CaptainRon

Well then this means we should invest in a one piece drive aluminum shaft then if we want to drive over 100mph?

157dB

Yep. and survive to tell about it.

CaptainRon

How fast are you guys going when your shafts failed on you? Drag racing or speeding down the freeway over 100? Here in Texas they increased their speed limits from 75 to 80mph in some areas. I did 100mph for a few just to past a few uh, "slower" vehicles and my car performed flawlessly. (75-100mph in about 3 seconds) Mines a 2012, is this issue with older stangs only or what?

freyes

I think one, maybe two OEM (steel) driveshafts have failed at high MPH. Failure of the OEM driveshafts failed near the slider, which is located at about the midpoint of the driveshaft. In order for the OEM driveshaft to fail, one must turn off the speed limiter in the ECU. I have not seen the failures of the OEM driveshafts, up close, so I cannot comment on the exact nature of the OEM failures. However, near the failure on the OEM driveshaft is a slider joint with fluted teeth on the transmission side of the driveshaft. These are very pronounced "gear-like" shapes that are formed on the driveshaft. These allow the two parts of the driveshaft to slide back and forth during operation. Since these teeth (for lack of a better word) are changes in cross section, they provide a stress concentration which may have aided in the destruction of the OEM driveshafts.

Several (1 to 2, possibly) aftermarket driveshafts (both manual and auto trans) have failed during sustained dyno runs at very high (7000+) rpms. The failure in one driveshaft that I examined was approx. 1/3 the distance from the front end side of the driveshaft. Failure was attributed to shock loading of the driveshaft. Shock loading of a driveshaft can occur by quickly releasing the accelerator pedal after a high RPM run. One should reduce RPM levels slowly to reduce the effects of shock loading. The vendor of the aluminum driveshafts has redesigned the V6 driveshaft to decrease the tube length (the straight portion of the driveshaft by 5" over the previous design. The straight length tube is attached to the yokes that contain the universal joints. These are now longer to make up for the shortened tube. The tube length controls the critical RPM of a driveshaft. The shorter the tube length, the higher the critical speed of the driveshaft. One still needs to be careful when dynotesting any driveshaft. Make sure your tuner knows about shock loading and tell him to ease off on the gas pedal, rather that pull his foot off of the gas pedal.

That being said, this is a very low number of failures, so I think we need to put things into perspective. It is very unlikely that your driveshaft will fail either at high MPH or RPM. If you are the cautious type, or you plan on turning off the MPH/RPM software limiter, you can opt for an aluminum or carbon fiber driveshaft. Both of these driveshafts have higher than OEM critical speeds. I recently pulled my OEM driveshaft and plan on getting it magnafluxed to see if there are any flaws present. I'm not concerned, but only curious to see if I had any potential problems. I have a Procharged 2011 V6 Mustang that puts out 430 RWHP, so I opted for the aluminum driveshaft from Shaftmasters, as I know first hand that the quality of their revised design driveshafts is excellent.

Remember to check the speed rating of your tires, and make sure they can handle the speed you want to take your Mustang to. Some Mustangs came with low rated tires. You can go on most tire websites and check your tires speed rating.

CaptainRon

I work as a OTR truck driver and just recently I just learned something that may be somewhat helpful to this subject. He kept ruining a U-joint every 7-9 months and just couldn't figure out what was causing the premature failure until just now.
The engine and transfer case/differential must be perfectly parallel with each other and if not it can cause distortion/harmonics that can lead to an early driveshaft death. The only thing that can possibly cause this is if a component such as engine mounts or suspension parts shift or change their position due to stress or wear.
Rebuilding a front end and leaving the rear alone can possible change the angle slightly and cause a harmonic in the drive shaft for example.. And if some of you guys out their are modding their stangs and doing the occasional hole shot then yeah, somethings gonna break eventually.

heres a nice article regarding the subject http://www.4x4wire.com/toyota/tech/driveline/

JayyVee

Shaftmasters has worked out the issues with their v6 shaft, and have released v2.

http://v6mustangperformance.com/news...sues-resolved/

Derf00

Good article with a solution and backed by research into the failure. Case closed.

freyes

I agree, I'm the engineer that helped solve the problem. westcoastsc.