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Apologies for raising this again

Austin Seven ring gear removal

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martyn nutland19/01/2020 13:51:01
124 forum posts
7 photos
I apologise to everyone for revisiting this but I'm having a lot of difficulty trying to remove chronically bashed up ring gear teeth from an Austin Seven flywheel. To be clear, these are teeth, milled directly onto the flywheel (not shrunk on ring gear) and not on the clutch cover, and I do not want to cut them away with a view to fitting new ring gear. The flywheel will go on a vehicle that will always be started on the handle or with a push. Thus, in a sense, this is a cosmetic exercise.
I am very adverse to putting the flywheel on the lathe because although my Chester Super B has plenty of swing, I'm afraid that the tool running over dozens of teeth is going to hammer the machine to pieces. Even if I did resort to attempting this on the lathe I can't see any realistic way of holding the piece securely. There's no boss worth speaking of that a chuck could get a grip on and fixing the thing to a face plate is going to cause the clamps to obstruct the cut. A mandrel through the centre hole might be a possibility, but I'm not sure one could get it tight enough to resist the pressure of the cutting.,
Is this an idea....there are two blind 1/2" BSF holes on the face of the flywheel (to attach a puller). Could I drill the holes all the way through and use them to bolt the 'wheel to a face plate?
The plan to date has been to mill the teeth off with a roughing mill or slot drill. To that end I've tried to do a set up on the mill with a rotary table and its dedicated three jaw self-centring chuck. I've adapted an Austin Seven flywheel puller (mentioned above) to try and grip the job. (Cross-piece of puller bolted tightly across the flywheel and the forcing bolt gripped in the chuck on top of the rotary table. However, when the job is tight it's horrendously out of true axially and side to side and when it's true it's loose in the chuck. NBG.
Could I...get rid of the rotary table/chuck set-up but retain the bolted on cross-piece and lock that in a milling vice mounted on its rotating base on the mill table. Then, rotate the vice under the cutter in increments?
Sorry to 'go on' about this. It's becoming a 'give up for good' moment.
Many many thanks in advance for any views/suggestions.
Bonne 2020 to one and all.
JasonB19/01/2020 13:59:57
19568 forum posts
2142 photos
1 articles

make an arbor that is held in the 4-jaw chuck and then put two short studs into the blind holes to use as drive dogs against the edge of two chuck jaws do you don't need to worry about it slipping on the arbor.

Cornish Jack19/01/2020 14:06:06
1190 forum posts
163 photos

From a position of absolute ignoramce, would this suggestion have any merit? I understand that you want to remove redundant teeth, without doing intermittent cuts. Being a non-engineer, I would get my trusty angle grinder with a cutting disc and remove each tooth individually and THEN put the fkywheel in the lathe to clean up. How close to the teeth roots you cut would determine the interrupted cut required.

Someone better qualified will be along shortly with the correct way of doing it.



Georgineer19/01/2020 14:07:27
451 forum posts
25 photos

Martyn, I can understand what you are trying to achieve, but not why you are trying to achieve it. I'm not familiar with the details of the Austin 7, but I presume the gear ring is normally hidden within the bell-housing and therefore invisible to the naked eye.

If your intention is simply to prevent a mash-up if somebody tries to use the electric starter, wouldn't it make better sense to simply leave the starter motor unconnected? It would be a simple matter to make some sort of insulating bush for one of the connections in the starter circuit, which would be invisible to all but the most determined of observers.


Baz19/01/2020 14:12:01
524 forum posts
2 photos

If it were mine I would drill your holes through and bolt it to a faceplate and turn the teeth off. If you mill the teeth off you will bash the guts out of a milling cutter and mill spindle bearings so might as well do it on the lathe and bash the guts out of a lathe tool and lathe spindle bearings. I doubt you will do any damage to either lathe or mill whichever way you choose to go, machine tools are designed to take a bit of abuse, spend a few years in industry and you would see them being abused on a daily basis, if industry were too precious about their machinery they would never make any money.

Nick Clarke 319/01/2020 14:30:39
1017 forum posts
36 photos

Attach the flywheel to a faceplate as you suggest but turn the teeth off with a trepanning cut so no intermittent cut. In effect you are cutting off what amounts to a thin 'ring gear'.



Edited By Nick Clarke 3 on 19/01/2020 14:31:37

Jeff Dayman19/01/2020 14:39:18
1974 forum posts
45 photos

Since hundreds of thousands of these cars were made, surely you can find another flywheel?

