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| Lightened flywheels https://www.ausmini.com/forums/viewtopic.php?f=2&t=92306 |
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| Author: | carter [ Tue Apr 05, 2016 1:58 pm ] |
| Post subject: | Lightened flywheels |
Gday all, just wanting some insight to lightened flywheels. Can you go too light? There are some lightened flywheels which are "not recommended for road use" why is this? What would happen if you put a really light flywheel onto a road motor? that's worked obviously..... Cheers fellas |
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| Author: | MiniBrad [ Tue Apr 05, 2016 5:48 pm ] |
| Post subject: | Re: Lightened flywheels |
One of the reasons for having a flywheel is for maintaining momentum when an engine is at idle & if too light a flywheel is fitted the idle will constantly be speeding up & slowing down from compression/power strokes & will run very lumpy, which in a street car will not be very pleasant at all, but a race engine needs to rotate a lot faster & is rarely at idle so it needs a light flywheel. Others might help explain it further as well in case of other reasons I've forgotten since I went to trade school. Brad |
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| Author: | 1071 S [ Tue Apr 05, 2016 6:06 pm ] |
| Post subject: | Re: Lightened flywheels |
Can you go too light?.. IMHO - no. I've run an 8lb Manx Racing flywheel ..and matching lightweight backplate on my road car for years (decades in fact). Maybe you have to get used to driving it ..but I couldn't say. The only other person to drive my car - the mechanic who does the annual brake test doesn't seem to have an issue either. I guess the only downside I can think of is the thin ring gear ..although I'm not really sure the thinness is the real problem but I have had to replace it. The engine was a bit lumpy with a 286 but the current 731 idles quite smoothly at under a thousand revs.. Cheers, Ian |
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| Author: | carter [ Tue Apr 05, 2016 9:47 pm ] |
| Post subject: | Re: Lightened flywheels |
I was looking at buying a lightened flywheel and saw the lightest one that "is not recommended for road use" and I though it'd be best to get but if my car won't idle or run properly it's not worth getting..... Anyone else have experience in a very light flywheel? |
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| Author: | 36 [ Tue Apr 05, 2016 10:39 pm ] |
| Post subject: | Re: Lightened flywheels |
What Brad said. Rougher idle, and more revs required for takeoff. On the good side is a faster revving engine. Don't do a diy machining job. Flywheel failures are fairly spectacular. A look at where the flywheel runs relative to the driver is fairly sobering. |
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| Author: | carter [ Tue Apr 05, 2016 11:02 pm ] |
| Post subject: | Re: Lightened flywheels |
So it would be OK for a road car just lumpy idle as if you had a race cam? No it wouldn't be a home job it would be bought from a mini shop and the lightest one I can find if it'll work |
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| Author: | 9YaTaH [ Wed Apr 06, 2016 3:13 pm ] |
| Post subject: | Re: Lightened flywheels |
carter wrote: So it would be OK for a road car just lumpy idle as if you had a race cam? No it wouldn't be a home job it would be bought from a mini shop and the lightest one I can find if it'll work Maybe not "lumpy"...just easier to stall on the road...you have to remember that they made the flywheel a particular weight for a good reason in the first place and as a compromise between outright performance and tractability...for example, it means when you are bringing up the clutch in a road car trying for a nice smooth change that it will do that. Get some good advice on the optimum weight for your engine tune/clutch type etc... |
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| Author: | 1071 S [ Wed Apr 06, 2016 7:40 pm ] |
| Post subject: | Re: Lightened flywheels |
carter wrote: So it would be OK for a road car just lumpy idle as if you had a race cam? No it wouldn't be a home job it would be bought from a mini shop and the lightest one I can find if it'll work No, not lumpy at all - in my experience... However, yes, it does take more care to drive... but BMC... Rover et al built cars for the masses ..And you have to remember that half the population is of below average intelligence .and ability.. Cheers, Ian |
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| Author: | drmini in aust [ Wed Apr 06, 2016 7:55 pm ] |
| Post subject: | Re: Lightened flywheels |
You can run the ultralight flywheel with a stock eg Cooper S backplate for a road car. Will still be much lighter than stock. |
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| Author: | TheMiniMan [ Wed Apr 06, 2016 10:04 pm ] |
| Post subject: | Re: Lightened flywheels |
Some light flywheels come with integral ring gear... i expect they will be the ones suggested not for road use When the ring gear is stuffed from multiples of starts with road use & crappy 2nd hand sh1t starters you have to either machine the ringear off & sweat/pin &/or weld a new ring gear on it would be a pain in the arse In saying that ... we all generaly take care of our starters & ring gears these days dont we? 
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| Author: | drmini in aust [ Wed Apr 06, 2016 10:11 pm ] |
| Post subject: | Re: Lightened flywheels |
Matt if running an ultralight one I would use a pre-engaged starter. Gemini or better. Not ye olde Lucas. |
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| Author: | 9YaTaH [ Thu Apr 07, 2016 8:16 am ] |
| Post subject: | Re: Lightened flywheels |
1071 S wrote: Rover et al built cars for the masses ..And you have to remember that half the population is of below average intelligence .and ability.. Cheers, Ian Only half?....Don't a lot of the ones below average intelligence and ability usually just give up and join the services where they can always rely on having someone around to tell them what to do  (PS in the olden days it was often the Magistrate who encouraged miscreants to "join the Navy" ....or else) |
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| Author: | slide [ Thu Apr 07, 2016 3:25 pm ] |
| Post subject: | Re: Lightened flywheels |
Steel ones can weld themselves onto the crank and can be a pain to remove. I use lightened cast ones, not greatly machined down, in both my road cars along with sturdy scatter shields fitted to the housing. Never had a problem with these. |
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| Author: | boomini [ Thu Apr 07, 2016 10:31 pm ] |
| Post subject: | Re: Lightened flywheels |
Im running a lightened med flywheel and intermediate plate on my motor. It is close to 13~1 compression 286 cam lightened balanced x drilled and nitrated crank. Revs like a dream all the way up past 8000rpm(very rarely) but yes requires extra revs too take off and stalls below 1000rpm idle. Im used to it now as I drive my mini like I stole it. Combined with the heavy duty pressure plate its a ning nong in heavy stop start traffic. |
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| Author: | 9YaTaH [ Fri Apr 08, 2016 7:42 am ] |
| Post subject: | Re: Lightened flywheels |
boomini wrote: its a ning nong in heavy stop start traffic. 
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