Super hard vibration at 70 when letting off gas

M

mustangt950

New Member

Mar 31, 2008

3

0

0

Apr 7, 2008

#1

• Apr 7, 2008

• #1

Pretty much like the title says. I have a fresh rebuilt T-5 and rear end. This was happining before i did anything to the drivetrain and i figured it wouldnt happen anymore but it still does. What happens is once i get to over 60 if i dont have my foot on the gas the vibrations will surge untill it gets back down to 60 or i give it gas again the higher the speeds the harder the vibrations. I thought i had seen something about this in some fourms i dont know if it was this one or not. it even does it if im over 60 shifting out of 4th into 5th as long as im not giving it gas it will do this clutch in or out. Anyone have any ideas or this happen to them?

 

Black95GTS

Active Member

Jan 8, 2004

1,644

3

38

Marlborough, MA

Apr 7, 2008

#2

• Apr 7, 2008

• #2

Check your u-joins on your driveshaft for starters.

Adam

 

95strokerPSU

Member

Jul 29, 2004

986

1

19

Sacramento from Philly

Apr 7, 2008

#3

• Apr 7, 2008

• #3

Rotate your driveshaft, especially if you're still using the stock one. And as mentioned above check u joints.

 

M

mustangt950

New Member

Mar 31, 2008

3

0

0

Apr 7, 2008

#4

• Apr 7, 2008

• #4

Can you be more specific on rotating the driveshaft i cant do it at my place i live in a APT with no garage so im gonna have to take it to my my dads friends shop and i dont know if hes gonna charge me cause he is the one that put the rearend and new tranny in. It is a stock shaft.

 

Zero_chance

Founding Member

May 29, 2001

1,244

7

59

Maricopa, AZ

Apr 7, 2008

#5

• Apr 7, 2008

• #5

+1 for the u joints. Same exact symptoms in my old 88 5.0 until I finally had the time to change the rear u joint.

 

Pokageek

Active Member

Jun 10, 2005

2,767

0

46

MA, USA

Apr 7, 2008

#6

• Apr 7, 2008

• #6

This happened to me..turned out to be a LOOSE drive-shaft! The bolts were hand loose!

 

1TallMF

New Member

Apr 17, 2006

955

1

0

Montreal

Apr 8, 2008

#7

• Apr 8, 2008

• #7

Deffinetly check the bolts, but the DS might also be out of balance. I had this problem at 70mph (very very bad vibration) because my stock shaft threw a weight, so I decided to put an aluminum one on, and the problem is almost gone. It still vibrates some above 90mph, but I only ever went that fast once (I don't drag race), so I don't care. I figure the 3.73's were set-up incorrectly, but I'm not sure.

 

fiveoho

15 Year Member

Apr 28, 2005

1,958

16

69

TN

Apr 8, 2008

#8

• Apr 8, 2008

• #8

subscribing

i have a VERY similar problem. my rearend was just recently gone thru with new ring/pinion, seals bearings, fluid, friction modifier and trak lok. i had my local ford dealership open the cover and check the tolerances. he said everything looked just fine.

i swapped out the transmission summer before last for a supposed 30,000 miles T5. i think it has issues but im not sure if this contributes to my vibration or not. i can run the car up to 60/70mph in 4th and let off and its fine. if i do that in 5th and let off, it vibrates

when the ford dealership checked the rear, he noticed the DS was not in the factory correct position. apparently during the trans install and troubleshooting, it had gotten rotated . after he turned it ( rotating the bolt holes ), the vibration did get better but its still there. i asked about the u joints and he said they visually looked good and 'felt' good.

can u joints go bad and still appear to look ok?

mine only vibrates when i let off the gas in 5th gear running 65+. no noises, just vibration

 

Zero_chance

Founding Member

May 29, 2001

1,244

7

59

Maricopa, AZ

Apr 8, 2008

#9

• Apr 8, 2008

• #9

Id recommend going to a dealership that has an electronic vibration analyzer. Theyll be able to go on a road test with you with the EVA going and it will pinpoint exactly where its coming from by the frequency and amplitude of the vibration. Every vibration has its own signature.

 

T

topless95

New Member

Feb 4, 2008

27

0

0

North Florida

Apr 8, 2008

#10

• Apr 8, 2008

• #10

what is going on with our cars??? I just had my t-5 replaced and I am now having the same issue, but mine starts above 80-85 mph when I let off the accel. I replaced the u-joints and had a d/s vib and I figured out that I had re-installed the front yolk on the d/s 180* out. I took it out and re-installed the front yolk to line up with the marks I had orig put on and the vib during accel is 90%better but the decel vib concerns me.

 

scaryclown34

New Member

Dec 15, 2005

20

0

0

new jersey

Apr 9, 2008

#11

• Apr 9, 2008

• #11

maybe your tires arent balanced

 

M

mamatried

New Member

Sep 28, 2004

21

0

0

Kentucky

Apr 14, 2008

#12

• Apr 14, 2008

• #12

i have a 2000 gt and its doing the exact same thing! only quits when i smash the pedal. and it really does it from about 50 mph +. let me know what you figure out, i was thinking that it might be the driveshaft too. all i know is that its a ****** to drive the car like that and is very annoying!

 

GTA_V6_Mustang

Active Member

Nov 29, 2004

1,326

3

39

Miami, FL

Apr 14, 2008

#13

• Apr 14, 2008

• #13

Mine is the same thing after 110ish mph. Since I never drive that fast I just ignore it. I know its the DS so I will deal with it till I get my aluminum DS

 

R

redfox91

Member

May 24, 2004

94

0

6

Northwest Arkansas

Apr 14, 2008

#14

• Apr 14, 2008

• #14

I am having the same issues as mustanggt950. Exactly!!!

 

Pokageek

Active Member

Jun 10, 2005

2,767

0

46

MA, USA

Apr 14, 2008

#15

• Apr 14, 2008

• #15

It shouldn't vibrate at all and shouldn't be anything you have to get used to.. Check the bolts.

 

Bosko5.0

Active Member

May 18, 2006

1,067

0

37

longwood, FL

Apr 15, 2008

#16

• Apr 15, 2008

• #16

When I had a bent axle i had a bad vibration above 55mph

It may also be the pinion angle.