ecm747x,
Have you ever noticed how the F-150 resonates when a big commercial vehicle is near it? Anyway, I think the F-150 is like the sound box of a stringed instrument. It has a lot of sheet metal to resonate. I bet that a good undercoating of sound deadening material would really help.
Your problem certainly sounds like it's resonance related. You can easily rule out factors such as wheels being out of balance by varying the rpm and road speed.
When I changed my exhaust, I noticed an odd damper/mount that is part of the transmission mount connecting the trans mount to the crossover exhaust pipe. There is also a weight on the exhaust itself. The implication is that the exhaust resonates and rather than redesign the exhaust Ford tried to dampen it. If that's the case, the solution could be as simple as changing the resonant frequency of the exhaust system, or better isolating the exhaust from the cab.
Has anyone tried removing the trans to x-over pipe damper? Maybe a kit from energy suspension will help. As has been mentioned, adding mass to the exhaust may help. The thing is, if you belong to this board, you're in a small group of F-150 owners. If you notice the problem you're in an even smaller group. This vibration problem most likely occurs on every F-150 to a lesser or greater extent but only a small number of people notice or care. Ford knows that and so the cost of redesigning an exhaust system is orders of magnitude higher than dealing with 0.01% of owners that notice the problem.


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'00 5.4L 4X4 Lariat (Black/Silver)
'99 Ranger 4.0L 4X4 XLT

 

Gah,My truck had this trans mount you mentioned.Ford took it off and put a newer one designed to fix the same problem with expedition.The vibration range changed from 63-70 to 55-80mph some fix.I also had a magnaflow single in dual out.The trucks vibration did not improve,but ford told me that the source was from new exhaust,ihad the stock muffler and tailpipe put back on with the factory hangers, still vibrates.

My 1999 xlt ext-cab 5.4 auto 3.55ls
vibrating shaking machine

 

I also feel the vibration between 66-69 mph. I have posted this topic before and nobody has had a good fix that works across the board. Yesterday I drove the truck until the vibration started, then I shifted to neutral. After 1-2 seconds the vibration went away. That leads me to believe it's in the tranny. I had originally thought it would be in the rear end or wheels, but now I think otherwise. Any thoughts. Try what I did and see what you think. Please post your results. Signature below.

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1999 F-150 Lariat, 5.4, 3.55 Ratio, Deep Wedgewood/Gold, Tan Leather interior, LineX bedliner, NO DOOR CRACKS.


[This message has been edited by Tim Lloyd (edited 11-20-2000).]

 

Tin Knocker,
I was wondering about that mount. Obviously it was designed for the factory exhaust system and so I'd be interested to hear if anyone has tried removing it once they installed an after-market exhaust. It seems to me that removing it would make a difference, maybe for the better. You already mentioned that it shifted your vibration to a wider mph range.

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'00 5.4L 4X4 Lariat (Black/Silver)
'99 Ranger 4.0L 4X4 XLT

 

Hey guys,


Well, I tied the exhaust system up in the back where it wouldn't move at all. I went down the road and there was no vibration at all. I stopped and took the strap off and what do you know it came back.
I told the mechanic at the dealership and he thought I was full of it so I had him drive it and he did note the vibration. I had him stop and put the strap back on like I had it and it went away. He called the techs' at ford and they said they were aware of it ( and my truck already had the weight on it just in front of the muffler) and they were sending some dampners that is to cure this. They won't be in till Tuesday so I will see if they helped at all or just transfered the vibration to another speed/ rpm. I will keep you all posted as to my findings...later guys

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ecm747x

2001 SUPER CREW XLT, BRIGHT RED
5.4L Triton, automatic 3.55 gears limited slip
tow package
16" tires
side steps
bed extender
ford/duraliner bed liner
60/40 seats
6cd changer
moonroof
sliding rear window

Soon to come Mods...

