PREPARATION


May 2006



tekst


This is my beloved 1983 mazda RX-7. It has a 12a rotary engine. I bought this car in 2004 from a scrapyard. I needed this car, because at that time the matra (which was my daily driver) was in the proces of a previous engine conversion. The matra's original 1600cc engine was replaced by a peugeot 1900cc engine. During this project i was driving very happily in the mazda. I realy liked the character of the engine. The way it revs and sounds and the smoothness

And then the matra's engine conversion was completed. The new 1900 engine was more powerfull than the original 1600 engine, but i was not satisfied. Now i was used to the rotary engine, the 1900 engine couldn't please me.


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The mazda's M.O.T. did expire, and the car was in a too bad condition for a new MOT. It had bad brakes, wheel bearings, tyres, steeringcolum, rust, exhaust and more. But the engine was fine! The mazda was put to rest in a shed.
A little thought popt in mind: Rotary engine in the matra? A rough measure with a tape measure told me the engine would fit.


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My brother Hans helped me to get the engine out.


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Well, here it is.


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The rest of it is no longer needed, so return to scrapyard.
Note the flower pot on the wall.


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The thing is, the rotary engine is a longitudinal engine, but it needs to go transversal in the matra. It needs a transversal gearbox. But there is no transversal gearbox for the rotary engine. So i have to fit an "alien" gearbox, using an adapterplate.
Which gearbox to use? There are a few requirement of the gearbox: The bellhousing must be big enough for the large mazda flywheel and the position of the starter motor. That must be positioned next to the gearbox, instead of next to the engine. Original matra gearbox and the peugeot gearbox can't be used for those two reasons.
I found two gearbox options, Citroen CX 2.5 or toyota celica 3gse. I prefered the citroen, because it is mainly the same as a matra gearbox, but it has a bigger bellhouse. However, the clutch mechanism and the position of the startermotor makes it too complicated to use. So toyota gearbox it was.


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Citroen gearbox: scrap metal.



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I got this toyota gearbox for free (thanks celica forum) It was old and worn. Ideal to "sacrifice it to science" I opened the gearbox (never done such a thing) and discovered that the gearbox was actualy in good condition!


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I need to make something to line up the gearbox with the engine. Normaly on the primairy shaft there is a little pilot shaft which goes in a little bearing in the flywheel. But this primairy shaft doesn't have such a pilot shaft. So i got this shaft made. This shaft comes in place of the primairy shaft, and it has the pilot shaft.


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Like this.


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A supplier from my work has a waterjet cutter. He made me a steel ring which will act as an experimental adapterplate. Engine and gearbox are now bolted together.


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Say "hello" to your future shell.

We are still in "investigating stage" There are 100's more things to sort out and at this point i'm not sure if this project will succeed. I don't start the actual engine conversion until i am sure it will work. So the matra stays on the road as long as possible with the current engine. As long i am not sure how this will end, i try to keep things as cheap as possible. Keeping in mind there might be a dead end.


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This is the 1600cc engine, which was originaly fitted in the matra. The rotary engine must be positioned exactly the same way as how the original engine was fitted. That way i am sure the driveshafts are positioned OK (i had loads of troubles with the driveshafts after the first conversion, caused by a badly positioned engine)
I don't want any welding or grinding on the chassis to receive the rotary engine. It MUST be suspended on the original chassis engine mounts.
On the original engine i made a jig which point to all engine mounts and the dif. The dif will be the reference point. So this jig gives me the position of the dif according to the engine mounts.


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The jig is now positioned with the dif reference point to the dif. Alligning the frame level and square. It now tells me where the engine mounts must be. Next to the alternator, next to the starter motor and in front of the rear exhaust port comes the mount points.

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