m1009 vibration

[turbinesurgun]

1009 vibraton. 1986 m1009, when i accellerate the truck shudders and vibrates a little bit in the back. i checked universal joints but they are all tight. cruising speed is fine. any suggestions? thanks in advance

 

[DokWatson]

Need more info than that. Has it always done it? If not, when did it start? Does it vibrate all the time, or at a certain speed?

 

[turbinesurgun]

just recently started it. under moderate accel and then when you get to the speed you wanna go and cruise it stops

 

[DokWatson]

Balanced tires recently?

 

[GM-M1008]

are your tires the same size ? are your tire balanced ?when was the last time you rotated your tires? are your rear tire wearing the same ? If you hit a pot hole or went off roading with the truck and hit something with you rear tires you might have a broken belt (not sure if you can feel it in the rear of the truck)

 

[GM-M1008]

Balanced tires recently?

sorry wasn't there when I hit reply

 

[OL AG '89]

Might be a transmission issue??? maybe slipping a little, while accelerating and then evens out once you get going. have you checked the trans fluid lately. check it see if it smells burnt...... or if it's getting discolored, brownish rather than RED....

 

[turbinesurgun]

the tires are all new probably less than 1k miles on em but this just started a few days ago. I had thought about the transmission too. gonna give it a service and see if it helps. thanks guys

 

[ODdave]

its the angle on the rear drive shaft u joints. mine dose the same thing

 

[turbinesurgun]

the angle is factory, do i need to replace the u-joints???

 

[ODdave]

do the rear springs sag?

 

[turbinesurgun]

Checked transmission fluid it was fine. So I put truck in neutral and climb under and shake driveshaft one time and figured out the problem. The rear u-joint is shot. When I checked it friday I had it in park and couldn't feel any play. With the transmission in neutral it loosened up and I knew right then what it was. Gonna pick up a u-joint and be back in bidness. Thanks everyone for your help and now I feel like a retard lol. I swear it is the original 1986 joint. It looks as if it still has the blue plastic inserts that hold the cups in.