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Mega S2000 Flywheel/clutch mod -


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Davemk1

 

Very light flywheel/clutch -

 

I recently made a modification to my 2014 Mega S2000 that I thought a few others might be interested in.

 

In 2014 when I built my car I left the stock Honda flywheel and clutch in place and it of course worked just fine. The stock combo weighs 27.5ish lbs (I never weighed the actual items but the webbernet says this is what they weigh). After a few years of use I wanted to up the performance so I installed a new lightweight flywheel with a stock clutch. This flywheel was 6 lbs lighter than the stock Honda part and brought the combo weight down to 21.5 lbs (actual weight). This worked well. It rev’d quicker and shifted great and I was happy…..for a while at least.

 

I recently stumbled on a very light flywheel/clutch combo made by Spec. It’s called a ‘Mini' because the pressure plate and friction disc are a few inches smaller in diameter than the stock items. The flywheel is very light aluminum and the pressure plate is also aluminum and of course smaller in diameter….meaning that the rotational inertia is lower. The system (flywheel, friction disc, pressure plate) all tolled weigh 13.2 lbs. This is 1/2 the weight of the stock Honda combo. For those that care the friction plate is unsprung and it’s rated at 400 ft/lbs so plenty of reserve for the low torque Honda engine.

 

I pulled the engine and removed the old ‘light’ set up and then did an inertia test comparing this against the 13.2 lbs Spec combo, I did this by mounting the pressure plate/disc to the flywheel and then placing it on a horizontal shaft so it could spin freely on the pilot bearing. So the flywheel is vertical. I then wrapped a string around the ring gear and tied a weight to it and timed the weight as it fell to the floor and spun the combo. I of course did this with both the light 21.5 lbs and the 13.2 lb combos. I gave the times to a mechanical engineering friend who ran the numbers and he told me that the super light combo took 56% less torque to spin up the lighter combo than it did the heavier one. That’s a big number.

 

After all that I finally installed the new super light combo and all went well and this just fell together. It started and idled just fine (maybe a smoother idle?) and I very nervously took it on a short test drive….and…..it worked fine. I feared that it would be very difficult to pull away from a stop but it was fine. I stalled it the first time but after that all was fine.

 

I have about 100 miles on the system now and all is well. It revs very quickly and it’s easy to feel that when accelerating hard in 1st and 2nd gear. This is exactly what I was looking for with my autocross competition use. When dropping the throttle the car has more engine braking and when hitting it hard again it pulls very hard and revs very quickly through the gears. It’s awesome. The throttle response is fantastic.

 

The downside? The only one I’ve found so far is that the trans and diff make more noise with less weight spinning around to damp out drivetrain vibration. It sounds normal when on throttle but when I’m cruising with very low throttle settings you can hear the gear lash doing its thing. For my use this is fine and I suspect most track or competition drivers would be fine with it too….However I don’t think I’d make this mod to a purely street driven car.

 

So that’s what I got. If anyone is interested and has questions let me know.

 

Dave

DSC_1295 (1).jpeg

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Ian Kinder (Bagpuss) - Joint Peak District AO

Sounds interesting. Looks like the slave cylinder has been changed to a concentric type.

 

@Si.Dalziel tempted?  Whilst the engine is out?

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Si.Dalziel
19 minutes ago, Ian Kinder (Bagpuss) - Joint Peak District AO said:

Sounds interesting. Looks like the slave cylinder has been changed to a concentric type.

 

@Si.Dalziel tempted?  Whilst the engine is out?


I’m not binning a clutch with only 1500miles on lol. It does look great though!

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Davemk1
52 minutes ago, Ian Kinder (Bagpuss) - Joint Peak District AO said:

Sounds interesting. Looks like the slave cylinder has been changed to a concentric type.

 

@Si.Dalziel tempted?  Whilst the engine is out?

 

Yes it's an annular throwout bearing. The clever thing is that there are two hydraulic hoses come out of it....one bolts directly to the banjo fitting on the line that typically bolts to the slave cylinder (in effect becomes an extension and adapter at the same time) and the other is a bleed line. These two hoses exit the hole in the bellhousing where the stock Honda fork protrudes and the bleed hose is very easy to access now. I bled it with one hand reaching down into the pedal box pushing the pedal and the other on the bleeder wrench. That was an unexpected bonus of the swap.

