FordExcursions.com Forums
rocketmantfj
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• Norwalk, CA, USA |
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• Registered on 8/7/2003 |
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• 5 posts |
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 Posted:11/27/2003 20:02 |
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Hi All,
First of all I love the forum, I've gotten lots of good information so far.
I just made a 700 mile trip from LA to Phoenix & back , the longest drive so far and I love my Ex even more..so do the gas station owners. The mobile living room is so smooth at 85 that I would have sworn I was doing 60.
My question is about a loud sound that only occurs at 90 or above and only with any throttle applied. I ran it all the way to 100mph and the sound is constant as long as I have any throttle applied, the moise disappeared immediately whenever I lifted my foot. Coastdown all the way back to 90 was quiet. The sound is almost a resonance, it doesn't appear to be tire hum or wind noise..I think both would remain once the throttle was lifted. It doesn't sound bad and the revs were still below 3000 so I don't think it was engine roar. Has anyone else run across this?
2003 limited 4x4, stock Firestone tires (still), 6" pro-comp lift, V10, headers, Flowmaster, home made cold air intake & K&N Filter.
Thanks
Rocketmantfj
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Matthew Crump
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• Omaha, NE, USA |
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• Registered on 8/22/2003 |
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• 16 posts |
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Posted:11/29/2003 11:13 |
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David,
My guess would be that you're hearing resonance in the intake assembly. As the throttle plates open all the way in the throttle body, they provide less of a barrier to the individual "pulses" of intake strokes, which can make the plastic of the intake assembly vibrate.
But it's kind of a cool sound anyway, isn't it. . . ?
Matt
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Tom boucher
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• Houston, TX, USA |
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• Registered on 8/27/2003 |
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• 43 posts |
• 1 Vehicle
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Posted:12/11/2003 22:29 |
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Possibly the drive shaft? If you were to drive, and when you hear the sound press your overdrive button to turn it off. You may or may not hear the sound. As the engine changes speed, if the sound is present, then it is not your shaft. If the sound goes away as the tach speed changes during shift, then it could be a shaft issue. Since the shaft is being powered while the pedal is to the metal it "could" be an issue. I am interested to see how it turns out. 
Tom Boucher
1 Wife
Too many kids
AND NOT ENOUGH TRUCKS!!! |
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Weatherlite
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• Mountain Home AFB, ID, USA |
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• Registered on 10/21/2002 |
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• 133 posts |
• 1 Vehicle
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Posted:12/12/2003 09:34 |
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Tom, actually what you're saying is incorrect. While I agree it's possibly a shaft issue you're statement about engine speed versus shaft speed is wrong. Shaft speed is completely independant of engine speed. Shaft speed is directly in proportion to wheel speed.
When you stay at 80MPH but take the OD off, the shaft will still be spinning the axle which then spins the wheels at 80MPH. However, the engine will increase in RPM since the transmission ratio just went from a .71:1 to 1:1. Make sense? Hope so.
Now then...if I remember correctly, one of Gearman's statements may apply here. He said something about it possibly being the torque converter if the vibration went away when you let off of the gas. That makes sense to me as well.
Hope you figure it out!
Mikie |
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monsta
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• The Big Island, HI, USA |
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• Registered on 1/5/2002 |
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• 1,056 posts |
• 2 Vehicles
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Posted:12/12/2003 14:09 |
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I say just don't go 90.
However, you should see if it is an RPM thing or a road speed thing.
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spartan
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• Nashville, TN, USA |
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• Registered on 7/17/2003 |
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• 86 posts |
• 1 Vehicle
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Posted:12/19/2003 11:24 |
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Hard to tell since we can't hear it, but my guess is " body boom " from a slight imbalance of the driveshaft. Lot's of lifted trucks get this at lower speeds. Anywhere from 55 to 75 MPH from mismatching u-joint operating angles and / or not enough spline contact. I had to lengthen my drive shaft 1.5 inches on a 4.5 inch lift to cure this problem. Since your truck is stock I would say it's shaft balance. If you really want to go 90 have your shaft balanced.
2000 XLT Premium, V10, 4.3 LSD Rear, Edge 4.5" Hanger Lift, Landyot Radius Rods, Hellwig Sway Bar, Dual Bilsteins, 295 75 16 Nitto AT's, Billet Grill, Lengthened and Balanced Driveshaft, Hella 450's, Insulated AC Lines, Modified ZooDad, Husky Liners F to B.
