Annoying vibration on highway..

[RoadWarrior222]

Hey folks,

Getting this really annoying vibration, it's inaudible but you feel it through the wheel. It's the '95 Escort Wagon. at a "certain" speed it kicks in, and it's like badadadum 1 2 3 4 badadadum 1 2 3 4 badadadum 1 2 3 4 badadadum

Repeating at about 5 second intervals... The annoying thing is, if the road is slightly bumpy at all, that overwhelms it and you don't feel it, so it's only on really smooth bits of highway. (Sux for testing)

If I go the same engine RPM (low gear) at a lower speed, I don't get it. If I go the same speed at higher RPM, I don't get it. It doesn't seem to do it under medium or hard acceleration, or if you lift off the gas, it's only steady speed with your foot on the gas maintaining speed or accelerating very slightly.

If I go fast enough (On a private road in Mexico) it goes away.

It seems like it's a beat frequency, and yah, I mathed it out, motor is at about 3100 which is 51ish revs per second, and the tires are rotating 900 times a mile, which works out at about 18ish revs per second, and 3 times that is 56ish, f1-f2 = beat frequency, = 5 ... hmmm

So it seems like tire rotation and engine rpm are getting close enough to make a beat somehow... but at all other speeds, I can't detect enough unusual vibration in either. (Well the 1.9 CVH was never the smoothest motor in teh world evarrrr)

My tires are slightly upsized, put 195/60R14s on it on BMW rims this summer... I'm having a feeling that if I had (a balanced) set of stock size to try that it would not happen. Just the 10 revs/mile difference.

Also wondering if new engine mounts would help... or not, because I'd go for poly and they'd transmit more...

Think I'm gonna try clocking a front wheel 90 degrees tomorrow, just in case that can damp a very faint vibe from them. See if it changes.

Ideas?

RW222

[contraption22]

Can you watch your 02 sensor and see if the condition is in sync with it's cycling?

[turbovanman²]

Didn't we go thru this already?

Tire balance, bad tire, motor mounts, natural resonance of the powertrain. Try unplugging the LU if possible.

[RoadWarrior222]

Yah the previous one was with out of balance tires that were also going bulgy, this is a different set...

---------- Post added at 02:35 PM ---------- Previous post was at 02:33 PM ----------


Can you watch your 02 sensor and see if the condition is in sync with it's cycling?May be making a narrow band gauge soon, so yeah, I'll check on that, because I did think that it seemed almost like a faint miss every few revolutions.

---------- Post added at 02:37 PM ---------- Previous post was at 02:35 PM ----------

Oh and it does it over about a 600 rpm 10mph range, so and I can just give it enough throttle pressure, like going uphill where it kicks out the lockup, when I'm near the bottom of the range, such that rpm increaase doesn't take it out of the range, and it still does it, so it's not lockup shudder.

---------- Post added at 02:40 PM ---------- Previous post was at 02:37 PM ----------

I'm thinking that not feeling anything at same road speed at 5000 RPM in lower gear kinda eliminated serious/detectable out of balance issues on the rotating assembly (i.e. wheels, tires, rotors, driveshaft, output side of tranny)

[tommyturbo]

I rode in a grls escort of about the same vintage that had a similar problem, every time the torque converter would try to lock up the car would vibrate like mad, sounded horrible. is yours an auto?

[RoadWarrior222]

Yah, auto, but it unlocks and it's still there (As long as I don't have the throttle too far open) also, I can get lockup as slow as 40mph and no shudder there.

[black86glhs]

Front wheel bearings are the first thing I'de look at. Next, outer tie rod ends. I have seen tracers that would do something similar and one of the tie rods would be loose. It would start small and get worse as the play got worse.

[RoadWarrior222]

I think Bryan gets the prize, now seems like drivers front tie rod again, cheap sh!t won't last 2 years. Wasn't enough play in it to feel last month, now can feel it.... though the vibe hasn't got any worse, it just does it a little at other speeds now, and given "smooth" bumps, i.e. ones that don't have sharp edges, I can hear it knock very lightly at low speed.....

Although... I do have another cheap balljoint that side, where the passenger one of that brand only lasted a year, and I felt a slight squirm in steering angle change, unlike tierods and more like BJs, so that might need yet another fugger.

[black86glhs]

Thankfully they are easy to do on scorts. I hate it when you put a cheap part on (especially when you read about others claiming how good they are and how long they lasted) only to find out you were right, it was cheap and didn't last long.:mad:

[RoadWarrior222]

Well, guess I was feeling it wrong when I wrestled the tire last time... a better inspection Sunday morning revealed the boot on the BJ had all but disintegrated (REALLY??? the rubber bands I get round broccoli last longer!!!) and that was unstable... then manipulating the tie-rod directly couldn't feel any play in it... so went and got a "certified" BJ with a year warranty (better than 30/60/90 day ones I hope) and stuck that on yesterday afternoon...

... and the vibration got a lot fainter again, back to how it felt when I first started to notice it... so loose BJ was making it feel worse in the last couple of weeks but still something is up..

Inspected the tire again very closely. Only thing I can see with it, is that it seems to have a slight hollow in one spot... checked and rechecked, it's not a bulge either side, it's a hollow :confused: How the hell do you get a hollow??? ... guess I'll be swapping tires around again.