coiled and hooked
on (under) the lever that the transmission cable attaches to, the cruise control attaches to, and the throttle attaches to.

If you have ever disassembled this whole thing to lubricate ( and I hope everyone here has done this at least once) you have to deal with this spring.

My motivation and comparison was that the 1980 300D has the smoothest and weakest throttle ever. I love that car.
But the 300SD makes my right leg hurt. I use cruise control a lot.

Tomorrow I will put on my daily 150 miles (4 days a week) and let you all know
how it went. Expecting the cruise control to work just fine.
Love the smoother operation.

I do keep an eye on the firewall mount point, I do lube the ball sockets, but I
did not know about that back of the pedal thing. I will check it tomorrow.

dieseldan44 · #15 04-23-2010, 10:55 AM

Quote:

Originally Posted by rhodes2010

Funny that this would come up tonight.

After years of thinking my 1983 300SD was just too darn tight.
I removed the spring on top of the valve cover that is coiled and hooked
on (under) the lever that the transmission cable attaches to, the cruise control attaches to, and the throttle attaches to.

If you have ever disassembled this whole thing to lubricate ( and I hope everyone here has done this at least once) you have to deal with this spring.

My motivation and comparison was that the 1980 300D has the smoothest and weakest throttle ever. I love that car.
But the 300SD makes my right leg hurt. I use cruise control a lot.

Tomorrow I will put on my daily 150 miles (4 days a week) and let you all know
how it went. Expecting the cruise control to work just fine.
Love the smoother operation.

I do keep an eye on the firewall mount point, I do lube the ball sockets, but I
did not know about that back of the pedal thing. I will check it tomorrow.

Ive run in to this spring...its a beast. So you just took it out altogether?

My cruise is totally removed, is its function to help regulate cruise only?

Does your '80 300D have it?

dd