Hello, my name is Derek and i am an active member on a few Ford panther platform forums, specifically
www.CrownVic.net.
I made the following post on an off-topic forum there, but another member reffered me to this site and to one of your members, AGNEM.
Here is a copy/paste of the problem, I hope this is the correct forum for this as I am seeing mainly engine-specific threads.
Ok, I am not quite sure how to describe this;
Ever since my father purchased this truck new (a 1994 f-450 cab/chassis, Steel dumping bed, 7.3l IDI Diesel) it seems to have an intermittent violent shake when the front end suddenly hits a depression or bump in road. It first started developing at around 1000 miles. THe entire truck shakes incredibly violently, it is very hard to describe but if you were to experience it, you would think you are about to die in the damn thing. It feels like a wheel is falling off or like the tie-rods have just fallen out. The force of the shaking transmits into a violent shake throughout the whole truck. The shaking is exhibited through the steering wheel, and any steering input is useless. Both hands need to be firmmmmmly grasped on the wheel or the truck will try and loose control. You can see it occuring when following or driving in fornt of the truck, looks like it will loose control any second. It won't stop doing it until the truck's speed is brought below 10mph, it appears to be self-perpetuating. It will occur more often/more violently with the more weight added to the truck. It will happen at any speed above ~10mph, including highway speeds. The faster the truck is moving the more severe as well, when it occurs on a rough highway you'd think the frame is about to snap thats how rough it is. You can feel it right before it will start to do it in the steering wheel, which we have learned since to promptly slow the truck down as fast as possible. It has gone into multiple dealers and private mechaincs numerous times to tryand remedy but no-one can figure it out. THe service manager at one of the dealers was a woman, and after she test drove it she returned looking very disturbed. She descibed it as the scariest thing that has every happened to her, and that she thought she was about to die
She had everyhting they thought could possibly cause it, without loosing her job.
At first it was deemed a brake system issue, all the calipers, rotors, brake lines, pads, master cylinder, hydro-booster, and power steering pump and hoses were replaced. Many of which multiple times, with no avail. THe rear end was checked as a possible cause (5.13 geared Dana 80) and was replaced to eliminate possibility. Over the years, both front and rear leaf springs, swaybars/endlinks/bushings, shocks and various suspension bushings, and ALL steering components were changed as well, nothing seems to solve this
THe truck has been inspected countless times, no-one spots anything unusual.
We have made several inquires about this, we have found a few reports of similar occurances, only in trucks with the 7.3l diesel. 2 mentioned sway bar replacement solved it, however we have already had them both replaced. It is obviously weight related to the heavy 7.3, I think it is suspension related as the steering is very tight under normal operation ...But i can't isolate any better than anyone else who has tried. I would like to upgrade the swaybars to the largest ones I can find, as fars as OEM goes these are the biggest, anyone know if there is an aftermarket set available? Also, anyone know if ENS makes poly bushings and endlinks for this thing?
The truck has less than 75000 miles, and was not used for much work during this time due to concerns. THis truck may just be cursed, as it is on IIRC its 4th transmission now, 2nd rear end, 3rd or 4th set of calipers with double that in rotor sets, an overall PITA headache. The only thing that has been absolutely trouble free is the engine and cooling systems, though at its mileage a diesel is hardly even broken in. I take that back, it did need new valve cover gaskets ;P THe eterior and interior are mint condition, as it wasn't even really used much and maintained exceptionally well. You think it would show us a little more respect ;P
This problem does not occur on any of our other f-450s, including my 96 f-450 which, suspension-wise, is virtually indentical. His truck and mine are the two lowest-mileage trucks in our fleet (mine has only ~22k, his ~73k)
I appreciate any help or suggestions you guys may have, and am hapy to be a new member on OilBurners.net
