22 replies to this topic

[minihewson]

Hi all,
could anyone please help me, i have machined my flywheel to make it lightweight. (5kg) but not thinking i machined without taking a measurement first and now wanting to put my engine back together i need to know the standard thickness of the flywheel so i can make spacers for the drive straps that hold the pressure plate. if anyone could tell me the thickness of the flywheel below the ring gear where the slotted holes are it would be much appreciated. thanks

It is off a 1275 a+ engine if this makes a difference.

[MRA]

You may have removed too much metal if it is a standard cast item they can explode at higher revs...

Pre verto type clutch not common on A+ engines.

[cooperrodeo]

My old bog-standard flywheel weighed 5.7kg. The lightweight one I got from Minispares weighs 4.5kg.

[minihewson]

When i weighed it before it weighed 8.3kg. but dont no if there are different types or not?

[minihewson]

You may have removed too much metal if it is a standard cast item they can explode at higher revs...

Pre verto type clutch not common on A+ engines.

would you recommend buying a lightweight flywheel rather than using this one? the last thing i want is to put a hole in the bellhousing or bulkhead

[bmcecosse]

As long as you have left a ridge at the ring-gear - to make sure it won't come loose - it will be fine. I used self-machined flywheels for years. Just use a wee pile of (nice new) flat steel washers to pack up the drive straps. When you assemble the backplate and drive plate to the flywheel - you will see how far the pillars from the backplate come through the main body - just add washers under the drive straps until they are lying level.

[Cooperman]

As long as you have left a ridge at the ring-gear - to make sure it won't come loose - it will be fine. I used self-machined flywheels for years. Just use a wee pile of (nice new) flat steel washers to pack up the drive straps. When you assemble the backplate and drive plate to the flywheel - you will see how far the pillars from the backplate come through the main body - just add washers under the drive straps until they are lying level.

If I remember correctly, we used to fit a wider starter ring gear to improve 'containment' when we had machined a standard pre-verto flywheel. That was years ago. Can you still get those rings I wonder?

[MRA]

You may have removed too much metal if it is a standard cast item they can explode at higher revs...

Pre verto type clutch not common on A+ engines.

would you recommend buying a lightweight flywheel rather than using this one? the last thing i want is to put a hole in the bellhousing or bulkhead

It really depends on a few factors.... how high are you going to rev it ?

Personally having seen what one can do I wouldn't use a standard flywheel above about 6000 rpm and I wouldn't use a lightened version at all, I would in preference use a steel or aluminium flywheel.

Bits of flywheel coming out at 6000 + rpm don't tend to stop at the transfer case, or bulkhead

[MRA]

As long as you have left a ridge at the ring-gear - to make sure it won't come loose - it will be fine. I used self-machined flywheels for years. Just use a wee pile of (nice new) flat steel washers to pack up the drive straps. When you assemble the backplate and drive plate to the flywheel - you will see how far the pillars from the backplate come through the main body - just add washers under the drive straps until they are lying level.

If I remember correctly, we used to fit a wider starter ring gear to improve 'containment' when we had machined a standard pre-verto flywheel. That was years ago. Can you still get those rings I wonder?

Yes the wider rings are still available, however its a bit pointless adding more weight to the outer diameter, which is where it will cause the worst effects

[bmcecosse]

I ran my 998 up to 9000 rpm with self-lightened flywheel - and still have all my 'bits'. But I certainly feel it's important to have that ridge to make sure the ring-gear is well retained (and that nicely radiused too) - I think the ring gear coming loose is possibly more likely than the flywheel 'exploding' -although it may be a two stage thing.... Has anyone ever actually known a Mini flywheel to explode in service ?

Edited by bmcecosse, 22 March 2011 - 10:43 AM.

[ANON]

Has anyone ever actually known a Mini flywheel to explode in service ?

saw a mini in a breakers yard by me years ago that had a flywheel let go, was a mess to say the least.

[bmcecosse]

Crikey! Had it 'exploded' - or had the tail broken off the crank? I have heard of that happening - equally alarming I'm sure.

[cooperrodeo]

There was a Mini at Goodwood Revival a couple of years ago with holes in the clutch housing. Something had obviously let go from the flywheel/clutch.

[Cooperman]

As long as you have left a ridge at the ring-gear - to make sure it won't come loose - it will be fine. I used self-machined flywheels for years. Just use a wee pile of (nice new) flat steel washers to pack up the drive straps. When you assemble the backplate and drive plate to the flywheel - you will see how far the pillars from the backplate come through the main body - just add washers under the drive straps until they are lying level.

If I remember correctly, we used to fit a wider starter ring gear to improve 'containment' when we had machined a standard pre-verto flywheel. That was years ago. Can you still get those rings I wonder?

Yes the wider rings are still available, however its a bit pointless adding more weight to the outer diameter, which is where it will cause the worst effects

That was originally recommended to me by my old friend and famous Mini racer Mo Mendham who was quite simply a brilliant mini-developer and driver.
He also used to add a few equally-spaced blobs of arc-weld to the ring/flywheel to ensure it all held together on his self-lightened flywheels.

[ANON]

Crikey! Had it 'exploded' - or had the tail broken off the crank? I have heard of that happening - equally alarming I'm sure.

had fallen to bits. looked like someone had taken an axe to the engine bay/bonnet!! housing was smashed to bits.