ASE tech info wanted
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Junior User
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ASE tech info wanted
I was hoping an ASE certified tech, of which I'm sure there are some here, could tell me if it is normal for a Heavy duty truck (8500-11500gvw) truck to bounce and hop up and down as Ford's tsb states as follows:
Some 2005-2007 F-Super Duty vehicles with a long wheelbase of 156", 158", or 172" (396, 401, or 437 cm) and equipped with a trailer hitch may exhibit a vehicle vertical vibration, often described as "hopping", on smooth or coarse road surfaces in the 42-48 MPH (68-77 Km/h) speed range. Although this behavior is considered normal for an over 8500 GVW truck, some customers may be sensitive to the concern.
My question is if that is truly a normal characteristic of a truck that costs 50k, or if it is a cover up because Ford can't or won't fix a problem that is existing on 1 in 10 superduties.
Thanks in advance
Some 2005-2007 F-Super Duty vehicles with a long wheelbase of 156", 158", or 172" (396, 401, or 437 cm) and equipped with a trailer hitch may exhibit a vehicle vertical vibration, often described as "hopping", on smooth or coarse road surfaces in the 42-48 MPH (68-77 Km/h) speed range. Although this behavior is considered normal for an over 8500 GVW truck, some customers may be sensitive to the concern.
My question is if that is truly a normal characteristic of a truck that costs 50k, or if it is a cover up because Ford can't or won't fix a problem that is existing on 1 in 10 superduties.
Thanks in advance
Post Fiend
Joined: May 2006
Posts: 10,007
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From: Central Florida
I am not an ASE mechanic, but I have played with some heavier equipment. The more weight they can handle the stiffer the suspension. Shocks can usually help, but Ford may not want to come up with a new valving for a non-safety related TSB.
although, because they specify with a hitch, I am thinking there might be an aerodynamic issue. If your not using your hitch, it would be interesting to see if the problem goes away when the hitch is removed.
although, because they specify with a hitch, I am thinking there might be an aerodynamic issue. If your not using your hitch, it would be interesting to see if the problem goes away when the hitch is removed.
Logistics Pro
Joined: Mar 2002
Posts: 3,881
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From: Wake Forest, NC
They are most likely noticing problems on the long wheel base with hitches because it stiffens up the rear frame. It is probably some kind of harmonic vibration. Yes I can see it happening, though I've never experienced it. With such a limited mph range and limited number of trucks it probably is a case of not wanting to try and eliminate it. However, because trucks have stiffer suspensions, I would assume it isn't unlikely to notice some sort of harmonic type vibration.
Logistics Pro
Joined: Mar 2002
Posts: 3,881
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From: Wake Forest, NC
Since I don't know exactly the type of "hopping" is going on I may suggest different shocks, or that vibration damper. Ford seems to always be big on those vibration dampers, they put them everywhere on trucks and cars in the past.
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Junior User
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I have another thread under "2006 super duty vibration" that kind of sums up my problems with the hop. I have tried everything under the sun: vibration dampener, new tires, new driveshaft, shimming carrier with all shims ford makes, etc. All to no avail. Now I am told it is an unfixable problem, and that it is normal. I am having a hard time believing it is normal for a truck to bounce, and think it is a common response as they dont know a fix for these or it may be too expensive to really deal with the issues. This is the reason I was interested in expert opinion from some guys if they are or have heard of this being a common issue on trucks in general (Chevy, Ford, Dodge) in this size category.
Senior User
Joined: Jul 2006
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From: Deep South Louisiana
The heavy suspension is the culpret. Does it bounce or vibrate while pulling a load? Most ride smoothe as a car when loaded down, mine does. Also I have exparience pulling hot shot and unloaded 1.5 tons do it worst! Dump trailers will bounce until the wheels come off the road... A lot of roads develop a washboard over time and it is very slight but that usually starts it going. I think it has something to do with physics...
I am a ASE masther tech but I think this has more to do with physics in which case you need to call on the scientiests in the community LOL
I am a ASE masther tech but I think this has more to do with physics in which case you need to call on the scientiests in the community LOL
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FTE Leadership Emeritus
Joined: Sep 2000
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From: Stephensville WI
I also think it is a harmonic issue, since it only happens at a specified speed range.
I would try removing your trailer hitch. That should change the harmonic frequency of the frame enough that it won't bounce at the specified speed range. If that cures the problem, you at least no what to attack.
One owner reported on the other thread that the installation of a 5th wheel hitch made the problem go away. While it was speculated that the weight helped, I think it was the additional cross member of teh 5th wheel hitch changing the harmonic frequency of the frame rails that actually did the trick.