Adding Super chip, Airaid F.I.P.K. Installing different exhaust, not sure which yet. Front grill guard. With light kit


MODS....
1) Lund x-terminator bug shield

 

Hey, good work ecm747x. You'll be helping out a great many people if you can resolve this. Hopefully Ford will release a TSB about exhaust resonance. I look forward to your follow up.


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'00 5.4L 4X4 Lariat (Black/Silver)
'99 Ranger 4.0L 4X4 XLT

 

Way to go ecm747x,May'be the boys at ford need a lesson on knot tying.Seriously where did you tie this on exhaust.I wonder if the dampner ford has for you're truck is the same as the one they put on my truck.I tried gah's idea today.I took off the new style dampner ford put on,took about 5 minutes to remove.I would describe it as u bolt muffler style clamp,with a 1/2" diameter rod welded to it,this rod slids into a bracket with a rubber bushing which is part of transmision mounting. The other end wraps around exhaust pipe crossover and clamps on with 2 nuts.Darn truck still vibrates,this part ford called a dampner on my repair order, seems more like a crossover support for left and right exhaust pipes.Dampner part # on my repair order is f85z-5e269-ea Description bracket&029783,and mf-clamp 029872.Good luck.

 

Hey Guys,


I tied my exhaust just aft of the muffler where the pipe turns out to go out behind the tire. I used a one inch cargo strap and pulled it up tight. (Two wrapps on the exhaust and wrapped the upper part around the frame, then took tie raps and pulled the center of the strap together so it looked like a figure 8 so to speak so the exhaust wouldnt go left or right and that got rid of the vibration)
I am curious as to if the dampners they send will cure it, if not I will hit them up for an extended warranty if it doesn't for my inconvienance especially on a new truck...We shall see...Later guys

------------------
ecm747x

2001 SUPER CREW XLT, BRIGHT RED
5.4L Triton, automatic 3.55 gears limited slip
tow package
16" tires
side steps
bed extender
ford/duraliner bed liner
60/40 seats
6cd changer
moonroof
sliding rear window

Soon to come Mods...

Adding Super chip, Airaid F.I.P.K. Installing different exhaust, not sure which yet. Front grill guard. With light kit


MODS....
1) Lund x-terminator bug shield

 

Are all these posts related only to a resonant vibration or are some of you experiencing a physical vibration you can feel in th truck. My truck has some resonance at 1900 to 2100 rpm but it is not very loud. I had the exhaust system cut off right at the crossover pipe and put in 2.5 inch pipes with a h-pipe about 6 inches past the crossover. It does have 2 chamber flowmasters so I would expect some increased sound levels, but if the pipes are routed all the way to the back the sound in cab in minimal. Perhaps the weight of the pipes and having the two mufflers welded together took care of the resonance. As far as physical vibration I would be more concerned with the u-joints that ford uses since they cannot be lubricated,ie no grease zerts.

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97 F150
sc, flairside
"SHOWTRUCKS USA" conversion package
2.5" dual exhaust
Flowmasters
K&N filter
Superchip



[This message has been edited by two-tone (edited 11-23-2000).]

 

Hi all,


Well the vibration is about 95% gone. The factory sent another weight to be installed. After driving it around and placing it in several places the vibration was still there but not as bad but still noticable. My truck came with one weight already installed and I took this one and started moving both of them around and finaly got a good combination. The vibration is hardly noticable at all. It can barely be felt at 55, where before the sterring wheel would shake and I could feel it in the seat. SO it has gone away to the point I am satisfied

------------------
ecm747x

2001 SUPER CREW XLT, BRIGHT RED
5.4L Triton, automatic 3.55 gears limited slip
tow package
16" tires
side steps
bed extender
ford/duraliner bed liner
60/40 seats
6cd changer
moonroof
sliding rear window

Soon to come Mods...

Adding AirForce One F.I.P.K. Installing different exhaust, not sure which yet. Front grill guard. With light kit


MODS....
1) Lund x-terminator bug shield
2) Super Chip>>>>Well Worth the Money