Vibration in blazer 4x4

So what you are saying is that when you put your truck in reverse, the front and rear tires both rotate, but when you put it in drive, only the rear tires turn and not the front? If so, you will need to put the truck on a lift and watch the driveshaft to the front tires. Check to see if it rotates both in drive and reverse. If it does not turn in both directions, you may have a problem i the transfer case. If the driveshaft in front is turning but the tires are not. then you can have a problem with the front axles or 4x4 hubs.

You will need to check things logically. Run the truck in the air and note where the vibration is at. Take the wheels OFF and put a few lug nuts to hold the rotors on, take the truck to 45mph or whatever the vibration is the worst. is it still there? if its gone, check wheels/ tires. if its still there, check rotors, axles. A drive shaft will make a rapid vibration at low speeds since it turns 3 to 4 times faster than the wheels. does it vibrate on or off the gas? Can you power through the vibration like go 60 and then coast back through? You have replaced a lot of parts that would not cause vibrations. Are you just changing parts willy nilly or is someone actually checking and verifying that these parts really bad?

Hello, I see you may a lot of changes and replaced a lot of parts. We leased an Explorer the same Year as yours. In our case there was a slight noise as well as vibration. The problem was the Front Hub bearings, They were bad at 18000 miles.

There are a few things I want to suggest. The spinning of the wheels on the lift will not load the bearings. A Dyno table can get everything turning with a load on it. As your vehicle is a 4x4, most Dyno's were 2 wheelers. You would have to call to find one for a 4x4.

Next, if the new Hubs do not help, have a look at the rotors. They are also balanced. You can spin balance the Wheel and rotor as a unit with a floor motor. It's not the best way to Balance because tire rotation or even shifting the Wheel on the lugs will UNbalance it. But this method CAN pinpoint a problem if a Balanced tire does not spin true when bolted to the vehicle. You will know the Rotor is off-balance and which axle is causing the problem.

Would be interested to see a Post of what you found.

Most vibrations are driveshaft being bent,worn u-joint,in need of balance,shocks,wheels,tires and more.I will bet ,swapping the complete rear axle will not change a thing. If it is lifted, you should know your in for problems. If not, and all else fails,strip the rear housing and go through it. The one you swap, may be more worn than yours and not even a good core to rebuild.

Check the u- joints are fitted in line, if ok check wheel balance both front and rear.

If you had no problems before the change in height, I suggest you check the pinion angle(s). Most suspension setups like the diff pinion to be at around 2degrees down when at rest. As you lift the body, you are changing the line between the trans output and the pinion. While the diff may still be positioned properly, the trans output is now higher, changing the actual angle which may cause the universal joints to partially bind under different load conditions.
What you may want to try is using "wedge shims" between the diff spring mount and the springs to move the pinion up and more in line with the transmission. It takes very little to change a lot so don't get crazy with them...usually only one or two will do the job.

very vague can be anything from tires- hubs-bearings-alignment-cv joints-driveshafts-u-jonts -shocks-axels

it could be as easy as checking to see if you have a dented rim.....

or as expensive as changing the "constant velocity joints" but only if it is a front wheel driven car.....

how are your shocks?

have they repacked the rear bearings..."but only if not rear wheel driven car"

you need wheels balanced, simple and cheap

:)

I have a '88 Ranger XLT extra cab 4X4 w/auto tranny (2.9L V6) that had a 2-piece driveshaft on it. After adding a 4" suspension lift, there was a strong vibration whenever I took off from a dead stop. I replaced the drive shaft with a beefed up 1 piece custom built by a shop specializing in drive shafts. The truck no longer had any vibration, and it hooks up immediately on exceleration. I found the shop on Ebay advertising drive shafts. All I had to do was measure the length from the transfer case/Tranny to the rear differential. The length of the new drive shaft allowed me to adjust almost 3/4" so all I had to do was get it close. I also took close up pictures so the shop could match up the correct flange on both ends of the driveshaft. The last thing I had to do was flip the crossmember brace so it wouldn't interfere with the new drive shaft.