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rocketmantfj
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• Norwalk, CA, USA |
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• Registered on 8/7/2003 |
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• 5 posts |
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Posted:12/22/2003 04:20 |
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thanks for all of the feedback. Driveshaft vibration was something that I was concerned about when I added the lift but I haven't felt anything that really feels like a vibration . I think Spartan might be onto something.....I'm not sure "body boom" is a technical term but it comes close to describing the sound.
Could the driveshaft balance / alignment problem be so slight that it doesn't become noticeable until that high of a speed, and only under load? Is this something that will become more apparent as U-joints and other driveline parts chalk up more miles?
I don't make a habit of driving over 90 but the open road lent itself to winding it up a bit to see how it handled. I might not ever get the beast up to 90 again...at least not intentionally. Given that, should I worry about this?
Rocketmantfj
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spartan
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• Nashville, TN, USA |
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• Registered on 7/17/2003 |
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• 86 posts |
• 1 Vehicle
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Posted:12/23/2003 09:19 |
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Oops - I didn't notice the lift in your signature. The term " body boom " is the term used to describe your condition in the lift business. If you have a six inch lift you will need a longer drive shaft. Also check your front and rear u-joint operating angles. They need to match or you will continue to get vibration there. Measure them, then use steel bolt on shims in the rear to match the rear angle to the front. You can do a quick check just by looking at the rear differential. If it is pointing up straight at the drive shaft, it's wrong unless they also installed a double carden drive shaft with the lift. Many, OK let's just say most, four wheel drive shops do this just to get the customer out of the shop without having to do any more work, like shimming and driveshaft mods to do the job right. They don't care if you ruin your u-joints or get vibration from the drive shaft. FYI - you may not feel it, but the u-joints and your drive shaft are vibrating all the time. You only feel and hear it at it's worst.
2000 XLT Premium, V10, 4.3 LSD Rear, Edge 4.5" Hanger Lift, Landyot Radius Rods, Hellwig Sway Bar, Dual Bilsteins, 295 75 16 Nitto AT's, Billet Grill, Lengthened and Balanced Driveshaft, Hella 450's, Insulated AC Lines, Modified ZooDad, Husky Liners F to B.
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Richard Smith
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• Knoxville, TN, USA |
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• Registered on 10/4/2003 |
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• 104 posts |
• 1 Vehicle
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Posted:1/4/2004 21:34 |
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David, I have 2003 EX V-10 with 7000 miles. Up until now my only complaint was the weak brakes - which I improved greatly with PFC pads. Now I have found an annoying "resonance" sound 1st at 47 to 51 MPH noticable but not to objectional - I can adjust my speed to get out of it. However, this past saturday I went on a 300 mile trip on the Interstate and traffic was really moving so I wandered up to 75, then 80 MPH. Guess what right at 76 or so this "resonance" started and only got louder as speed increased. It sounded like something was going to let go, so I backed off.
In OD it started at about 2200 RPM (3.73 axle). I turned off the OD and the "resonance" occurred at the same speed but at 2900 RPM. I guess this rules out engine/trans/converter but not the rear axle or driveshaft. Has anyone fixed this problem by balancing the driveshaft? Did you put in different U-joints??
Thanks for listening. Love my white EX, Richard from Knoxville, Tn[quote] |
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spartan
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• Nashville, TN, USA |
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• Registered on 7/17/2003 |
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• 86 posts |
• 1 Vehicle
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Posted:1/8/2004 23:23 |
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Same thing - " body boom " from driveshaft imbalance. Excursions suffer from this phenomenom routinely. Mine did, yours does, it's no mystery. Fix it and move on. If you can't fix it drive 75 MPH or less and be safe. Your brakes aren't suitable for cruising faster than that any way.
2000 XLT Premium, V10, 4.3 LSD Rear, Edge 4.5" Hanger Lift, Landyot Radius Rods, Hellwig Sway Bar, Dual Bilsteins, 295 75 16 Nitto AT's, Billet Grill, Lengthened and Balanced Driveshaft, Hella 450's, Insulated AC Lines, Modified ZooDad, Husky Liners F to B.
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