ACPT Carbon Fiber Driveshaft, Thread #2 - Page 8

Blaiser · 10-24-2006, 11:27 AM

Rootus owes me LUNCH...YES!

krees23 · 10-25-2006, 04:04 PM

For what it's worth... after the new DS I'm always wanting to shift into 6th - I'm already in 6th, its just that the pull seems like I'm in 5th... weird, but I'll guess I'll have to get used to it...

DimitriosSTI · 10-31-2006, 08:16 AM

i just got my d/s installed. there is a difference in performance but i think it is not so much as some have noticed. Perhaps you guys (USDM sti) have a heavier stock d/s. Maybe you should start buying and modifying some stock EDM sti driveshafts! I can give you the part number for the companion flange that you need. I will weigh my d/s to see how heavy it is. the acpt feels lighter but not by much.

No vibration at all up to 120mph. it's a good mod but i am not sure it is worth the $$$ on the EDM sti. but this is just an unjustified opinion until i weigh my stock d/s.

RainMaker · 10-31-2006, 09:37 AM

Quote:

Originally Posted by nhsilversti

look at the 2 plots closely, unfortunatly on saturday the started the pull at 2k. the motor got a little loaded up BEFORE 2700rpms where the OLD plot started. i think if they had started at 2500-2700 the numbers would have been up earlier.

Having dyno'd loads and loads of STI's I can asure you that it doesnt work like that. Start at 2k or earlier WOT for the best spool. Any later and the spool starts to suffer.

Clearly alot changed between the two dynos, and you are submitting that the only difference was the driveshaft (not the weather, barometer, etc).

Wow.. so then the new DS lost you some spool... and gained you nearly 40lbft of torque in some places.

Thats amazing.........

**nhsilversti** · 10-31-2006, 10:25 AM

Quote:

Originally Posted by RainMaker

Having dyno'd loads and loads of STI's I can asure you that it doesnt work like that. Start at 2k or earlier WOT for the best spool. Any later and the spool starts to suffer.

Clearly alot changed between the two dynos, and you are submitting that the only difference was the driveshaft (not the weather, barometer, etc).

Wow.. so then the new DS lost you some spool... and gained you nearly 40lbft of torque in some places.

Thats amazing.........

you should get ahold of franz diebold automotive and confirm for yourself that it is the same WOT tune. as i had stated, there were drivability changes made at low/part throttle, nothing drastic or that would affect the WOT part.
yes there was a few months between the 2 graphs but, here in new england may and october are about the same for weather.

ted

ps. you start pulls at 2k or lower for bigger turbos? interesting imo

**stituner420** · 10-31-2006, 08:45 PM

Does anyone know if this DS will fit on the new limited 07's?

STInk · 11-05-2006, 12:08 AM

"The change in mass of the driveshaft is so close to the axis about which it spins... is so trivial that physics just doesnt seem to back up the claims."

Don't be so sure. For one the stock DS has a 2 degree bend in the center, more under load; how do you account for this with the "radius" argument? How much power is lost just going thru this joint? And don't forget this loss is before another gear box and two more CV joints; are losses fixed amounts or are they multiples? The CF shaft is half the weight, roughly 12 lbs, and trust me - you feel it. You feel all 200lbs!

I've written about the benefits before, so let me just say - when I get a new car I will pay ACPT to build me a carbon DS, no matter what it costs.

TheLimitedProject · 11-05-2006, 12:46 AM

Quote:

Originally Posted by stituner420

Does anyone know if this DS will fit on the new limited 07's?

We're about to find out

It better.

BlueWRXSTi2005 · 11-08-2006, 05:14 AM

I'm still waiting for mine and I ordered it forever ago.

I wonder what's taking so long?

crand002 · 11-08-2006, 01:21 PM

^Same here

***Nivek*** · 11-10-2006, 05:04 PM

Who did you order it from?

AnorexicSTI · 11-11-2006, 03:31 AM

Regarding my vibration problem between 165-175 km/h
-----------------------------------------------------
Ok I finally got down there. I took off the DS protection plate, so it could not rub that, but guess what? It was rubbing on the thing ABOVE it... there is a tiny ring there... but it's not even deep at all... like maybe 0.25mm... very very minor scuff... that is why the vibration has been getting less and less... in fact, it is pretty much non-existent now... I guess the resonance at that speed (about 170 km/h = 105 mph) causes the shaft to "bow" and slightly hit the mounting area for the diff.

I doubt it's out of balance... my understanding is that if it's out of balance, the vibration gets worse with speed.

Problem is, I don't think there is anything I can do about something like this short of GRINDING that area and painting it... which is what I will probably do.

DimitriosSTI · 12-02-2006, 02:24 AM

i weighted my stock EDM sti d/s. it is 20.9 lbs which is about 5 lbs less than the stock USMD d/s so maybe you guys should consider buying and modifying EDM d/s for some weight savings.

my acpt is still 7.5 lbs lighter but you guys need the acpt much more than people with EDM or JDM driveshafts.

JJ18Sniper · 12-02-2006, 08:06 AM

Quote:

Originally Posted by DimitriosSTI

i weighted my stock EDM sti d/s. it is 20.9 lbs which is about 5 lbs less than the stock USMD d/s so maybe you guys should consider buying and modifying EDM d/s for some weight savings.

my acpt is still 7.5 lbs lighter but you guys need the acpt much more than people with EDM or JDM driveshafts.

Interesting how your driveshaft is lighter then ours to begin with. It bolted on completely without modification for you?

