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Aermacchi motorcycles

We are reverse engineering a 1966/1967 Aermacchi CRTT road racing motorcycle. Our goal is to reverse engineer every part, and making the resultant CAD available for educational and hobbyist purposes. We will make a few parts to explore manufacturing processes, and have some fun.

At some point, we all die. Before we go, we should pass on our knowledge or inspire others. We hope you will join us in our crusade to publish not only drawings but the engineering knowledge it took to make these amazing machines. We want to inspire others to do the same with their machines, whether it is cars, boats, aeroplanes, pens, knives, guns or anything historical. A loftier goal would be to inspire a young person to learn to engineer, and in turn, improve their life and the lives of others. It would be great to pass the love of classic motorcycles to the next generation.

At Global Dimension, we certainly don’t know everything and we look forward to this being a community effort. The drawings and CAD will be available under a Creative Commons BY-NC-ND 4.0 license.  This means you can use the blog articles and drawings for free, as long as you:

  • attribute these items to Global Dimension (BY).
  • do not charge (NC) for them or things you make from them.
  • do not be tricky and just change something to get the around the license (ND).

If you do want to charge people, feel free to talk to us, we can work something out.  You will be surprised how flexible (cheap) we can be.  We just need enough money to afford our passions.

Aermacchi CRTT motorcycles are lovely, no?


Harley-Davidson Aermacchi short track frame

Harley-Davidson Aermacchi motorcycles are very potent flat track racers you could buy from the Harley-Davidson dealers.  They were called CRS (250cc) and ERS (350cc), and had


Harley-Davidson Aermacchi frame tube sizes

During the process of reverse engineering Aermacchi CRTT, SS, H, early CRS, late CRS and ERS, we kept track of the common tubing sizes used


Aermacchi CRTT and Paul Brodie modifications

Paul Brodie ( designed and made his own CRTT frame a few years ago, and he was kind enough to share his drawings with me.


Reverse engineering an Aermacchi CRTT tank

The tank of a Harley-Davidson Aermacchi CRTT is an iconic masterpiece of design. The classic shape of the long rectangular tank with gracefully radiused edges


Reverse engineering an Aermacchi CRTT frame

Why reverse engineering an Aermacchi CRTT frame?  Well, I had a dream to go to Bonneville and race a CRTT based bike and try to


H-D Aermacchi 39984-69P, REAR CHAIN ADJUSTER ASSEMBLY Adjuster Body

Perhaps you missed the article on the ‘Threaded Shaft’ for the Harley-Davidson Aermacchi part number/description of ‘39984-69P, REAR CHAIN ADJUSTER ASSEMBLY’?   We are going to


H-D Aermacchi 39984-69P, Rear Chain Adjuster Assembly Threaded Shaft

What is a ‘39984-69P#Shaft#, REAR CHAIN ADJUSTER ASSEMBLY Threaded Shaft’?  Does this keep you awake at night? The rear axle adjusters of Harley-Davidson / Aermacchi


H-D Aermacchi 39984-69P, Rear Chain Adjuster Assembly

Rear axle adjusters come in many flavours.  Today we are going to look at the Aermacchi Harley-Davidson adjuster that came on the 350cc street bikes,


Naming conventions for Aermacchi / Harley-Davidson project

A discussion on naming conventions is a pretty dull topic, but it is vital if you want your project files to be organised.  We are


H-D Aermacchi 7801P NUT, 10mm

What do we know about this nut?  On Aermacchi bikes, it is used a few times around the front wheel/brakes.  The parts catalogue call it

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