What causes DEATH WOBBLE ?????? - Page 2 - Diesel Forum - TheDieselStop.com
7.3L IDI Diesels (Not Power Strokes) Technical discussion of topics related to vehicles powered by the 7.3 Liter In-Direct Injection Navistar engines.

Reply
 
LinkBack Thread Tools Display Modes
post #16 of 26 (permalink) Old 08-06-2018, 12:11 PM
Junior Member
 
Join Date: Oct 2012
Posts: 29
My Photos: (0)
Feedback Score: 0 reviews
I have a 2000 model with 7.3 2wd. I wonder if this death wobble is the result of worn components or if it is what is causing the components to wear. Can't figure mine out. At the dealership now waiting to speak again with the mechanic working on my truck. My pressures are run at 60 psi. Ford calls for 55 on the fronts. By raising the pressure to the max for the tire (mine is 80psi also) do you think this will fix it?
tretpflyr is offline  
Sponsored Links
Advertisement
 
post #17 of 26 (permalink) Old 08-06-2018, 02:29 PM
Senior Member
 
Join Date: Nov 2008
Location: Salina, Kansas
Posts: 1,537
My Photos: (0)
Feedback Score: 0 reviews
Quote:
Originally Posted by tretpflyr View Post
I have a 2000 model with 7.3 2wd. I wonder if this death wobble is the result of worn components or if it is what is causing the components to wear. Can't figure mine out. At the dealership now waiting to speak again with the mechanic working on my truck. My pressures are run at 60 psi. Ford calls for 55 on the fronts. By raising the pressure to the max for the tire (mine is 80psi also) do you think this will fix it?
Look for loose tie rods, strut bushnigs, I-beam bushings, and ball joints. All of these things can cause the death wobble, as well as tires.

1993 F-350 crew cab non-turbo 5 speed transmission
35 years a mechanic on large stationary engines natural gas and diesel fired, and other industrial equipment.
oldrebuiltdodge is offline  
post #18 of 26 (permalink) Old 08-19-2018, 07:45 PM
Member
 
Join Date: May 2017
Location: Huntsville, AR
Posts: 50
My Photos: (0)
Garage
Feedback Score: 0 reviews
i dont know if your still needing it but this is a video that might help.
DevilDog6154 is offline  
Sponsored Links
Advertisement
 
post #19 of 26 (permalink) Old 08-19-2018, 11:51 PM
Junior Member
 
Join Date: Jun 2018
Posts: 2
My Photos: (0)
Feedback Score: 0 reviews
Read my previous post. After many searches, I have concluded many things can cause it. Ford suggests 55psi for a soft ride so they can sell more trucks (make the ride more comfortable). My front tires psi is 78 and I won't go lower.
gb23 is offline  
post #20 of 26 (permalink) Old 08-25-2018, 11:17 AM
Junior Member
 
Join Date: Oct 2012
Posts: 29
My Photos: (0)
Feedback Score: 0 reviews
I will follow your advice. Update. Took it to dealer for front end alignment and they found worn tie rods and joints as well as "fasteners".
I told them it might be that drag bar but they said no. I rest drove it then took it back because there was a bolt missing underneath that they forgot to put back in! Pic attached. After all day yesterday they admitted to me that they can not get it to align, must be drag bar. They are going to keep it for another week.

Oops, can't post pic, using iPad. Can't drag and drop.
tretpflyr is offline  
post #21 of 26 (permalink) Old 08-25-2018, 11:18 AM
Junior Member
 
Join Date: Oct 2012
Posts: 29
My Photos: (0)
Feedback Score: 0 reviews
Running 60 in mine.
tretpflyr is offline  
post #22 of 26 (permalink) Old 09-16-2018, 03:59 PM
Junior Member
 
Join Date: Sep 2018
Posts: 1
My Photos: (0)
Feedback Score: 0 reviews
I had this happen on my 2 w/d f250 7.3 and mine seems to have been caused by bad tires and I had a large bracket that was cracked and separated that attaches to the frame. Had both replaced and it never happened again. Good luck Hope you find your problem.
Rhonda Knight is offline  
post #23 of 26 (permalink) Old 09-17-2018, 11:01 AM
Junior Member
 
Join Date: Oct 2012
Posts: 29
My Photos: (0)
Feedback Score: 0 reviews
Ford dealership used an aftermarket part (drag link?) that did not work out too well so they got the original Ford part in there and problem mostly solved. I am installing a new red head gear box that will correct for the loose steering and then the fix will be in. Thanks, y'all have helped a lot.
tretpflyr is offline  
post #24 of 26 (permalink) Old 09-17-2018, 08:24 PM
Senior Member
 
Join Date: Dec 2002
Location: Central Alabama, USA
Posts: 2,094
My Photos: (0)
Feedback Score: 0 reviews
OK, I haven't answered this question in a long time. I will once more for those that are interested in understanding "cause" not treatment of symptoms. So far everyone is wrong and claiming that treating this or that symptom solved the problem, it did not it just moved it from a diagnostic perspective.
The issue is lack of stiffness, low mass, low energy degradation system and a phenomenon called resonance. Given enough source force impact any assembly can be made to resonate energy at its natural frequency or the net natural frequency of multiple assemblies mated together, system natural frequency. An object being impact resonated will act as a force multiplier of 10 to 50 x the source force. Given enough force some assemblies will maintain this system of vibration energy with a very low continuing source force after the starting impact. In the vibration diagnostic business that is called locked resonance. Once a vibrating system is created very little energy is needed to keep it going like swinging a child on a swing, the major energy required is starting the system to vibrate, then just a small cyclic push will keep it swinging. That is why some report that they hit a pot hole, a RR track, a curb or ran it with severely unbalanced tires and had to come to a complete stop to eliminate the shaking. The follow on source force didn't have to be as severe as the big starting impact to support the vibrating system.
Some things make it make likely, mechanical looseness, front end mods like bigger tires, bad steering dampers, and unbalanced tires. That's the cause, but its a problem that has to be managed by symptoms or peripheral parts. You cant change the "cause" physics, it is induced resonance amplitude. Think of a bell, impact it and it acts as a resonating force multiplier. Sure , you can dampen in but given enough source force it WILL resonate. Oneof6

