Hey all,

I've been struggleing with a vibration in my '97 F350 2wd long bed crew cab with 160k miles for some time now. I'm to the point where I have to get this taken care of but am still confused on where to start. I had another thread going here but I want to get all of the symptoms listed in one place and hopefully someone will see something and have an answer or at least a good direction to head in.

https://www.ford-trucks.com/forums/1...vibration.html


1. Vibration at the gas pedal and trans hump.
2. It seems to be worse at 70 mph but I have felt it going much slower also.
3. I have had times where if I take it easy I can get as far as 20 miles where it's back to normal before the vibration appears. I cannot repeat this all the time. I find this confusing. Overheating trans?
4. If I touch the brakes while it's vibrating and keep my foot on the throttle the vibration seems to go away. Of course it could just be the change in engine rpm when the lockout disengages I guess. Turning on my hazards seems to have no affect on the torque converter in my truck as some have suggested here.
5. If I put the truck in neutral when the vibration is bad and let the engine idle the vibration completely goes away.
6. If I put the truck in neutral but keep the throttle up the vibration does not go away until I let off on the throttle.
7. I'm occasionally getting a clunk in the floor when taking off and turning from a standing stop. Not sure if this is related.

This may not be related either but I've been having issues with tailshaft extension housing bushings. I replaced one at about 150k miles that solved a droning/vibration issue but it came back in about a year. The second one I put in had play in it right out of the box. That vibration doesn't seem the same nor as harsh as this one. I'm going to do that bushing again in the next week. The last time I changed it I thought I saw some aluminum come out of the trans but it might have been my imagination and unfortunately the pan I was using was not totally clean to be sure. I did a trans service maybe 5k miles ago and other than the typical metal on the magnet it looked normal and the filter looked fine. The transmission seems to shift fine. The two thoughts I have are torque converter or maybe the center support in the trans. I'd like to add a trans cooler hoping it might help in the short term if it's the tc.......any suggestions on a good brand and size?

Jeff

 

Spent another day lying under the truck looking for the source of the vibration I've been experiencing. I found that the center yoke that slips over the rear of the front drive shaft must have been cast by a five year old. It wobbles at least 1/4" where the rubber boot straps to it. I took it off just to be sure there wasn't a bigger issue and was surprised it was made that way. How does garbage like this gets put on a truck. I also opened the torque converter inspection cover and ran the truck. The ring gear is moving out of true by 1/16" which doesn't sound like much but it sure looks nasty. I also checked every nut that attaches the flex plate to the torque converter and not one of them moved at all when I rotated the motor with them using a big long box wrench. Neither seem to be the source of the vibration I've been experiencing. I'm just coming up with either the transmission or the lock out torque converter........neither of which I know anything about. No idea what to do next

Jeff

 

Might the flex plate not be attached properly to the crankshaft?

 

............or cracked?

 

OP , have you looked at the u joints "closely " ?

 

If the flex plate is cracked it's not anywhere that can be seen with the inspection cover off. Of course I have no idea on the flex plate being loose from the crank shaft. I will say that whatever it is I'm feeling through the gas pedal and on the transmission hump it isn't always there. I've been leaning away from a flex plate issue for this reason.

I've had the drive shaft off several times during this process and can't see any movement or binding in the u-joints. I replaced them not too long ago and also had the drive shaft balanced. I am still not happy with the fit of the yoke in the tailshaft housing bushing. It seems that the bushings I've been getting vary a good bit in their ID. This one is much better than the one it replaced but not as good as the first one I got. You can move the yoke a little bit in the current bushing.

Jeff

 

After reading & re reading your first post, I think it might have something to do with the TC ...

 

That was where I was heading but then today happened.....somebody please kill me!!!!! So I'm driving along and there's no vibration. I stop to make a left turn and as soon as I go I hear/feel a pop from somewhere beneath me or at least that's where it felt like it was. Now the vibration is back. Less than 1/2 mile later I stop for a right turn. When I take off I feel/hear the pop again and then the vibration is gone. What the heck is going on with this thing??? This popping thing seems to have started around the same time as this vibration/rumble in the floor and gas pedal. I have not taken the motor mounts out yet as I think I'd need a hoist. I just don't like the idea of trying to lift that engine with a floor jack on the oil pan. Is there something in the suspension or frame that can shift/twist and allow some metal to metal contact transmitting more road feel through to the frame and then go back into position at other times?

Jeff

 

Look at the control arm bushings on the front

 

There really aren't lower control arm bushings on these trucks so I'm assuming you mean either the radius arm bushing or the I-beam pivot bushing. They look good visually so I guess I need to take them apart to have a really good look at them. I'm going to start with the radius arm bushings because that makes more sense to me what with where the clunk seems to be coming from. However, if I need to pull the pivot bushings I want to verify that I don't need to compress the springs to remove them from these trucks. The manual I have doesn't mention compressing the spring but I'd like to make sure from someone who has done this before. Don't want any painful surprises!!!

Jeff

 

Because nothing can be easy......I got the passenger side radius arm and I-beam off and sure enough the I-beam bushing was beat. I'm sure hoping that's been the cause of my vibration problems!!! My problem now is that I decided I might just as well change out the radius arm bushing while I'm this far into it too and the replacements don't look like they're going to fit. When I put all of the bushings, washers and spacer on the end of the radius arm there's barely one thread sticking through to get a nut on it. This is even without adding the thickness of the radius arm bracket. I went back to the auto parts and they checked the part number for my truck as well as a few years prior and they all use this replacement bushing set. Has anyone ever run into this problem???? I'll post pictures of the old and new bushings later when I get home.

Jeff

 

Yep, I have had the exact issue on my 1971 f100 4x4. The aftermarket bushings were really thick and unfortunately you need the washers to keep them from tearing and splitting. You can try looking up radiuse arm bushings for an older truck. My experience is that napa has the parts that most closely resemble factory spec. Or, take the bushings to the band saw and cut an 1/8" or so off each one - if they're good rubber then it won't hurt a thing to thin them out a bit. The bushings I bought were like 1 1/4" thick - way thicker than necessary. Also, make sure the radius arm is pushed all the way into the bracket and your not cheating yourself.

 

I managed to get the radius arm bushings on by compressing what I could get on there and letting it sit a bit. I did that a few times with just the outer bushing and the washer and eventually I was able to get the spacer in there too along with the heat shield on the passenger side. I think it took care of a good bit of the vibration but I'm still getting the clunk when turning from a standing stop. I ordered a set of sway bar bushings to see if that's the cause. It's hard to tell if the vibration is completely gone because the truck now needs an alignment and I can't get it in until later this week depending on how my jury duty goes this week but I'm optimistic. I have yet to feel the vibration through the gas pedal since I replaced the bushings.

Jeff