[was: "My brother and his Stalker won the lottery, they're intact" -editor]
My brother's Super Stalker's been done for a while now and he's been taking it on various drives to get used to it. Many of the drives involve heading up into the local mountains to drive on twisty roads, early in the morning before anyone's out. This Saturday he was coming to a blind righthand turn at about 30mph and starts his turn in - no steering!
He managed to get the car stopped before it headed over a huge cliff on the other side, but which left him stopped in the middle of the on-coming traffic lane - on a blind curve. Because it was early morning, what could have be a very different story wasn't a big deal.
After he's stopped he tried letting it coast and turned the wheel again, and it turned like nothing was wrong. He gets it safely off the road, gets out and has a serious look to see WTF just tried to kill him.
As you may know, Brunton, the manufacturer, speeds up the steering by cutting the steering arms short and adds a part for the steering tie-rod to connect to. Picture a traditional rod-end with its swivel ball; now picture instead of the ball it's a one-piece part, no ball, and the hole is tapered. The part is screwed into a threaded hole drilled through the shortened steering arm, and the steering tie-rod end slips into the tapered hole.
The thread on thier fabricated part is massive, maybe 5/8" diameter, and right where the thread stops is where it failed, breaking clean off. The reason why the car acted like nothing was wrong when he turned the second time is because the castor on the non-steered wheel made it track the wheel that was still steering. The reason it failed on corner entry is because he had the brakes on, which pulled the left wheel outward.
My brother's learned that FOUR other cars have had the same failure. I looked at the pictures (I'll post them tonight) and asked him if the steering tie-rod that slips into it could have bottomed out and applied a sideways force. He said no, that it has plently of over-travel. I then asked how tight he'd tighened it. Due to how the part is designed, the body itself bottoms on the cast iron suspension arm, placing their adaptor not only in tension, but bending due to how the hole is never at exactly 90 deg to the arm (which is curved.) In otherwords, one side of the adaptor bottoms before the other, placing a huge bending force in addition to being under tension, in effect, saying, "tear here."
I'm posting this in case anyone has a Stalker or is contemplating modifying an upright to do what they did. On possible solution is to countersink the hole slighly so that the body doens't contact the steering arm, but it's not a great situation.
[edit: He says that Brunton changed the steering design since he bought his kit. Don't know what they did but it sounds like they became aware of "issues."]
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Midlana book: Build this mid-engine Locost!,
http://midlana.com/stuff/book/Kimini book: Designing mid-engine cars using FWD drivetrains,
http://www.kimini.com/book_info/
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