How to design a fly wheel?

[Orphan]

Hey guys,

Just wondering how hard it is to use solidworks to design a flywheel. Honestly I have no experience in the area though I can use solid works well enough to get by. Interested in trying to design a flywheel for a manual conversion for an engine that never came with a manual transmission and there are no known current production flywheels to fit the engine.

Would love any info or links provided.

What considerations etc do I need to take into account. I'd like to eventually get it made up if it is of usable quality.

Thanks guys.

 

[Tmoose]

Probably start with the flywheel/flexplate from the engine because that fits the crank flange (snug ((+0.001/-0.000 inch) fit on pilot diameter, matching bolt circle) and provides (probably) a starter ring gear and maybe an ignition reference pin. Most stock flywheels are zero or neutral balanced, but some have some unbalance to complement or complete the crank system's balance.
The fore/aft offset must be adjusted as necessary to get the clutch or converter positioned correctly with the transmission/bell housing. If This adjustment results in a thinner flywheel, minimum clutch friction surface thickness should 1/2 inch or so. If the adjustment results in a thicker flywheel, the extra weight may make the engine feel a little lazier than stock. As the transmission moves away from the engine, the transmission input shaft unplugs from the crank pilot bearing/bushing. May need an adapter type bushing (sometimes made as part of the flywheel) to match the trans input shaft anyhow
Some clutches have locating dowels that will need to be included. Need to check to be sure you are Getting a clutch combo that handles the engine torque and rpm, has the right trans spline.
FW needs Clearance for clutch disc hub/springs, and a groove with drain holes to manage rear main seal leakage.
NHRA used to ban cast iron flywheels on engines capable of over 6000 rpm. Any old mild steel is pretty strong.

Solidworks will help make a nice model and drawing, but the appropriate tolerances and dimensions must be worked out.

Gotta work out how to mate the trans to the engine. If the adapter plate has thickness that will tend to add thickness to the FW too. If the starter is trans mounted instead of block mounted it will define the ring gear and its location

 

[Orphan]

Thanks Tmoose.

Starter is block mounted. Any thoughts as to whether a full bell-housing is better/worse than adapter plates? There are both on offer from various companies and all slightly different in thickness/requirements.

Surprisingly I understand a fair bit of what you said as most of the custom flywheels on offer have other parts with them relating to what you have said.

If its any help the engine is a 1UZ-FE toyota V8.

Would most likely be steel, cost effective and strong. Don't really need a sub 5.5kg flywheel on an engine with plenty of power and most people supercharger anyways.

So first step is to measure up the flex plate aye. To what tollerance would you recomend? Will get my ANU engineering buddy to use his fancy tools haha, don't wanna be going at it with a ruler lol.

 

[tbuelna]

Orphan,

The hardest thing on a flywheel (or flexplate) to reverse engineer is the exact gear tooth profile of the ring gear teeth. Since the ring gear has a large number of teeth, and must mesh smoothly with a starter pinion that has a very small number of teeth, the ring gear tooth form geometry is usually highly modified from standard. It will require the services of a skilled and well equipped(ie. expensive) gear inspection facility to evaluate just exactly what mod's were made to the gear's basic geometry to get it to work correctly.

Other than that, make sure you get the rotational MOI where it needs to be, check to make sure you have adequate safety margins for burst strength for the materials and speeds you are designing at, and check to make sure that your new flywheel's natural frequency doesn't coincide with any of the existing modes in the driveline.

Good luck.

 

[patprimmer]

On many engines with automatic transmissions, the ring gear is a separate item welded to a pressed metal flex plate. This can e cut off and welded to a custom made steel flywheel.

Regards

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[thundair]

The flywheel OD was often just related to the starter as it was at one time a reduced gear to start the engine with using an electric motor.
Now the starter can be purchased with the gear reduction built in so no longer do you need the huge diameter flywheel to attach the starter ring.
My point is that you may find a nice 11" clutch and even a corresponding flywheel that will bolt up to the crankshaft. Machine away the starter ring and bolt the flex plate to the new flywheel..

I don't know anything but the people that do.

 

[StefanHamminga]

Patprimer is correct, the 1UZ item is a weld on, at least on mine... I think I even took measurements on it once, it may still be floating around on the Lextreme forums.

Stefan Hamminga
EngIT Solutions
CSWP/Mechanical designer
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