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Vibration
Problems
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Index:
Introduction:
Vehicle vibration has
become a common and reoccurring complaint with the 3rd
Generation 4Runner and Tacoma.
I had a very bad vibration in my 96 4Runner from day one.
In my quest to cure this problem I had to battle with
Toyota all the way through arbitration and I ended up having to
fix the vibration myself, because they could not.
I will save my war story with Toyota for another chapter.
In my efforts to fix my own truck I have learned a few
things that I would like to pass on to those of you having the
same problem. I hope
to save you some time and frustration.
There are many things that
can induce a vibration in the truck, but it seems that most of the
common vibration problems in the 3rd Generation 4Runner
and Tacoma are centered in two areas, balance and wheel/tire
defects. There are
lots of different things that can cause vibration, but I am only
going to focus on the two areas listed above which I feel are the
most common in these trucks.
If your truck vibrates
only when you hit the brakes, then you most likely have warped
rotors and this page does not apply to you.
If your steering wheel oscillates slightly back and forth
at highway speeds with no vibration felt in the vehicle then that
is most likely an alignment issue and this page does not apply to
you.
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Balance
/ Haweka Adapter:
I have gotten tons of
email from people that have had a truck that drove nice and
smooth, then the dealer touched it.
The stories are usually the same.
The dealer talked them into an unneeded rebalance or they
just got new tires and their trucks now shake and never did
before. They have had
it rebalanced, and rebalanced, and rebalanced and it never gets
any better. They have
lead weights all over the wheel.
Think about it two lead weights on opposite sides of the
wheel, and they are the same weight. I have seen this time and time again on 4Runners and it just
does not make sense at all. How
in the world does this happen?
Here is the problem.
The wheels used on the 4Runner/Tacoma are “lug centric”
and are not the more common “hub centric” wheels like on most
cars and light trucks. Hub
centric wheels are centered on the vehicle hubs using the center
hole in the wheel. That is kind of simple.
On lug centric wheels the wheels are centered on the
vehicle hub using the lug bolt holes and not the center hole.
When the wheels are made and machined they are done so
using the lug holes to mount the wheels to the machines that make
them. The lug holes
are the true center of the wheel and not the center hole.
So, if the center hole is not in the true center you can
understand how mounting the wheel to the balance machine using the
center hole is not going to work very well.
The wheel needs to be mounted to the balance machine using
the lugholes. This is
done with a flange plate adapter made by Haweka.
The Haweka
adapter firmly locks the wheel onto the balance machine in its
true center. It holds
wheel very solid and prevents movement.
Toyota realized they had a problem with balancing these
wheels and issued a Technical Service Bulletin (TSB SU002-96) requiring the
Haweka adapter when
balancing these wheels. The
problem is that it seems that few Toyota dealers know about the
TSB let alone have the adapter.
While on one of my many, many
visits to the dealer to get the vibration fixed, I saw one of my tires on their balance
machine. I walked
over to it and grabbed the tire and shook it. It wobbled all over the place.
I asked they guy how he thinks he can balance the tire with
it moving around so much, “all the truck wheels do that.” That my friends, is the very center of the problem.
If they cannot get the wheel to hold still on the shaft
there is no way they can ever properly balance it.
The Haweka adapter
does two very basic things. First
it mounts the wheel to the balance machine the same way it is
mounted to your truck, and second it locks it to the shaft of the
balance machine and prevents movement so you get a consistent and
proper balance.
When you have your tires
balanced with the Haweka
adapter you will be surprise how little weight the tire will take.
I have Michelin LTX (courtesy of Toyota arbitration) and I
have one tire with no weight at all and the other three with just
one small one. Before
the Haweka adapter I had weights all over the wheels installed by
the dealer.
If you ever get new tires,
or decide to have them rebalanced you really should do yourself a
favor and make sure the shop has and uses the needed Haweka
adapter before you let them touch your truck.
It is possible to get a balance without it, but why
take the chance and have to go back, and back again.
You have the greatest chance of having it balanced right
the first time, every time using the adapter.
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Wheel
Defects:
If the wheels are not
round enough they will cause your truck to shake.
That was my problem; I had two wheels that were not round
enough. Round enough
you say? Believe it
or not wheels are not perfectly round.
They are close, but not perfectly round. Mine were so bad you could jack the truck up and spin the
wheels and see with the plain eye that they were not round. This is what was causing my vibration.
The wheels are measured in
two directions. Using
the center of the wheel and going outward is called radial runout.
If you look at the wheel on its edge, spin it and see any
side-to-side movement that is called lateral runout.
There are specifications as to how much of radial and
lateral runout is acceptable, but the less the better.
There is a point where lateral and radial runout can be
felt as a vibration. As
far as I can tell this concept is way beyond Toyota to understand.
They put 17 new tires on my truck to cure a vibration
caused by radial runout in two of the wheels.
They kept insisting it was a tire problem, but I knew
better because I ran my own tests and proved it was the wheels.
I eventually got tired of having Toyota installing new
tires on bad wheels and then improperly balancing them on top of
that. I replace the
two bad wheels and balanced them with the Haweka adapter and the
vibration was gone for good.
I will discuss later on
the easiest way I have found to test your wheels for defects.
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Tire
defects:
Just like wheels, tires
can have excessive radial and lateral runout.
Again too much and it will present as a vibration even when
they are perfectly balanced.
I am sure you can understand how this works just like the
wheels and I will not go into it again.
There is another defect in
tires that can cause a vibration called loaded road force
variance. The tires
and pass a visual inspection, a radial and lateral runout test, be
perfectly balanced, but still cause a vibration. This is due to the internal defects in the tire.
