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Apologies for raising this again

Austin Seven ring gear removal

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Russell Eberhardt19/01/2020 19:07:46
2599 forum posts
85 photos

The flywheel fits to the crankshaft by a short taper. You can turn a matching taper in the lathe with a short threaded section for a holding nut. Fit the flywheel to that and it will run true and should turn easily.


Former Member19/01/2020 20:01:55
1329 forum posts

[This posting has been removed]

Phil P19/01/2020 22:08:55
639 forum posts
166 photos

I lightened the flywheel on my Austin Seven Special many years ago, I used a spare crankshaft to set it up in the Harrison lathe and remove a few pounds of excess weight, it certainly helped with slicker gear changes and blipping the throttle when double de-clutching etc.


I also fitted a newly manufactured Phoenix Engineering crankshaft, this shows it set up in the lathe for hand lapping the taper between it and the flywheel.

I had already previously experienced a loose fly wheel prior to that, and did not want to repeat that again.



Mike Poole19/01/2020 22:29:44
2694 forum posts
64 photos

That really does look like a crank that would have a severe rigidity problem if any tuning was applied to that engine. I am not surprised that lotus 7s use all sorts of different engines.smiley


Steviegtr19/01/2020 22:48:05
1355 forum posts
140 photos

Takes me back to my 1st car, a Morris miner 1000. Then 1100, then twin carbs & 3 branch, then 1800 MGB engine & gearbox,, then the car broke in half. Traveller model with alloy roof & bolted side beams was never very strong. Lightened flywheels were a good way of getting the engine to rev more freely but often became lumpy at the bottom end. Bought a MGB GT after that. Jesus that was 50 years ago. Need to sort out a funeral plan & my will.

martyn nutland20/01/2020 07:14:18
111 forum posts
6 photos

Many thanks all. I will have a go and report back.

The question as to 'why bother' is sensible. It's just that, although it will be out of sight, it looks and is a mess and offends the eye.

Back soon

Stueeee20/01/2020 19:01:45
60 forum posts
Posted by Mike Poole on 19/01/2020 22:29:44:

That really does look like a crank that would have a severe rigidity problem if any tuning was applied to that engine.

Lots of Austin Seven engines with 2 bearing crankshafts have been tuned for performance, not usually to the extent of this motor, which also has a 2 bearing crank -albeit a reproduction EN40 Nitrided one rather than the Austin factory item.

Former Member20/01/2020 20:35:51
1329 forum posts

[This posting has been removed]

Stueeee20/01/2020 21:04:17
60 forum posts

Yes 2 plugs per cylinder, It has a twin spark distributor driven directly off the end of the camshaft.

Howard Lewis20/01/2020 21:47:13
3536 forum posts
2 photos

I believe that the technique with the two bearing crank, (which was less prone to breakage than the later three bearing one ) was to fit low compression pistons in 2 and 3, and high compression in 1 and 4. When the crank whipped at high revs, the compression heights became nearer equal so that each cylinder then produced, all other things being equal, equal power.

Not sure whether it was the Austin 7 or the 1172 Ford E93 engines, tuned by Colin Chapman, which brought about the 750 Club ruling that "The function of the Inlet and Exhaust ports shall not be reversed"


Eric Lucas08/04/2020 10:17:46
5 forum posts

assuming it’s not a racing Special we are talking about, then making the flywheel lighter, then it means

it will tick over like a bag of hammers.

surely it’s nicer to have an old engine running like a sewing machine on tickover?

why not leave the teeth on?

(both me and my 1933 Morris 10 have all our teeth )

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