Sponge Bob Bit Rot

There is nothing major wrong with Sponge Bob Square Trike, but there sure are a lot of little things. As I am writing this, I feel the sudden need to make a list, but it will have to wait…

Last Sunday, we wanted to ride to the monthly club meeting, so I spent some time on Saturday resolving a couple of little things on Sponge Bob and troubleshooting a couple of others.

Sponge Bob has had a few issues with reliability. Seems that he never fails to start, but he sometimes doesn’t make it to the destination. Recently, inspection was due. In the short trip to the inspection station, it threw/broke the one and only belt. In sunlight, the alternator light is very easy to miss, so I was blissfully unaware. Upon arrival, about a 10 mile trip, the engine was seriously hot as the cooling fan is driven directly off the back of the alternator.

As luck would have it, the inspection station is next door to (and owned by) a tractor dealer, so I was able to peruse their selection of belts and find one that worked well enough. However, in the short ride home, the new belt was itself shredded. I think that I chose one that was a reasonably proper length but too wide.

Also, the crank pulley on this engine has had a hard life. At some point the distant past, I was going to change the pulley to dress up the engine. After much struggling, I discovered that it had been welded to the crankshaft, but not before I had bent it trying to remove it.


It’s tough enough to straighten a pulley enough to keep it in service on an engine, but try it when you have to do it in place on the engine.

If the distance between pulley faces is variable, it will definitely chew up a belt, which is probably exacerbated by the wrong width or wrong V angle, which seems likely with the tractor store belt. I put a proper stock belt on and rolled the engine manually to see where the wide spots were, where the belt sank deeper into the pulley than it should, then worked on narrowing those areas with a deadblow hammer. I was able to get it where I no longer saw any significant change in the belt depth.

The brakes do a slightly irritating thing wherein they sometimes hang partly engaged, particularly the right wheel. Sometimes, I have to come to a complete stop or even roll backward a bit to free it. In this mode, the trike pulls slightly to the right and you can tell it’s just not rolling right.

I spent far too long searching for but not finding my good jack and ended up using the motorcycle lift (which actually does a pretty good job as a rolling engine jack) to lift the right wheel for removal. There is an adapter plate to let me run Chevrolet wheels on the old four bolt VW hubs, then the big ol’ 36mm nut that holds the hub on the axle. I have on a couple of past occasions, on another trike, had to cut that nut off because it seized badly enough that I couldn’t break it loose. Even without being seized, it is normally torqued to 217 foot pounds. I am very happy I got an electric impact driver some time back. I needed it to change the blades on a BushHog mower, but for this, it made short work of removing and reinstalling the wheel hub.

Inside, I didn’t find anything obviously wrong, but there were two weird things. First, the spring looks like it used to have paint on it and the paint was now a gummy kind of coating. At first, it looked like it was solid and could possible prevent the spring from retracting, but upon closer examination, I don’t think it really would. I cleaned the spring and put a bright and shiny spring back in place. While I had the spring out, though, I found that the brake shoes rub pretty hard on the backing plate, which is in itself how it works, but they seemed to drag pretty badly. I removed them, cleaned the surface rust off the backing plate and reinstalled them. I’m not sure that was enough to address the issue, but regardless of the other difficulties Sunday (described below), the brakes didn’t hang. This will require continued monitoring. It is, afterall, only the brakes. 🙂

I also did a little looking at the speedometer. It’s a VDO speedometer and pickup coil, set to pick up 5 boltheads on the front wheel. It worked very well for a long time, but over the last few years, it became intermittent and finally doesn’t indicate at all. It powers up and does it’s power on self test, but it no longer indicates any speed, actual or imagined. I checked the pickup coil itself; it reads 750 ohms. I have thus far found documentation for the resistance reading for another line of coils, so I don’t know if this is the correct reading for *this* particular sensor, but it is neither open nor shorted. A good place to start. I will put the oscilloscope on it to verify whether or not it is generating a signal.

So, when Sunday came, we headed to Fort Worth. Trike ran great until we got on the highway and tried to go highway speeds. Then the engine would cut out like the switch was turned off. Just slowing down wasn’t enough to restore operation. It needed a minutes or two to “catch up”. That symptom usually indicates fuel starvation, but it hits so suddenly and completely that I don’t think it will turn out to be a fuel issue. Fuel starvation is usually a lean-out condition with backfiring and such.

Then again, I have been fooled before.

It happened multiple times. My first thought is the key switch. It is the stock switch from a Honda CX500, which is what the front forks on the trike came from. The switch energizes a couple of relays in the back of the trike for powering stuff, but to save a little back and forth wiring, I run a couple of things directly off it. I may have thus overloaded it, maybe burning the contacts and making it intermittent. Sometimes, I have to jiggle the switch a bit for the engine to start, which is why I thought bypassing it might help. We stopped once and I tried bypassing the key switch by using a jumper to directly energize the main relay, but the problem persisted. We were running late by then and elected to park the trike in a safe place and ride two-up on the Spyder to get to the meeting.

