Driveshaft question
 

Has any one replaced the driveshaft because of a lot of power gain, and is it necessary to do so? I know the the driveshaft for a v6 is known to fail in high speeds (110+). i was wondering because i might buy gears and lsd.

I know a lot of guys have switched to aluminum driveshafts for the sake of strength at high speeds, shaving off weight, and lessening vibration. I've heard people shaving .2 seconds off their time after making the switch and haven't heard of anyone that got a good aluminum driveshaft that later regretted it

The driveshafts were more of a problem with earlier models; I think newer ones (2007+) have slightly different driveshaft designs that make them stronger.

And 2/10s off track speed, not likely. They do help make the driveline smoother, and if you have any vibration, will probably get rid of it. My stock driveshaft had a vibe at around 74 mph, but it was replaced under warranty.
The alum shaft I'm running now, it did make for smoother power, and sure some weight savings. But 2/10 in the quarter mile, I dont think so.

I was just wondering if I should replace the driveshaft(2006) when I get gears and LSD, I've heard of people who have

The earlier model S197's had u-joint caps that were pressed-fit into place, but some time in 2006 Ford changed the design to include retaining clips. Not many of the earlier DS's have let go, but they are a concern if you plan to mod your car, especially if you install shorter gearing. Shorter gears will reduce the safe top speed of 113mph to as low as 90mph, depending on gearing. If your DS does not have the retaining clips, then a good aftermarket aluminum DS may be a wise expenditure. I got one for our 2005 vert from PowerHouse - no regrets.

very happy with my driveshaft. smoother ride (especially on highways) and improved acceleration from a stop. these improvements are subtle individually but together it is a solid upgrade on performance. worth it if you got the extra cash.

Im probably going to stop performance mods after 4.10 gears and diffrential. I have just enough money atm to spend on both. I just want to make sure i dont need a better DS for the mods.

An aluminum DS won't ADD HP. It WILL free-up some HP (in other words, it will REDUCE some of the HP you lose in the driveline; in this case from rotational mass). You're probably looking at freeing up only single digit RWHP, roughly 5. But it all adds up.

You'll definitely feel the difference of the 4.10s. You might feel a slight difference with a driveshaft.

Once you have gears in, you'll spin that driveshaft faster. It's a good upgrade, but IMO is not essential when you have a very limited budget and wish to spend money on other items. And you can always replace it later.

If you are getting the gears done, that is an excellent time to go ahead and upgrade the driveshaft, too.

So would recommend buying a DS with the gears and diff?