Engine Vibration Above 3000rpm

5.0foxbody91

New Member

Dec 27, 2015

6

0

1

Dec 27, 2015

#1

• Dec 27, 2015

• #1

Hey guys, I'm new to this forum, I've always loved mustangs, and I finally got one. It's a 91 lx hatch. I've had some trouble with it, but I have most of the problems fixed except for this vibration one. The shifter will vibrate like hell above 3000 rpms, whether I'm sitting still or going down the road. I'm not sure of what it is, I just bought the car about a month and a half ago. I'm thinking harmonic balancer, or an engine balance problem, but I'm not sure, any suggestions or tips, would be greatly appreciated, this car means a lot to me. Thanks in advance!

 

Black1987

my wife Bedazzled my input shaft

15 Year Member

Jan 9, 2011

1,064

595

174

NC

Dec 28, 2015

#2

• Dec 28, 2015

• #2

Is this a manual or automatic? I would inspect your transmission mount and mounting hardware first. If the car is lowered at all, also check the pinion angle. Is the vibration the whole car or isolated to the shifter? If the vibration is the whole car, I would then proceed to look at the motor mounts and harmonic balancer.

 

Reactions: A5literMan and 5.0foxbody91

90sickfox

Wasn't a pretty sight...and I've got big hands

SN Certified Technician

Mar 2, 2015

6,945

5,816

213

Dec 28, 2015

#3

• Dec 28, 2015

• #3

Check the driveshaft, too.

 

Reactions: A5literMan and 5.0foxbody91

5.0foxbody91

New Member

Dec 27, 2015

6

0

1

Dec 28, 2015

#4

• Dec 28, 2015

• #4

It's a manual transmission, the trans mounts and motor mounts I already had checked, and they looked good. I had someone check the drive shaft and u joints, and they were good. I would think if I leave he shifter in neutral, and I'm sitting still, the problem is in front of the trans. I can feel major vibration in the shifter, but there is some vibration through the dash too. What would I check for on the harmonic balancer?
Thanks guys!

 

90sickfox

Wasn't a pretty sight...and I've got big hands

SN Certified Technician

Mar 2, 2015

6,945

5,816

213

Dec 28, 2015

#5

• Dec 28, 2015

• #5

If you have a stock fan check that also....I had one that had one of the plastic fins broken.....it would vibrate the hell out the car.

 

Reactions: 5.0foxbody91

90sickfox

Wasn't a pretty sight...and I've got big hands

SN Certified Technician

Mar 2, 2015

6,945

5,816

213

Dec 28, 2015

#6

• Dec 28, 2015

• #6

The harmonic balancers (factory) have a rubber insulator between the belt hub and the body. What I do to check is disable computer advance ( the plug by the distributer) and check number one tdc and put a timing light on it. The timing should stay constant at say 10 degrees or whatever its set at. If the rubber is poking out it also could indicate a bad balancer. There are alot of factors that can cause a vibration. I'm no expert . noticed it happens sitting still so no drive line issue will cause that. Its got to be ahead of the trans. Flywheel, clutch, balancer, fan, etc

 

Reactions: 5.0foxbody91

5.0foxbody91

New Member

Dec 27, 2015

6

0

1

Dec 28, 2015

#7

• Dec 28, 2015

• #7

Thanks for the input guys. I just checked the fan, it was okay. Then I noticed the balancer was wobbling at idle, is this normal? Or is that the problem?

 

5.0foxbody91

New Member

Dec 27, 2015

6

0

1

Dec 28, 2015

#8

• Dec 28, 2015

• #8

Next I'm gonna disconnect the timing advance plug, and I'll check it that way, thanks 90sickfox!

 

90sickfox

Wasn't a pretty sight...and I've got big hands

SN Certified Technician

Mar 2, 2015

6,945

5,816

213

Dec 28, 2015

#9

• Dec 28, 2015

• #9

No problem....I don't know as much as a lot of these guys but I've been messing with these cars for a while now. Hope you find your problem.

 

Reactions: 5.0foxbody91

jrichker

StangNet's favorite TOOL

In Remembrance. Thank you for your contributions

Mar 10, 2000

27,512

2,813

234

Dublin GA

Dec 30, 2015

#10

• Dec 30, 2015

• #10

5.0foxbody91 said:

Thanks for the input guys. I just checked the fan, it was okay. Then I noticed the balancer was wobbling at idle, is this normal? Or is that the problem?

Click to expand...

If the balancer was wobbling, it is definitely time to replace it.

 

Reactions: 5.0foxbody91

OneWheelPeel

Active Member

Dec 23, 2015

250

42

48

North Carolina

Dec 30, 2015

#11

• Dec 30, 2015

• #11

Another thing you could check is the shifter bushing. My shifter would vibrate insanely at about 3k in neutral and in gear. I took out the hurst shifter and saw that the bushing was cracked. I put a new bushing in a pro 5.0 shifter and that fixed it.

 

Reactions: 5.0foxbody91 and stykthyn

5.0foxbody91

New Member

Dec 27, 2015

6

0

1

Dec 31, 2015

#12

• Dec 31, 2015

• #12

I was actually about to ask if that was the problem, I ordered one awhile back but I never put it on, I think it is in the shifter now after looking at it. Do you happen to know how to install a shifter bushing? If so could you walk me through it? I appreciate it man.

OneWheelPeel said:

Another thing you could check is the shifter bushing. My shifter would vibrate insanely at about 3k in neutral and in gear. I took out the hurst shifter and saw that the bushing was cracked. I put a new bushing in a pro 5.0 shifter and that fixed it.

Click to expand...

pro

 

5.0foxbody91

New Member

Dec 27, 2015

6

0

1

Dec 31, 2015

#13

• Dec 31, 2015

• #13

jrichker said:

If the balancer was wobbling, it is definitely time to replace it.

Click to expand...

I'll go ahead and replace it while I've got it, thank you.

 

OneWheelPeel

Active Member

Dec 23, 2015

250

42

48

North Carolina

Dec 31, 2015

#14

• Dec 31, 2015

• #14

5.0foxbody91 said:

I was actually about to ask if that was the problem, I ordered one awhile back but I never put it on, I think it is in the shifter now after looking at it. Do you happen to know how to install a shifter bushing? If so could you walk me through it? I appreciate it man.

pro

Click to expand...

All you do is take your shifter boot off and the heat/sound rubber thing. Then you unbolt the four shifter bolts. Remove the shifter and then you will see a "bowl/cup" area that the bushing will go into. You will know when you see it. After that you just connect the shifter and bolt it back up.

 

Reactions: 5.0foxbody91