DIY Flywheel

[Chassis 33]

Right folks, I seem to have backed myself into a bit of a corner. I'm working on a project with an Audi V8 and mating it to a Ford T5 gearbox, so far I have engine and flexplate/starter ring, gearbox, starter and custom bellhousing. The bellhousing was primarily designed for the VAG engines with a smaller cylinder count that use the 228mm diameter clutch. I had hoped to use the 240mm clutch from an S8 but it would appear that this will foul the bellhousing.

Option 2 is to use a 10bolt 228mm dia flywheel, however this means I need a different starter and it appears that solid (ie not dual mass) 10bolt 228mm flywheels are rare as hens teeth (unless someone can tell me otherwise)

So....
Option 3
Retain the original ring gear (that does fit in the bellhousing) make a custom 6061T6 aluminium flywheel with a case hardened 1018 steel insert using an AP/Tilton/Alcon et al 7.25" clutch pack,

What do you reckon? Sensible idea? I'd design in and run a decent bit of FEA on it, I've access to a full machine shop and such like so that's not a problem, the bell housing is a certified scatter shield so it it does go wrong the risk of injury is reduced....what could possibly go wrong???

Regards
Iain

[stevieturbo]

If it's made properly, it should be fine. But Ive never liked aluminium flywheels. I really dont see the point ?

[Chassis 33]

Fair point, at least with steel I don't have to worry about S-N curves and fatigue so much.
Regards
Iain

[The Black Flash]

Not much to a flywheel, really. I've just had something similar done for my Alfa-Honda conversion. The issue I had was that the engine is externally balanced, (the flywheel has to be out of balance), so I had to get the whole assembly balanced up, but I doubt a v8 would have that problem.

[anonymous-user]

I seriously wouldn't bother with an alluminium one. Remember the difference between "mass" and "rotational inertia" is all about where the material is positioned relative to the centre of rotation. using a high strength material like steel allows you to use thinner sections to support the CF loads where you don't want to have material (due to it not adding much inertia, but still adding mass!).

A well designed steel flywheel, with properly calculated / stressed sections is the ideal

[Chassis 33]

I guess one advantage of a steel or aluminium flywheel that has a separate friction surface insert is that for small runs it's easier to heat a uniform disc without distorting it (when case hardening the friction face) that it is a flywheel with multiple thickness's etc?

Regards
Iain

[Pumaracing]

Max_Torque said:

I seriously wouldn't bother with an alluminium one. Remember the difference between "mass" and "rotational inertia" is all about where the material is positioned relative to the centre of rotation. using a high strength material like steel allows you to use thinner sections to support the CF loads where you don't want to have material (due to it not adding much inertia, but still adding mass!).

A well designed steel flywheel, with properly calculated / stressed sections is the ideal

As high strength aluminium alloy like HE15 has about half the tensile strength of average flywheel steels but only about 1/3 the density I would say the opposite. You can make the flywheel twice the section thickness of a steel one and still save mass and inertia. Obviously very high tensile steels could be used but the cost would be extortionate.

[anonymous-user]

Pumaracing said:

Max_Torque said:

I seriously wouldn't bother with an alluminium one. Remember the difference between "mass" and "rotational inertia" is all about where the material is positioned relative to the centre of rotation. using a high strength material like steel allows you to use thinner sections to support the CF loads where you don't want to have material (due to it not adding much inertia, but still adding mass!).

A well designed steel flywheel, with properly calculated / stressed sections is the ideal

As high strength aluminium alloy like HE15 has about half the tensile strength of average flywheel steels but only about 1/3 the density I would say the opposite. You can make the flywheel twice the section thickness of a steel one and still save mass and inertia. Obviously very high tensile steels could be used but the cost would be extortionate.

True, but the issue comes in a practical embodiment of a real flywheel, where if you want any kind of durability you need to have some kind of hard friction surface for the clutch plates to bear upon. Most ally flywheels use bolt on steel inserts, and by the time you have arranged for suitable sections to allow these to attach (and withstand the CF forces) then you are back to where you started. Of course, these days, you could use some fancy "metal sprayed" technology, but it's probably not the average DIY undertaking.

Finally, long term effects like creep and work hardening make ally flywheels a little bit more tricky that a steel one. Of course, what you really want is a Ti one ;-)

[CrashTD]

If I understand correctly option 2 involves an Audi Flywheel? Extremely rare to find a VAG part which is not used in other vehicles. If you can provide a part no or some more details I can check where else it may be used.

[Chassis 33]

I believe the VR6 flywheel is both 228mm and 10bolt - 021 105 273 H seems to be the part number.
Regards
Iain

[CrashTD]

A vr6 flywheel should not be hard to find if that's what your after. There is one on ebay at the minute.

[Chassis 33]

CrashTD said:

A vr6 flywheel should not be hard to find if that's what your after. There is one on ebay at the minute.

This one? http://www.ebay.co.uk/itm/G60-VR6-clutch-flywheel-...

Thats a G60 thats only a 6-bolt effort
Regards
Iain

[CrashTD]

http://www.ebay.co.uk/itm/VW-Golf-mk1-2-3-VR6-02A-...

Comes with a free engine too.

Failing that try Sanburn Autos in Coventry or Stephens VW Dismantles in Essex. I would confidently say that finding a flywheel off a VR6 is easier and cheaper than any custom job.

[Chassis 33]

Sadly the 400mile round trip in the Jeep to collect it at 20mpg more than doubles the cost! Thanks for the heads up on the breakers though.
Regards
Iain