After the meeting, we met with people for lunch, including one of my trike gurus, and discussed this problem. In conversation, he was describing some of the wiring details on his trike and he said something that tripped a thought… he said his key switch doesn’t have any load on it except for a *continuous duty rated* relay and it occurred to me that the relay I am using is a standard 30A Bosch style relay, but I don’t recall it being “continuous” duty rated. Since I bypassed the key switch, but not the main relay, it could be the source of the problem.

Once we finished lunch and headed for home, we stopped at an auto parts place for some wire and a pair of pliers. How I got away from home without a pair of pliers eludes me, but I have another now. I decided to bypass all of the switched power to the ignition system with a wire directly from the battery to the coil. While finishing up that working, it occurred to me that I needed to include the fuel pump, so I did a little more rework to add a branch to it. I used a spare fuse holder as a “switch”. It looked promising for a few miles, but sure enough, the engine still cut out once got up to highway speeds.

Oh, and another fun note. While doing that work, I noticed that a weld between the body and one of its braces is broken. I thought I heard a noise back there.

As for the engine, I may still be reasonably sure it’s not a fuel problem, but I am beginning to have my doubts. It doesn’t cut out at a specific speed, but it lets you run at a decent speed for a while, then cuts in and out like a bouncing power lead, no matter how much that slows you down. Then you look at it (and stuff gets a chance to cool or otherwise reset; maybe refill the fuel bowl) and you get back underway and it’s fine for a while. The rest of the way home, we took a back roads path that let us run 60 or less and it made it without further incident. That does sound a little like a fuel pump that can’t keep up. As long as fuel consumption doesn’t empty the fuel bowl faster than the pump can maintain, it runs fine, then suddenly it starves for fuel. All of my bypassing *should* have eliminated anything on the positive side of the ignition chain, leaving only the grounding components, which could *still* be it.

I am finding mixed information as to whether or not a stock VW ignition system uses a ballast resistor, but I’d bet it does. The ballast resistor is there to reduce the voltage (well, technically, the current) supplied to the ignition coil primary through the contact points in the distributor. It’s absence in this case isn’t necessarily the knell of doom, but they *did* put them there for a reason. Though not specifically about the VW, this article describes the function of the ballast resistor very well.

You may (or may not) recall that I found badly burned points in the distributor once before, bad enough that I misdiagnosed it as a physical engine problem… scroll down a little to find the points story.

Sooooo… If I inspect the points now, when they have only a couple hundred miles on them and find them burned or worn more than just a little, then ignition system damage and malfunction resulting from this missing ballast resistor could be a factor what’s happening and may particularly to help explain why the wiring changes I made on the road would make zero difference.

Or it might be a fuel problem, regardless of my apparent reluctance to consider that… 🙂

Even if *this* problem turns out to be fuel, the electrical issues that I have mentioned still need to be addressed. The key switch needs to not require jiggling to start the engine. The main relay should be rated for continuous duty. There probably should be a ballast resistor in the ignition chain. And that crank pulley needs to go.

I promised a list of little deficiencies that need to be addressed. In no particular order, of course….

  1. Right brake release needs to be monitored.
  2. Verify that the key switch is not damaged then…
  3. Rewire the front of the trike to not draw power directly off the keyswitch.
  4. Speedometer fails intermittently (more like works intermittently) and …
  5. I have a matching tachometer to install, along with …
  6. Indicator lights on the dashboard for turn signals, transmission reverse, etc.
  7. Shifter needs rework or replacement.
  8. Need front fender; mostly notice when it is raining.
  9. Need rear fenders; mostly notice when driving through mud.

Of course, I could make list of bigger items, too…

  1. Replace front fork with springer or some other front end that doesn’t require impressive upper body strength to maneuver in a parking lot.
  2. EFI conversion.
  3. Body rebuild.

This last one would be a major undertaking, no doubt. So many things that are kind of little in certain ways, but major in others, could be fixed. For example, the actual shape of the storage boxes is best described as squarish. It’s not obvious until you look pretty close, then it’s almost whimsical how not square it is. There are gaps in the seams that are wide enough to see through and I have, in fact, used them for temporary wiring as described above. The storage boxes are also not water proof, though they are surprisingly rain resistant. You might have some dampness at the edges of the boxes if the trike is left out in the rain, but they will definitely get water in them if you drive in the rain. The body is supported by a nearly symetrical crisscross of square tubing braces, almost all of which are badly welded. There was no paint applied to the underside at all.

A new body for Sponge Bob should still be roughly the shape it is, just more refined. I don’t particularly like the diamond plate steel that was originally used. It does hide minor fabrication imperfections, by obscuring them in a veritable forest of intentional imperfections. Still, it has it’s charm.

The only big change I might do is to work fenders into the body, rather than the more common application of trailer fenders. Trailer fenders do have the advantage of being ready to use, however, and they would better done with axle mounted brackets rather than hard mounted to the body like the old ones were.

The EFI conversion begins to sound like the easier project. I think I would accomplish that by converting another engine and replacing this one. That would be one good way to at long last swap out that crank pulley.

This last sentence was to add thirty eight words for a total of 2300. 🙂

2 thoughts on “Sponge Bob Bit Rot”

  1. Almost a stream-of-consciouness list of small problems. 🙂 If this were your only one it would make a lovely summer project. As it is, it almost sounds like a good school-year project for a high school auto shop class (do those even exist now?)


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