weird vibration

[catmandoo]

about a year ago i started getting a weird vibration in my 92 1/2 ton ext 2wd sb,it would come on at about 62 up to about 68 then go away,i've checked everything i can think of ,it really seemed to get worse after i put a clutch in it,well anyway i pretty much gave up on finding it.well last week i was out in cal for the races and was cruising down the freeway to our friends house in his 98 1/2 ext 2wd sb and his does the same thing,his has 45,000 miles on it mine has 420,000,has anybody else experienced this vibration ,what it feels like is the back wheels hopping,kinda like the wheel is out of round,but above or below those speeds it's smooth as glass.

[Dvldog 8793]

I have the same vibration but I know what causes mine. When I put in the Gearvendor I had my driveshaft shortened. That is when my vibration started. So I know it is a balancing issue with my drive shaft. The shop that did the work said they will rebalance it but I just haven't had time. Anyways, it might be a driveshaft issue. I would say that any vibration that you've had for that long has to be a balance probalem someplace. If it was a bearing or U-joint going bad I would think it would have went by now.
Hope this helps...
L8r
Conley

[N9Phil]

I also have a vibration in my 95 Suburban. It starts around 33 to 35 mph and quits at around 39 to 40 mph. I had the front end aligned and the universal joints replaced and they thought that it might be in the transmission. The vehicle has 213000 miles. I believe that there are some solenoids that are used in the Trans for shifting but I have tried leaving the Trans in second gear and when it reaches 33 to 35 mph it still vibrates. If I get the speed up to 40 mph and put the trans in neutral, it still vibrates a little when it slows down to the problem mph so I would think that the problem is not the trans. I need to crawl under the vehicle and check my motor and Trans mounts to see if this could be the problem. If all else fails I will probably drop the drive shaft and get it balanced. This problem has been going on for a few months and at first I thought that it was just a bad stretch of road (denial that there could be a problem with my pride and joy :( ).

N9Phil (IL)

[catmandoo]

my 92 is a 5sp and his 98 is an auto,and they do it at exactly the same rpm's ,i noticed mine before the clutch but it seems worse after and sometimes it gets to hopping something fierce,i was just wondering if this was a typical problem with the ext cab short box's!!

[Truenorth]

I have the same prob with my 97 ext-cab, -short box. I have verified and my U-joints are in good condition, as well I have removed and flipped my drive shaft but made no difference. I get the vibration/hopping at around 60 -65 mph.

[ttpost]

have you checked your shocks? i see alot of different rigs come in with the same problems, 90% of the time it is the shock absorbers. all tires have a hard spot in them where the belts join. balancing makes up for some of it but if your shocks are weak and tires somewhat out of balance (which they do with wear) it can cause this problem good luck

[catmandoo]

i might also add that as far as my 92 is concerned it is rpm or load related,as if i downshift to 4th it will do it from about 45-48,but in 3rd i have never noticed it

[Simzie]

I had a very similar problem with a extended cab s-10 pick-up I had many years ago, just about drove me nuts, turned out to be the driveshaft center support bearing. the actual bearing was good, but the rubber isolater that supported the bearing was bad, I had a vibration a certain speeds, but was most noticeable was if I was backing up a steep grade, it felt like the truck was gonna shake apart, Did this from the day I bought the truck new, no surprise, the dealer was even clueless. Wasn.t till I got my wife to drive it and I stuck my head underneath to see what the shaft was doing, was amazed at the amount of travel it was going through.... My first suggestion is to check that the support is tight to the crossover and true, that is, +/- 1 degree perpendicular to the shaft. Give the shafts a good hard shake by hand forward and aft of the bearing, and a good visual inspection, if in any doubt replace the assembly, I sure you will resolve your problem....good luck, Simzie

[catmandoo]

i looked at the hanger and it feels pretty tight,i might just change it for the heck of it,as i said it seemed to get worse after the clutch change.so something is up somewhere in the driveline.after the clutch i thought maybe the clutch wasn't balanced so replaced it again and still there .