Mitsubishi, Nissan, Mazda manuals= M10x1.25.This test is a good example of the amount of force needed to really damage a good-quality knob, specifically with my WC-Lock insert. Sure, these values are more than you can inflict with your hand, but you can still easily cross-thread a polymer knob and damage the threads permanently. You can hang a fully loaded Subaru off of one of my shift knobs without it breaking! To convert the 17,800N load that the brass thread was subjected to, that is about 4,000 pounds! I think it is impressive that they could not even break one of my shift knobs using the machine. An important note is that the brass threads were not damaged by the test and still worked smoothly. The brass continued to increase in load without a failure. You can see in the black line how the polymer thread first failed at about 50mm, and then the second thread failed around 65mm with the third thread breaking around 72mm. This shows that using a brass thread insert with the WC-LOCK attachment yields a tensile strength MORE THAN four times that of solid polymer threads. ![]() 2 samples - copolymer cylinders with "WC-LOCK" Brass Thread Inserts.2 samples - copolymer cylinders with standard polymer threads (no inserts).This testing was conducted two outside sources: The specific technical details of this attachment method will not be discussed, but I will show proof that it is extremely strong compared to polymer threads with no metal threads. Over time, I developed the unique brass insert attachment method I call "WC-Lock". This did not help as the insert still came loose. I then tried making the hole smaller than the brass piece and pressing them together with glue. The inserts kept coming loose during regular use. I first tried using epoxy, superglue, and loctite to secure the inserts in. I began using a brass thread insert that I custom-machined for each knob. In my desire to produce the best all-around shift knob available, I decided to find the best solution to fix the weak polymer thread issue. Cross-threading during installation or stripping during hard use are two common issues myself and my early customers faced when I make copolymer knobs with threads cut directly into the polymer. Plastic threads tend to get messed up easily compared to metal threads. The main problem with Polymers is that they are basically strong plastics. Overall, there is not much of a difference here, especially when considering the use of a shift knob, so we can consider the two materials equal. Copolymer has a better chemical resistance than Delrin, and slightly less porosity, meaning it has a more consistent appearance. For example, Copolymer has a compressive strength of 15K psi, while Delrin is 16K psi. Both of these materials have physical properties within 10% of eachother. Here is a brief description of the material:ĪCETAL COPOLYMER is very similar to ACETAL HOMOPOLYMER (trade name: Delrin, by the DuPont company). I have been producing the Copolymer shift knobs for some 2 years now. Although I have many solutions for this, from knob protector booties to wrapped knobs, one good solution is to use a different material. Simply put, metal shift knobs get hot in the summer, cold in the winter. To test 2 types of threads on Polymer (Copolymer/Delrin) shift knobs. I want others to add to it also, pics, dimensions, weight, reviews, etc. This thread is going to be a collection of all the shift knob information I have gathered over the past few years.
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