5.0L (1979-1995) Mustang Technical discussions on 5.0 Liter Mustangs within. This does not include the 5.0 from the 2011 Mustang GT. That information is in the 2005-1011 section.

1991 mustang vibration problem

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Old 09-22-2015, 11:44 AM
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mdj89
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Default 1991 mustang vibration problem

I have a 1991 mustang with a vibration problem. I replaced everything except I do have a sticky brake caliper on the passenger side an it evens vibrates when im accelerating could that be my problem?
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Old 09-22-2015, 01:04 PM
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88 orangepeel notch
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Not likely, but explain your vibration in a little more detail. At what speed?, is it in the steering wheel or do you feel it in the seat ?, mostly on acceleration, braking, or no load cruising speed?

Be as discriptive as possible , so we can narrow it down for you.
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Old 09-22-2015, 01:13 PM
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Urambo Tauro
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Originally Posted by mdj89
I replaced everything except I do have a sticky brake caliper on the passenger side an it evens vibrates when im accelerating could that be my problem?
You replaced everything except the caliper? Holy crap; that must have been expensive.

A sticking brake caliper (depending on how it's stuck) would just be providing constant pressure. The only way I can think of this creating a vibration is if this pressure overheated the brakes, causing the rotor to warp.
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Old 09-22-2015, 01:47 PM
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silver91gt
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could be a number of things, driveshaft bolts loose, worn out u-joint in driveshaft, wheel balancing weights could have fallen off, front wheel bearings could be worn, rear axle bearings could also be worn, axles could be bent, I would rule out brakes since it does it while accelerating.
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Old 09-22-2015, 02:11 PM
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mdj89
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I have new tires an theve been balanced twice. New motor mounts, shocks, struts, rotors and front wheel bearing an a new rack and pinion but, I do know the passenger side tie rod end has been patched up an I also had the dealer check the drive shaft an they said it was fine. But yes I feel it during acceleration an breaking by how the brake pedal feels. It does it off an on at times very strange.
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Old 09-23-2015, 07:39 AM
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88 orangepeel notch
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II don't know what a tie rod thats been " patched up " looks like, but I'd like to lol.

Seriously though, anything that rotates can cause a vibration, Most of the parts you threw at it would not cause a vibration . An intermittent vibration is going to be very hard to chase down with the discription your giving. I'd start with u-joints first, based off what your saying.

The pulsing brake pedal is a warped rotor.

Last edited by 88 orangepeel notch; 09-23-2015 at 08:00 AM.
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Old 09-23-2015, 08:41 AM
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mjr46
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Originally Posted by silver91gt
I would rule out brakes since it does it while accelerating.
I wouldn't................................I can't believe all of the previous posts have discounted a dragging brake caliper as "not a possible cause".......................I can't tell you how many cars have come into my shop with a dragging caliper on one or both sides and the complaint from the customer is car has mild and or bad vibration...........due to the caliper dragging and thus having overheated/warped the rotor..........OP, FIX the caliper first and verify no calipers are dragging to eliminate that as a cause...........and YES A CALIPER DRAGGING/STICKIN WILL CAUSE A MILD/BAD VIBRATION WHILE ACCELERATION AND OR DRIVING DOWN THE ROAD AT SPEED. You have to eliminate this as an issue before going any further with diagnosis.
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Old 09-23-2015, 08:49 AM
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Originally Posted by mdj89
I have new tires an theve been balanced twice. New motor mounts, shocks, struts, rotors and front wheel bearing an a new rack and pinion but, I do know the passenger side tie rod end has been patched up an I also had the dealer check the drive shaft an they said it was fine. But yes I feel it during acceleration an breaking by how the brake pedal feels. It does it off an on at times very strange.
that's because the caliper can be intermitantly hanging up......seen it tons as the braking action heats the rotor up/caliper up, it begins to drag more and more, sometimes it only takes a few minutes, sometimes it can be an hr or so, depends on heat build up and or hitting that sweet spot where it'll hang up......the vibration on braking is no doubt a rotor as mentioned "warped".........most likely as a result of the caliper overheating it from dragging........I'd replace the brake hose going to that caliper as well, often they can collapse thus keeping pressure held to the caliper as fluid heats up.......seen both scenarios.........in short replace caliper and hose and retest after repair with wheels raised in front having a person spin the wheels as you hit the brakes and let off, making sure no one wheel drags or locks up as soon as pressure is let off pedal.......should be immidiate release. oh and you'll need to replace the rotor/s as well to eliminate vibration on braking, or turn them
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