for several months now, my van has had a significant vibration at speed, usually while maintaining speed, which i'm having a heck of a time figuring out. the vibration seems to be vertical not horizontal, so my first thought was tires. at first it seemed to be coming from the front, so i put a different pair of tires up there, and the vibration seemed to be less for a week or two, but came back to its previous level. then it seemed to be rear, so i took the pair of tires i had taken off the front, had them balanced, and put them on the rear. no change.
shocks are KYB and were installed last august. the tires i started this problem with were new at the same time.
alignment seems pretty good, last spring i did tie rods and radius arm bushings, last august i did axle pivot bushings at the same time as i did the shocks. i just checked the alignment with a tape measure yesterday, checked it 3 times while rolling it forward 10 feet between each measurement. readings ranged from 5/32 to 3/32 of toe-in, so its close enough. tire wear is fastest in the center of the tires, with both inboard and outboard sides keeping nice thick tread.

so i'm trying to figure out what the heck this vibration is, because it makes me feel unsafe as i burn up the highways.

for what its worth, the van currently weighs 8700#, with a GVWR of 9500.

any thoughts of what to look at next?

 

We're both running a bit close to our max GVWVR, mine is 8600 sticker and I'm right at 7800# most days, almost never more, rarely less.

Right off I'm thinking tires since it seems to be vertical in nature---not too likely its anything else; its reasonable to assume the KYB shocks are still good though I'd do the bounce/rebound test anyway.

Even though the tires were new its not too unusual to experience what they call "tramping" IIRC. If severe enough it can bash a set of shocks pretty quickly, affecting them pretty much according to their damping and quality.

If its possible to swap yet another set of known good tires to the front that'd be my only WAG. Things like this certainly need to be addressed ruling out something major about to happen.

 

yeah, my tires honestly scare the hell out of me. i pulled the fronts when i did cause i felt like they were about to blow or do something ugly, so i took them down to the tire shop, got them balanced, he said one was a little out of round but should be fine if it stays on the rear. they sat in the shop for a month until it got bad again, at which point the rears had thrown several small chunks of tread and were scaring me, so i traded those around with no difference in feel, and plan to have them balanced before i put them back on. the front currently has a silly little pair of 16.5s because they're what i found to replace the threatening tires that i thought were to blame at the start of all this. they're only a load range d, so i can't put them on the rear for a test cause they'll be overloaded back there.
i have another pair of the 16.5s that are in good shape which i could try, but i haven't tested them elsewhere to know if they feel right.

on a related note, the tires i have on the front were installed about a month ago, with tread depth of about 3/8 even all the way across the tire. now the centers are worn down to 1/4" with both edges still at 3/8. is it just me, or am i beating the hell out of these things in no time at all

 

Josh, you know I'm as perplexed about your tire issues as you are. It just struck me though, are you confident your wheels are sturdy enough. Not all wheels are up to the task and some flex in the wheel could act a lot like an out of balance tire.

I also find myself wondering how much time you spend on gravel? Sharp gravel kills tires, and if say daily your spending a good amount of time on gravel and pavement the wear differences could be a big part of your wear issues. In particular I'd imagine where you live you might be rather quickly transitioning from highway to gravel. Hot soft tries from highway travel then being poked with sharp gravel could be a real issue.

 

I have had similar issues in my 3rd last Van ...it had King Pins....It was combination Radius Arm Bushings and broken belts in the Tires....One side had bad bushing and the other was a Tie rod end and a collapsing brake line that would cause the calipers to stick and make that side hop....I changes the Radiius Arm bushings and the tie rod ends and New Tires and it was eliminated...cost me 1000 in parts and about 2 days in time and 150 alingment......
My Van at the time was a 89 E350 460.....

 

those are some valid questions there brute. as for the wheels themselves, they're rated for 3000-odd pounds and 90 PSI, while the tires are rated the same 3000-something and 80 PSI. as far as i know, its quite rare to see a 16" wheel on 8-lug with a lesser rating.

for time on gravel and all that, going home is highway most of the way, then a mile on a 35 road, which is driven closer to 50, then about 2 blocks of low speed pavement, and a couple hundred yards of gravel. so yeah, pretty quick transition from highway to gravel. outside of my own driveway, i don't spend a ton of time on gravel, just the occasional recreational trip up logging roads or whatever.

as for kingpins and other steering components, the kingpins are the only part of the system i haven't done a lot with. they have maybe 1/16" vertical play, visible when jacking up the truck to lube them, and minimal in other directions. radius arms bushings and tie rods are about a year old and still seem to be in good shape.

 

And as for your tires wearing on the inside, they are over aired!


Run a line of chalk across the treads of the tire. Then drive forward about 15 feet. Then see where your chalk line is mostly gone. If it's mostly gone in the middle, tires are over inflated, if it's gone on the outsides, theres not enough air in them.


Never run your tires at what the door jam says, or what the tires say, I found on certain cars, following that, will make them wear to much on the outsides, and on most trucks, to much on the inside.


