Cox engine spring starter scratch guard.

Cribbs74 wrote:

andrew wrote:I have not tried it, but there might also be some benefit of adding a piece of small diameter shrink tube to the section of spring that wraps around the cylinder.

Great idea about adding shrink tube to the nose of the case.

I wonder if it would cause the engine to retain heat.  Good idea Indra!

Thread-bump.. I like this idea.. but wonder the same as Ron.. regarding the retention of heat.. The nose of the case is generally "cooler" and fairly well-lubricated though.

Wondering if maybe "partially" shrinking the sleeve would be better? Shrink it down small enough to where it won't slip-off over the drive-plate. This would allow some space for air.. and also be easier to remove after it gets worn. If shrunk "tight".. the case could be scratched trying to get a blade (#11 for example..) in-between to slice it off.

I got curious.. and found my heat-shrink assortment to do some test-fitting. My smallest size was perfect for the spring-wire. I pushed it on around the loop that fits around the case at the bottom of the engine cylinder.. and a bit into the coiled-section of the starter-spring. Then I applied some heat and shrank-it tight.



My largest diameter of heat-shrink tubing wasn't large enough to fit over a "standard-round" drive-plate.. so I thought; why not slit-it open.. and not shrink it at all..

Most 1/2" nominal heat-shrink tubing won't fit over the standard "round" Bee's drive-plate.. and definitely not over a hex one. I cut the heat-shrink tubing to a length of 1/2" (12.7mm) and slit it open to install it around the nose of the crankcase.




I'm not sure how the slit-sleeve will hold-up.. or stay in place.. but I am sure that it will provide some anti-scratch protection while "in-place".. without impeding the operation of the starter-spring or the engine.

Oldenginerod wrote:Roddie.  Won't that heat-shrink on the crankcase nose shrink when the engine heats up?  I mean, that's what it's supposed to do, right?  Since it's now split, there's nothing to restrict it from shrinking as far as it likes.  A couple of wraps of insulation tape may be a better option.

You know Rod.... I actually wondered if a non-slit sleeve of it would "self-shrink" with the heat of running the engine.. but I honestly don't think that the front-end of the case gets hot enough.

I have two different types of heat-shrink tubing. The one I used in the photos came from Radio Shack.. and has a more "plastic" (glossy) appearance than other type; which looks more like a rubber (resembles the old neoprene tubing). The latter has a higher shrink-rate and seems to need less heat to activate.

I also tried cutting a 2" long x 1/2" wide strip of thin-clear plastic to coil inside of the starter-spring.. but it could have been cut "shorter".. to maybe 1.25"-1.5" so as not to overlap.




The 1/2" (12.7mm) measurement effectively covers the area of the cases' nose between the drive-plate. If one were reinstalling a crankshaft.. a piece of non-slit heat-shrink tubing of that length could be installed prior to pressing-on the drive-plate. As I mentioned; "my" heat-shrinks' ID was too small to fit over it.

Here's a crazy thought... How about dipping/swabbing the starter-spring in "liquid-rubber"? Here's a product that I've had in my shop for years.. and it hasn't dried-out. There's a brush in the cap.



.. do you think it would bind-up the coil? It wouldn't penetrate between the coils.. so they would still move against each-other. The question is; would the liquid-rubber "flex" with the springs' twisting.. or would it "split-out" between coils? Maybe it wouldn't matter.. as long as the rubber stayed adhered?