If you must get the teeth off the one you have, if it were me, I'd grind a few teeth off to make room for a saw blade width. Then cut the major part of the rest of the teeth off with a bandsaw. Mill the rest off to a clean diameter by mounting it on a pivot pin and rotating it past a 1/2" or larger dia cutter. Just food for thought.

Stueeee19/01/2020 15:11:11
67 forum posts

I would drill 4 new holes through the flywheel at 90 increments and clamp it to your faceplate. Unless it's a late flywheel (with the conventional lined centre plate) these holes could be covered by the clutch lining when the motor is re-assembled. I have machined several A7 flywheels either to lighten them or to machine the register for a shrunk on ring gear. A7 flywheels are made of a pretty tough steel, so it's worth making sure that it isn't going to shift while you're machining it.

Edited By Stueeee on 19/01/2020 15:17:59

norman royds 219/01/2020 15:12:41
48 forum posts

I look for a picture on your forum whit no picture.i would suggest fitting boss where it fits to engine trying to keep it central better if there was hole in centre of the flywheel to work from. and grip in four jaw to centre. but remove the teeth with anglegrinder

Steviegtr19/01/2020 15:13:15
1779 forum posts
235 photos

Might be wrong but I think that flywheel maybe quite hard steel. Maybe you want to do this job just because if you do not it will bother you. Like I should have done it grr.

old mart19/01/2020 15:33:40
2472 forum posts
169 photos

I agree with Jeff's suggestion, why not just get a refurbished flywheel, probably with a ring gear shrunk on, then you will be able to start by bump starting, crank handle and electric start. You wont have to worry about the lathe or mill, the teeth might be flame hardened on the old flywheel.

Neil Wyatt19/01/2020 15:45:09
18409 forum posts
718 photos
78 articles

There's one on eBay, 4 hours to go £25, 0 bids, if you are quick.


Dave Halford19/01/2020 16:00:51
1142 forum posts
11 photos

I wouldn't subject rotary table gears to that sort of treatment especially with the extra leverage that the height of a three jaw chuck gives. If the table has 4 tee slots bolt the flywheel direct to it using the 1/2 BSF holes, if it's a 3 slot table that leaves you your faceplate idea as the best bet.

Brian Wood19/01/2020 16:59:59
2317 forum posts
37 photos


For me Cornish Jack has outlined a completely practical solution without the need to hammer the guts out of any machinery. The finishing cut(s) to remove the residual roots should be at slow revs with a heavy depth of cut to remove them like a hard skin on a casting.

I also think you will need 4 through bolts [at least] to clamp this down to a faceplate to prevent things moving about with vibration



HOWARDT19/01/2020 17:30:57
653 forum posts
15 photos

Clamp the flywheel to the mill table then with use of x and y hand wheels roughly mill off the teeth. Make a mandrel to fit the bore with a flange on the chuck side that has two or one drive slot that the stud can be driven by and a nut or washer and bolts on the end. Then finish turn on this.

You may think it daft to try to mill round a circle with x and y hand wheels but you may be surprised how easy it is and how close you can get.

Speedy Builder519/01/2020 17:33:03
2186 forum posts
152 photos

Here is a scary idea, mount the flywheel onto its crankshaft, then turn it between the centres of the crankshaft. If you use fine cuts, I wouldn't see that it was a problem turning the teeth off. My old Boxford has been subjected to far worse when I turned a complete crankshaft with 1.5" throw on each journal !

noel shelley19/01/2020 18:15:09
228 forum posts
3 photos

Cornish Jack is on the money. Either cut the teeth off by hand or set up on a face plate and rig the grinder as a toolpost grinder. BUT as others have asked WHY take the teeth off ?


Brian Wood19/01/2020 18:38:01
2317 forum posts
37 photos


I wouldn't chop the teeth off anywhere near a lathe, think like the late John Stephenson. He wouldn't have mucked about, do the brutal bit in a vice and then clear up the mess later using a lathe.

Martyn must have his reasons for wanting to do this, I wouldn't question them.



JasonB19/01/2020 18:41:54
19568 forum posts
2142 photos
1 articles

No, JS would have welded up the gaps between the teeth and then skimmed it to look tidy. The heating and subsequent cooling from the welding would also mean the teeth were no longer hard as witches bits. devil


Edited By JasonB on 19/01/2020 18:44:05

Brian Wood19/01/2020 18:52:15
2317 forum posts
37 photos

So he would Jason, I hadn't though of that.


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