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where do you feel the shudder or shaking the most, the steering wheel or the seat?
is the truck loaded?
seat, i suppose.
not steering wheel
loaded or unloaded
I would check the trans mount and the drive shaft
turning the wheel sometimes makes it worse
what exactly might be the issue?
I have seen broken mounts cause a shudder and even banging
broken transmission mount....other possibilities if this is not the case?
If the drive shaft has loose u joints under load it can vibrate and if the trans mount is loose it changes the drive shaft angle
If the rear differential has limited slip or a posi traction design with clutches it can shudder or vibrate
and this would only be at a higher rate of speed (33 mph exactly, is when it starts, and then smooths out at higher speeds
it would also do it on turns when the axles need to turn at different rates
and not while coasting/not accelerating?
tires can be like this, at certain speeds the out of balance can be felt more
but that would cause vibration while coasting too, right?
You should look at the rear tires also
if tires they would vibrate at the same speed , coasting or acceleration
so, transmission mount, drive shaft, rear tires....one of the three or all, anything else?
that is where I would start
vibrations felt in the seat are usually from the rear of the vehicle
and if all good there, (last question) where to look next?
trucks do make a lot of torque and with older trucks the drive train usually does not get fixed until something fails
Loook carefully at the drive shaft yokes. I have seen them split and take a long time to fail
alright. Thanks for the info. Not I can feel less stupid when talking to the mechanic.....;-)
I would first look carefully at the tires, trans mount and the drive shaft and if I did not see anything I would remove the drive shaft and move the u joints and look closer at the yokes
you could even look at the leaf springs for rust
if the pins break the leafs can move
you are welcome
again, that would cause vibration while coasting too, though, right? this is only under acceleration that I get the vibration
I would check the ring gear back lash and take a fluid sample to make sure the read differential is not an issue
1st, or after checking the other before mentioned areas
All these test can be done when the truck is on a lift and not take too much time
I just look around many times something sticks out
Great. Anything else?
Sometimes I run the vehicle on the lift, you would be able to hear the differential or see the drive shaft as it moves
great for spotting axle bearing noises
This might have aXXXXXshaft and if so the hanger bearing might be bad
k. Answer accepted. Have a good night!