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My 3.9lb Comp Flywheel Crack into half in track day pratice

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My 3.9lb Comp Flywheel Crack into half in track day pratice

Old 04-24-11, 12:25 PM
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My 3.9lb Comp Flywheel Crack into half in track day pratice

I was so suprise when this happend. I thought i blow another 3th gear ( if that happend this will be 4th tranny i broke on 3 car different type of car but all NA)

This happend at my locoal track day pratice event. Last session of the day. First warm out lap. was driving around 70% to warm out my tires and my pace. around 1/2 of lap i shift into 3th about 5-10 sec later. I heard a very loud "Kang Bang" !!!! from transmssion !!!!! i thought
dam not again. not another 3th.... because when thia "Kang bang" happend the trasmssion also jump into Netural....... i roll back into pit use my 2th gear at same time i can heard loud rumble noise from tranny

in the pit try to start car again.. wont start... you can heard the starter making funny noise. and i was able to bump start the car and i am ok to **** all the gear.... so i suspect tranny is fine

After tow it back to shop... decide to take off starter to inspect the problem

this is what i found !!!


a peace of peace of my fly wheel !!!!!!!!!!!!!!!!!!!1 I was so shock...................
this is a last thing i think i will brake on my car but good thing is the clutch still hold in place

wonder if it fall off. how many more damage it will produce

did any one have similar experience on road race track ? i knwo this happend on Drag car all the time
but not expect happend to my car
some spec of my car
13B with TEC2 170whp 125lb shift at 8200RPM

QM 5.5 clutch. stock 81 tranny comp fly wheel ( now broken into half)

4.7 final drive with torsen LSD

using a 195/50/15 R1R
Attached Thumbnails My 3.9lb Comp Flywheel  Crack into half in track day pratice-2011_04_23_sa22c.jpg   My 3.9lb Comp Flywheel  Crack into half in track day pratice-flywheel.jpg   My 3.9lb Comp Flywheel  Crack into half in track day pratice-flywheel02.jpg   My 3.9lb Comp Flywheel  Crack into half in track day pratice-flywheel03.jpg  
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Old 04-29-11, 05:11 PM
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What brand was the flywheel? I wouldn't have thought 8200rpm should break a flywheel.
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Old 04-29-11, 05:20 PM
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Man that's a widowmaker, glad u dodged that bullet.
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Old 04-29-11, 05:41 PM
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I've never heard of a 3.9lb flywheel for the rx7.....I think I've seen 7.5 and 8.5

But, yeah. Light flywheels are fragile. Proceed with care.
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Old 05-01-11, 11:32 AM
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Originally Posted by Prof. Chaos View Post
What brand was the flywheel? I wouldn't have thought 8200rpm should break a flywheel.
Mazda Comp is one of lightest flywheel... is hard to imagine with this flywheel the engine really wake up
So do i. i think this is a reason why The real race parts are not intent for street use.....( i have to drive my car on public street to race track. in Asia is almost impossible to get track and trailer to tow the car... but i still think flywheel will hold up... i should Fried the clutch first before thi.

Man that's a widowmaker, glad u dodged that bullet.
yes. i was very lucky. the force of that fly wheel even cut upper part of starter into half !!!
but i will still go for ultra light weight flywheel!!! but i think i will use mazdatrix version this time

I've never heard of a 3.9lb flywheel for the rx7.....I think I've seen 7.5 and 8.5

But, yeah. Light flywheels are fragile. Proceed with care

the real race flywheel. even the heaver one weight under 5lb......
I just hope my next flywheel wont crack into half


here are some of pic of my remain... i can say now i have F1 car type of clutch

no starter or flywheel.... lets push start it
ha
Attached Thumbnails My 3.9lb Comp Flywheel  Crack into half in track day pratice-sa22c-001.jpg  
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Old 05-03-11, 03:16 AM
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sucks. i take it you don't have a ballistic blanket or scatter shield? maybe this was a sign. either way, i'm glad all this was, was an incovenience (DNQ/DNF) and that you didn't get hurt by any of it.
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Old 05-03-11, 10:34 AM
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Originally Posted by Barban View Post
I've never heard of a 3.9lb flywheel for the rx7.....I think I've seen 7.5 and 8.5
Originally Posted by diyman25 View Post
but i think i will use mazdatrix version this time
...
the real race flywheel. even the heaver one weight under 5lb......
my guess as to what is going on
3.9kg = 8.6lb
5kg = 11lb

mazdatrix alum + counterweight
5.4kg = 12lb
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Old 05-03-11, 02:43 PM
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