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Care to explain?


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Evo 9 mr they gave a alum roof. Super high up weight reduction. Coming from a moto x back ground this is hybrid weight/ a tiny bit unsprung. Super low in the chassis which doesn't carry as much effect as if he shaved that 17lbs off the roof. Placebo effect. Your brain rationalizing $1500 down the pooper.


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Evo 9 mr they gave a alum roof. Super high up weight reduction. Coming from a moto x back ground this is hybrid weight/ a tiny bit unsprung. Super low in the chassis which doesn't carry as much effect as if he shaved that 17lbs off the roof. Placebo effect. Your brain rationalizing $1500 down the pooper.


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So what does reducing rotational mass mean to you?


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Evo 9 mr they gave a alum roof. Super high up weight reduction. Coming from a moto x back ground this is hybrid weight/ a tiny bit unsprung. Super low in the chassis which doesn't carry as much effect as if he shaved that 17lbs off the roof. Placebo effect. Your brain rationalizing $1500 down the pooper.


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- Oh god this must be a troll, this is one of the worst comments I have ever read! Blasphemy!!!

- I know... This is an old post...

- The reason they put aluminum in the roof is to lighten up topside for handling. You want to keep all your weight as low as possible. Other wise you will feel the car roll. It is also nice to just lose unsprung weight.


- What the driveshaft does is lighten the load on the engine freeing up power already made. The engine will now, with this driveshaft, have to spin 17lbs less which will in turn be transferred to the wheels/ ground where it's supposed to be.

- Another posted it does not show up on a dyno, is there any proof? EvoM has proof that replacing with lighter rotors freed up 12whp and 7wtq on their dyno.
 

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The name of the game here is reducing moment of inertia which varies with the square of the radius to the point of mass. A drive shaft is relatively thin, meaning it has a very small radius and thus, has a relatively small moment of inertia already. Compare savings by lightening a flywheel which has a fairly large radius. Compare moment of inertia between large diameter rims & super low profile tires vs small diameter rims & tires thick sidewalls. Finally, compare $$$ spent paying credit card bills vs. $$$ gaining interest in the bank.
 

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The name of the game here is reducing moment of inertia which varies with the square of the radius to the point of mass. A drive shaft is relatively thin, meaning it has a very small radius and thus, has a relatively small moment of inertia already. Compare savings by lightening a flywheel which has a fairly large radius. Compare moment of inertia between large diameter rims & super low profile tires vs small diameter rims & tires thick sidewalls. Finally, compare $$$ spent paying credit card bills vs. $$$ gaining interest in the bank.

Point being? I get the whole point of it. So are you justifying this with interest in the bank for your cheap 4 door mitsu family cars not loosing as many revs between shifts.
I don't get the logic on this piece at all. I might as well get arp hardware for my drive shaft as well then...


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...Meaning the moment of inertia of a drive shaft is already low, so there isn't a whole lot left on the table in terms of gain per $$$. Perhaps consider spending your sheckels on the cutest, shiniest, *lightest* rims you can get your hands on and make out in multiple ways.
 

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...Meaning the moment of inertia of a drive shaft is already low, so there isn't a whole lot left on the table in terms of gain. Perhaps consider spending your sheckels on the cutest, shiniest, *lightest* rims you can get your hands on and make out in multiple ways.

So you're then agreeing with me. Perfect.


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not really. you're advocating aluminum roofs. that has nothing to do with moment of inertia wrt car's engine and drive train. it has its place, but not in this discussion.

Yes it does. The carbon fibre drive shafts serve two purposes. Mainly weight for extreme track cars who want to shed a few pounds and yes to bring the moment of inertia at the outer edges of the driveshaft down if you need me to draw you a vector diagram I can. Bottom line you achieve this with less weight. Also contributing to a lighter car as with a aluminum roof which is your highest point. Which the drive shFt is not. It's considered hybrid weight. Take a physics course or two.


