The car came with white plastic “star nuts” for attaching the wheels. These aren’t the two-prong white plastic through-hole wing nuts that I had on my RC10 way back in the day. These are three-prong nuts having no through-hole. They’re quite interesting. They are very delicate. I don’t want to wear the plastic in its ability to hold the wheel in place. Therefore I’m using these as little as possible. They’re on the car with the wheels off but with the wheels on I’m using an aluminum 5-40 locknut up front and for the rear I’m using the 8-32 white nylon nuts that came off the original steering blocks.
Almost every screw in the car has been swapped from black-on-the-outside steel alloy to black anodized 7075-T6 aluminum, made by fastener-express.com. I visited fastener-express.com in person at their Orange County factory and saw how they make their screws. I was pretty impressed. Their smalls-sized screws are aged to T6 after the screw is formed out of 7075. I have been reading about various materials online and here is my summary of what I know. 7075 was secretly invented by Japanese more than half a century ago. It’s about twice as strong as 6061 and weighs about the same. 7075-T6 is approaching the strength of titanium grade 5 in its tensile strength. The only aluminum alloy that claims to be clearly stronger than 7075 is this new stuff called 7068, which hasn’t hit widespread use yet.
There are eight screws on the car that I’d consider reverting back to black steel alloy. These are the eight highly structural #4-40 screws that hold various pieces of the chassis together – four screws on the front nosehead tubes, two side screws into the rear bulkhead, and two screws into the rear of the gold anodized aluminum transmission cover.
A total of six titanium #4-40 3/4” length socket cap screws are used in the suspension mounts – four screws in the rear, for both top and bottom of shock, and two screws in front for the top of shock. These titanium screws used are Racers Edge part #069. They’d better be made of titanium grade 5 alloy and not of grade 2. Making a titanium screw this small out of grade 2 would be quite a mistake for strength reasons. There is no mention on package of exact material used, only “titanium”.
When building up the rear shock standoff (top of shock), I followed Edinger instructions and put the white flanged bushing on with flange facing forwards. Edinger instructions tell you to put an aluminum washer between the back nut and white bushing, but I suspected that the aluminum washer has a sloppy hole and that it might touch the shock cap, being of a sufficiently large diameter. I found some 1/32” thick black nylon washers that came from a B4 front-end, that not only are smaller in outer diameter but also fit more snugly onto a #4-40 screw. I’m using a thin steel zinc-plated #3 washer on the socket head side of the 3/4” screw, reason being that it increases the surface area of stress on fiberglass when shocks are impacted. With the exception of what I think is one tiny nut in tranny shell and one large nut to hold down the outdrive gear shaft, all nuts are 6061-T6 alloy, ordered from fastener-express.com. They don’t make their own nuts but sell them in order to better cater to customers looking for a complete fastener solution. Even the tiny #2-56 nuts holding the backside of the rear A-arm swaybar link ball studs are aluminum locknuts.
(Continued in next post.)
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