whtbronco
Full Access Members
So I've been chasing vibrations in my '04 Expedition for quite a while, 288k miles. One I was certain was the A/C compressor, and had made plans to replace it. I'm totally lost on this, but after replacing the fuel pump my wife said the engine was running smoother and the vibration was gone. Sure enough the vibration I thought was the compressor is now gone.
I still have a speed related vibration with maybe more than 1 cause. Speed range is 40-70mph, 47-56mph is the worst, and almost all with the torque converter locked. 2WD, AWD, 4WD makes no difference. I got rid of most of it with new rear cv axles and wheel bearing hubs, all Motorcraft parts. I couldn't find the rest for a long time, but it wasn't too bad, my wife couldn't feel anymore. Seemed to be getting worse a couple months ago so I started looking again and found a rear driveshaft u-joint and the slip yoke both with a little play. So I replaced the slip yoke with a new Motorcraft yoke and put in new Dana SPL u-joints. Still not satisfied I had the driveshaft checked. It was .007" out of round, but was straightened anyway. Also got new tires around this time. Once again the vibration was back to fairly minor, I notice it, my wife doesn't. The last few weeks it seemed to be increasing once again and only present when the torque converter locked in 4th gear. As soon as the converter locked it started and got worse up to like 52-53mph and then subsided entirely by 70mph. I started thinking the converter or lock up clutch was failing. Trans shifts smooth still. The vibration would get much worse under coast, mostly in the 47-57mph range. I am confused because coasting vibration is usually rear drive line not transmission. Dropping into neutral resolved most of the coasting vibration, but it was still present in the 47-57mph range once below 47mph it would settle to a gentle vibration again and below 38mph it's gone.
Monday night on my way home it shook violently like something broke for ~1/4mi once I got to about 50mph. I peddled the throttle and it calmed a bit while I was off the throttle, but came right back when I got on it, but I was almost home. Once I stopped and turned into my neighborhood I had no vibration again. It's always smooth under 35mph. So of course I looked even closer at stuff. Couldn't find anything in the garage. Took my wife for a ride, she felt the passenger floor vibrating, but nothing near as harsh as what I had felt a little earlier. The rear diff was still properly filled to around .9" from the fill hole. Now I'm wondering if it's a rear pinion issue. I decided to just fill it up to the fill hole, adding about 1/2qt. Since it's easy to drain and if it is associated with the pinion that might help a bit. Well that helped get rid of like 50% of it, my wife said the floor wasn't vibrating on the passenger side now. So that tells me that it might actually be a bearing in the rear diff that's worn out, likely on the pinion, and the extra gear oil kinda covered it and calmed it a bit.
Having been really focusing on this over the past week I found that there is a very slight vibration in 3rd, a tiny bit more in 4th, but still when the torque converter locks it gets worse.
I am familiar with torque converter shudder and this is not it. Shudder is kind slow, like rumble strips, this is a more typical speed sensitive vibration. Now that said the brief episode last Monday could have been violent shudder I suppose.
My thought is maybe the vibration of the pinion in the rear diff is only noticeable at certain speeds and certain loads. Since in gears 1-3 I'm usually accelerating there is slightly more load on the pinion than when the torque converter locks which can occur at 38.5mph or faster. Then the load on the pinion decreases and it can shake around. By the time it gets up to 70mph it's just too fast to feel it.
If this was a solid axle I'd have pulled the cover for inspection and measure the backlash. There is a bit of play between the pinion flange and the cv axles, but it's not much and very hard to identify if it's too much.
Any other thoughts? It may be that I have a trans and a diff issue, I hate vibration it drives me crazy chasing it down.
I still have a speed related vibration with maybe more than 1 cause. Speed range is 40-70mph, 47-56mph is the worst, and almost all with the torque converter locked. 2WD, AWD, 4WD makes no difference. I got rid of most of it with new rear cv axles and wheel bearing hubs, all Motorcraft parts. I couldn't find the rest for a long time, but it wasn't too bad, my wife couldn't feel anymore. Seemed to be getting worse a couple months ago so I started looking again and found a rear driveshaft u-joint and the slip yoke both with a little play. So I replaced the slip yoke with a new Motorcraft yoke and put in new Dana SPL u-joints. Still not satisfied I had the driveshaft checked. It was .007" out of round, but was straightened anyway. Also got new tires around this time. Once again the vibration was back to fairly minor, I notice it, my wife doesn't. The last few weeks it seemed to be increasing once again and only present when the torque converter locked in 4th gear. As soon as the converter locked it started and got worse up to like 52-53mph and then subsided entirely by 70mph. I started thinking the converter or lock up clutch was failing. Trans shifts smooth still. The vibration would get much worse under coast, mostly in the 47-57mph range. I am confused because coasting vibration is usually rear drive line not transmission. Dropping into neutral resolved most of the coasting vibration, but it was still present in the 47-57mph range once below 47mph it would settle to a gentle vibration again and below 38mph it's gone.
Monday night on my way home it shook violently like something broke for ~1/4mi once I got to about 50mph. I peddled the throttle and it calmed a bit while I was off the throttle, but came right back when I got on it, but I was almost home. Once I stopped and turned into my neighborhood I had no vibration again. It's always smooth under 35mph. So of course I looked even closer at stuff. Couldn't find anything in the garage. Took my wife for a ride, she felt the passenger floor vibrating, but nothing near as harsh as what I had felt a little earlier. The rear diff was still properly filled to around .9" from the fill hole. Now I'm wondering if it's a rear pinion issue. I decided to just fill it up to the fill hole, adding about 1/2qt. Since it's easy to drain and if it is associated with the pinion that might help a bit. Well that helped get rid of like 50% of it, my wife said the floor wasn't vibrating on the passenger side now. So that tells me that it might actually be a bearing in the rear diff that's worn out, likely on the pinion, and the extra gear oil kinda covered it and calmed it a bit.
Having been really focusing on this over the past week I found that there is a very slight vibration in 3rd, a tiny bit more in 4th, but still when the torque converter locks it gets worse.
I am familiar with torque converter shudder and this is not it. Shudder is kind slow, like rumble strips, this is a more typical speed sensitive vibration. Now that said the brief episode last Monday could have been violent shudder I suppose.
My thought is maybe the vibration of the pinion in the rear diff is only noticeable at certain speeds and certain loads. Since in gears 1-3 I'm usually accelerating there is slightly more load on the pinion than when the torque converter locks which can occur at 38.5mph or faster. Then the load on the pinion decreases and it can shake around. By the time it gets up to 70mph it's just too fast to feel it.
If this was a solid axle I'd have pulled the cover for inspection and measure the backlash. There is a bit of play between the pinion flange and the cv axles, but it's not much and very hard to identify if it's too much.
Any other thoughts? It may be that I have a trans and a diff issue, I hate vibration it drives me crazy chasing it down.
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