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so now you're advocating the lightened drive shaft? and sorry, i didn't know your doctoral dissertation was "on the benefits of aluminum roofs in moto x and evo applications". i'll defer to your wisdom and call it a night.
 

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This thread from NASIOC showed increase in horsepower and torque with going to a lighter driveshaft as well as 200-250 rpm increase in spool. More dyno proof. An increase of 9.3whp/10.3wtq.

http://forums.nasioc.com/forums/showthread.php?t=2015402

- I'd say 2 out of 3 test results result with a conclusion that a driveshaft helps and is beneficial. Money vs benefit is a topic for another day.
 

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Discussion Starter · #56 ·
There's always going to be haters out there.....
I guess I'll update the thread. I ran the driveshaft for a good 3k miles and in that time I probably launched the car at the strip 20 times @ 580whp. The first issue I had was that the rear diff got damaged from the repeated abuse, it didn't break but it def started sounding like the gears were damaged. The following week the drive shaft broke on me on the front section at the track during a launch.
DDS replaced the shaft free of charge and they did so without to much fuss. The new shaft they sent me has a slightly thicker section (were it broke) and a different weave pattern. This shaft I've had for 3-4k miles @ 630whp and is still runing strong although I haven't had a chance to go to the track with the new power.

So I had the OEM shaft back on the car for 2 weeks and I immediately noticed the difference.
At the end of the day this is not a mod everyone is going to do and from the few that do get a lightweight DS even fewer are going to spend the $$ on a carbon one. The same way 99% of Evo owners won't get a exhaust like mine....is ok, no placebo effect here.
For the people that always go in to these threads to hate, remember, if nobody gets and try's these parts then you'll never now if a new or different item works or not, progress would stop if nobody tried anything new.
 

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Did the actual shaft break? I had mine break at the front yoke, which was 2 piece pre-installed by DSS (300 torque). DSS was pretty easy to work with on replacing mine under warranty but the new shaft I received has a 1 piece front yoke. Just curios on how yours broke and which front yoke type you have. I mostly AutoX my X but do use LC frequently. I agree, car feels better with CF driveshaft but it's not a mod for everyone.
 

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I bought the carbon one. I don't need to justify my purchases to anyone. Have I made excessive purchases that I will not utilize fully? Yes, but every little bit helps in making power.

I had been told in advance that the front yoke was off by 1/1000 in size from OEM and caused the leakage in the rear. I did ask DSS about it prior to ordering and they stated that the issue had been corrected. Mine should be arriving next week (according to tracking) and I will measure them prior to installation.
 

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I bought the carbon one. I don't need to justify my purchases to anyone. Have I made excessive purchases that I will not utilize fully? Yes, but every little bit helps in making power.

I had been told in advance that the front yoke was off by 1/1000 in size from OEM and caused the leakage in the rear. I did ask DSS about it prior to ordering and they stated that the issue had been corrected. Mine should be arriving next week (according to tracking) and I will measure them prior to installation.
There is no reason to justify the buy, there is proof showing it frees up power on a dyno. Also transient response of the engine or whatever it's called.
 

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I bought the carbon one. I don't need to justify my purchases to anyone. Have I made excessive purchases that I will not utilize fully? Yes, but every little bit helps in making power.

I had been told in advance that the front yoke was off by 1/1000 in size from OEM and caused the leakage in the rear. I did ask DSS about it prior to ordering and they stated that the issue had been corrected. Mine should be arriving next week (according to tracking) and I will measure them prior to installation.
Since I'm the one who mentioned to Madmartigan about the yoke - one minor clarification - the new "correct yoke" was about 1/1000 different from stock. the new yoke does not leak. I don't know how off the old yoke was because I didn't measure that one, I just sent the entire DS back and got one which had a different yoke. I can tell because the original DS had a black yoke and the new one had a silver yoke (similar to OEM) the silver one was only 1/1000 different from the stock and has not given me any issues.
 
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