Now that I have my catastropic failure addressed, another thing I
noticed on my recent trip is that at about 70mph, I start getting a
vibration, it's a very slow one compared to speed. Kind of a whump
every second or two, on and off. Doesn't go away completely in
between but kind of winds up more every other second or so. It's not
a horrible truck is gonna fall apart one, but it was enough to keep me
below 70. Last time I did any highway driving over 70 was a few
months ago and definitely didn't have it then. Truck is an 89 K3500
Thanks in advance,
Remove driveshaft and have it balanced if ujoints check out okay. The
reason it cycles is that he is getting a harmonic vibration and it
sound like it is starting in driveshaft.
Perhaps if the u joints are okay he could put a worm clamp on the shaft and
try moving it around to see what happens before he goes to the aggrevation
and expense of pulling the shaft and sending it out.
Or perhaps he should check his motor and transmission mounts first.
But hell, I'm sorry what do I know? I'm just a troll.
Well you are a troll sometimes by some of your very actions but your
idea has some merit but experiance has taught me the GM driveshafts
are rarely balanced well from factory and as they age, flex and rust
they tend to go out of balance even more and make their imbalance
known if way such as this. One way to give more insite as to whether
it is a balance problem is to place vehicle in neutral at that speed
and if it is a balance issue it will not change it much at all. It is
does change a lot it may be ujoints. If it was motor mounts it would
show itself at speeds other than this and be of different nature.
Which begs a question that's been in the back of my mind for awhile: will it
damage a GM automatic transmission (4L60) to put it in neutral while the vehicle
Might sound like an inane question, but I'm pretty sure that somewhere I read an
instruction manual that cautioned against putting the transmission in question
into neutral while the vehicle was under way.
There is no such thing as a inane or stupid question. No it will not
hurt it at all. The reason for the caution in manual is so that
someone trying for neutral does not go past it and into reverse. There
was a time in the old GM days that R was below L so you had to be
really carefull downshifting.
Now you are acting like a Troll again! You just cannot seem to shake
it. BTW, I have personally had to have the driveshaft balanced on 6 of
my own 4x4 over the years. $ of them where GM's and one of those 4 was
on a then new 89 4x4 Suburban that had a simular mild rumble at
cruising speed. Dealer said it was "normal" for warranty concerns so I
pull driveshaft myself and at my expense had it checked for balancing
and it was out of balance and rumble it did go away when it was
properly balanced as did problem I was having in other 4x4's.I have a
drive shaft on a Jeep Cherokee that need balancing when I get a change
to pull it and get it done.
No just pointing out that most of the time your response is bs. A little
dianose's might be nice befor the op start's ripping his truck apart.
<You just cannot seem to shake
So what does it matter how many shafts you have had balanced? I've had 4X4's
for 30 years and not had one balanced. Hi performance cars are another
story. But it doesn't matter. A bit more info from the op is needed.
You might put your truck up on a lift and run it in gear and see if it is
possible to observe where it is vibrating.
I did that when I thought I had a bad driveshaft, turned out to be a wheel
out of balance.
Ok guys finally drove on the highway again to try and get some more
answers, this is what I found. The vibration feels like it starts at
my feet and comes up from there through the seat as it gets worse
every couple seconds. If I drop it in neutral it seems to go away at
speed. I tried reproducing in 1st and 2nd gear at the same and higher
rpms and could not. Should I start checking the u-joints? I don't
mind replacing them if they need to go, just want to check them first
if possible. Also, my truck has the center bearing on the shaft to
the rear wheels since it's an ex cab, is there an easy way to check
that? I've heard many different ways to check the u-joints so I would
be interested to hear what you guys have to say on the best way to do
Do you feel the vibration under your feet? Under your ass? In your hands? Do
you feel it only at 70+ mph? Have you tried to duplicate in different gears?
Trying to determine if it is rpm sensitive or just MPH sensitive.
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.