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Discussion Starter · #1 ·
I have a sypdershaft 1pc DS on my 2008 GT

My mods are:

4.30 Gears
Steeda Tri-ax
Corsa Extreme Exhaust
SLP LongTubes
SLP Catted X
Steed U/D Pulleys
Steeda Charge Motion Plates
Steeda CAI w/90mm MAF
NX Plate kit w/ 125 shot
Spydershaft 1pc Driveshaft
Steeda Sport Springs
Steed Adj Upper Control Arm
Front Tower Strut Bar

My car vibrates like crazy after 75mph and feels like the car is going to fall apart over 100mph. The noise and ride quality are absolute garbage after 75mph.

I have tried different pinion angles according to what Steeda suggests as well as Leonard racing suggests to no avail.

This weekend I am going to try and put the stock DS back in to see if it goes away or if it is related to the gears.

From what I have read on other forums, an LSD would take care of the problem because apparently Ford's design is the main issue. Yet, others have no issues. The car the DS came off of had no issues with vibrations and had a set of 4.10's on the car.

Has anyone else experienced anything similar? I'd hate to think I am alone on this one. I would much rather remove the driveshaft and sell it to someone with 3.73's or 4.10's than purchase an LSD for .21 of a second on the 1/4.

-Narsh
 

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05 BOSS 302
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The gears ratio should have nothing to do with the vibration. Have you tried clocking the driveshaft?
 

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Discussion Starter · #3 ·
clocking the driveshaft? Forgive my ignorance but is that the same thing as balancing it? Or do you mean turning it?
 

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05 BOSS 302
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Yes unbolting it, turning it and bolting it back in in a different orientation.
 

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I had a situation with that as well it was actually rubbing the rear upper brace on the d/s loop....also it had to be re-balanced...
Have u had it re-balanced ?
 

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Did you have Leonard check the balance on the driveshaft? Your LSD wouldnt have anything to do with this. If an lsd was vibrating like that, it would come apart.
 

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Discussion Starter · #8 ·
Thanks for the replies everyone - I am going to yank it out this weekend and see what is going on. I'll check to see if anything is rubbing. I do hear some rubbing when I roll off the clutch in 1st every now and again so it may be that. I'll have it rebalanced next week.
 

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I had MAJOR MAJOR MAJOR vibration problems with a one piece aftermarket shaft on my '05. To make about a 3 month story short, the shaft will only work in one position in the automatic cars. If the shaft is balanced correctly, it will take turning it to every possible bolt pattern on each end to get it right.
I was involved with a research and development experiment on a local level and might get arthrightis typing it all up here. Three shafts were on the car all vibrated to like you described unless turned to the "sweet spot" on each end. It was anywhere from terrible to dangerous.
The one on the car now still needed balanced to get it right. It's ok now. But wow what a time consuming process. Don't blame the gears. Adjust with the shaft, knowing that would have saved me a lot of time. Good luck
 

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bump for details, I have the exact same problem...even after reclocking (multiple times) and messing with the pinion angle.
 

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If you're having issues, and you have done the "clocking" thing, then your best bet would be to pop off the diff cover, throw a dial indicator on the differential carrier flange and check for runout. Ford has had a lot of issues with out-of-round carriers, and if it's bad enough, it will throw a vibration back up the driveline. Have you noticed that there are a select few cars that have "driveshaft" vibrations even after going to two or three different manufacturers? Have you noticed virtually none of the cars that also did an aftermarket limited-slip diff have any "driveshaft" problems?

If you've reclocked the shaft, verified pinion angle, know your rear suspension is tight with good bushings, and know that your wheels are in balance, you probably have a diff with excessive runout.
 

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05 BOSS 302
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Not saying that isn't his problem but why would he not experience the same vibration issues with the stock 2-piece driveshaft? The second half of the shaft would still vibrate, would it not?
 

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There are a couple of reasons for that... First, the length of the shaft is so much shorter that it would take a MASSIVE runout to shake it hard enough to be felt in the car. Second, the CV-style joint in the middle of the shaft is much better at handling multi-axis misalignment than a U-joint type coupling. Because there is play in the middle of the shaft, it effectively acts as a vibration damper. The mass of the shaft helps there, as well.
 

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Have you noticed virtually none of the cars that also did an aftermarket limited-slip diff have any "driveshaft" problems?

If you've reclocked the shaft, verified pinion angle, know your rear suspension is tight with good bushings, and know that your wheels are in balance, you probably have a diff with excessive runout.
Sucks to be me then. 3 DS' from two separate companies. One was returned with a refund and the other two were shipped off for balancing/run out check. Runout on one was so bad it couldn't be fixed. The other had runout and was able to get within specs. Unfortunately the vibrations stayed. The TruTrac was installed in between the 2nd and 3rd DS, so that wasn't it. After two pinion seals and two pinion bearings, I gave up and put the stock DS back in there.
 

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Discussion Starter · #16 ·
Wow! Thanks to everyone for all the replies!

Let me go down the list of what I have done to date,

I purchased the drifeshaft from a good friend of mine. It did not vibrate in his car - he had the same mods as I did except 4.30's - he had 4.10's. But every car is different.
Before the driveshaft went on, I put the 4.30's in and had no vibration - little gear whine but that was to be expected with Motive making the FRPP gears.
We installed the DS and Steed Upper Control Arm, adjusted the pinion angle to resolve the rediculous vibration. The whine on the gears was also amplified 10 fold.
We readjusted the pinion angle to Steeda's specifications. The vibration shifted from 40-60mph where it sounded like a Cessna and vibrated accordingly over to 75 and up. This was more acceptable.
I had my gears re-set a second and third time to assure it isn't the gears.
I called the Manufacturer to seek advice and even though I didn't purchase it first hand they were very very helpful. The general advice I got there was to turn the shaft to 180 deg., rebalance it, or go with a detroit tru-trac.
So this is where I am at now.
Yesterday we removed the Spydershaft and put back the stock DS. There is still a slight vibration at 80mph. Nowhere and I mean nowhere near the Cessna-like vibration and noise (gear-whine included) I was getting before, but still a vibration.
I'll be slapping on new wheels and tires on Thursday or Friday. That will rule out tire balancing.
I will also adjust the pinion angle and try to make sure there is absolutely no vibration before putting on the Spydershaft.
I am definitely having it rebalanced before putting it on. I don't want to sell it because I already miss the quick acceleration I had before.
I'll keep everyone posted with the progress and thanks again for all your suggestions.

-Narsh
 

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There are a couple of reasons for that... First, the length of the shaft is so much shorter that it would take a MASSIVE runout to shake it hard enough to be felt in the car. Second, the CV-style joint in the middle of the shaft is much better at handling multi-axis misalignment than a U-joint type coupling. Because there is play in the middle of the shaft, it effectively acts as a vibration damper. The mass of the shaft helps there, as well.[/quote

you forgot to mention that the stock D/S is filed with rubber in both shafts also ! (Thanks Ford for for using warped lsd ) !
 

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Just a longshot, but have you checked your axles for runout? It does not take alot to bend those tiny 8.8 axle shafts, a bad pothole, running over a small log or rock, etc....

pull the brake rotors, and rotate the rear axles with a dial indicator on the faces to check.
 
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