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Cats Citroën Net A-type 652 Conversion

Disclaimer: This page only provides information based on the personal opinion of the author. The author can't be held responsible for damage in any way that could result from modifications mentioned here.

Homemade bracket.

First the flywheel problem. In order to get the flywheel to run freely, the toothed belt is moved. Any decent engine rebuilting shop can push the toothed belt +/- 6mm to the engine side of the flywheel. The flywheel has to be machined for this (the toothed belt can't be moved as is because it sits against an edge on the flywheel). This is quite inexpensive. The belt is heated to take it off and put it back on, the same way Citroën got the belt on. At the same time the flywheel can be lightened and balanced as well. It's now also possible to replace the 652 toothed belt with one from a 602cc flywheel! This way the 602 starter can be used.

Modified flywheel Modified flywheel Modified flywheel

On the left the original flywheel, on the right a modified one. (click on the picture for enlargement)

How to make your own sensor bracket

This sounds more complicated then it really is...

Cutting Bracket Cutting Bracket

What we want to do is take the piece with the sensor holes out of the 652 bellhousing and position it on the 602cc bellhousing. With a sliding ruler, measure 20mm on the 602 bellhousing where the engine studs go through it. Do this on the right top and bottom stud holes of the bellhousing. Now connect the 2 markings over the outside of the bellhousing using a flexible strip of some sort. You will now have a 20mm section on the right front part of the bellhousing marked. With a thin cutting disc on the angle grinder, cut of the marked 20mm. Make sure you position the grinder on the correct side of your marked line, you only want to cut off 20mm, not more. After cutting, about half of the engine stud holes is left on the bellhousing.

Cutting Bracket Cutting Bracket Cutting Bracket

Now we do the same on the 652 bellhousing but with a few important differences. This time the part cut off has to be 20mm wide so put the grinder on the other side of your marking. Also, you'll want to leave the sensor locating holes onto the piece you're cutting from the bellhousing. So around these holes, the section being cut off will be much wider then 20mm.

Cutting Bracket Cutting Bracket

It's better to leave the cut-off section a bit wide and trim it after it has been cut off. Before cutting off anything, measure the length of the engine stud holes. With the 652 section placed onto the 602 bellhousing, the holes should be the same length as before you started cutting. The critical breaking point of the bracket is between the top engine stud hole and the top sensor hole. Leave as much metal on the bracket here as possible.

Cutting Bracket

Most of the cutting doesn't have to be very accurate, only the final length of the engine stud holes is important. It's important that the cuts of the engine moutning holes on the bellhousing and bracket are paralel. The better they fit agains each other, the less risk there is of breaking the bracket due to exessive loads on a single point. Trial fit the bracket on the 602 bellhousing and cut off the bellhousing what is in the way, especially around the sensors, they have to be completely free. When fitting the locating/guidance tube on the engine stud on this side be very carefull. This is a small tube that normally locates the bellhousing on the stud properly. Fitting it can make the bracket snap. The location tube can be left out when you can't easily fit it.

Cutting Bracket Cutting Bracket Cutting Bracket

Cutting Bracket Cutting Bracket Cutting Bracket

Between each sensor and the bellhousing should be a big washer. Leaving out this washer will make the pin on the flywheel decapitate the sensors on startup. The big advantage of this method is that it's the only way you're 100% sure the sensors are in the correct position. You can further strengthen the bracket and make it look smarter by using liquid metal to fill up the holes.

Modified bellhousing Modified bellhousing Modified bellhousing
The modified bellhousing. Sensor bracket can be seen hanging on the side. (click on the pictures for enlargement)

Cutting Bracket Cutting Bracket

Engine and gearbox can now be mated together. It can be a bit of a fiddle with the separate bracket, leave out the sensors while fitting. Make sure The sensor have plenty of room and don't touch the bellhousing anywhere.


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