hapnermw

About 18 months ago I decided to put in an ACPT carbon fiber driveshaft at the same time I put in a new clutch. I used a high grade aluminum connector to replace the rear guibo and a new high quality rubber guibo for the front.

Last month while I was at Laguna Seca it failed. The break occurred at the front just at the end of the aluminum to carbon fiber coupler.

http://gallery.me.com/hapnermw#10000...&bgcolor=black

Prior to failure, downshifts entering turns became difficult. It was clear something was keeping the clutch from fully disengaging.

When it broke, the out of control end took out the weld connecting the front housing to the torq tube.

There was nothing in the HPDE use of the car that would account for this failure. Either this driveshaft was defective or its design is poor.

I gave ACPT a call to see what they would have to say about the failure. They took a message and never called me back.

If you are thinking about using an ACPT driveshaft, you might want to think twice

http://www.acpt.com/

2000BSME

I would never buy a cf driveshaft. Seen too many failures/units used.

AU N EGL

How long is the life cycle? Dont think they were designed to last more then one season, if that.

John Shiels

DO NOT mix this company up with ACP Advanced Composite Products from PA and owner Kerry Hitt.

froggy47

Good to know if a company is selling sub par parts & it's hard to hide since AG invented the internet.

OKsweetrides

Would love to see pics, but it needs fruit login info. Which end was it that failed? Was the transaxle end, or the clutch end? I'm havin a bit of trouble understanding the orientation.

I've had the DS installed since 2006 (bought from LG which I think may be the same manufacturer) and it's got about 8K miles on it or so. I'm curious to look at the damage.

CF is tricky, any knick or imperfection can lead to the broom of a thousand whiskers.

hapnermw

Sorry about the picture issue ...

It failed at the front of the shaft. At the front there is an aluminum coupler that is inserted into the carbon fiber tube. Where the coupler ends and the carbon fiber is on its own, the shaft failed.

The shaft didn't have any scratches or nicks when it was installed. It likely had been incrementally failing for months because I noticed the track downshifting getting harder at a track day previous to when it failed.

Z06Norway

can you change the settings in me.com gallery so we can see the pic ?

i have a CF, but opted to go for pfadt and so far no problem, it has a hard life behind my 472 Katech engine in GT2 racing

So maybe we can change the discussion to a bad CF product and not all ?

Or is there reports on failure of Pfadt product also ? anyone ?

Rune

0Randy@DRM

We had one explode in a f-body on our dyno. Lucky no one got hurt, it turned into a million pieces.

Randy

mgarfias

Thats the best part about carbon, you get a broom rather than a 4' long metal tube flopping around at 5000rpm

z06801

I have seen the machine that Pfadt engineered to torture there CF drive shafts, and I am very comfortable putting one in my car

RX-Ben

ACPT may be the OEM for all the shafts (LG, Pfadt). Mark Williams gets their shafts from them as well.
Any differences may be in the aluminum ends and the bonding technique.
Stuff breaks at the race track. Including the revised stock aluminum shafts.

BRISLS1

If that is the case, I would do a price check before buying.
As the song goes "One of these things is not like the other".

TS Motorsport

350z's run carbon driveshafts and they run fine for 100k + miles. I agree with everything that was posted though, if there is any damage on the driveshaft, or if it's out of balance the driveshaft is defective & in time it will go bad.

hapnermw

Here is the correct URL for the picture of the failed shaft.

http://gallery.me.com/hapnermw#10000...&bgcolor=black

OKsweetrides

That's intriguing. I was expecting it to fail at the joint region; not mid shaft.

hapnermw

It is the joint, what you don't see is that the aluminum coupler extends that far into the shaft (about 6").

John Shiels

Is it me or does that thing look fairly crude? Not what I am use to seeing.

hapnermw

The coupler got beat up when it failed. I wasn't around when the torq tube was removed so I didn't see the initial state. I saw it later when this broken piece was hanging from partially loose bolts.

I had expected the end to have been solidly attached to the front rubber guibo but instead the bolts had broken loose and the coupler had thrashed around in the tube breaking the weld. I don't remember seeing the guibo. Possibly it was ripped off during the failure.

At the time I asked the mechanic if it was possible that the coupler had come loose causing the shaft to break instead of vice versa.

He felt the carnage was all the result of the tube breaking.

The failure was just a mild pop as I was braking for a corner.

froggy47

The link still not working (for me anyway) they call you back yet? I would call again.