[krees23]

Originally Posted by DimitriosSTI

I wonder why everyone stopped posting their impression on their cf driveshafts? I want to find out if the balancing/vibration issues have been resolved as my driveshaft will arrive soon.

I just put it in this morning and took it out for a test drive. Everything fit perfectly, no clearance problems with the floorboard or driveshaft shield. It took 30 minutes to put in.

Initial impressions - No vibration problems experience up to 100 MPH (um, closed track, of course ). That diff clunk is gone, the shifting is alot smoother - even from 4th to 5th. Upshifts and downshifts are smoother overall. The acceleration increase is noticable, but not dramatic until you put your foot down in 5th gear, then its like - wow.

[blindfold]

i'm still on the fence since it is quite a chunck of money, do you guys get the same feeling as if you got a crank pulley or is it more noticeable, i've read through numerous responses but if anyone is around Atlanta,GA area, i would love to take a ride and buy you lunch to discuss further about the ACPT unit

[Nivek]

I would like to know where you got your comparison from because I feel that this modification is nothing like a crank pulley. The only thing they have in common are the fact that they are lighter than stock and they both are a part of the drivetrain. However, they function quite differently in delivering the car's power to the wheels. Rather than getting into some nitty gritty details, here is what some others have said when analogizing the additional performance gains from installing the driveshaft to gains experienced with other modifications.

They rate this modification up there much closer to that of a turboback exhaust.

Some say it is like going Cobb Stage 1 again while others attest that if it is done in conjunction with the Brake Man rotors, it is more like doing another Cobb Stage 2.

[AnorexicSTI]

Hi. I've read this entire thread and did a search for "ACPT install" and couldn't find specific instructions on the install. I just got mine today, but would like to read somebody's install thread before I begin. I've done uppipe, TBE, ported the wastegate on the turbo, pulleys, shifter bushings, etc. so this should be a piece of cake compared to those... but I wouldn't mind knowing the torque specs for the various bolts (I don't have the STi manual - anybody want to email me a PDF version? ) and any other issues. I plan on removing the protection plate to save weight since I don't rally and I don't want the rubbing issue. I have a Group N tranny mount, but all other bushings are stock.

If somebody could kindly send me a link for the install, that would be awesome. Thank you!

[Doctor Subie]

Originally Posted by STIGUY88

Hi. I've read this entire thread and did a search for "ACPT install" and couldn't find specific instructions on the install. I just got mine today, but would like to read somebody's install thread before I begin. I've done uppipe, TBE, ported the wastegate on the turbo, pulleys, shifter bushings, etc. so this should be a piece of cake compared to those... but I wouldn't mind knowing the torque specs for the various bolts (I don't have the STi manual - anybody want to email me a PDF version? ) and any other issues. I plan on removing the protection plate to save weight since I don't rally and I don't want the rubbing issue. I have a Group N tranny mount, but all other bushings are stock.

If somebody could kindly send me a link for the install, that would be awesome. Thank you!

Just installed it tonight, followed some of the basic directions from the 1st thread on this topic. Basically, you are going to do this, once you get your car up fully on jackstands:

1) Remove midpipe. Some say you don't have to, but why make it harder on yourself? For my midpipe (APS), it blocked 1 bolt on the protection plate, so I just got it out of the way
2) Remove protection plate, put aside
3) I started to loosen as many bolts holding the stock driveshaft together--a set of 4 at the midway point, and the set of 4 attaching it directly to the rear drive axle
4) Go and place the car in neutral, if it isn't already
5) Go back under car and find that the driveshaft can now rotate readily, allowing you to get access to the rest of the bolts holding it together. Rotate it so you have access to said bolts, then place it back in gear to hold it so you can loosen bolts.
6) Place a rag or piece of cardboard beneath the driveshaft point closest to the engine. When you pull it out, a slight bit of drivetrain oil will dribble out (don't worry, you lose only a small amount). I then removed all the nuts and washers attached to the bolts, and pulled the bolts out. You will find the driveshaft simply drops down, and you can pull it out.
7) I reused the set of bolts/nuts from the rear-attachment point, when attaching the ACPT shaft. The 'hard part' about attaching the ACPT shaft is getting the splines lined up with the drivetrain splines, to allow it to slide in. Not a big deal if you have another set of hands to help support the driveshaft.
8) I don't know torque specs, but I just tightened to fairly tight with 2 sets of wrenches (the position of the bolts won't allow a socket head).
9) I'm paranoid, so I reused the protection plate. I gave it more clearance by using a set of 2 washers per bolt put between the plate and the attachment points, and have not had any rubbing issues.

