Prudence, my 87 Town Car

[Lutrova]

It's hard to quantify or equate it to something, but I'd say it doesn't really feel sharp. I am less inclined now to think it's one of the wheels. Didn't notice much of a vibration today, though I deliberately took things slow and easy, sticking to smaller surface streets. But I did feel like the car might not make it up the incline out of the underground parking garage. Shifted in and out of gear a bit once we got to street level and it seemed like something approaching normal power returned. Turning also feels a little more difficult than yesterday.

So my money is on something somewhere between the transmission and differential. Shifts feel normal and there wasn't a puddle of fluid beneath the car, so hopefully the trans is fine. I think the play now is just to leave things be tomorrow and try to limp over to the rear end shop Monday morning.

[Hillbillycat]

Regarding the dreaded ATC servo, I found a quick solution how to get intermediate heat - not just full heat or full cold.

Pull the clear hose from the servo, install a vacuum-T and about a foot lenght of vacuum hose. This is your "adjuster" hose. Then plug this end with a bevel head coarse wood screw. By adjusting this screw you can manually dial in for the amount of vacuum leak.

[Lutrova]

That seems like a decent and simple fix. Will have to rig that up. I assume you leave the screw end just dangling into the glove box.

Took the car into the differential shop a week ago today. Had a lot of movement in the rear u joint, and I guess the guy could feel some play in the pinion bearings. Or something like that. They took things apart and found the pinion gear was also needing replacement. And the rear axles had a pretty deep groove where the bearings rested on them. So I now have new u joints, rear axles, bearings, and ring and pinion gears. The job cost more than I paid for the car, but it's stuff I wasn't going to be able to do myself, and my rear end noise is gone. They also had it done the same day.

Unfortunately, none of those parts seem to be the source of my vibration. We drove on arterial roads for maybe 15 minutes without issue, but once we were back on the freeway the vibration started back up. Seems to be strongest around 40-50 mph and smooths out but is still noticeable as you get to speeds above that. I'm also not sure if there isn't something that feels off at idle. When it is vibrating I think I can feel it most in the steering wheel, but it also comes through in the floor and pedal.

I had checked the transmission fluid level at the shop and it seemed to be good and red, but looks pretty grey when wiped off. It also sounded like there was a higher pitched whir coming from the back of the engine, a bit like a turbine.

This whir, combined with the loss of power climbing out of the parking ramp until shifting out of gear and back, are making me wonder if the transmission is going out. Though the vibration and the stiffer steering also seem to me like they could be one of the front wheels, or something with the steering, or the PS pump failing. Though the pump or any other accessories wouldn't cause a vibration, I'd think, without a strong smell of the belt burning up.

I think I have a good deal of narrowing down still to do. Probably start by looking at the front wheels. If it's transmission related, maybe I can start by seeing if a fluid and filter change will do anything.

[87gtVIC]

The job cost more than I paid for the car, but it's stuff I wasn't going to be able to do myself, and my rear end noise is gone.

This is probably true for most any major repair on these ol' cars nowadays.

[gadget73]

worn axles is really common. they are the inner race and the axle is case hardened. Think of it like an M&M. The mushy bit underneath the hard shell eventually deforms, the hard part cracks off, then its just bearing rollers running on soft gooey middle bits. Run it long enough and the axle will break off. Trust me when I tell you this is not the most entertaining thing, especially if you have drum brakes. Discs will mostly keep the wheel under the car, drums will not. Having been driving both when an axle broke and when a wheel parted company with the car, the latter is far worse.

usually the pinion gears don't wear, but the bearings can. Thats what makes it whine. Axle bearings are more of a hum and a vibration.

[Lutrova]

The M&M analogy is pretty similar to how the differential shop guy described it. I don't know just how much hardened axle I had left, but it's something I never would have thought needed to be checked. Hopefully if it were to go out there would be enough of a noise that I'd notice something was amiss before a wheel just up and left. Though I've seen that situation at least three times along I-15 in the past year.

As for the pinion gear, I forget exactly why it was in need of replacement. But the car must've sat for quite some time because there was some pretty deep pitting on at least the ring gear. They said they cleaned out a bunch of rust inside the case. They also told me the replacement ring and pinion were used, but basically new. Came out of a Mustang that was swapping to something other than 3.27s.

Far as the cost of repairs go, I figure just about any car will eventually require major repairs. My parents got out of a VW Touareg because of a transmission issue and bought a 2013 MKT as a replacement. Within two years that Lincoln had to have its tranny replaced. I guess if you always drove new cars you could (probably) dodge that, but then you're just paying up front to avoid potential headaches later.

***

Thinking a little more about the TC's latest vibration - is it possibly the torque converter? Is that something that fails on these vehicles? And if so, could it produce a persistent vibration?

[Tiggie]

I've never heard of a AOD eating a torque converter under normal usage. Something else usually goes first. I don't think it would cause a vibration if it did.

How old are your tires? Do you have a spare you can swap around to see if one is not balanced?

My 88 had a slight vibration which I am certain was due to a tweaked driveshaft.

[Lutrova]

Tires are from mid 2015, but I don't think they were actually mounted until sometime in 2018. I had Firestone fix a flat on the right rear tire a month or two ago and they mounted it 'backwards'. Turns out I actually have white walls, but the strip has browned so much it blends in with the rest of the rubber. Since then I've been meaning to bring the other three into the local do it yourself garage to flip them around too. I'm pretty sure they have a road force balance machine, so I could verify everything's right.

