FD3SLS1

iTrader: (1)

Well I've been fighting a high frequency vibration that starts around 80 MPH and progressively gets worse as speed increases. The vibration can be felt in the seat but not thorough the steering wheel. The vibration can be felt in 4th, 5th 6th and in neutral with both clutch depressed and released until the speed drops below 80 mph.

Here is a list of everything that has been done with no effect on the vibration.

High speed balance tires, twice by two different shops
Installed hub centric wheel spacers to replace my flat wheel spacers.
Replaced driveshaft carrier bearing with the VooDooChicken bearing.
Replaced stock rearend and axles with 8.8 swap and 1000 hp Axles.
Replaced front hubs. (notice play in them even thou i wasn't experiencing and vibration from the steering wheel)

Here are the only things I have left before I run out of options

Remove driveshaft and have it re-balanced
Replace original 138k mile Flex disk
Replace rear hubs.

Am I missing anything?

I didn't really notice it until after I did my 5 lug conversion but then again I hardly ever go on the interstate since my daily commute is all on secondary roads.

Anthony Toal

It is probably the 8.8 kit, a lot of us have the same issues, join us on the other thread, we are all trying to pool together all the information and different cause and effects

ls1247

iTrader: (2)

Here we go again...join the club

FD3SLS1

iTrader: (1)

The vibration has been present both before and after the 8.8 swap.

voodoochikin04

iTrader: (3)

Harmonic balancer?
clutch & flywheel?
Tire noise?
Did you check the rear driveshaft CV joint when you had shaft out?

Anthony Toal

did you do your 5 lug swap before everything? what rotors did you go with

BudRacing

iTrader: (3)

I'm a believer that it's the transmission.

FD3SLS1

iTrader: (1)

Harmonic balancer? New underdrive install about 10k ago
clutch & flywheel? New ls7 installed 10k ago
Both would be eliminated once the transmission was in neutral and would be RPM based more so than speed based.

Tire noise? nope, tires are quiet.

Did you check the rear driveshaft CV joint when you had shaft out? I didn't pop the cover off but I did rotated it thought its full range of motion and didn't feel anything abnormal.


Did you do your 5 lug swap before everything? Yes
what rotors did you go with? Re-drilled stock rotors

I'm a believer that it's the transmission - With no change in 4th, 5th 6th, or N the only cause could be a worn tail shaft bushing.

Anthony Toal

you might wanna check the balance of the rotors, that would make sense why it doesn't matter what gear your in or when clutch is in or out. Everything your describing points from the output shaft back and what from you stated

"I didn't really notice it until after I did my 5 lug conversion but then again I hardly ever go on the interstate since my daily commute is all on secondary roads."

makes me think those can be your culprit from the change

BudRacing

iTrader: (3)

I definitely wouldn't consider that the only cause, but it certainly could be. It seems others have tried this over the years ouside of our immediate V community. There are a couple threads on this forum if you search for "t56 tailshaft bushing". None that I've read so far have been conclusive.

The only thread that has been conclusive is this one: https://ls1tech.com/forums/manual-tr...bration-5.html

Also, just because 4th vibrates, doesn't mean it's not a mainshaft. The rest of it is still spinning and can transfer vibes when the input and mainshaft are locked together in 4th gear.

voodoochikin04

iTrader: (3)

Sorry I somehow missed it still did it in neutral.

FD3SLS1

iTrader: (1)

Think I'm going to install a ounce or two of balancing beads in the rear wheels and see if that improves the vibration I'm having. If the vibration decreases than at least I can rule out the trans and driveshaft and then focus on in the hub/rotor/wheel area.

BudRacing

iTrader: (3)

Hub bearings sound more like tire noise.

FD3SLS1

iTrader: (1)

Most of the time but not always, I just replaced both of my front hubs neither made any noise but both had a slight amount of play in the bearings.

jmilz28

iTrader: (13)

Assuming it doesn't do it at 0mph, sounds like driveshaft. You won't easily find anyone who can balance that shaft. I've only found PowerTrain Industries, and only as part of a total rebuild.

voodoochikin04

iTrader: (3)

Anywhere that can Balance a two piece shaft can do the OEM V driveshaft.

jmilz28

iTrader: (13)

I personally have not found that to be the case...though it seems quite rational. 6 different drivetrain shops in Houston have told me no, all pretty good sized. The only place I've found that would would only do so as part of a rebuild: PowerTrain Industries. Apparently, the connections on both ends are oddball-ish. If you know of some definitively that will, throw out the name!

voodoochikin04

iTrader: (3)

Any shop that does Porsche performance should have the low down.

Choppy_Idle

In the old world and producer of the GKN 2-piece driveshaft it is also difficult to find the right balancing shop which does a good job, naturally I come to the wrong one which has only the Dollar signs in his eyes and payed 800 for a shitload of crap, so beware of sad sacks, only being in a balancing shop and balance your driveshaft CAN mean nothing, if the issue exists anyway and noise sounds like the same as before...

But don't worry, this was only my experience here, think most of them doing their job correctly!

Greetz
Ron

voodoochikin04

iTrader: (3)

I can't recall who it was but a client of ours in Florida got his balanced for under $100.