Good luck, all in all, install took ~1.5 hours or so, and that includes the time it took me to get it up on jackstands, etc...

[AnorexicSTI]

Thanks for the awesome write up Doctor Soobie... I'm all alone tonight so any tips of getting it in the tranny withOUT another set of hands?

(Ignore above) it's easy... it's only 14 lbs and was easily glided in with 1 set of hands...

BUT... I got a problem! it's rubbing in the tunnel probably because of the Group N tranny mount I got... this is such a PITA... why don't they just make that Group N mount HARDER and not also taller so it raises the tranny...

I tried grinding away a bit of the tunnel (it has 2 "layers" of metal or sound deadener type material there)... but it still rubs... so I will probably need to put the stock tranny mount back in.

[AnorexicSTI]

Originally Posted by Doctor Subie

1) Remove midpipe. Some say you don't have to, but why make it harder on yourself? For my midpipe (APS), it blocked 1 bolt on the protection plate, so I just got it out of the way
3) I started to loosen as many bolts holding the stock driveshaft together--a set of 4 at the midway point, and the set of 4 attaching it directly to the rear drive axle
4) Go and place the car in neutral, if it isn't already
5) Go back under car and find that the driveshaft can now rotate readily, allowing you to get access to the rest of the bolts holding it together. Rotate it so you have access to said bolts, then place it back in gear to hold it so you can loosen bolts.

7) I reused the set of bolts/nuts from the rear-attachment point, when attaching the ACPT shaft. The 'hard part' about attaching the ACPT shaft is getting the splines lined up with the drivetrain splines, to allow it to slide in. Not a big deal if you have another set of hands to help support the driveshaft.
8) I don't know torque specs, but I just tightened to fairly tight with 2 sets of wrenches (the position of the bolts won't allow a socket head).

1. I simply disconnected the 4 hangers and then "rested" the catback exhaust on a 3" high UPS box. This saves quite a bit of time over removing the midpipe and also reduces the risk of having an exhaust leak if the gasket has a hard time sealing. Whenever you can avoid having to take apart an exhaust piece and not have to replace or clean a gasket, I think it is worth it to do the alternate method.

3. You don't need to loose the 4 bolts in the center of the stock driveshaft. Simply remove the 2 14mm bolts for the "bracket" that keeps the center portion up. The 2 pieces can be removed as a "unit"

4+5. Putting it back in gear does nothing... it will still turn... at least in 1st gear.. what I did was leave it in neutral and use the e-brake. The hardest part of the install was having to go back and forth to release and apply the e-brake. You can also stick something under one of the tires to "jam" it from moving...

7. This is actually really easy.

8. The bolts have a squared off corner so they press up against an edge on the ACPT driveshaft to prevent it from moving. This allows u to just use a 12mm wrench on the nut to loosen and tighten. However, on 2 of them (diagonally opposite) the "gap" between the bolt and "flat edge" on the ACPT driveshaft was about 2mm... I had to jam a flathead screwdriver in there to prevent the bolt from turning. Did anybody else have this issue?

[AnorexicSTI]

Ok I changed out the Group N mount back to stock... and the rubbing is gone. I checked out the "ring" and it's not even a ring... just VERY light surface scratches... the CF seems pretty tough! The metal on the floorboard was ground down a bit, but the CF didn't wear down at all!

