Pedal to the metal (accelerator assembly rebuild)

Moby came with dual Kadron/Solex carburetors, something with which I had no experience.  At first, I was extremely tempted to replace them with a more familiar stock, single carburetor setup, but did not have the parts at the time.  As I began to buy what was needed for the swap, I got to know the dual Kad system a bit better and, at this point, have even grown a bit fond of them.  I have, however, had a few troubles getting them to function perfectly – mostly in getting them to idle at a reasonable RPM.  One of the more common idle problems (with all carbs, not just Kadrons) lies in the accelerator linkage.  Wear and biding within these parts contribute to poor function of the carburetor(s) throttle arm(s) so checking this system in its entirety seemed like a good starting point.

The first indication of problems in the accelerator linkage showed up in the accelerator pedal.  When depressed, the pedal moved to the right instead on going straight down.  This lateral movement is a sign of damage to the accelerator pedal, mounting pin (bolt), hinge, push rod, lever, and/or pivot block.  To find out what damage existed, I removed the pedal splash pan under the front of the bus and disassembled the the linkage system in order to inspect all the connection points.  Replacement parts and repair kits are readily available at various VW vendors, and their relatively low cost makes it worth replacing all parts that show a little wear and tear.  The hinge and pivot block (I have no idea what the real name is for the latter) are welded to the body so I opted not to replace these for the time being as wear on them was minimal and replacing the other parts greatly improved linkage function.  I also did not replace the accelerator pedal, but this was only a result of the fact I erroneously thought I had a spare in the parts bins.  A new one, along with a new bolt, will be picked up in a future parts order.  Just replacing the few parts I did made a huge difference and, with the linkage improved, I could move on to the carburetors themselves.

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The original linkage setup under the accelerator pedal. The push rod passes through the floor and attaches to the pedal. It’s really a pretty simple system!  To disassemble, pop the spring clip off the push rod and lever shaft, disconnect the push rod from the lever, pull the lever out of the pivot block, and then remove the accelerator cable.  In some cases the spring clips may have been replaced with various substitutes which might be a little more difficult to remove.

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Accelerator refurb kit. They come in different varieties depending on what needs replacing; individual parts can also be bought. This kit is a pretty basic one, with just a lever, push rod, two spring clips, two washers, and a cupped washer.

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Here is the lever (left, middle) and push rod (right, top) from the kit compared to two original sets. The lever dimensions are pretty much identical in all cases, but the push rods varied in length.  The new replacement was the shortest. The bottom rod, which came from Moby and might be a replacement, was a tad bit longer and the middle rod (a known original part) was the longest of the three. A longer push rod would provide maximum articulation of the carburetor throttle arms and I’m not convinced the new, shorter rod is providing adequate range of motion.  However, without having multiple kits to compare, I can’t make a call which replacement parts/kits are best or even if there are additional differences. This is something I’ll need to pay attention to at part swaps. If you happen to do this work on your bus, send me the measurements of the OG rod and your replacement in the comments below.

The hole where the push rod attaches to the lever often becomes distorted as it wears out. The top left hole shows the wear found on Moby’s lever while the middle hole is the replacement lever, and lower hole is on the OG spare from my old bus.

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Moby’s push rod where it attaches to the accelerator pedal has a well-defined groove worn into the rod by the pedal. The pedal’s attachment point is also worn, much like the lever hole above, and will need to be replaced in the future.

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Wear at the junction between the push rod and lever was not as bad, but still noticeable.

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One characteristic I noticed about the replacement lever is a sharper bend than what is found on the OG spare.  Moby’s lever, however, has a similar bend and makes we wonder if it is a replacement part or if the OG spare was flattened at some point.

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Moby’s lever was twisted a bit as a result of a PO forcing a stuck accelerator cable by stomping on the pedal.  Photographing the twist turned out to be a challenge, but it can be seen here best by looking at the space between the lever and workbench as indicated by left red arrow.  The lever arm turns slightly up, creating a larger space than what is found with the new lever on the right.

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In addition to the wear found underneath the floor, the accelerator had become loose around the bolt. With a pair of pliers, I tightened the pedal (red arrow) around the bolt and then applied a little grease on both sides.

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Push rod and washer: greased and ready to attach to the accelerator pedal.

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Insert the rod through the push rod boot and then attach to the pedal. Originally, only spring clips were used to hold the rod in place and prevent any unwanted movement or slippage. I found that enough slop remained in the linkage (most likely due to the parts not replaced) to pop the spring clip off when the pedal was fully depressed so I used a 7/32″ circlip (E-clip) for extra security.

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7/32″ circlip (E-clip) on the left. The kit and original setup use the cupped washer to lock the lever shaft in the pivot block. Once on, these washers are difficult to remove so I opted for the E-clip – with a simple twist of a small screw driver, they easily pop off.

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Passenger side view.  Assembly is the reverse of taking everything out – attach the cable and push rod, insert the lever into the pivot block, and then attach the various clips. Not visible in the picture is a washer between the pivot block and lever. Since no spring clip is used here, it is important to eliminate any extra space so the lever shaft can’t slide horizontally in the block. Similar to the steering linkage, where all motion should be focused on turning the wheels, all motion here should be centered around moving the cable. Side-to-side slippage should be reduced as much as possible.

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Driver side view. The circlip on the push rod is not pictured here, but I added it later for reassurance.

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One thought on “Pedal to the metal (accelerator assembly rebuild)

  1. Pingback: Pedal to the metal (an unexpected revisit) | Zero to Sixty . . .Eventually

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