car vibrates at about 75+ mph

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Oct 3, 2012 | 12:35 PM

k_stewart_21

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From: vian, ok

car vibrates at about 75+ mph

like it says while driving at about 75 or mor mph, the car has a slight vibration. car has new u joints, tranny mount, driveshaft, rearend, torque arm etc... so i dont think it is in the drive line. i had a heat shield hitting my pipes so i thought that was it but once i removed the heat shield the same vibration was there. could be moter mounts???any ideas guys???? thanks

Oct 3, 2012 | 01:04 PM

nomoneyz

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From: Apple Valley - So Cal

Have you recently had your tires balanced?

Oct 3, 2012 | 02:18 PM

wrd1972

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From: Central Kentucky

OP,
If you have 6 speed, drive at 75MPH in 4th and note if the vibe is there. If its vibe free, shift to 5th and note if its there, Then go to sixth and do the same thing.

If you are vibe free in 4th but detect vibes in 5th and 6th gears only, you have T56 wear and tear so go here:
https://ls1tech.com/forums/manual-tr...vibration.html

Oct 3, 2012 | 02:53 PM

bufmatmuslepants

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I can't post links from my phone but search for THAT DAMN 5th/6th GEAR VIBRATION. Does it do it in 4th 5th and 6th?

Oct 3, 2012 | 03:37 PM

R3DLT1

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From: Bartlesville,OK

Quote:

Originally Posted by nomoneyz

Have you recently had your tires balanced?

I would go with what this guys said. I work at Firestone and driven many cars that have and out of balance wheels and it usually beggings at 60mph.

Oct 4, 2012 | 05:25 AM

Drew-Bot

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question mine does it as well, but when it was on the dyno we saw the wheels spining and shifting up and down slightly. Could this be caused by the gear as well or just the tire or wheels being bent. If so then I guess its just a fluke. The trans is out of the car getting a new ls7 clutch put in today, but i am already out 1800 im 2 scared to ask him to check the gears and raise my price lol My car has only 38k on it as well so I would hope its just the rim/tire.

Oct 4, 2012 | 08:41 PM

k_stewart_21

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From: vian, ok

tires have been balanced, and its a automatic car...you can hear this vibration. and feel it when u put ur hand on the floor. its not to bad but does get worse at higher speeds. i let off the gas and the vibration goes down a bit

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Oct 5, 2012 | 10:53 AM

k_stewart_21

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From: vian, ok

Poly tranny mount and I ain't real sure. I put the motor in it in July 11, and guess its just gotten worse since

Oct 5, 2012 | 11:13 AM

#10

wrd1972

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From: Central Kentucky

Quote:

Originally Posted by k_stewart_21

Poly tranny mount and I ain't real sure. I put the motor in it in July 11, and guess its just gotten worse since

You will get many more vibes with the poly tranny mount. Put the rubber one back on and see if the problem is gone. If you are not hardcore racing, you dont need a poly mount since rubber mounts go fo $25 new.

Oct 5, 2012 | 11:30 AM

#11

speed_demon24

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Quote:

Originally Posted by k_stewart_21

Poly tranny mount and I ain't real sure. I put the motor in it in July 11, and guess its just gotten worse since

I was chasing an 80+mph vibration forever. I finally bought an LS1 rubber mount on amazon for $45 that cured it. It's supposedly quite a bit stronger than the LT1 mounts.

Oct 5, 2012 | 12:11 PM

#12

k_stewart_21

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From: vian, ok

I went through 2 rubber mounts in 3 months on my old red car and it ain't got the power this white one has. But it's worth trying I reckon

Oct 5, 2012 | 12:16 PM

#13

djjab57

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Quote:

Originally Posted by wrd1972

This was going to be my responce, You notice more vibes when going to poly mounts. You get use to it though

Oct 6, 2012 | 02:17 PM

#14

k_stewart_21

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From: vian, ok

The sound is terrible though. That's y I don't think it's the mount. The floor barely vibrates

Oct 7, 2012 | 08:49 PM

#15

96LT1355Z28

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From: Holden, MO (KC)

Have you changed ride height of the car? The poly mounts are known for transmitting noise through the floor as said above. If you've lowered the car you may have a driveline angle issue. I'd try a rubber mount first though.

Oct 7, 2012 | 08:59 PM

#16

k_stewart_21

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From: vian, ok

Yeah I did. Guess ill try the rubber mount when I get off work in two weeks.

Oct 7, 2012 | 09:04 PM

#17

Mattyfresh89

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From: Boston

I have developed a vibration and somewhat of a thumping noise from the rear. Turns out my Panhard bar bushings, torque arm bushing and trans mount are all junk!

Something to look into

Best of luck

matt

Oct 7, 2012 | 09:12 PM

#18

k_stewart_21

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From: vian, ok

I have brand new Bmr panhard bar, torque arm, sub frames, etc. the tranny mount is the only thing that's over a year old

Oct 8, 2012 | 09:35 AM

#19

Mattyfresh89

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From: Boston

I chased this problem down in my last car. I could feel it in the steering wheel and *** of my seat.

Replaced springs (lowering kit) - didn't help
Replaced all ball joints -didn't help
Got it aligned and wheels balanced -didn't help

one day I got a power steering leak from the pressure line to the rack. So I had a friend replace the line and the rack...problem solved

Hope you find out what the problem is