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Discussion Starter · #1 ·
Checking to see if anyone has this similar problem...

Had my 4.10's for a few months now. They're awesome! But now at high speeds, once I let off the gas there is a lot of vibration going on... feel it on the floor board of the car and can hear it too.. no vibration while accelerating (even at high speeds), only when I let off the gas. Anyone else have this problem or know what may be causing it? Like to see if its something I can fix before I take it in to a shop. Appreciate the help.
 

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I don't think it's the gears. More than likely it's your driveshaft that is out of balance and it having to spin faster at speed becuase of your 4.10's isn't helping it any.
 

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I suspect your driveshaft as well.

Here's some info on whats most likely happening.

Your stock gear ratio is 3.31:1. You've changed yours to 4.10:1, as you said before. This dramatically increases the speed your driveshaft rotates at high speeds.

In stock form (3.31:1) many people experience driveshaft failure at around 125mph. With your gear ratio (4.10:1) your "failure" speed is right around 100mph (3.31 divided by 4.10, multiplied by 125mph).

If you've been driving at speeds over 100mph, its surprising that your drive shaft is still attached to your vehicle at all.

Being that its rotating so much faster than it was meant to, particularly with 4.10's at speeds over 100mph, some vibration should be expected.

And its not the vibration i'd be worried about, its what to do when the driveshaft lets go at 100+mph. :happyhapp
 

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i have the same problem in my mustang

is your around like 80 and then it viberates as you slow down??
mine doesnt do it as much anymore, i just would run to 80 and slow to 70 and repeated it for awhile and it dramatically reduced it!

but dang i never though about that driveshaft spinning so much faster, ive done 120 with my 4.10s but thought since the failure was at 125 i wouldnt go any farther.. hmmm...alum. DS is next in my book if i keep the car

its for sale BTW
 

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Yeah its a common misconception that the driveshaft fails when the car is going a certain speed. The truth is that its because the driveshaft has reached a certain speed that it gives up. It's not always the case, but seems to be pretty common in these vehicles.

Oh and just for shits, I figured out that going 120mph with 4.10's is the equivalent of going 148mph with 3.31's. Way over that 125mph "safe zone." :hihi:
 

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Yeah its a common misconception that the driveshaft fails when the car is going a certain speed. The truth is that its because the driveshaft has reached a certain speed that it gives up. It's not always the case, but seems to be pretty common in these vehicles.

Oh and just for shits, I figured out that going 120mph with 4.10's is the equivalent of going 148mph with 3.31's. Way over that 125mph "safe zone." :hihi:

omg...
thats really scary
well i guess my DS is a little better then what i thought eh?

so do you guys think a alum. DS will cure this?
 

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Discussion Starter · #7 ·
Yeah, mine does it at around 80 mph. Thanks to everyone for their input. I have been looking at switching out to a one piece aluminum driveshaft. This will help, right? I've been talking about it for a while now, but now with this info... i'm putting my order in this weekend!
 

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Discussion Starter · #8 ·
I found a one piece alum driveshaft at www.rpmoutlet.com for $540 and free shipping. Been looking but that's the cheapest i've found. They also sell a driveshaft safety loop... in case the driveshaft breaks in high speed.
 

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Beware of RPM Outlet. They are notorious for lost orders and other such problems.
 
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