Sometime after the 2014 engine rebuild (160,000 miles) I noticed a slight vibration in 3rd gear at 30-50mph. Not until last week (176,000 miles) when going on a test drive on the freeway, when I hit 70mph I knew something was very wrong due to excessive vibration, almost violent. The whole car, not just the steering.

I think I may have found the problem. In a 2011 thread “Steering vibration, can't find cause” someone mentioned wheels bouncing.
With the wheels off I noticed on the rear tires there was inside wear, but none 180 degrees around. (This did not appear on the front tires, but these were once on the front.)

Image: Left, same tire rotated 180 degrees. Right, same tire rotated 180 degrees.
I’ve never had a tire do this before but I can imagine this could cause “bouncing” at high speeds. I suspect this may be the main cause of the vibration.



I also tested for bearing wear:
I did the wiggle test to check the rear bearings. No movement whatsoever L & R.
Did the wiggle test to check the front bearings. Both L & R did go “clunk” but not “KLUNK.”
If I replaced the front bearings, would I expect a little clunk?

I sort of measured the free play in the differential by measuring how far I could turn the wheel before the drive shaft started to move. Is this amount of free play acceptable?



I will replace the tires. I’m currently looking at Kumho Solus TA11 (185/70 R13).
Maybe a better choice than the Kendas on now.
Then another test drive.

Thanks for reading.

 

Don't forget shock absorbers, stabilizer bar links, and wheel balance. All of these cohld also be contributing factors, and you wouldn't know u til your new tires exhibited the same weird wear pattern. I'm going with wheel imbalance which would get worse as they wear strangely, then a blown out shock on that corner. Report back,

 

Thanks for the reply.
I did not think my description of the first image would be clear. The lopsided wear is on both rear wheels.
I've had tires wear uneven, mostly on the inside and all around the circumference. New tires and rebalance all the way around would be the easiest fix for this issue.

 

How old are those Kendas anyway? I can't really tell from the pics what the wear issue is but if its fine up to 70mph then I would suspect tires/balance first.

 

The tires are 12 years old and have 18,000 miles on them. They were on the front up until 4 years ago when I moved them to the rear.
There is some vibration at lower speeds, and I would say it has gradually increased over time. This is the frist time on the freeway in many, many years and the vibration did not really kick in until I was at the end of the entry ramp, probably at 65mph.

Attached image of just one tire. The top part shows wear on the inborad side. The bottom is the same tire but rotated 180 degrees also showing the inboard side. The wear changes from near nothing to the greatest amount of wear as the tire is rotated. It is no longer "round" and I believe would spin slightly aysemetrically around the axel.

New tires have been purchased. I'm working on scheduling instalation.

 

Ok, those tires are 2 years too old! LOL. Good to see you are getting new ones. I think they are basically oblong from sitting unused too long. I first thought you had flat spotted them doing a panic stop but it doesn't look to be the case.

 

Might be good to check your driveshaft. Bad U joints can cause a bad vibration at freeway speeds and could make a big mess of your car if it failed at speed.

 

U-joints are on the list.
I also need to check the preload on the front bearings. As far as I can tell they have never been replaced in 176k miles.

Is it possible to check the U joints with the driveshaft still in the car.
A. Parking break on and in neutral
B. Parking beak off and in 1st gear
I imagine only a gross failure wouild be evident trying to shift the driveshaft along the U-joint axis with the driveshaft still installed.

 

Are these the original brake rotors at 176k miles? Most rotor replacements require new bearings to be installed with races, as it's easier to put in new and repack rather than bang or press out the old races to reuse them. Bearing preload tends to be over analyzed. As long as the rotor isn't shifting under pressure, the bearings are well-greased with high temp grease, and the seals are intact, you should be able to tighten the retainer down so it doesn't make a full revolution and call it good (*note: this is JUST the brake rotor on the rotating assembly for the spin-test). I've never used a fish scale to gather rotational force, and just do it by hand and feel, never had a problem on such a light car.

As to the driveshaft, there's a significant amount of gear lash that equates to about 10deg of rotation from stop to stop. This is a combination of tolerance stacking between the transmission and the differential, but you should be able to feel how much slop there is between the spiders on the rear U-joint by trying to move it in all 4 directions of the spider. If you get any movement at all, the driveshaft likely needs to be replaced, because most garages won't have the right parts to replace this type of U-joint. I went with Mazdatrix driveshaft with replaceable, conventional U-joints and I carry a spare spider instead of a spare driveshaft. The front U-joint isn't easily accessed without pulling out the driveshaft entirely, which can get messy as the Trans leaks out of the tailshaft while it's out.

