Lightened Flywheels

[jansens]

I can't remember what mine weighed but I did go measure the cuts and they are 3 inches wide on mine.

Simon

[Greig Smith]

Simon it shouldn't be a problem, we're 2.5 lbs down on ours in the race cars and they are still very tractable

Some folks will always be purists, I can respect that, in the Giulietta world I'm the guy folks contact for originality details on 750 Sprints. If originality is your thing, I have no issue with that.

The nice thing about lightening the flywheel or fitting a Phoenix crank etc is that it's a hidden benefit. On a 7, reducing the reciprocating mass on the flywheel by a small amount will assist in reducing the flexing of the crank, but its main benefit will be fractionally faster gear changes both up and down the box, we are not talking about racing changes here, rather just a fraction of time saved in every standard gear change all of which help to make us a little less of a mobile chicane to the rice rocket racers on the roads out there.

We're gearing up for the engine / box rebuild on the '28 R Type saloon and it'll get an Andes 2nd gear, a wedged early head and a little off the flywheel before being balanced. The updraft manifold will get drilled out and I'm eyeing a nice set of Tony's new pistons. Externally she will look stock '28.

Aye
Greig

[Ruairidh Dunford]

The externally standard approach is the most fun in my experience. What’s not to like?

[Steve Hainsworth]

I agree with the last two posts.
Modifications (unobtrusive ) should be dependent on the intended use.
I would add that if you use your car a lot for long journeys (as I do) it is best to modify inlet valve throats, Tappet radius increase and better carburettion, followed by correct gearing.-I have not lightened the flywheel .
I do use a stock "37 head but it tends to be a little harsh.
I use a 4 speed Crash box (double helical gears) which is fully rebuilt and a 5.25 CWP in a 1930 casing.This gives a really good advantage on long hills we encounter getting in and out of Wellington NZ. It also is much quieter than a 3 speed.
I should add this is all in my November 1928 R saloon.
I have noticed in the last 12 months the car is going a lot better, I put this down to the engine finally freeing up after 7 years of hard motoring . It is on its first rebore (+20) and I machined everything to tight limits when I put it together (new 7 workshop pistons and new Remax 1-5/16 crank ).
The thing I worry most about are the original Austin rods.
The addition of a Full flow filter makes everything last much longer  as there are lots of rubbing surfaces in an Austin Seven engine, particularly in the timing gear area, also roller bearings are very sensitive to wear from metallic particles in the oil. I use Penrite  Shelsley Light 20/60  oil which has high zinc content
Best wishes for 2019
Steve Hainsworth  Wellington New Zealand.

[Ritchie Wilson]

The thing I worry most about are the original Austin rods.
The addition of a Full flow filter makes everything last much longer  as there are lots of rubbing surfaces in an Austin Seven engine, particularly in the timing gear area, also roller bearings are very sensitive to wear from metallic particles in the oil. 

What is the general layout of the filtration system Steve?

[Chris KC]

Here are some pics.
The assembly as shown weighs 20lb.

It has new linings, kind of suggesting that the previous owner got cold feet!


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[dickie65]

Hi Folks,
My flywheel is cut down leaving pillars weighs 3.98 kilos.
The coverplate and clutch plate springs etc will weigh almost as much again.
I seem to remember the whole lot as an assembly weighs about 7.5 kilos.
So the flywheel is only part of the story.
This is on a 1933/34 engine and will rev to over 6000 rpm ( Nippy Gearbox and back axle ratios )
It needs 2500 to pull away on a hill start. I use 4000 rpm for Hillclimb starts
It is happiest at around 4000 rpm so not a good set up for a heavy Austin 7
I am running a silly camshaft / big valves / slipper pistons etc.

Happy New Year
Dickie

[Greig Smith]

Chris I'd have no hesitation whatsoever in using your flywheel, the drill holes are far apart, neatly done and while it's taken a small amount of weight off, it hasn't sacrificed strength at all... in fact you've got quite a lot more there that could still be drilled out without sacrificing the necessary strength. Keep it as it is, it'll be ideal for a road car.

This is what I had in mind when you said that your flywheel was a bit like Swiss cheese.... it's called Drillum & was well favoured by the riders of the day.

Aye Greig

[Chris KC]

Less obvious than the holes is that a fair bit has been skimmed off the engine side face of the wheel.
I must say though Stuart's observation that it is a steel flywheel - something I admit hadn't really crossed my mind - gave me a fair bit more confidence.

Yes, drilling lightness was once a thing! I own the remains of an ex-Jack French chassis which was given this treatment - at least I still own the holes! It doesn't do much to promote longevity.

[Steve Jones]

There's certainly metal that can be removed from the engine side of the flywheel but a word of caution. I did this once but, eventually, the flywheel centre boss cracked away around its complete circumference due, I imagine, because too much was taken off. A good radius was formed at the junction of the boss and the flywheel but it still broke away. The only indication that this had happened was a slight 'rumbling' from the engine at tick over and when taking up load.

Steve