DimitriosSTI · 12-02-2006, 09:48 AM

no it requires some redrilling of the rear diff companion flange. the usdm sti has a different bolt pattern on the d/s

10-24-2006, 11:27 AM	#106
Blaiser Spec C Club Car: 06 white w/gold STi Fav Mod: gt40r Location: Orange, CA Posts: 1,223 IWSTI Addict since: Apr 2005 Trader Rating: (6)	Rootus owes me LUNCH...YES! This ad is not endorsed by this member. Please register or login to hide this ad.

12-02-2006, 09:48 AM	#120
DimitriosSTI Amateur STI Driver Posts: 13 IWSTI Addict since: Sep 2006 Trader Rating: (0)	no it requires some redrilling of the rear diff companion flange. the usdm sti has a different bolt pattern on the d/s This ad is not endorsed by this member. Please register or login to hide this ad.

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10-25-2006, 04:04 PM	#107
krees23 Senior STI Driver Car: 2005 Subaru STi Fav Mod: Cobb Swaybars and Kartboy Endlinks Location: Minnesota Posts: 351 IWSTI Addict since: Oct 2005 Trader Rating: (1)	For what it's worth... after the new DS I'm always wanting to shift into 6th - I'm already in 6th, its just that the pull seems like I'm in 5th... weird, but I'll guess I'll have to get used to it...

10-31-2006, 08:16 AM	#108
DimitriosSTI Amateur STI Driver Posts: 13 IWSTI Addict since: Sep 2006 Trader Rating: (0)	i just got my d/s installed. there is a difference in performance but i think it is not so much as some have noticed. Perhaps you guys (USDM sti) have a heavier stock d/s. Maybe you should start buying and modifying some stock EDM sti driveshafts! I can give you the part number for the companion flange that you need. I will weigh my d/s to see how heavy it is. the acpt feels lighter but not by much. No vibration at all up to 120mph. it's a good mod but i am not sure it is worth the $$$ on the EDM sti. but this is just an unjustified opinion until i weigh my stock d/s.

10-31-2006, 08:45 PM	#111
stituner420 Gold Member Car: 04 WRB STi Fav Mod: ACPT CF DS + Cobb Stg 2 Location: Central TX Posts: 1,048 IWSTI Addict since: Apr 2004 Trader Rating: (3)	Does anyone know if this DS will fit on the new limited 07's?

11-05-2006, 12:08 AM	#112
STInk STI Driver Posts: 227 IWSTI Addict since: Apr 2004 Trader Rating: (1)	"The change in mass of the driveshaft is so close to the axis about which it spins... is so trivial that physics just doesnt seem to back up the claims." Don't be so sure. For one the stock DS has a 2 degree bend in the center, more under load; how do you account for this with the "radius" argument? How much power is lost just going thru this joint? And don't forget this loss is before another gear box and two more CV joints; are losses fixed amounts or are they multiples? The CF shaft is half the weight, roughly 12 lbs, and trust me - you feel it. You feel all 200lbs! I've written about the benefits before, so let me just say - when I get a new car I will pay ACPT to build me a carbon DS, no matter what it costs.

11-08-2006, 05:14 AM	#114
BlueWRXSTi2005 Amateur STI Driver Car: 05 Subaru WRX STi Fav Mod: Cobb AP Stage 2 Location: Holland, PA Posts: 45 IWSTI Addict since: Sep 2006 Trader Rating: (1)	I'm still waiting for mine and I ordered it forever ago. I wonder what's taking so long?

11-08-2006, 01:21 PM	#115
crand002 The Next Petter Solberg Car: 06 WRX STI Fav Mod: Front license plate delete Location: San Diego Posts: 914 IWSTI Addict since: Aug 2006 Trader Rating: (2)	^Same here

11-10-2006, 05:04 PM	#116
*Nivek* www.Subie.tv is niiice Posts: 10,067 IWSTI Addict since: Aug 2003 Trader Rating: (10)	Who did you order it from?

11-11-2006, 03:31 AM	#117
AnorexicSTI Spec C Club Car: 05 WRX STI - Spec A Fav Mod: Starving my STI Location: Lightweightville, Canada Posts: 1,734 IWSTI Addict since: Sep 2006 Trader Rating: (15)	Regarding my vibration problem between 165-175 km/h ----------------------------------------------------- Ok I finally got down there. I took off the DS protection plate, so it could not rub that, but guess what? It was rubbing on the thing ABOVE it... there is a tiny ring there... but it's not even deep at all... like maybe 0.25mm... very very minor scuff... that is why the vibration has been getting less and less... in fact, it is pretty much non-existent now... I guess the resonance at that speed (about 170 km/h = 105 mph) causes the shaft to "bow" and slightly hit the mounting area for the diff. I doubt it's out of balance... my understanding is that if it's out of balance, the vibration gets worse with speed. Problem is, I don't think there is anything I can do about something like this short of GRINDING that area and painting it... which is what I will probably do.

12-02-2006, 02:24 AM	#118
DimitriosSTI Amateur STI Driver Posts: 13 IWSTI Addict since: Sep 2006 Trader Rating: (0)	i weighted my stock EDM sti d/s. it is 20.9 lbs which is about 5 lbs less than the stock USMD d/s so maybe you guys should consider buying and modifying EDM d/s for some weight savings. my acpt is still 7.5 lbs lighter but you guys need the acpt much more than people with EDM or JDM driveshafts.