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Good workshop practice? NO.

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lee webster30/08/2021 18:50:21
20 forum posts

I have a confession to make. I have started to dismantle my Austin Seven engine so that I can start designing the half size model. (Is it half size or half scale?) Today I wanted to remove the flywheel which is held onto the crankshaft by a taper and large nut. The nut was easy to remove and I have a flywheel puller. It consists of a bar of steel an inch wide by ¾” thick by about 2 ½” long. It has a threaded hole in the middle and 2 holes that line up with 2 blind threaded holes in the flywheel. All threads are ½” BSF. My puller was missing the central bolt. I remembered that the last time I used it to remove a flywheel I had to use a lot of heat, brute force and swearing. It took several days to get that particular flywheel off, and the middle bolt was beyond saving. So, I had a puller, but no very important bolt and ½” BSF isn’t available locally. I found a piece of steel rod about the right diameter, and I had a ½” BSF die. What I didn’t have was the correct die holder. I had bigger and smaller, but not the right size. There was only one thing I could do. Sorry, you might want to cover your ears. With the steel rod clamped in the vice I used a pair of water pump pliers to turn the die. I cut about 1 ½” of (wonky) thread and screwed the puller into the 2 flywheel holes and tightened down my home made bolt. It seemed to be working until I realised that one of the flywheel bolts was pulling out of its thread. The flywheel threaded holes are only about ½” deep at the most. I removed the bolts and cleaned out the holes as much as I could. Re-assembled and tightened I started to hit the middle bolt very hard. Several moments later the flywheel sprung off the taper and I could remove it. I still have the crankshaft to remove, then I can measure the crankcase and produce a 3D drawing before 3D printing it.

Speedy Builder530/08/2021 19:16:56
2449 forum posts
195 photos

Hi there Lee - That will be some project ! Which engine is it, the magneto one, the 2 bearing crank or 3 bearing.

Removing the crank can be difficult, made easier if you can tap the rear bearings off the crankshaft BEFORE removing the crank itself.

Most of the original dimensioned drawings for these engines are available on the 'net.

Let us know more as there are several A7 owners on this site.


brian jones 1130/08/2021 19:23:12
347 forum posts
62 photos

one ape way to remove a flywheel on a taper, as well as applying heat is to het a 4lb mallet and a brass or alu block to protecct the shaft thread, then you lever out the flywheel against the play there is in the main bearing and give the shaft a smart wack on its end - needs some skill to judge how much before you do damage, but it worked for me on a stationary engine flywheel, 3ft dia weighing 1/4 ton. erindoors built a fire of straw up around the shaft first and quenched it with water then i wacked it. popped off and nearly fell on my legs

all the farm poultry were smart enoiugh to stay up the other end of the yard.

Russell Eberhardt30/08/2021 20:20:03
2720 forum posts
86 photos

My first Austin 7, a Ruby, would often loosen the flywheel itself with a loud rattling sound, an interesting roadside repair which I became quite proficient at!


lee webster30/08/2021 21:55:52
20 forum posts

Bob, the engine is about 1930, two bearing with dynamo.

brian jones 11, An Austin Seven flywheel can "fly" off the taper if you are not carefull. The suggested way is to leave the nut on the crankshaft, but loosened. I didn't do that!

Russell, The flywheel taper and rear hub taper are both a bit suspect. I lapped a flywheel onto its taper many years ago. That quietened it down.


brian jones 1131/08/2021 00:27:47
347 forum posts
62 photos
Posted by lee webster on 30/08/2021 21:55:52:The suggested way is to leave the nut on the crankshaft, but loosened. I didn't do that!

In my experience using the nut as a cap to hammer the shaft is a bad idea and can seriously weaken the thread

a definite NO NO

lee webster01/09/2021 09:12:43
20 forum posts

Even with the nut in place the puller bolt locates on the end of the crankshaft without touching the threads. Mind you, a badly alligned puller could damage the threads. I think the crankshaft is OK, they are prone to breaking, but I won't know until I remove it. It could be a spare engine for someone once I have finished with it.

Nigel Graham 201/09/2021 17:02:56
1775 forum posts
22 photos

Using pump pliers to turn a die can easily result in snapping the die in half, which won't help.

I'd suggest you obtain appropriate die-holders and tap-wrenches for the tools you have.

Speedy Builder501/09/2021 18:54:43
2449 forum posts
195 photos

Lee, if you don't know about this link, you should have a look. All dimensions for Austin 7 engines, crankshafts etc etc.

Austin 7 archive drawings

lee webster02/09/2021 08:55:04
20 forum posts

I couldn't agree more Nigel. My shopping list gets longer every day!

Thanks Speedy, I already have two of the drawings. Very useful they are too.


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