hello all,
my 1980 yota pickup has been vibrating for the past year or so and still have not figured it out. the vibe is a humming type of vibe rattles my dashboard.
it vibrates in the front end when:
*high rpms in 1st and 2nd gear, low rpms in third only when under load. kind of stops until higher speeds.
*when I'm doing 75km+ it heavily vibrates when i let off or pop it out of gear, and when i press the gas in gear it subsides a little.
*85km+ just steady vibration until i slow down to 70ish in gear or not.

I have changed all bearings and seals front and rear, steering stabilizer, new locking hub on one side. I took the rear driveshaft out and drove it in 4wd vib. still there. all ujoints have been changed. rear detroit looked in really good shape. there is a little play coming from the front and rear driveshafts going to t-case.I never changed my transmission oil until recently and it was really gunky and milky. and i have never changed oil in the t-case.

I really need some advice and not from my friends, which is basically why i did all that work. it was all a learning experience for me as i now know my truck pretty well now.

I'm thinking t-case, but if you guys have any clue i will gladly listen,

thanks for reading!!!

 

I have put them on jack stands and pulled the drive shaft looking for vibrations before. You can also have some one rev the motor and get under there looking and feeling for things.

 

Is this a rethread? sounds familiar...

Cheapest things first; Alignment & wheel balance first. If a calliper isn't grabbing and you didn't check wheel when balanced, test wheels for straightness out of 4x4 with front end to something like a tree and jack up one rear wheel at a time. When spinning in gear at idle you should be able to tell if the wheel is straight or not and the tire roundness then switch front to rear. Axles are a bit harder to tell, need the wheel off and a steady hand with marker near edge of hub, if it skips you're screwed I could actually see the bend at hub with axle out rolling it on a flat table.

My truck had a shake but I knew the rear wheel was bent like it hit a solid wall, pushed in 2-3 inches on one side. When I balanced the wheels they looked not too bad, same with tires. When I tested the axles I noticed a slight error at the hub. Was lucky to find 2 axles in the pick-a-part, got rid of the vibration

If its not any of the above, I'd suspect the drive shaft. Rotate the bolting to flang 180 deg one at a time and see if any diff? Your supposed to mark them so they go back the same as everything is balanced together at factory.

Can't believe you didn't change all the fluids, thats the first thing to do when getting a vehicle imo.

Just what I'd do?

 

Are your motor mounts original, rubber hard and dried out ?....was getting some vibration in my 80 and new mounts did the trick...

 

my mounts have come apart/unbonded and no vibration at any speed? cant replace them right now cause of the frame bend, misaligned by about 3/4" just have to watch my torque....