Hello, my name is John Kelly and this is the WeberAuto YouTube channel. Today I am
going to demonstrate how to use the new NVH app to diagnose a driveshaft speed
related vibration. I have a vehicle set up with a vibration
installed on it, and we are ready to go drive, do a road test, so let us set the
app up for the vehicle that we are going to use here, so if we start the app,
agree, the vehicle that I'm driving is an older vehicle that is not in our
database of vehicles, but you can actually use this app on any vehicle
as long as you enter the vehicle information that's required, so in this
case we will go with "Unlisted Vehicle" in the upper right hand corner,
this is a four-wheel drive truck, so I will click on four-wheel drive, we have to
enter the number of cylinders in the engine, this is a six-cylinder engine, we
have to enter the rear axle gear ratio, to find the rear axle gear ratio and we
have a link, that reads "Find my Axle Gear Ratio" right there on the screen,
scroll down, this is a GMC, so we will select GMC. General Motors vehicles have a code
label somewhere in usually the glove box or the trunk area, and you will find
a code that begins with the letter F or the letter G, four trucks it is the
letter G, and this truck has a GU6 axle code, so scroll down to where you
find GU6
and look in the next column, it gives us the axle gear ratio of 3.42, so we
will hit done, we will come to the axle gear ratio box and punch in 3.42
it asks us for the transfer case gear ratio on this
four-wheel-drive truck, if you're driving around in two wheel drive, or four-wheel
drive high, what you normally wouldn't do on dry roads, the transfer case gear
ratio is just simply 1.0, alright so the next thing that we need is the
transmission gear ratios, so we will click on transmission gear ratios, this is a
four-speed transmission, but notice we can hit the plus or minus buttons to
select the number of speeds in the transmission, and that this is a four
speeds, so I selected 4, we can just go with default gear ratios if you don't
know your gear ratios are. but I do know what transmission this this has. and the
way I find that out is to look at
"Find my Transmission Gear Ratios", the link right there on the screen, and
scroll down to GMC, and on the code label that I have on this truck, I have a M30
and so M30 here is a 4L60-E transmission, and if I scroll over there is the
gear ratios; 3.059, 1.625, 1.0, 0.696, so I will come back here and punch in
3.059, 1.625, 1.0, and 0.696.
the app needs to know the transmission gear ratios to calculate the rotational
speeds of some of the parts on your truck, so the last thing you have to
enter for whatever vehicle you want to test is the tire size, this truck has 235
75, 15, tires on it, so now we hit start, it brings us to the "Vehicle View" where we
have a powertrain view of a four-wheel-drive vehicle, and now we are
going to hit "Start Recording" and go drive it and see if we can pick up this
vibration, so let us go ahead and and see if we can find. I am going to sit the
iPhone on the dash, cover it up with the piece of paper, so the Sun does not
overheat it,
let us go see what we can find.
there it is showning up
driveshaft
first order
it looks liee we have got a third-order tire along with it
so here we are at 73, 74, miles an hour we have got glowing driveshaft, glowing
tires, it looks like we have multiple vibrations on this vehicle
looks like it is worse at the higher vehicle speeds
driveshaft speed is around 50,
50 revolutions per second
I am going tell the app to stop recording, we can get off and go back
I will give it a name 2001
GMC, Sonoma, with a D1 driveshaft
vibration and hit save, the app will analyze the data it has recorded and tell us
thinks it has found as the source of the vibration. Remember the app will give us
the highest average amplitude frequency over the time that we drove, so it is
telling us to have a third-order tire speed related vibration as the primary
cause of the shaking as we drive, and of course you can click on "How do we fix
this vibration" brings up a help file that tells you how to repair that, but lets
go back and look at the totals, notice we have third order tire was detected
225 times during our road test, and a first-order drive shaft
was detected 156 times, and let's see what speeds they
were worse at. On the third-order tire, it looks like 70-74 miles an hour it was
detected 158 times all the other vehicle speeds were
pretty minor, let us look at the first-order driveshaft, it was detected
109 times between 70 and 74 miles an hour, and the rest of the time
looks like 50 to 54 miles an hour it was detected 14 times, so a lower speed at
lower speeds it came in and again at higher speeds.
Engine vibrations, there were few they were picked up, second order engine was
the most, second order engine vibration on a V-6 engine is is one of those
normal vibrations that we should not be feeling in the passenger compartment, so
this old ruck actually has three different vibrations, but the one with
the highest average amplitude of 0.148 was the third order tire, followed by first-order drive shaft at 0.169
now that is a higher amplitude, but it was only detected 156 times versus the
225 times for the third-order tire, so it's not just
amplitude, it's a weighted amplitude level based on how many times it was
detected.
let us look at our graph
there is a lot of blue there, that blue is the drive shaft speed related vibration
this graph shows amplitude versus time and the color represents the frequency
of the part on that on the vehicle
Okay, well, that is how to manually enter into vehicle's information, once again
this app will work on any vehicle as long as you can come up with the gear ratios
and tire size, and number of in engine cylinders, and so on
it will work. Alright now the app gave us help for the third-order tire
speed vibration, but if we go all the way back to the first menu here, and look
under the diagnostic help icon, and then diagnostic procedures, it has a separate
menu item, as you can see here, for tire speed related vibrations, and it breaks
it down by the orders, drive shaft speed related vibrations and the their
particular orders, engine speed vibrations and their orders, and each
type of vibration has its own specific diagnostic procedures that all of those
procedures are in these help file links. while we are driving here, if we click on
if you go back to the main menu and click on Tools, there is several tools
here are available and we'll take a look at these in in different videos, but one
of them is just simply a vehicle speed signal that would be based off of the
GPS speed signal as we drive, so it says we are doing 33 miles an hour, and that matches
our speedometer
The GPS vehicle speed is actually more accurate than your speedometer because your
speedometer is based on the tire size that you have on your vehicle, and as
your tires wear out your speedometer becomes less and less accurate, we have a
Live Data tool wherer we can just look at the frequencies and the amplitudes that
are being measured as we drive down the road, so it will show you the top five
frequencies as far as amplitude levels with a tool, we have a strobe light tool
that will actually flash your camera's flash a certain number of times per
second and will use that tool in another video for engine, for abnormal engine
vibrations, and then we have another tool for measuring driveshaft u-joint working
angles, and help for correcting those. This has been a demonstration of using
the NVH app to detect driveline or drive shaft speed related vibrations, It turns
out we picked up a few other unexpected vibrations on this old truck at the same
time, thanks for watching.