Vibration in rear

[Truenorth]

Bought a used 97 1500 Silverado. There seems to be a vibration in the rear of the truck which is very noticeable at speeds between 60 and 75 mph. The vibration is not always constant and varies in intensity. I have opened the rear diff and cleaned, inspected and replaced gear oil. I have taken off the drive shaft inspected for dents and weights(they seem to be all there), checked the ujoints, reintslled the drive shaft 180 degrees from orginal position. All 4 tires have been rebalanced and rotated(to avoid possible rim issues).

What elese could I check? Is there anything else that would cause a vibration in the rear of the truck?

At a loss,
E

[markrinker]

Leaf spring mounts worn out? How many miles and what type of use?

[catmandoo]

i have had a similar vibration in my 92,here is what mine feels like,it doesn't shake it feels more like the back end is hopping it's kindof a slow vibration like 3 times a second or so as opposed to a tire vib which i would so is 6-8 times a second and mine hits between 62 and 68 above or below that it doesn't do it and it comes and goes,i have the 5spd so i don't know if that makes it worse or not where i really noticed it was after i changed the clutch,it was there before but it seemed to get worse after the clutch,funny thing it doesn't get any worse.i've rotated tires checked the balance and everything checks out i would sure like to find out what the heck it is.

[catmandoo]

mine has 405,000 and it's all highway unloaded.spring bushings,thats one thing i never thought about,i'll have to check into those.

[catmandoo]

well today i really did some timing of this vibration type experience ,i had about 800 lbs in the back and going down the road at 60 it's fine ,hit about 63 and it's fine for about 10-20 seconds then it starts what i would call hopping in the back it started weak and gets more intense ,it lasted for about 10 seconds and then went away for about 3/4 of a mile and it did it again ,,if i let off or get into it a little it stops,it just seems to hit at a certain load .i've also noticed it in 4th gear at about 45mph it does it too,kinda like it's rpm related rather then speed.

[Truenorth]

My truck only has 114,000 KM.. Did some more testing. It seemed to get a little worse as I turned left in a long curve on the highway and go away slightly as I straightened out(speed was about 70mph). Weight did not seem to affect this vibration(I had my ATV which weighed about 600lbs) and was almost the same.

[bigmikestud]

Several things to check here. You might have someone follow you on the highway and look for wheel hop, etc., could be shocks. Also, you can balance a dog turd but when it rolls down the road it won't be round. We have new balancing equipment available now to check for "road force" variation. They used to shave tires on balancing equipment to make them round thinking this would cure potential wheel hop. What the root cause for some of this problem is wheel/tire mismatch. Better stated, heavy spot on combination needs to be matched with light spot. Or, high spot to low spot. Example: Tire has dimple in side where belts overlap, this would be your low spot if using a dial indicator to check tire diameter. Now, place that tire on ground and this area becomes high spot because the tire is stronger in this area. When you roll these combinations down the road you get potential bouncing effect causing vibration at certain speeds. The factory has been matching tires and wheels for years (dot next to stem) with a $500,000 machine. Now we have one that can do this at your local tire dealer. To find one go to: www.gsp9700.com (http://www.gsp9700.com) and enter your zip code. The newer model can also give you readings for "lateral force measurement", this can tell you the best combination of all 4 tires to keep from pulling one way or another. What this balancer is doing is placing up to 1400lbs. of rolling force against your tire while they spin it. It will then give feedback on how much "road force" your wheel/tire combination might give. If your truck has more than 20lbs. or more you might want to have them matched. Your friendly tire dealer can show you more and how this works. Yes, I'm a Hunter Engineering Distributor but I'm also a truck/car enthusiast and can't stand my rig vibrating. I have a '96 dually that can't be properly balanced without the system I've described. In fact, I use the optional 3-jaw chuck adapter to properly center the wheels on the balancer shaft. Truck wheels are heavy and if you don't center them properly they will cause trouble on the road. Hope this helps and feel free to E-mail at: bmsp51@yahoo.com

[catmandoo]

hey bigmike thats something new or at least i haven't heard of it yet but i've been mostly out of the business for going on 12 years now,god how things change.i have actually wondered about this and the dimple so to speak in the sidewalls have always bugged me,the tires are pushing 60.000 so its probably time to send em packin.right when i got my job i have which i drive 60,000 to 70,000 miles a year i would run em and rotate every 5,000,or once a month and if i caught a nail or something i would take it in and get it patched , til i hit about 1/3 tread then if i got a nail i'd just put a plug in it,figured the tire wasn't worth the effort to pull off and take in and spend 12.00 to 15.00 to get it fixed,have 3-4 of those and i could buy a new tire.and in over 600,000 miles i have only had one flat on the road and of all times the spare was flat too should check them more often,actually the set of tires i have on now.have never gone down other then in the winter(knock on wood).i put em on last june ,so i might just get a new set and see what happens.thanks for the info though could come in handy someday,

[Alaska Aviator]

Originally posted by Truenorth:
My truck only has 114,000 KM.. Did some more testing. It seemed to get a little worse as I turned left in a long curve on the highway and go away slightly as I straightened out(speed was about 70mph). Weight did not seem to affect this vibration(I had my ATV which weighed about 600lbs) and was almost the same. I have exactly this same "harmonic" vibration - it usually occurs at about 65 and then is gone by 75 doesn't matter if I'm in drive or over drive so it seems to be speed dependant and not engine RPM dependant. If I am just below the speed that it occurs at I can make it happen by entering a long left hand turn - it kind of sounds like a "hollow" rattle - don't know how else to describe it. The vibration doesn't bother me as much as the sound. It's driving me nuts! If you guys figure out what it is please let me know. At least I know there are some others out there with the same problem - 175,000 on the vehicle - mostly unloaded highway miles. I had my rear driveshaft balanced and put a new bushing in the transfer case - no change.

Help!

TIA
AA
:D

[VA_GMC]

I've noticed some similar symptoms with my '97 2500. The vibration begins around 65 -- its odd though because it will vibrate for 2-3 seconds and then it will be smooth as glass for the next 2-3 seconds and the cycle goes on. When going through dips in the interstate it seems to vibrate more when the weight of the truck is lessened coming out of a dip. RPMs don't change anything - brought it up to the same RPM in 2nd with no vibration. I was wondering about the carrier bearing on the d-shaft and the posi track rear. --?

[ttpost]

look at your lugs on the tires,are they even or are some lower than others, if so it is a good indication your shocks are shot, or spring bushings. shocks can cause alot of vibration. good luck

[Shuck]

My experience has been that about 90% of vehicle vibrations are caused by tires. I don't know what the crap is wrong with tire manufacturers that they can't make a round or equally weighted tire - or what is wrong with tire shops that they can't figure out how to mount and balance a tire properly, but it really seems to be a problem.

My suburban is going into a tire shop here in St. Louis that does road force balancing to get my vibration taken care of once and for all. It is positively ridiculous that it is so hard to balance a set of tires these days.

I would take a look at the tires before anything else. And then I'd probably take another look before I did anything to the drivetrain on the vehicle. Usually drivetrain related vibrations will exist at lower speeds and only get worse as you go faster. Tires tend to phase in and out.