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Eriks

610 Coupe project

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Hi,

 

I'm currently restoring a 610 from 1975. It is an original SSS, and while planning everything I realize it would be nice to have thoughts and questions and feedback collected in one thread.

 

 

image.jpg3_zpsaedxzuit.jpg

 

Today I'm thinking about flywheels. I will not do any dramatic changes to the original car. Its will get the original color and original interior etc. However I've found a L20B engine to replace the original L18. The engine comes without flywheel. I understand that the L20B had a 200mm flywheel in 610s, and bigger and heavier 225mm in 620s because the latter is more of a workhorse. My L20B came from a 620, but my car is not gonna pull a trailer or carry something heavy. Its just gonna pull itself and me and my friends in it, and preferably in a lively manner. So I'm thinking that the flywheel should be lighter than the original flywheel from the 620. But how light should I aim for?

 

The car is for hassle free street use, weekend trips, and hopefully some winding roads.

 

I would appreciate some thoughts on what flywheel I should be looking for. Thanks :)

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A heavier flywheel is used to store kinetic energy in the form of spinning motion. This is an advantage for getting a heavy vehicle and load moving from a stopped position. Once moving the heavier flywheel weight is no advantage. 

 

Weigh your 620 wheel. I have measured several 200mm, 225mm and 240mm and they were 9.5Kg or 13Kg. Car 225mm (Z car) were lighter because the engine was more powerful than the L 4 cylinders. Generally smaller engines or heavier vehicles use heavier wheels. I have a 9.5 and 13 Kg 25mm wheel. Depends on what it was used on.

 

You can easily run a 9.5 KG (21 pound) wheel on your 610. Some lighten them further but there are disadvantages to this.

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Thanks. Well thats a thing, I do not have a flywheel and I will have to find one. I'm just not sure what I should try to find. But from what Im reading I' circling in on a flywheel between 7 and 10 kgs. Not sure yet If there would be a noticeable difference between 7 and ten, or aluminium or steel. But I could of course find both and experiment

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Ah... well you will want a 200mm 6 bolt L20B wheel. The larger 225mm pressure plate likely won't clear the four speed case inside.

 

The flywheel absorbs spinning energy. It can save it or be released when slowing down. It doesn't waste it, it just stores it. This is good for getting a vehicle rolling from a start, but it also absorbs energy when accelerating in gear too. A lighter wheel spins up easier and the energy saved goes into accelerating the vehicle. 

 

The ideal flywheel would weigh more at idle but be lighter when accelerating the car.

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Ah... well you will want a 200mm 6 bolt L20B wheel. The larger 225mm pressure plate likely won't clear the four speed case inside.

Sorry, slightly confused - the car has the original 5speed dogleg. Will a 225mm flywheel be too large to fit with a 225mm clutch kit?

 

And when looking at lightened flywheels: Just thinking that to only consider the total weight of a flywheel is misleading. I guess it mean something how the weight is distributed. E.g. i suppose a 20lbs flywheel with 15lbs at the edge comparer to 15lbs close to the centre will perform completely differently.

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I'm worried that it will 'rub' the inside of the transmission....
 

So here's the difference in the discs photo2_zps3fe34a2e.jpg

Here's where the pressure plate rubbed the bell housing when I turned the engine over by hand
photo1_zps0a0427ff.jpg

Here's what I'm up against trying to get it running now
th_IMG_3401_zps667d4bab.jpg

Any ideas ??


The four speed is an F4W63 your 4 speed is an FS5W63A and fits the same engines. It is always used with a 200mm pressure plate. I don't know of it will work with a 225mm or not.

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But if a 225mm clutch do fit, will it be a benefit or a disadvantage compared to a smaller clutch ?

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But if a 225mm clutch do fit, will it be a benefit or a disadvantage compared to a smaller clutch ?

 

The strongest 200mm clutch is the one for the old Roadster all other are only strong enough for 4 cylinder cars. If you have a 225 flywheel you can use the clutch from trucks and L six cylinder engines.

 

I run a 240 mm clutch in a dogleg and it doesn't rub.

 

The FS5W63A is not exactly the same size/shape as the F4W63 which were only used with the 200mm clutch. 

 

Good to know about the 240mm fitting though.

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