My van weighs around 7000lbs, and I did that chalk line trick, and I only need about 55-60psi in my back tires, and 60psi in my front tires to wear down nice and flat.

And I now have about 20k miles on my back tires done, and they still look brand new, tread wear is perfectly flat down across the tire. They are GoodYear Silent Armors, 235/85R16


As for your vibration...did you have it aligned after replacing the tie rods? When I did the tie rods on the motorhome few years ago, I did align it real quick with a measuring tape, and with that, it did look close... but when I did have it align 3 days later, oooof was it ever bad. Camber was right on the money! Toe was bad! And it did have abit of a pull and vibration till I did have it aligned. Although, the camper has the original front shocks....so it could have abit of tire hop without a perfect alignment.

 

john, that seems logical, but when all tires are carrying a load within just a few hundred pounds of their rating, i'm of a mind to make sure they have somewhere close to their rated amount of air in there. i think those fronts that are wearing so fast are rated 65 PSI and have exactly that much in them. i just don't want to blow one up by running it under-inflated and over-hot.

 

Regarding tire pressure...........

I'm running about 7800# in my E250 with Michelin LTX 245/75-R16's under 70 psi all the time, front and rear, stock steel wheels. After 62K miles tread wear is even all the way across. My door sticker suggests 245-75-R16's with lower psi than I run.

Just a bit of info, hope it's not drifting too far away from the OP.

Hope to learn what causes this vibration Josh----hopefully nothing too spendy!

 

Josh,

After chasing down vibrations in a couple of different vans myself, here are a few thoughts;

Tires: if you've rotated them around and/or off the vehicle with no change, move on to other areas, the tires aren't the problem...unless perhaps, if you are running tires that are load rated below what you need for the weight you are carrying. I had a Quigley 4x4 E350 that would go into a "death shake" when I went over bridge abutments. We shook down the suspension and replaced torque arm bushings, etc. with no improvement. It had load range E tires that "appeared" to be in good shape and had 60+% of tread left. Finally determined that the tires had a fairly soft sidewall design to start and were old, and the sidewalls were getting softer with age. We put new tires on, with a firmer sidewall design, and have had no more issues.

Suspension: Shake it down thoroughly. If anything has play, fix it.

Wheels: Have your tire shop spin them, tires off, looking for a bent rim.

Drive shaft: This would be my guess. Check u-joints. A bad u-joint can cause a vibration that feels like a tire balance issue. If u-joints are good, pull the drive shaft and take it in and have it balanced.

Other thoughts: Drive at speed with someone in another vehicle following you. Have them watch each tire one at a time while you are driving, looking for a shake.

Good luck.

Bruce

 

for the tires, i checked them all last night, and found the fronts at 70, so i dropped them to their rating of 65, and the rears at 75 where i left them. i'll be on the road in a couple hours to see if that smoothed things out any, and hopefully it'll straighten out their wear pattern.

all the rims spin perfectly straight when on the vehicle and spinning by hand, so if one is bent, its certainly not very far.

balance issues in the driveline are possible i guess - i did u-joints about a year ago and have greased them a few times since then, including once after this vibration thing started, and they were all tight at that time.

on an unrelated balance issue, when i put my engine back together i did notice that one of the studs on the torque converter was half-stripped, so i don't know if my loctite is still holding that nut on there. but i don't think thats causing my vibration cause that nut was missing before i had everything apart, long before the vibration started, and the vibration depends on vehicle speed not engine speed.

i'll try to grab a friend sometime this week to drive alongside and have him inspect my spinning wheels for anything funny

hotairjunkie, was your vibration issue vertical like mine, or more of a death-wobble kind of thing? it seems the soft sidewalls would give more sway than vertical issues, right?

 

Josh did this vibration onset coincide with your U-joint replacement by chance?

 

no, the u-joints were almost exactly a year ago, when i was diagnosing my rearend problem.
the vibration has only been happening for a few months here

 

My death wobble issue was with a Quigley 4x4 conversion with a solid front axle, so it doesn't really apply here. I was only mentioning it because it illustrates how a soft sidewall tire can affect things.

I've had a couple vans that had vibrations that were hard to figure out that both came back to driveline issues. One was an out of balance drive shaft, and one was a u-joint issue.

If you've already spun the rims and they don't show any wobble, and you've rotated out all the tires without the problem going away, they it sure seems like you need to start looking at the driveline.

I'd put the rear end up in the air on jack stands and run it up to speed. You can watch the drive shaft for wobble that way. If you feel the vibration this way, then you've eliminated everything in the front end, since it isn't moving. Then, take the rear tires off and do it again. If you still have a vibration, then you've eliminated the rear tires and rims.

My bet is still on a u-joint or a bent or out of balance drive shaft.

 

Just an idea to toss into the convo on driveline vibrations. I've read that dynamic mass damper stuff like dynabeads in tires works great on drivelines but haven't tried it. I've read of people just putting some oil in the tube for example.