All tires have variances in the stiffness of the sidewalls.
As the tires roll with a load on them and they roll onto a
soft section of the sidewall the truck will settle slightly down
toward the road. As
it rolls to a stiffer part the truck will be raised up slightly.
When the sidewall variances are the same on both sides this
causes an up and down motion in the truck.
When the sidewall stiffness is different from right and
left side when the tire is viewed on edge, then this can induce a
side-to-side movement called a lateral variance.
If these variances in
sidewall stiffness get to be too much you will feel it as a
vibration. There are
other things that add to this like the way the tire casing is
constructed and if it has seems or not, but it all ends up causing
the same problem. The
problem is how can you measure for this and correct it?
Until recently you really could not, but there is hope.
There is a new type of balance machine on the market called
a road force balancer and Hunter makes it.
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Position
Balance:
There is a process called
position balancing, or OEM match mounting.
This process can reduce the overall amount of radial runout
from the wheel/tire assembly. This is done by doing a radial
runout test on the wheels and then the wheel and tires.
Remember wheels and tires are not perfectly round.
The idea of position balancing is to find the high spot on
the wheel and line it up with the low spot on the tire.
This reduces the overall amount of radial runout in the
wheel/tire assembly and gives a smoother ride.
The process can be time consuming and is not normally done.
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The
Easy Fix:
Hunter recognized a market
for a new type of balance machine and developed the GSP-9700
Road Force Balancer. This machine will automatically do several checks
automatically in a very short time that once took a very long time
to do manually. In
addition it can check tires for internal defects that contribute
to loaded road force variations.
Force variations only show up when there is a load on the
tire. Because of this
it is very, very hard to find this problem.
The thing that separates
the GSP-9700 apart from the
rest is that it can put a load on the tire to simulate the load
the tire will have driving down the road.
It uses a roller that is pressed against the tire as it is
turned on the balance shaft and looks for the force variations.
With this technique the GSP-9700
can give you the smoothest ride possible out of the wheel/tire
assembly.
The first thing that is
done is the wheel/tire assembly is mounted onto the balance
machine using the proper flange plate.
The machine then checks the wheel for lateral and radial
runout. If this is
within acceptable limits it will then press a roller against the
tire to simulate it being loaded on the road.
It checks for force variations, which is reported in
pounds. If the tire
passes this test then the machine will then run a test to
determine how the tire should be positioned on the wheel to give
the overall smoothest ride. It
will take into account radial runout of the wheel, tire and the
force variations in the tire.
The operator marks the wheel and the tire in the spots
indicated by the machine. The
assembly is removed from the balancer and taken to the tire
mounting machine where the tire is rotated on the wheel to match
the marks indicated by the balancer.
The assembly is then
mounted back on the machine and then given a traditional dynamic dual
plane balance.
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My
Personal Experience:
I have a Ford F-150 that
had a vibration problem since new.
I took it back to the dealer and had them rebalance it with
no change in the vibration. I
then took it to a friends shop, that is one of the better shops in
the area, He has a GSP-9700
and had them do their thing.
The initial checks showed
that I had two wheel/tire assemblies that had real high road force
variations. One was over 80 pounds and one was 60 pounds.
The tire with the 80 pound reading was found to be
defective and had to be replaced.
After the work up all the tires now range from between 25
and 35 pound of force variations.
This greatly improved the ride of the truck to a point it
was acceptable. It is
not perfect. The interesting thing was the operator told me that I would
still be able to feel a slight vibration in the truck as anything
over the 15-20 pound range can be felt.
He told me this before the tires where remounted on the
truck. He was right.
The only way to make it
perfect is to put better tires on the truck.
It came stock with Goodyear Wranglers and I hate them.
I cannot wait for them to wear out so I can replace them
with the Michelin LTX. He
said that the LTX is consistently the best truck tire they have
seen with the normal force variations at a consistent glass smooth
6 pounds.
The Michelin tires on my
Maxima finally wore out after over 80,000 miles of use and had
them replaced with, of course new Michelins.
On the way home from the tire store I noticed a vibration
in the car that has never been there.
I took it back to the tire shop and had them rebalanced.
Not much of a change.
I then took it to my
friends shop and had them balanced on his GSP-9700
and the car was back to glass smooth.
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Recommendation:
The front ends on the
4Runner and Tacoma are super sensitive.
If you have something that is just slightly out of whack
you will definitely know it on these trucks.
If you have a vibration and believe it to be cause be the
wheels and/or tires, then you should not waist your time by going
to a shop with old technology.
If your time is as valuable as mine then you should find a
shop with the needed Haweka adapter, a GSP-9700,
and a technician that has a clue.
The easiest way to find
what you need is to go this web
site and use their shop locator function to get a list of shops
near you that has one. Next
call the shops and make sure that they have the Haweka
adaptor for your wheels. If
they tell you that they do not have it or don’t need it, then
hang up and call the next shop.
Do not waist your time with them.
If they are willing to spend $10,000 on the state of the
art road force balancer, and not get a set of Haweka adapters to
go with it then they probably are not smart enough to work the
machine anyway.
When you find a shop
that has both items make an appointment and have them do a road
force variation work up and see if you need to replace your wheels
or tires and then get a good old-fashioned balance.
The combination of the GSP-9700
and the Haweka adaptor
should cure the most common cause of vibration in the 4Runners and
Tacomas. This
combination will give you the greatest chance of getting you
vibration problem fixed on the first visit as possible.
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