You would be feeling a clunking from the rear that gets worse with speed if the rear U-joint were toast, and the front U-joint usually causes a shift lever that's all over the place at certain harmonics, and gets better with speed as it self-centers.

 

Extremly helpful. Thanks.

The front rotors were replaced May 1994 at 87,000 miles, about 90k ago. Rear rotors replaced July 1991 at 73,000 miles. I did find the rear bearings were replaced in 1988, but no evidence of the front bearings ever being replaced.
I did use the digital fish scale to get an idea of the front bearing preload. The FSM list a range of 0.45 to 0.65 kg. I got 0.08 for the right, and 0.14 for the left. No matter what else I find the preload needs to be adjusted. It may be wise just to replace the rotors and bearings at this time.
Break pads are very good, all the way around. (I prefer coasting to stop lights.)
I tried to shift the rear spider in 4 directions, but did not feel any movement. I'll try again. I have not noticed any earatic movement of the shift lever, but I'll take a closer look.

Waiting on the tires to be installed. Should be tomorrow.

 

(*psssst,... no need to quote entire posts, as it makes it harder to scroll.)

On the front brake rotors, if you take them apart - which you'd have to do anyway to install a new rotor - you may be able to tell if the bearings are new, based on corrosion and Brinelling of the metal races. Any hashing discoloration on the races means they should be replaced, as running bearings too tight, or sometimes too loose, can cause this metal fatigue. Google it up for the physics behind it. Anyway, if the front brake rotors have been replaced, then LIKELY the bearings were done at that time, because it's twice the work to push out old races just to reuse them as it is to put in new bearings with new rotors. Regardless, if you decide to put on new rotors, then get new bearings which come with new races properly machined as a unit. I've had good luck with Timkin, though any quality Japanese bearing should work fine.

Your loose wheel bearing could be the cause of your odd tire wear, as it would allow that wheel to do weird things under cornering, then you rotated tires to the back. Checking wheel bearings about 100 miles after install will sometimes show you need to tighten them a bit more, but the FSM initial specs account for this; they get looser over time. More important is that you nearly fill the cavity between the inner and outer bearing with bearing grease. This serves 2 purposes; it prevents corrosion from water getting past the seal or condensation from heating and cooling cycles, and it ensures fresh grease gets rolled around the assembly when it spins. You should leave just enough air gap for the grease to have some expansion when hot. Make sure to install your grease caps, too - as they're the outted bearing seal effectively.

I like to replace the inner seal with new rotors because they're cheap insurance, but most guys reuse what's there if they aren't compromised or damaged. This is more important if you live in an area that salts roads or lots of rust and corrosion. Let us know how it goes,

 

While your doing all that brake work (which sounds like it really needs to be done BTW) get some stainless brake lines all around. It will make the brakes feel even better when you are done.

 

Noted.
Actually the breaks are fine. I did have to do a panic stop from 45mph when someone coming from the other direction made a left turn directly in front of me, and I was in the far right lane. Came within 4 feet from hitting broadside.

I coast to stop signs and lights to save wear on the breaks.

Wheels with new tires stacked up in the garage.

 

Guarantee, you it's those 12-year-old tires.

 

I adjusted the perload on the front bearings per FSM and Longduck.

Checked the rear spider and found no movement in any direction. The front was more difficut as the best I could do with the heat sheild in place was to try and move the drive shaft grabbing it further toward the rear. Still no movement.

For the clunk-to-clunk rotation of the drive shaft I took a 4 x 11 " strip of paper, wrapped it around the drive shaft and marked where edge overlapped. That gave me a length of 205mm, the circumference. Then using my old metal right angle ruller leaning up against the drive shaft I could mark the extents of rotation between the clunks (image). With the trans in neutral and the parking brake on, I got a measured distance of 3mm on the circumference which yeilds 5.27 degrees of rotation. Not 10 degrees so I'm not sure my method is valid.

I took the front calipers and brackets off to get a better view of everything. I'm in the process of cleaning the parts then I'll reinstall the brakes. Put on the wheels and take a test drive.


I refined the proccess once I had the circumference measured by simply marking a strip of blue tape on the drive shaft with the metal angle adjusted so the long side on the floor was more parallel to the drive shaft.

Also:
Checked the Differential and it is still full.
Changed the oil and filter. Much easier with the car up in the air.

 

Quick trip on the freeway at 80mph and I did not feel anything but the road bumps.

New tires and maybe a little bit of setting the front bearings.

Thanks to everyone who responded. Lots of excellent information for down the road.
I will, probably later this summer or early fall, replace the rotors, pads, inner and outer bearings and the outer seal.

Thanks again.