Bad Vibrations

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bbbngowc

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Feb 28, 2007

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Oct 28, 2007

#1

• Oct 28, 2007

• #1

Hey peeps, I'm getting heavy vibrations at 1000RPM in my 91 Fox (stock). Once the needle goes past 1000, everything is nice. What's up with this?

 

RYC CUKR

Founding Member

May 19, 2002

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Orlando

Oct 28, 2007

#2

• Oct 28, 2007

• #2

Have you done anything to the car lately that involved the DS?

If so I would check that and make sure that all of the bolts on the DS to differential plate are tight.

Also do you still have the dampner, dogbone, on the diff housing? If you don't you might want to find one at the JY and put it on.

 

J

JamesB88

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May 29, 2004

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North Kansas City

Oct 28, 2007

#3

• Oct 28, 2007

• #3

Check your harmonic blancer, mine was coming apart and it made the car vibrate pretty bad.

 

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bbbngowc

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Feb 28, 2007

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Oct 28, 2007

#4

• Oct 28, 2007

• #4

RYC CUKR said:

Have you done anything to the car lately that involved the DS?

If so I would check that and make sure that all of the bolts on the DS to differential plate are tight.

Also do you still have the dampner, dogbone, on the diff housing? If you don't you might want to find one at the JY and put it on.

Click to expand...

Seeing that I don't know what the DS is, I'd say no, I haven't done anything to it.

What's a dampner, dogbone, on the diff housing?

 

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bbbngowc

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Feb 28, 2007

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Oct 28, 2007

#5

• Oct 28, 2007

• #5

JamesB88 said:

Check your harmonic blancer, mine was coming apart and it made the car vibrate pretty bad.

Click to expand...

Yeah I was told the harmonic balancer could be the problem. Before I changed it, I wanted to make sure this is what it really was. It's a bytch to change.

I checked mine and it's pretty solid, doesn't move or anything. The rubber looks good too. How did yours look?

 

J

JamesB88

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May 29, 2004

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North Kansas City

Oct 28, 2007

#6

• Oct 28, 2007

• #6

mine the rubber was comeing out, start the car and look at it, mine wobbled alittle.

 

Repostyle

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Jun 11, 2005

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Portland, OR

Oct 28, 2007

#7

• Oct 28, 2007

• #7

bbbngowc said:

Seeing that I don't know what the DS is, I'd say no, I haven't done anything to it.

What's a dampner, dogbone, on the diff housing?

Click to expand...

DS = Drive Shaft
On your rearend there's a dampener that looks like a dog bone. It's two square blocks bolted to the front of the differential housing.

Where do you think the vibration is coming from, rearend, frontend, engine, steering, etc.? Without knowing this its kind of hard to say "oh yeah it's the ..."

Are you in the same gear each time when your doing 1000 rpm or does it do the same thing in all gears at 1000rpm.

All I can say from expierience is U-joints. I had a vibration at a certian speed and it turned out to be warn out U-joints. I'm not saying that's what your problem is, just saying that's one possibility

 

cenok is family

15 Year Member

Jun 25, 2003

1,409

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79

Norman, Ok

Oct 28, 2007

#8

• Oct 28, 2007

• #8

Repostyle said:

DS = Drive Shaft
On your rearend there's a dampener that looks like a dog bone. It's two square blocks bolted to the front of the differential housing.

Where do you think the vibration is coming from, rearend, frontend, engine, steering, etc.? Without knowing this its kind of hard to say "oh yeah it's the ..."

Are you in the same gear each time when your doing 1000 rpm or does it do the same thing in all gears at 1000rpm.

All I can say from expierience is U-joints. I had a vibration at a certian speed and it turned out to be warn out U-joints. I'm not saying that's what your problem is, just saying that's one possibility

Click to expand...

+1

 

B

bbbngowc

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Feb 28, 2007

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Oct 28, 2007

#9

• Oct 28, 2007

• #9

Repostyle said:

DS = Drive Shaft
On your rearend there's a dampener that looks like a dog bone. It's two square blocks bolted to the front of the differential housing.

Where do you think the vibration is coming from, rearend, frontend, engine, steering, etc.? Without knowing this its kind of hard to say "oh yeah it's the ..."