 

dave

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Greenstreak-Andy D

Interesting you found little difference with such a light clutch, pulling away from a standstill.

 

The first flywheel option you spoke about, i may consider at some point if i need to pull the engine out.

 

Andy

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Davemk1
56 minutes ago, Greenstreak-Andy D said:

Interesting you found little difference with such a light clutch, pulling away from a standstill.

 

The first flywheel option you spoke about, i may consider at some point if i need to pull the engine out.

 

Andy

 

It surprised me too. I worried that the only way I'd get the thing rolling was by doing a big tire smoking burnout!

The guy at Spec told me that when the national class Honda S2000 guys compete in their Hondas that they can have a hard time pulling away smoothly. They don't care about this for autocross of course but it makes getting on/off the trailer and to the start line a bit of an adventure!

 

But because my car is so light it should be OK to drive on the street. It seems that the mass of the flywheel needs to somewhat match the weight of the car. Heavy car needs more stored energy in the flywheel to help get the car rolling.....light car can get by with the light flywheel. It makes total sense when I think about it. My car weighs 558 KG which I would guess is about 1/2 the weight of the Honda S2000 and the flywheel is about 1/2 the weight of the stock Honda part. I know that's an over-simplification but there's some logic to it.

 

dave

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Dave Eastwood (Gadgetman) - Club Secretary

I’d be wary of using an unsprung clutch plate on a road car, without adding the damping in somewhere else in the drive line at least. But these setups can work really well in competition, (or on the road, if you accept the potential for increased drive line wear etc from the possible shock loading).

 

Interesting mod, though.

 

I’m using one of the lightest non-alu. flywheels around on the blue car, and having sorted an issue out recently that stopped it starting, I must admit it caught me by surprise yesterday just how quickly the Honda engine spins up and revs, even with the standard diameter components!

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Andrzej

I had bad experience with unsprung clutch plate in a trackday car . This was different type of clutch - classic just without springs (taken from diesel wit dual mass flywheel originaly - was supposed to be stronger..., matched with low power NA 150HP engine with solid flywheel ) . After approx 10 or so trackdays the rivets in clutch plate broke during important challenge :-/ .

I was talking later to the guy who is building engines for national hillclimb etc, he strongly advise to use sprung clutch plates , as he says - something must broke if there are no springs, I dont understand all that harmonics, vibrartions etc of engine but probably it has something to do with it  (? but maybe I misunderstood his explanation of the topic .. bu I remember the conclusion and advice : "use sprung clutch plates only"  :)

But, as I was recently looking for lightweight options for my zetec , I saw a lot of shops selling no-springs clutch plates for racing / trackday applications . So people are installing solid plates somehow and drive with ? maybe in lighter cars it does work ? 

 

Anyway , thank You Davemk1 for sharing Your next experience and feelings!

I am in the process of choosing and fitting a lighter flywheel and clutch too, in fact the parts are on the shelf already, bu it will be no so lightweight as Yours. Read and wast talking to some motorspord teams services , they say that on lower gears there is huge difference, less in high gears, and I hope for better gearchanges (now with heavy flywheel there is some "lag" when blipping throttle on downshifting)

 

Wonder what is the diameter of Your clutch plate and if it is sintered (like this one :  https://www.burtonpower.com/ap-racing-184mm-sintered-clutch-plate-1-x23-spline-cp2012-165fm3.html

or cerametalic . like such one : https://www.burtonpower.com/helix-paddle-clutch-plate-215mm-ford-puma-1-7-76-2351.html

I have read that the first one type is difficult to all that trailer loading/unloading car an parking

maneuvering ?

 

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Davemk1
18 minutes ago, Andrzej said:

 

Wonder what is the diameter of Your clutch plate and if it is sintered (like this one :  https://www.burtonpower.com/ap-racing-184mm-sintered-clutch-plate-1-x23-spline-cp2012-165fm3.html

or cerametalic . like such one : https://www.burtonpower.com/helix-paddle-clutch-plate-215mm-ford-puma-1-7-76-2351.html

I have read that the first one type is difficult to all that trailer loading/unloading car an parking

maneuvering ?

 

 

Mine looks a good bit like the Burton Power part.

 

dave

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