Morning All!
I consider myself a pretty decent wrench but have something strange going on that me and a couple of other full time mechanics have never seen. Need some help, thoughts, ideas from the experts!
Truck is a '00, 2 wheel drive, Supercab, 7.3, one owner (me) with 148k on the clock. Truck doesn't get drove much, maybe 1~2k a year, but when I need her, I need her. Truck has never been in any shop except for tires and front end inspection. I have done all work myself so I know it's done correctly. (trust issues with my vehicles)
Background: Tires, wheels, U-joints, center carrier bearing, all replaced about 4k ago. At the same time, the entire brake system was replaced EXCEPT hard lines, master cylinder and ABS pump. Speaking of which, this truck has 4 wheel ABS. During brake system rebuild, all front wheel bearings, seals and such were replaced. All parts were high quality, Spicer, Moog, Motorcraft. Brake parts were all Power Stop with slotted and drilled rotors all around. At this time, front end was inspected and the only other part with wear was the sway bar bushings. Those and the end links were replaced also.
Now the problem: Started last Wednesday, on the way to hardware store all was normal. When I started the trip home, started feeling a vibration at about 45 mph. When I slowed for a turn, vibration continued but felt like more of a pulsing than a vibration, even without brake applied. Continued toward home and when I went to slow down for turn into the road I live on (55 mph to 0), truck almost went into the dreaded Ford Death Wobble (very familiar with this!). Driving slowly down the road home, 15-20 mph, it almost felt like a seriously warped rim or someone pulsing the brakes. The slower I drove, the more pronounced it was. No noise, nothing else different. Hmmm, I have to check this thing out....
Fast forward to Saturday morning. Took truck out and around the block, almost 10 miles where I live. No evidence of any vibration, pulling or anything out of the normal. Get truck in my shop and check tire pressure, all good. Jack up front end, everything rolls smoothly, no calipers dragging, no unusual loose motion anywhere I can tell. Ok, I'll drive it this afternoon on errands...
Drove close to 60 miles Saturday afternoon, on road, in town, speeds from 15 to 70 mph without one hint of an unusual vibration. Then, I'm heading home from my last stop, traveling at about 60 mph, had to slow for a car, did not apply brakes but when speed dropped thru the 45 mark, vibration started back and continued the 15 mile trip home. Vibration would diminish a little at around 50 and would get worse as I slowed. Same thing, at real slow speeds, felt like brakes pulsing or something trying to bind up then release. Made it home and parked, scratching my head.
Got up Sunday morning and thought "what the he!!" drove the truck to breakfast, about 25 miles RT and not one ounce of vibration anywhere!
I should mention when it starts this, it seems like the front end wants to pull left. However, our roads around here are so screwed up, it's hard to tell!
Thoughts, Ideas, Suggestions??? I have a good front end shop and plan to take it to them the first opening they have. Still not convinced it's in the front end though. Is there any way the ABS unit could cause this behavior?
Thanks in advance!
I consider myself a pretty decent wrench but have something strange going on that me and a couple of other full time mechanics have never seen. Need some help, thoughts, ideas from the experts!
Truck is a '00, 2 wheel drive, Supercab, 7.3, one owner (me) with 148k on the clock. Truck doesn't get drove much, maybe 1~2k a year, but when I need her, I need her. Truck has never been in any shop except for tires and front end inspection. I have done all work myself so I know it's done correctly. (trust issues with my vehicles)
Background: Tires, wheels, U-joints, center carrier bearing, all replaced about 4k ago. At the same time, the entire brake system was replaced EXCEPT hard lines, master cylinder and ABS pump. Speaking of which, this truck has 4 wheel ABS. During brake system rebuild, all front wheel bearings, seals and such were replaced. All parts were high quality, Spicer, Moog, Motorcraft. Brake parts were all Power Stop with slotted and drilled rotors all around. At this time, front end was inspected and the only other part with wear was the sway bar bushings. Those and the end links were replaced also.
Now the problem: Started last Wednesday, on the way to hardware store all was normal. When I started the trip home, started feeling a vibration at about 45 mph. When I slowed for a turn, vibration continued but felt like more of a pulsing than a vibration, even without brake applied. Continued toward home and when I went to slow down for turn into the road I live on (55 mph to 0), truck almost went into the dreaded Ford Death Wobble (very familiar with this!). Driving slowly down the road home, 15-20 mph, it almost felt like a seriously warped rim or someone pulsing the brakes. The slower I drove, the more pronounced it was. No noise, nothing else different. Hmmm, I have to check this thing out....
Fast forward to Saturday morning. Took truck out and around the block, almost 10 miles where I live. No evidence of any vibration, pulling or anything out of the normal. Get truck in my shop and check tire pressure, all good. Jack up front end, everything rolls smoothly, no calipers dragging, no unusual loose motion anywhere I can tell. Ok, I'll drive it this afternoon on errands...
Drove close to 60 miles Saturday afternoon, on road, in town, speeds from 15 to 70 mph without one hint of an unusual vibration. Then, I'm heading home from my last stop, traveling at about 60 mph, had to slow for a car, did not apply brakes but when speed dropped thru the 45 mark, vibration started back and continued the 15 mile trip home. Vibration would diminish a little at around 50 and would get worse as I slowed. Same thing, at real slow speeds, felt like brakes pulsing or something trying to bind up then release. Made it home and parked, scratching my head.
Got up Sunday morning and thought "what the he!!" drove the truck to breakfast, about 25 miles RT and not one ounce of vibration anywhere!
I should mention when it starts this, it seems like the front end wants to pull left. However, our roads around here are so screwed up, it's hard to tell!
Thoughts, Ideas, Suggestions??? I have a good front end shop and plan to take it to them the first opening they have. Still not convinced it's in the front end though. Is there any way the ABS unit could cause this behavior?
Thanks in advance!