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The Aermacchi Project, Part 7: Serendipity Strikes Again!

Left side cover, in process of cleanup. The key that pushes the shaft-and-ball bearing linkage that operates the clutch is to the left. I was told that someone badly overtightened the clutch, resulting in the key being dimpled and possibly slightly bent.

This is the seventh installment of a series detailing Margie Siegal’s restoration of a 1973 Harley-Davidson 350 Sprint. Start at the beginning with Part 1.

The clutch rebuild is NOT going well. I have put the clutch together and taken it apart twice. Despite all efforts, the clutch arm that connects to the clutch cable just waves around without connecting to anything. Frustrated, I call a mechanic friend. He is leaving on a trip and can’t come over to look at it. He suggests to keep excavating until I find something.

The clutch arm is on the left side. I pull the cover off. This looks promising: the left side cover is full of black goo and metal chips, and the rubber stop for the kickstarter is destroyed. Also, the “D” shaped piece that pushes on the linkage that goes through to the clutch plates on the other side had an indentation in it. A new rubber kickstarter stop is on eBay! I Buy It Now.

The clutch is still inoperative. I send photos of the left side to Lancaster Sprint. Ron Lancaster builds Sprint racebikes and does Sprint restorations. Like everyone else involved with Aermacchis, he is amazingly helpful. He says he thinks he knows what is wrong with my bike, rounds up parts and sends them to me Priority Mail. I am assured that I will get the parts Thursday or Friday so I can work on bike over the weekend.

Four out of five parts of the linkage. The short shaft (not shown) is threaded and adjusts.

The Post Office, unfortunately, is not as helpful as Lancaster Sprint. The parts never arrive, and I need those parts to work on the bike. I call Moto Italia, another source for Aermacchi parts, who is a couple hours away. Leslie, the owner, says he has the parts I need and will be open until I get there. Off I go. Traffic, of course is horrible, but I finally get to the little store in the back of a shopping mall. Leslie and I start discussing the clutch. He says that he recently rebuilt the clutch on a similar Aermacchi … and had to put an extra ball bearing in the linkage. A light bulb goes on.

A word of explanation here: The clutch operates by squeezing the clutch lever, which is attached to the clutch cable, which is attached to the clutch arm, which pushes the linkage that operates the clutch through a little tube. The linkage is composed of a short threaded rod, a ball bearing, a longer rod, a second ball bearing, and a second rod. Sort of a Rube Goldberg design, but it works. That is, it works on other Aermacchis, mine currently not included.

I ask Leslie to add an extra ball bearing to the bag of parts he is putting together for me, and fight my way home through still more traffic. Up bright and early the next morning, I get the linkage out, blast the tube with WD-40 to clean out residual goop in the tube, lightly coat the linkage with grease and reassemble with the extra bearing. The clutch now works. Amazing. I have been working on that #$%^&* clutch for at least a month. And if the Post Office hadn’t delayed the parts from Lancaster Sprint (they showed up several days later) I would never have figured it out.

Published on Jun 26, 2019

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