I could definitely see one of the tires causing my vibration. But it doesn't seem like that would also cause slipping from a standstill or going up a ramp. Then again, these symptoms could also be totally unrelated. The transmission has continued to shift normally and hold all the higher gears through this latest episode. Maybe the uphill slip is something that's been present for a lot longer, I just haven't encountered the right conditions to observe it before.

[gadget73]

Converters in an AOD don't have clutches like other transmissions. its mechanically bypassed in 3 and 4, so no clutch to slip and cause shuddering.

[Lutrova]

Well then maybe my slipping issue is just something totally unrelated. I had thought that maybe the torque converter was knocked loose or out of alignment when we dropped the engine back into the mounts. But if that were the case, then maybe it would've been apparent much sooner.

My sister visited this past week, so I didn't have any time to poke around with the car until this evening. But I did take a quick look at the front wheels. And by take a look I mean I spun them and looked for movement.

https://www.youtube.com/watch?v=zJE7Kydl5ug

The left front is acting similarly to the right front. It's very quiet on the video, but there's a somewhat higher pitched whir when the tire is spun by hand. Maybe that's normal, but it sounds a little uneven, like whatever is producing the sound is 'catching' a little more at one spot in its rotation. I also had a clear noise and kind of wobbly feeling when pulling at 12 and 6. There's also movement at 9 and 3, though any sounds seem to be coming from somewhere beyond the wheel.

Never having looked at this before, I don't know if what I'm feeling and hearing is a problem or just the way these things are. Hearing the noise as the wheel spun seemed like an a-ha moment until I got a similar sound out of the opposite wheel.

[gadget73]

Ever re-packed those front wheel bearings? The slop seems like the bearings are not set quite tight enough. I can't hear anything specifically but if the bearings haven't been greased in a good while they're due for at least an inspection and re-pack. If that was done not long ago and no damage was found, tighten the center nut a bit. Probably won't need more than one or two notches on the nut to take the slop out.

[Lutrova]

The front brakes were done in the summer of 2019 by my old neighborhood mechanic. He probably packed the bearings then, as I found one that way when the dust cap had come off.

I took all four tires in this past Saturday for remounting and balancing. Turns out half the wheels had no weights at all, and all four were out of balance. I also found they all had a bit of runout, both radial and lateral. Don't know just how bad they are, but I doubt they developed the problem just in time for my vibration. Tires were rotated when they went back on, as it was probably time for that anyway. Before I drive the car around to see if that fixed anything, I'd like to get the steering and suspension looked at. Everything looks to be in good shape, and I have records stating tie rods and left upper control arm bushings were done in 2016. But I still don't know what I'm really looking at, so having a second opinion seems like the way to go.

After putting the tires back on I couldn't feel any slop at 9 and 3, while the slight rocking at 12 and 6 remains. So maybe ball joints? I'm also still hearing this sound of metal being brushed once in every wheel rotation. My current theory is that the front rotors might have enough lateral runout to brush the pads even without braking. Maybe heat from the brakes expands everything and exacerbates the problem, which would be why I didn't notice a vibration at a cold start, but it eventually builds after 10 or 15 minutes. If so the auto craft shop ought to have an on-car brake lathe, which goes for something like $15/axle.

Out of balance tires or rotors wouldn't explain my greater difficulty turning, especially at slow speeds. But maybe the symptom is unrelated. I think, too, that my slipping out of 1st while driving uphill might be unrelated as well. A trans fluid change seems to be on the horizon.

[gadget73]

you won't get movement from bad ball joints unless you put a jack under the lower control arm. With the supension at full droop the spring pressure will take up any slop there is to be had. Still sounds like slightly loose wheel bearings to me.

the ball joints could still be wasted, so it would be worth putting a jack under the arm to unload it and check. They seem to last 120-150k.

when you do the service, see if the gasket for the filter is missing or on wrong. If it is, the trans will suck air and do dumb things, particularly in low gear. Also be careful about re-torquing the filter. Apparently one of those bolts runs through the valve body near the 3-4 piston and cranking it on too hard can make it stick.

[Lutrova]

You were right, it was loose wheel bearings. I took it into the auto craft shop and the two guys working there immediately identified it as such. I had been too intimidated to adjust it at home, not wanting to mess things up further. But it didn't take much tightening and the vibration was gone. Amazing how such a small fix can make such a dramatic impact on the car's performance.

The older mechanic looked over the steering and front suspension with me and felt everything else was solid. I suppose that wouldn't necessarily include the ball joints, but if the car is behaving then I'm not too worried about it.

It really is nice driving the car now. No rear end whine or wind noise. Just cruising down the road listening to the AC blow. Which is good because it was 112 today. Never thought I'd see the mirror thermometer max out.

Next up is reinstalling the ATC sensor, seeing where that's currently at. Then I guess it'll be time to change the trans fluid and see how many leaks I can address. I thought I had a leak from one of the trans cooler lines, but they looked dry on the lift today. Maybe it's the dipstick, and if not that then the pan gasket.

[Mainemantom]

Only 112, it isn't even August yet. Got a ways to go. I have worked in 122 out in Needles and at top of the mountain before going down into Nevada toward State Line. Death Valley is now about 122. That heat is like a furnace and deadly.