2002 F250 7.3L PSD, bought new now at 226K miles, 4R100 Auto, Crew Cab, Short Bed, ITP Regulated Fuel Return system, ITP head to head SS oil cross over, Hutch in tank mod
Harpoon de tank vent, DIESELSITE Dahl 100 Pre-Pump Fuel Filter, DIESELSITE Return Fuel Line Cooler, DIESELSITE Engine Coolant Filter, DIESELSITE Auxilliary Transmission Cooler, DIESELSITE Gage Package, Pyro, Trans & Boost, Extreme Diesel AD injectors, Ford AIS Air Filter System, BTM straight through muffler, Moog Ball Joints, Rancho Shocks, Rotella ELC Coolant ,Stock Engine Program
Modified for I-Pod Connection
We b playing Scotland The Brave to Jimmy Hendrix
Oneof6 is offline  
post #25 of 26 (permalink) Old 09-17-2018, 09:37 PM
Lifetime Supporting Member
 
ArcticDriver's Avatar
 
Join Date: Apr 2015
Location: Longmont, CO
Posts: 3,616
My Photos: (0)
Feedback Score: 0 reviews
Does this mean inside every Powerstroke there is a “Death Wobble” lying in wait for the opportune moment to strike?


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
2002 F-250 4x4 CC SB 7.3 PSD w/4R100. 182,000 miles.
NOS Black CPS. ScanGauge-II, AIC, Bilstein 5100, Stancor GPR, Marinco Mod, B&W Turnover Ball, Michelin Defender LTX


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
2002 F-250 4x4 SC LB 7.3 PSD w/ZF-6. 177,000 miles.
NOS Black CPS. ScanGauge-II. Bilstein 5100. Noco Mod. Michelin Defender LTX 285/75/16.

SOLD:
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
2000 F-250 4x4 SC SB 7.3 PSD w/4R100. 164,000 miles.
NOS Black CPS. Rebuilt Fuel bowl w/gold spring, 6.0 Cooler, Walker BTM, Stancor GPR, Michelin LTX M&S2.
ArcticDriver is offline  
post #26 of 26 (permalink) Old 09-18-2018, 07:55 AM
Senior Member
 
Join Date: Dec 2002
Location: Central Alabama, USA
Posts: 2,094
My Photos: (0)
Feedback Score: 0 reviews
The potential for impact induced vibration is not limited to Fords, Power PSD or any particular vehicle. Some front end assemblies damp, resist acceleration forces, more than others. Others like old Jeep front ends and trucks with leaf spring loaded steering assemblies. Sometimes one can move the point of resonant frequency to a frequency it is less likely to be resonated by adding mass, which lowers the frequency, or stiffening which raises the frequency. The target should be having the system natural frequency 25 to 40 % higher than the expected excitation frequency for units running below first critical. So the answer to your question is yes but no more than any object impacted in its operation. One can't remove the potential for natural frequency excitation one can only build a machine where the natural frequencies of individual parts and net assemblies are unlikely to be resonated during normal operation. Much preventative Engineering goes into rotors and assemblies like turbines, power plant fans, fluid drives and heavy equipment. Testing called "Bump Testing" is even done on large foundations when there is a suspected resonant condition that will coincide with the machines rotational frequency. That is cause, what owners are calling here "Death Wobble" is the effect and the solution is to not shade tree Engineer mechanism mods with man years of Engineering in them and expect no negative resultant. Front ends are not maintenance free, they can't have points of mechanical looseness, keep the tires balanced, preferably with a Hunter Force Balancer, a good steering damper and stick with stock tire sizes, that's what the assembly was Engineered for. Oneof6

2002 F250 7.3L PSD, bought new now at 226K miles, 4R100 Auto, Crew Cab, Short Bed, ITP Regulated Fuel Return system, ITP head to head SS oil cross over, Hutch in tank mod
Harpoon de tank vent, DIESELSITE Dahl 100 Pre-Pump Fuel Filter, DIESELSITE Return Fuel Line Cooler, DIESELSITE Engine Coolant Filter, DIESELSITE Auxilliary Transmission Cooler, DIESELSITE Gage Package, Pyro, Trans & Boost, Extreme Diesel AD injectors, Ford AIS Air Filter System, BTM straight through muffler, Moog Ball Joints, Rancho Shocks, Rotella ELC Coolant ,Stock Engine Program
Modified for I-Pod Connection
We b playing Scotland The Brave to Jimmy Hendrix
Oneof6 is offline  
Sponsored Links
Advertisement
 
Reply

  Diesel Forum - TheDieselStop.com > Ford Diesels > 7.3L IDI Diesels (Not Power Strokes)

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Diesel Forum - TheDieselStop.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome