Pulsating vibration
Cargo Master
Joined: Dec 2008
Posts: 3,221
Likes: 323
From: SW PA
Not proportional to engine RPM would indicate something being driven, not driving.
Laughing Gas
Joined: Nov 2013
Posts: 1,207
Likes: 60
From: S.E. Louisiana;so far USA
Laughing Gas
Joined: Apr 2018
Posts: 1,244
Likes: 12
I recently got my truck aligned and they spun the castle nut holding the drag link and tie rod together completely stripping it (Of course, they said nothing to me). I had a weird vibration/bounce, and looked under to see that nut was completely loose. Getting a new nut and torquing it down fixed it. Maybe something like that?
Maybe a u-bolt nut has come loose on your rear end? When I was trying to diagnose my problem, I read where someone's u-bolts were slightly loose and they rubbed right through the rear axle.
Maybe a u-bolt nut has come loose on your rear end? When I was trying to diagnose my problem, I read where someone's u-bolts were slightly loose and they rubbed right through the rear axle.
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Posting Guru
Joined: Nov 2011
Posts: 1,302
Likes: 5
From: Burlington, WI
I will be sure to check out the U bolts when i pull the axles out to replace the wheel bearings back there. They're original, they've got a bunch of miles on them and new ones are cheap. Seems worthy of replacement to me!
Everything in the steering linkage and such is tight and good. All the cotter pins and nuts are still in place and nothing moves or jiggles when I shake them.
Also yes, I cannot drive out of it like you would if you have a bad tire. 55mph on up it has it, and the timing/feeling of the pulsating never changes. Some days it's more prominent than others, but that's just about it.
Everything in the steering linkage and such is tight and good. All the cotter pins and nuts are still in place and nothing moves or jiggles when I shake them.
Also yes, I cannot drive out of it like you would if you have a bad tire. 55mph on up it has it, and the timing/feeling of the pulsating never changes. Some days it's more prominent than others, but that's just about it.
Laughing Gas
Joined: Apr 2018
Posts: 1,244
Likes: 12
It does sound like it is something other than the driveline side. Out of curiosity though, have you tried getting it up to speed, putting it in neutral, and letting it coast to see if there is any change in the pulsation?
Laughing Gas
Joined: Jan 2018
Posts: 898
Likes: 70
From: Coos Bay
If you never had an alignment maybe its time. Should be done anyway and at least that can be ruled out. I see rigs that look like they're crab-walking all the time and wonder how it feels, if theres vibrations or odd sensations in the handling.
other thing is maybe go to local tire/suspension place and just have them do a “shake down”. Most times its free and honestly, sometimes its good to have a fresh set of eyes look over what we’ve looked at.
other thing is maybe go to local tire/suspension place and just have them do a “shake down”. Most times its free and honestly, sometimes its good to have a fresh set of eyes look over what we’ve looked at.
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Posting Guru
Joined: Nov 2011
Posts: 1,302
Likes: 5
From: Burlington, WI
No shops around me will align a truck with twin I beam suspension. The most they'll do it toe. I did that much in my driveway with a tape measure.
I have tried putting it in neutral while driving. It does not change it at all. That's what leads me to believe it's something "rolling". I guess I'll see what the rear bearings look like when I break open the rear end.
I have tried putting it in neutral while driving. It does not change it at all. That's what leads me to believe it's something "rolling". I guess I'll see what the rear bearings look like when I break open the rear end.
Laughing Gas
Joined: Jan 2018
Posts: 898
Likes: 70
From: Coos Bay
Since you mention that, my 2002 had a hum from the rear above 40. Didn’t matter if on throttle, off throttle, or in neutral. Come to find out, The bearing made a slight groove on the axle shaft where they touch. I got a repair bearing and it solved that issue.
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Posting Guru
Joined: Nov 2011
Posts: 1,302
Likes: 5
From: Burlington, WI
Well that would suck! I will be ordering the parts to do a rear end rebuild pretty soon here. It's been kinda cold up here lately and my garage isn't heated (or very big), so working on this thing can be a real slow kind of process! I also plan to rebuild the trans some time this winter as well, just to rule the rotating torque converter out of the equation (plus to fix the annoying front pump leak).
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Posting Guru
Joined: Nov 2011
Posts: 1,302
Likes: 5
From: Burlington, WI
Well everyone I'm back. I hate seeing/leaving threads open ended, so I figured I'd hopefully wrap this one up.
First off, the rear end was *much* worse than I thought. The left wheel bearing had a good amount of up/down play, the differential side bearings were shot and my trac-loc clutches were toasted to a black crisp. Shafts look fine, gears and such look fine so they are being re-used. I'll likely run 80w90 or so in it with some Motorcraft limited slip additive to keep is happy again. For the outer wheel bearings I ordered two Timken SET20 bearing sets to replace the worn out tapered and ball bearings I had.
I also found one of my newer tires from 2018 has some large gashes/splits in the tread as well!
Of course now I had to take the opportunity to pull the trans and rebuild it since it's clutches decided to take a trip to the pan back in November before I parked it.
At least now this driveline will be better than new!
First off, the rear end was *much* worse than I thought. The left wheel bearing had a good amount of up/down play, the differential side bearings were shot and my trac-loc clutches were toasted to a black crisp. Shafts look fine, gears and such look fine so they are being re-used. I'll likely run 80w90 or so in it with some Motorcraft limited slip additive to keep is happy again. For the outer wheel bearings I ordered two Timken SET20 bearing sets to replace the worn out tapered and ball bearings I had.
I also found one of my newer tires from 2018 has some large gashes/splits in the tread as well!
Of course now I had to take the opportunity to pull the trans and rebuild it since it's clutches decided to take a trip to the pan back in November before I parked it.
At least now this driveline will be better than new!
Laughing Gas
Joined: Jan 2016
Posts: 828
Likes: 66
From: Hartford, WI
Glad it seems like you have it diagnosed and getting it back in order!
LOL! Burlington, WI and Hwy83 shows in the picture. I’m North of you. Take 83 North up to Hartford, WI and I’m like 5 minutes West of town. About an hour away from ya. I’ve got a 77 SB 4x4 F150 and I stuck a 460 in it out of a 77 F350 2wd. Would live to find a clean 77 F150 or 250 or 350 2wd drive truck to play with as well. Your truck is nice looking!
LOL! Burlington, WI and Hwy83 shows in the picture. I’m North of you. Take 83 North up to Hartford, WI and I’m like 5 minutes West of town. About an hour away from ya. I’ve got a 77 SB 4x4 F150 and I stuck a 460 in it out of a 77 F350 2wd. Would live to find a clean 77 F150 or 250 or 350 2wd drive truck to play with as well. Your truck is nice looking!
Lead Driver
Joined: Nov 2000
Posts: 6,637
Likes: 349
From: Albuquerque
Thanks for the post. I also have a 77 Jade Green metalic truck with the same kind of problem not servere at all but irritating. Every thing has been gone through including the entire rear end but not lately. Anyone have a good way to check the axel bearings without pulling the axle out? I wonder if the bearing seat in the housing might be worn till loose.
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Posting Guru
Joined: Nov 2011
Posts: 1,302
Likes: 5
From: Burlington, WI
Glad it seems like you have it diagnosed and getting it back in order!
LOL! Burlington, WI and Hwy83 shows in the picture. I’m North of you. Take 83 North up to Hartford, WI and I’m like 5 minutes West of town. About an hour away from ya. I’ve got a 77 SB 4x4 F150 and I stuck a 460 in it out of a 77 F350 2wd. Would live to find a clean 77 F150 or 250 or 350 2wd drive truck to play with as well. Your truck is nice looking!
LOL! Burlington, WI and Hwy83 shows in the picture. I’m North of you. Take 83 North up to Hartford, WI and I’m like 5 minutes West of town. About an hour away from ya. I’ve got a 77 SB 4x4 F150 and I stuck a 460 in it out of a 77 F350 2wd. Would live to find a clean 77 F150 or 250 or 350 2wd drive truck to play with as well. Your truck is nice looking!
Thread Starter
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Posting Guru
Joined: Nov 2011
Posts: 1,302
Likes: 5
From: Burlington, WI
Thanks for the post. I also have a 77 Jade Green metalic truck with the same kind of problem not servere at all but irritating. Every thing has been gone through including the entire rear end but not lately. Anyone have a good way to check the axel bearings without pulling the axle out? I wonder if the bearing seat in the housing might be worn till loose.
For me it was obvious the outer axle bearings were junk as soon as I pulled the wheels and drums off. I had a good amount of up/down movement in the shaft with everything still bolted together tight.
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