Originally published in the Austin-Healey Magazine, March 2003
Many Austin-Healey owners seem to have some misconceptions about the "door check mechanism" installed on their 6-cylinder big Healeys (the mechanism for the 4-cylinder big Healeys will be the subject of another article). I'm talking about the mechanism that connects the door to the doorjamb, apart from the hinges themselves. Some people believe that this mechanism is supposed to hold the door in any position, but in fact it is designed to hold the door open only when the door is extended to its full open position.
Regarding the mechanism itself, it is composed of a "sandwich" consisting of a springy "star" washer, an operating lever, and a composite friction pad, all with the same "outside diameter". This group is held together by a screw/threaded stud (which is welded to the bracket that attaches to the hinge pillar, or "A" pillar) with a hex nut, right-hand thread on the left door, and left-hand thread on the right. Finally, there is a little "wrench" that grabs the nut across two of its flats - a true "spanner", as the Brits would call it. This wrench is held to the operating lever by another small hex screw.
As the door opens, the design is such that the spanner/wrench tightens the nut, thereby clamping down on the sandwich of spring/star washer, operating lever, and friction pad. To adjust this mechanism, you want to tighten the nut so that with the additional tightening caused by opening the door, the "friction sandwich" grips tight enough to hold the door open. As the door closes, the hex nuts "back off' and loosen the friction stack. Thus the door should stay in the "open" position, but should NOT stay open at just any position short of fully opened. At those intermediate positions the friction stack is squeezed less and thus doesn't hold. It's not supposed to.
Thus, the "staying" power of the assembly increases the farther the door is opened, and if properly adjusted it is only tight enough at the door fully open position to hold the door in position. I've seen cases where the friction washer was missing or broken, and I don't know of any replacement. They seem to be made out of a phenolic-like material. When you disassemble these pieces treat them very carefully. They'll last forever with proper respect.
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