I get a slight vibration at around 105 mph to 110 mph, but it seems to be only on acceleration... and not under slowdown passing thru that range. It's just a minor vibration through the seat... I've got aftermarket seats bolted right to the floor pan without sliders so more vibration ("feel") comes through the seat... I bet if I had the stock seats, it would barely be noticeable. Good thing the vibration is so high... and not at 60 mph like some people reported... I'm not usually going fast enough to feel the 105 mph vibration.

Now, that being said, is there a company that sells just a HARDENED tranny mount WHILE PRESERVING geometry of the mounting? Why the hell does the group N mount raise the tranny? What purpose does that serve? If anything, it raises the COG of the car!

[Nivek]

I would bet a lot of money rhat you have the wrong mount. Who sold it to you? Get the box and check the part numbers. The group n mount is identical in shape and size to the stock one. The only difference is the material.

The wrx one is taller by 6 to 8 millimeters. If yours is taller, then you have the wrx one. Take it out immediately. I know one sti owner who broke his cf shaft because a vendor shipped the wrong mount and there was extreme contact. The vendor acknowledged.fault and acceptedresponsibility.

What is the part number? Maybe I can help?

[AnorexicSTI]

Originally Posted by Nivek

I would bet a lot of money rhat you have the wrong mount. Who sold it to you? Get the box and check the part numbers. The group n mount is identical in shape and size to the stock one. The only difference is the material.

The wrx one is taller by 6 to 8 millimeters. If yours is taller, then you have the wrx one. Take it out immediately. I know one sti owner who broke his cf shaft because a vendor shipped the wrong mount and there was extreme contact. The vendor acknowledged.fault and acceptedresponsibility.

What is the part number? Maybe I can help?

F$CK... Modern Garage/Cobb Tuning sold it to me... I asked them about it and they said it should be the same height but the guy I was talking to didn't know for sure... I'm gonna give them a tongue lashing on monday. Thanks for the heads up.

I don't have the part number, but from what u describe, I have the WRX one (about 6 mm taller after it was "squished")

[nhsilversti]

Originally Posted by DimitriosSTI

I wonder why everyone stopped posting their impression on their cf driveshafts? I want to find out if the balancing/vibration issues have been resolved as my driveshaft will arrive soon.

other than the problem my car has with the shaft in, i dont know about any others. i think my car is allergic to this thing, lol

RELAX AND ENJOY IT WHEN IT IS INSTALLED

ted

[AnorexicSTI]

I just got mine in a group buy. It shipped 10/2 and I received it 10/5. Do all the recent ones have the longer yolk? How can I tell for sure?

Furthermore, does anybody have a vibration "accelerating" through 110 mph? Cruising at that speed or reducing speed through that range, I am ok... but if I get on the gas I hear a vibration. Maybe it is the shaft hitting the brake cables or "grazing" the tunnel... hopefully installing some stiffer bushings will help?

[krees23]

Originally Posted by STIGUY88

I just got mine in a group buy. It shipped 10/2 and I received it 10/5. Do all the recent ones have the longer yolk? How can I tell for sure?

Furthermore, does anybody have a vibration "accelerating" through 110 mph? Cruising at that speed or reducing speed through that range, I am ok... but if I get on the gas I hear a vibration. Maybe it is the shaft hitting the brake cables or "grazing" the tunnel... hopefully installing some stiffer bushings will help?

I guess I'm lucky, I don't have any vibrations up to 100 MPH up to hard acceleration. I'd go higher, but location/conditions aren't right for it.

[DimitriosSTI]

did you guys notice any improvement performance wise?where is it most noticeable?low end?

[La Mer]

Originally Posted by DimitriosSTI

did you guys notice any improvement performance wise?where is it most noticeable?low end?

did you read this thread at all?!?!