Are you in the same gear each time when your doing 1000 rpm or does it do the same thing in all gears at 1000rpm.

All I can say from expierience is U-joints. I had a vibration at a certian speed and it turned out to be warn out U-joints. I'm not saying that's what your problem is, just saying that's one possibility

Click to expand...

The car idles at about 1000RPM. It vibrates at idle. And the vibrations are coming from the frontend of the vehicle.

I've already changed the engine mounts too. I thought that was the cause at first. After I changed the mounts, the car still shook (violently).

 

SuperStang83

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Mar 21, 2001

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Boyertown, Pa

Oct 28, 2007

#10

• Oct 28, 2007

• #10

Take a look at your harmonic balancer, I have seen that problem before.

 

Repostyle

Member

Jun 11, 2005

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Portland, OR

Oct 28, 2007

#11

• Oct 28, 2007

• #11

So your vibration happens all the time including just parked and idling? Okay, that narrows it down to the engine. It could be the HB or maybe it dropped a cylinder. Have your checked the compression and made sure all cylinders are firing?

 

B

bbbngowc

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Feb 28, 2007

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Oct 28, 2007

#12

• Oct 28, 2007

• #12

Repostyle said:

So your vibration happens all the time including just parked and idling? Okay, that narrows it down to the engine. It could be the HB or maybe it dropped a cylinder. Have your checked the compression and made sure all cylinders are firing?

Click to expand...

Actually I haven't checked the firing. I did check the spark plug wires but I didn't check to see if they're all firing. How do I do this?

 

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bbbngowc

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Feb 28, 2007

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Oct 28, 2007

#13

• Oct 28, 2007

• #13

If one of the cylinders wasn't firing, wouldn't I feel that through all RPM's? Once I accelerate past 1K man the engine smooths right out.

 

Repostyle

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Jun 11, 2005

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Portland, OR

Oct 28, 2007

#14

• Oct 28, 2007

• #14

not nessacarily, it might feel smoother but it could still be missing. To check it the easy way: Start the engine. Pull one plug wire at a time, if the engine starts to run worse then that cylinder is firing, if you don't hear a change in the idle that cylinder is dead.

If the cylinder is dead then it could be one or all of a few things. Injector, plug, wire, valve... etc.

 

Repostyle

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Jun 11, 2005

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Portland, OR

Oct 28, 2007

#15

• Oct 28, 2007

• #15

PS. you can pull them from the cap so you don't have to reach down by the hot exhaust.

 

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bbbngowc

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Feb 28, 2007

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Oct 29, 2007

#16

• Oct 29, 2007

• #16

Dude! Looks like you may be right. The first wire I pulled had no change in the car idle. It still shook like hell. Not to say that it's NOT the HB, but for now, I'll go with the plugs, wires or distributor. I'll test some more today and see exactly what's going on.

Thanks.

 

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bbbngowc

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Feb 28, 2007

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Oct 30, 2007

#17

• Oct 30, 2007

• #17

I went to test the other cylinders and man what a shock! I pulled it off the distributer ok, but when I went to connect the wire back ... it was a shocking experience! I'm not doing that again. Is there another way?

 

black87ttop

Member

Oct 29, 2007

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burlington,new jersey

Oct 30, 2007

#18

• Oct 30, 2007

• #18

hahah lol. Oh man they were supposed to tell you to use a pair of platic pliers, or metal ones witha real heavy rubber handle. did you just get the car, has it always vibed? Did it just start out of nowhere? Possible the owner before you put the wrong flywheel on. I put a new billet steel flywheel on that i bought off ebay. whoops seller listed it as wrong weight and when i drove the car it almost fell apart. But check your firing order and just start checking things off.

 

F

FourEyes

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Sep 24, 2007

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NC

Oct 30, 2007

#19

• Oct 30, 2007

• #19

If you have a temp sensor. one of those point and shoot ones you can check the headders. The temps will be drastically different. I found this out by having a 302 firing order with a 351 cam. Thought it was cam timing or this or that. Just pulled out a temp sensor and saw that only 1/2 the cylinders were fireing and well figured out that the plugs were in the wrong order.