my lightened flywheel

[kevo]

how do all,
thought i'd have a go at lightening my spare 318is flywheel, so here it is. i weighed it before and after to get a bit of geek data to laud about

it weighed originally 9.35kg's
i managed to safely get it down to 6.77kg's
which is a saving of 2.58kg's
or to be even geekier 27.5% less

to balance it i put it onto a grinding wheel balancer and worked my way round till it stopped resting in the same position. it took me a while to do but it's pretty good now. oh and i also cleaned up the face of the clutch as it had gotten very ridged. i'm hoping to get it in soon and will be fitting the shorter ratio e36 box at the same time too.
cheers
Kev

[Turbo-Brown]

Fair play dude!

Have you got any way of checking the face to face balance too? Suppose it's not all that thick so it shouldn't make all that much difference but be interesting to know if it's out.

[march109]

By my reckoning (and educated guess) thats equivelent to around a 40kg weight saving over the whole vehicle in first gear. Frankly I could to the proper math but I can't be bothered right now.

[kevo]

i don't have a way of checking the face to face balance, tbh though after seeing how much clutch dust there was stuck in various places and with the face being so rough i'd guess it wasn't perfectly balanced to begin with so i'd hope it's now within tolerance.
kev

[doggydoo2000]

Nice. The guys who are preping my car are having mine done too - it must make quite a difference once done - I'd be interested to know - whens it going back on? - I'm sure others would be interested in getting theirs done , a new revenue stream for you??

[kevo]

could be, i'll probably start doing them if people are interested, i'll just make sure there are no issues with mine first as i've only done this one so far. it'll be going on in a month or so after my next rally.
Kev

[kevo]

how do all, i've managed to fit the e36 closer ratio box and lightened flywheel in the car and took her for a spin earlier, wow. the thing is much much quicker, the box changes things dramatically also as with 14's on and standard road tyres the speedo shows 100mph at just under the redline 7000rpm. but one of the nicest things about her is the way it now revs, the thing picks up super quick, at idle the needle flies round the guage and settles back down much quicker, a definite improvement and as i've found a huge lump of aluminium in work i may even try and make a lighter ally one to get the weight down further, but we'll see. on the whole though a highly recomended mod.
Kev

[march109]

What engine have you got?

[kevo]

1796cc m42 lump

[march109]

and you fit an E36 gearbox? From the E36 318is I assume? Whats the difference in ratios?

[kevo]

yes from an e36 318is, fifth gear is 1:1 i.e. the same as fourth in the standard box, and all the other gears are bunched up closer. i have a 4.45 ratio diff on it aswell which closes things up again.
Kev

[Dave_M3]

Are you sure the ratios on the E36 box are bunched up closer?
I was working it out once from various places that I found ratios of both boxes and the E30 seemed to have smaller steps between most of the gears...
Would like to be proved wrong though

Great job on the flywheel though!!!
I must do a pair of M20 ones for my cars soon, I wonder which could be made lighter? An M20 or M42 including the difference in the M20s heavier clutch...

Also be interested to know will an M20 flywheel fit an E36 box?

@March109: The one thing I I can never get into my head right in Physics and Mechanics is Circular motion, Inertia and those kinda things, grand everywhere else but annoying since it's one of the more useful aspects of engineering

[kevo]

e36 1st 4.23 2nd 2.52 3rd 1.66 4th 1.22 5th 1.00

e30 1st 3.72 2nd 2.02 3rd 1.32 4th 1.00 5th 0.80

what ever the ratios in the flesh it's a massive leap especially linked up to my 4.45, no good as i have it for a road car though, if i'm doing a flat out to top speed i change up into fourth at 55 mph. it'll do a bit more but thats when it's best to change for the best pull.
Kev

[march109]

Don't get me started on angular momentum, angular kinetic energy, rotational energy and all the other concepts that make my head spinsince A-level physics.

Its done my head in but I have two very good simplified equations one is on my website:
Ratio of 1lbs of flywheel mass to Xlbs's of sprung mass =
0.5 * (r * 2) * (g * 2) + R2 / R2

Since its a ratio you can argue that its directly comparable to kg's : kg's

The equations I use were written by pro motorsport engineers, they are different but it is guess work since it all depends on where the mass is taken from the fly and also that the fly is not a perfect disc it also has topography with mass.

[Dave_M3]

[quote="kevo"]e36 1st 4.23 2nd 2.52 3rd 1.66 4th 1.22 5th 1.00

e30 1st 3.72 2nd 2.02 3rd 1.32 4th 1.00 5th 0.80

So, difference between gears are:
1st-2nd
1.71 for E36, 1.7 for E30

2nd-3rd
0.86 for E36, 0.7 for E30

3rd-4th
0.44 for E36, 0.32 for E30

4th-5th
0.22 for E36, 0.2 for E30

Sorry, but I was right it seems
Such a pity since good E30 iS boxes are tricky to find and e36 iS boxes would be newer and easier to find.

Looks like the S50b32 6 speed is the only way forward


RE: March, Jesus... That makes things abit easier!!!
Fancy giving me grinds in maths, I have a repeat in two weeks time, lol.


I've just realised something after I posted the link up on E30owners too since it's a good thread (Hope ye don't mind )

But anyways, Dicko was remarking how nice the lathe was and then I realised it's the same one we use in college of which I was promised one of 3 by by lecturer at the end of the year since they were closing a few workshops. I later found out that all 3 of them were sent to the scrapyard and were crushed!!!

[Onz]

Nice work kevo,

how long did it take to do the flywheel??

[march109]

RE: March, Jesus... That makes things abit easier!!!
Fancy giving me grinds in maths, I have a repeat in two weeks time, lol.

I finished A-Levels is 2000, I'm just a bit rusty myself so wouldn't fancy my chances. Integration still gives me nightmares , though maths and physics are actually the subjects that you remember the rest of your life.

[kevo]

it took me a good couple of hours to do as it's the first one i've done and cast iron is quite awkward to cut but it wasn't too difficult, i'd certainly recommend it to others with similar facilities to go ahead and do it.

As for the ratios your right, the reason i called called it a close ratio box was because of the fact that it shortened everything down so much compared to the old box due to the fact that it's designed to run alongside a 3.25:1 diff ratio and not a 4.45:1 So a bit incorrect on the terminology front but i would recomend it to anyone with say a 3.64 lsd as it may suit a road car then and also a 3.64lsd is easier to find than a 4.1lsd so could be useful for some?
Kev

whats the address of e30 owners? never seen that site?

[Onz]

Is this the one you were looking for?

http://www.e30owners.com/forums/index.php


Are you going to start selling these flywheels?

[kevo]

not sure if i'll sell them yet, i've got the other one in the garage so i'll be taking that into work for lightening soon, i'll see if theres any interest in that one on an exchange basis.
Kev

[Onz]

Well let me know ;)