lococost
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| posted on 12/5/07 at 09:38 PM |
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DIY disc drilling
What do you guys think?
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blakep82
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| posted on 12/5/07 at 09:41 PM |
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looks nice, but to be honest, i wouldn't, its easy for them to be out of balace, but looks like you made a good jub of it though
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svenkev
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| posted on 12/5/07 at 10:00 PM |
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disk
and what about this?
 
Rescued attachment PICT0690.JPG
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BenB
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| posted on 12/5/07 at 10:20 PM |
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On a 7 you really really really really really really really really really really really don't need drilled or vented discs.... Unless your pads
are JZ that is!!!!
They just create possible fracture points... which having seen what happens when a brake disc explodes isn't something I'd want to try and
create on my car....
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RazMan
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| posted on 12/5/07 at 10:22 PM |
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quote:
Originally posted by svenkev
and what about this?
Ok I have to ask ..... why? Surely the holes are possible fracture points and the half moon cutouts are reducing the swept area of the disc, not to
mention how much the disc is weakened. I just don't see the sense in doing that to a perfectly good disc.
[Edited on 12-5-07 by RazMan]
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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rusty nuts
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| posted on 12/5/07 at 10:26 PM |
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Is it worth the risk???????
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nitram38
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| posted on 12/5/07 at 10:37 PM |
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Only ever needed if you race the car on a circuit.
They may extend the point that you get brake fade and give you an advantage.
If you ever get to take full advantage of them on the road, then watch your licence!
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JoelP
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| posted on 12/5/07 at 10:48 PM |
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there is some small advantage to be gained in unsprung mass, but its slim. Some aesthetic gain too maybe, plus maybe some satisfaction. 
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RichieW
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| posted on 13/5/07 at 02:10 AM |
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Nicely done but really a waste of time I reckon
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mangogrooveworkshop
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| posted on 13/5/07 at 12:17 PM |
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I have only one bit of advice for you......
see yesterdays posting on flywheel lightning,
then make a decision based on that.
Linky thing
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lococost
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| posted on 13/5/07 at 07:29 PM |
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Speedholes, they make the car go faster!
quote:
Originally posted by JoelP
there is some small advantage to be gained in unsprung mass, but its slim. Some aesthetic gain too maybe, plus maybe some satisfaction.
I only did it for reason 2 and 3.
They're supposed to carry out more water and dust, but I'm not sure if it would make such a difference, as for weight loss, the discs
weigh over 3kg, and I took a little more then 100g off, so that really doesnt matter, same goes for sturdyness, I'ld be well surprised if it
made a difference, I looked at some existing models and copied them, so it's not like I'm trying to reinvent the wheel.
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liam.mccaffrey
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| posted on 13/5/07 at 09:14 PM |
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personally i wouldn't use self drilled stuff without MPI'ing them first then i might still not use them.
Especially after the pic of that flywheel going pop
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gaza 47
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| posted on 15/5/07 at 09:18 AM |
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Nice job.
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takumi
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| posted on 17/5/07 at 09:04 AM |
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Excellent job, I think I'll make a jig myself, albeit not quite as many holes.. maybe just 3 per row..
w.ref to balancing, i wouldn't have thought a tiny imbalance at that radius would have any effect.
I've lightened a 2L pinto flywheel on my lathe (disgustingly heavy) to almost 1/2 the weight - removing around 4kg potentially another kilo
could have come off safely.. occassionaly the engine has over reved to a tad over 7000rpms, no vibrations no engine wobbles at all..
RobinHood 2B 2.0i pinto, Keihin 38mm Carbs, lightened flywheel, O'Mori remote filter kit, 10 row oil cooler. Modified head, 10.2cr, special
valves FR22 cam, 4- 1 header.
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flak monkey
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| posted on 17/5/07 at 09:10 AM |
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If you think you can remove 5kg from a cast pinto flywheel (which weighs about 8 or 9kg in the first place), dont come crying to me when it goes bang.
Its not the balance you need to worry about.  Plus if you have just skimmed some off the back of it, it will be miles out of balance, and will need
at least statically balancing.
They'll take the stress a few times, but not for long.
Theres a reason race flywheels are made from steel (and usually something like EN8 or EN16), not cast iron.
Mines lightened, but its only had the large rim removed from the back, I wouldnt have considered using it if it had more than that removed.
As for brake discs, at such a small radius being a gram or 2 out of balance wont be too noticeable. I would worry more about heat propogated cracks,
but as long as you keep an eye on them you'll be ok. Brake discs arent spinning all that fast (roughly 1000 times to cover 1 mile - so at 60mph
1000rpm give or take).
David
[Edited on 17/5/07 by flak monkey]
Sera
http://www.motosera.com
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takumi
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| posted on 19/5/07 at 10:45 AM |
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I removed the same rdige of iron from the reverse face, turned out to be (punn) over 4kg worth of dead metal.
Assuming the flywheel has to stay together under centrifugal force, removing the outer donut of iron makes the flywheel strategically stronger.
So comparing the 1600 pinto flywheel and 2000 flywheel, the 1.6L would be more lightly to disintergrate..?
Removing the outer mass, you increase the center strength to outer mass ratio, which can only be a good thing..
.tak
[Edited on 19-5-07 by takumi]
RobinHood 2B 2.0i pinto, Keihin 38mm Carbs, lightened flywheel, O'Mori remote filter kit, 10 row oil cooler. Modified head, 10.2cr, special
valves FR22 cam, 4- 1 header.
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