FMS Aluminum driveshaft=GOOD

[DMAN302]

After having my rear changed out to 3.73's a bit ago I found there to be some serious vibration out of the rear end, along with noise and serious vibration in the shifter. All the bad stuff began at about 35-40MPH so I was worrried it might be a problem from the gear install, but since the FMS driveshaft was still 150$ I figured I might give it a try. The result is NO vibes at speed and a almost vibless shifter!!! I you have some drivetrain problems after gear install then I HIGHLY recomend you spend the cash...car is smooooth as glass.

 

[88stangmangt]

if you take the shaft off it must be balanced again or it will vibrate...........but if you get a new one you will be fine like your case....................

 

[dastang2]

how would just replacing a driveshaft with made out of a different metal make it stop vibrating and why would you need to rebalance after taking a used aluminum shaft off. i am not saying againts anybodies posts, i just wanna know these things. would an aluminum flywheel also cut down on the vibes

 

[maverick0716]

The rumour about the green dots that you have to line up is total BS. The pinion isn't balanced so there is no reason for the driveshaft to be mounted in a certain way. Just stick it on, torque it to 80 ft/lbs. and you're good to go. If it vibrates, it needs to be balanced, that simple.

 

[DMAN302]

Not positive about the reason why but I know it has to do with the reduction in weight of the alum shaft vs the factory...this in terms of rotating mass is very helpfull in reducing the transfering of the vibes...most likely the vibes have always been there but are enhanced by the driveshaft turning faster because of the 3.73. Physics are beyond me but I assure you the car has a very different feel at speed, gone is the mack truck feeling and sound.

 

[maverick0716]

Your stock driveshaft was probably imbalanced a little bit. With your stock gears you won't notice much but with 3.73's you would for sure because the driveshaft spins way faster (you're right). The main things I like about the FMS aluminum driveshaft are the heavy duty U-joints and the lightness of it.

 

[HISSIN50]

the stock DS is dynamically balanced at the factory (balanced with the whole rotating assembly). people whom remove them w/o marking the relative position can experience vibs.

has nothing to do with Dman - you all hit it right on the head. the DS with gears spins faster than before, and imbalance (and heavier rotating assembly) show vibs.

:OT: how did your DS look? i was surprised to see some decent sized weights on the alum one. i figured they could get it closer to balanced, w/o so much counterweight....

 

[Daggar]

Driveshaft Vibe

Another thing to consider is the possibility of a bad U-joint. I had a very similar thing happen to me. Took the driveshaft out to replace the clutch and pressure plate and reinstalled the same driveshaft. It didn't take long to begine to feel a vibration. After about a week, it bothered me enough to take the thing apart again to see what it was that I'd screwed up on the install. I got as far as removing the driveshaft when I noticed that the knuckle on the end of the drivshaft didn't flop around freely and it struck me as odd. In this case it moved feely in one direction but needed to be manually positioned along the other axis. Once I removed the U-joint the problem was evident. One of the sealed bearing caps was completely dry. After the installation of the new U-Joint all was well but until the removal and reinstallation of the driveshaft there were no symptoms that anything was amiss. Knowing that rebalancing of a driveshaft for removal and reinstallation is not necessary it made a lot of sense.

Just another consideration.

 

[The Shape]

The DS even made a difference in my stock GT. I still have the stock gears, but went ahead and bought the DS before the price jumped. I didn't realize how many vibrations I had until I put it in. The car is alot smoother with it. I assume my factory shaft had gotten out of balance over the years or something.

 

[drgn5.0]

if you take the shaft off it must be balanced again or it will vibrate...........but if you get a new one you will be fine like your case....................

I'm sorry, but this is complete bull. obviously you have never taken one off for a clutch or tranny replacement.

 

[DirtyD916]

glad you like it. but how does the fms ds stack up to the frpp ds?

 

[WrongWay]

It's the same driveshaft

 

[blackstangt]

what no way....

 

[5ive.oh]

I hate you all.

 

[bmo37]

ford actually switched vendors for making there driveshafts so there are older ones and newer ones (which are made by different companies hence the price increase from $159 to $259) as far as the aluminum driveshaft goes.

Also a thought, the factory drive shaft is balanced, but after driving it for any length of time you begin to build up rust, which accumulates in different spots on the shaft making it unbalanced, this is when people have vibration on a stock driveshaft.

Another benifet of the aluminum versus steel driveshaft

 

[DMAN302]

5ive.oh don't give up on us just yet..I think someone needs a hug.
I wounder if I can find some poor bastard on EBAY that might think my "factory original" ford mustang driveshaft may have some value as a collectable item.

 

[5ive.oh]

In desperation I found an aluminum DS at a junkyard from a camaro, but it was 4inches too short. I am kinda glad though, wouldn't want to desecrate my car with it.

 

[Daggar]

i think the real reason is the joints simply go bad on the shaft and need replacement.

I second that emotion. Surface rust is not enought to cause a balance problem unless you're also missing chunks of metal from the driveshaft. There's just enough RPMs in the driveshaft to make that a factor.

 

[drgn5.0]

Also a thought, the factory drive shaft is balanced, but after driving it for any length of time you begin to build up rust, which accumulates in different spots on the shaft making it unbalanced, this is when people have vibration on a stock driveshaft.

This is a decent thought, but in the same theory, the driveshaft would also be out of balance if you spray painted it cause i believe the paint would have more weight to it. i think the real reason is the joints simply go bad on the shaft and need replacement.

 

[HISSIN50]

all the little things do add up, but normally there is quite a bit of tolerance in the 'acceptable' or 'balanced' specs - that rust should not be a factor. however, if one one end of the spectrum already, toss in a little more imbalance and it could happen......
my two cents.