I would try removing your trailer hitch. That should change the harmonic frequency of the frame enough that it won't bounce at the specified speed range. If that cures the problem, you at least no what to attack.
One owner reported on the other thread that the installation of a 5th wheel hitch made the problem go away. While it was speculated that the weight helped, I think it was the additional cross member of teh 5th wheel hitch changing the harmonic frequency of the frame rails that actually did the trick.
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Junior User
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The heavy suspension is the culpret. Does it bounce or vibrate while pulling a load? Most ride smoothe as a car when loaded down, mine does. Also I have exparience pulling hot shot and unloaded 1.5 tons do it worst! Dump trailers will bounce until the wheels come off the road... A lot of roads develop a washboard over time and it is very slight but that usually starts it going. I think it has something to do with physics...
I am a ASE masther tech but I think this has more to do with physics in which case you need to call on the scientiests in the community LOL
I am a ASE masther tech but I think this has more to do with physics in which case you need to call on the scientiests in the community LOL
FTE Leadership Emeritus
Joined: Jul 2002
Posts: 42,561
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From: Long Island USA
Change the shocks. In a case like this, I'd get an adjustable shock like the Rancho 9000x's, and play with it until it goes away.
It does sound like a harmonic - and how do we deal with harmonics? Hydraulic dampers. Otherwise known as shocks
If the thing is really doing that bouncing in the rear with a load, a heavy shock should tame it right down.
The problem is, Ford doesn't have a shock heavy enough to dampen it
It does sound like a harmonic - and how do we deal with harmonics? Hydraulic dampers. Otherwise known as shocks
If the thing is really doing that bouncing in the rear with a load, a heavy shock should tame it right down.
The problem is, Ford doesn't have a shock heavy enough to dampen it
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Junior User
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Thanks for the input, I will continue to work on it myself, enen though it is under warranty, as I will not sit and tolerate it like others have learned to do. It is quite annoying and embarrasing to take passengers in the "Jack Rabbit". I think that's what I'll start calling her. Been trying the driveshaft weights discussed earlier, and working with tire pressures but no luck yet. Maybe shocks next, it currently has the stock ranchos that come with the fx4 kit.
Thread Starter
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Junior User
Joined: Jan 2008
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The heavy suspension is the culpret. Does it bounce or vibrate while pulling a load? Most ride smoothe as a car when loaded down, mine does. Also I have exparience pulling hot shot and unloaded 1.5 tons do it worst! Dump trailers will bounce until the wheels come off the road... A lot of roads develop a washboard over time and it is very slight but that usually starts it going. I think it has something to do with physics...
I am a ASE masther tech but I think this has more to do with physics in which case you need to call on the scientiests in the community LOL
I am a ASE masther tech but I think this has more to do with physics in which case you need to call on the scientiests in the community LOL
FTE Leadership Emeritus
Joined: Jul 2002
Posts: 42,561
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From: Long Island USA
You could have a bad shock - maybe you can get them to replace them before spending your own money - although the time to get it to the dealer to be worked on is always a killer for me - I'd rather spend up to $300 than bring it to the dealer, because of the wasted time.
The FX4 shocks are a joke - they are probably not helping.
I gotta say, in my opinion, it's not "normal".
But it wouldn't be the first time, nor the last, that a dealer (of ANY brand!) figures out a way to say "no".
The FX4 shocks are a joke - they are probably not helping.
I gotta say, in my opinion, it's not "normal".
But it wouldn't be the first time, nor the last, that a dealer (of ANY brand!) figures out a way to say "no".
Thread Starter
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Junior User
Joined: Jan 2008
Posts: 57
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You could have a bad shock - maybe you can get them to replace them before spending your own money - although the time to get it to the dealer to be worked on is always a killer for me - I'd rather spend up to $300 than bring it to the dealer, because of the wasted time.
The FX4 shocks are a joke - they are probably not helping.
I gotta say, in my opinion, it's not "normal".
But it wouldn't be the first time, nor the last, that a dealer (of ANY brand!) figures out a way to say "no".
The FX4 shocks are a joke - they are probably not helping.
I gotta say, in my opinion, it's not "normal".
But it wouldn't be the first time, nor the last, that a dealer (of ANY brand!) figures out a way to say "no".
Senior User
Joined: Dec 2006
Posts: 366
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From: Rhode Island
My 2008 will set up with a slight bouncing feeling at about 42mph. It is a small speed window that it occurs in, I'd say 42-44 mph. At first I thought it was my torque converter continually locking and unlocking or a driveshaft needing to be balanced. After reading a previously posted tsb I gave up on solving the problem. Now I just speed up or slow down to avoid it.