TORSION BAR TECH
|The torsion bars are a major part of the Toyota 4X4 IFS system. IFS, being that
Independent Front Suspension that we all know and hate. If one
chooses to retain the IFS system, there are ways to beef it up for off road use.
One of those ways is to swap out the stock torsion bars for a set of heavier duty
Torsion bar suspensions have been around for a long time. First introduced in the 1940s, the basic idea
is that a long bar mounted horizontially along the frame will act as the spring for the suspension. The
bar does this by twisting with the up and down motion of the suspension. It's actually a rather
complicated system, but has found itself in a varity of cars and trucks. They are found in large cars,
compact cars, large trucks and of course, compact trucks like the Toyota.
One advantage of torsion bars is that the ride hieght of a particular vehicle can be easily adjusted. This
makes alignment a bit easier. Torsion bars are found the Toyota 2 wheel drive pickups. They are also
found on all of the North American IFS Toyota 4X4s built from 1986 through 1995. When Toyota
introduced the Tacoma in 1995, they did away with the torsion bars in favor coil springs.
The Toyota torsion bar suspension did not die with the introduction of the Tacoma. When Toyota finally
(and unfortunely) ditched the solid front axle in the overseas Hilux during the 1998 model year, they did
not choose the Tacoma coill over front suspension. They instead went with a torsion bar IFS, very
similer to the '86 through '95 North American Toyota 4 wheel drives. Why they did this is anyone's
guess. It's possible that the torsion bar suspension is a bit stronger for off road use, which would be
important, considering that most overseas Toyotas are used for off road utility and farm use. The
Tacoma coil over suspension provides a smoother and softer ride on the highway, than does a torsion
bar suspension. In North America, on pavement ride quaility in newer trucks has taken a precedence
over off road ability for many years now.
SWAY-A-WAY TORSION BARS
The stock Toyota 4X4 torsion bars are 22.8mm thick. Aftermarket bars are available in 25mm and
26mm sizes, with 26mm being the most common. The Sway-a-bars are 25mm thick. I prefer this brand
because the bars do not have as high a spring rate as some of the other aftermarket bars. Higher
spring rate equals stiffer suspension.
So why even bother changing the torsion bars? There are two reasons to do so. One is if you have any
sort of aftermarket bumper or winch or an engine conversion which puts more wieght on the front of the
truck than stock. The other reason is if you plan to crank up the bars for lift.
The stock bars are not designed to withstand added wieght up front. They are also not designed to
withstand being cranked up. In both cases, over time, the bars will begin to sag and may eventually
even snap, if they are continually cranked to maintain ride hieght.
After market bars are thicker and sometimes made out of better materials to better withstand being
cranked and handle heavier wieghts up front. When aftermarket bars are installed the suspension can
be cranked up about 1.5 inches. Some claim more, but I in fact believe that the optimum ride hieght,
other than stock, is between 1 inch and 1.5 inches. Anything higher and the suspension becomes very
bouncy and even dangerious.
The problem with cranking the bars at all, is that you are effectively drooping the suspension to at or
near it's maximum downtravel point. This can cause some problems in terms of axle boot wear on
trucks without manual hubs. There is no problem running the stock CV joints at this angle as they are
designed to run at a maximum angle of 22 degrees. With the suspension already drooped out, when on
the trail, you will find that your truck has little or no downtravel. Another inch or so of downtravel can
be gained by cutting the upper bumpstops down to about 1/4 inch, but this is a fairly minimal gain.
Other problems involve the suspension being out of alignment, specificly in negative camber, when the
bars are cranked up. I have not found this to be a problem, but uneven tire wear could occure. I have
not found an alignment shop willing to align the truck without returning it to stock height, but I have
heard of others who have. I'm not yet convinced it's even a good idea to even bother aligning the truck
in this condition. The steering linkage is also at it's maximum downtravel point and this can cause
added wear to the steering linkage, the tie rod joints, tie rod joint boots and the idler arm. It's always a
good idea to add an idler arm truss, such as from Downey, if you crank up the bars.
The final problem, is not just limited to cranking up the bars. This involves just changing the bars to
aftermarket units. Suspension uptravel will be severely limited. In stock form, there is very little travel
with the Toyota IFS. About 4 inches both up and down. But with aftermarket torsion bars cranked up,
this is limited even further to about 2 to 3 inches of total travel. A 4" lift and a travel kit, may help this
some. The Downey/Rancho suspension, with torsion bars and special upper A-arms, claims 10 to 11
inches of travel. I'm not convinced, but I'm sure it's better than the 2 to 3 inches I'm experiencing.
Installing new torsion bars is not particularly difficult. But there are some problem areas. The adjusting
nut and bolt at the rear of the torsion bar must be removed. These bolts are usually seized after
experiencing years of road grime. Cutting the bolts off is extremely difficult. In my case, I just kept
cranking the bolts using a very long cheater bar until they finally snapped. I was luckily able to get
them out. Your results may vary. Just keep this in mind and plan on buying new nuts and bolts from
Toyota. They are not that expensive.
Rather than go into detail on how to install the bars, I've included several links below to sites that
already do a good job of that. Plan on at least 1/2 day to replace the bars. This is entirely due to those
darn adjusting bolts. Otherwise the whole proceedure wouldn't take more than a few hours.
In the end, it's all worth it. With more than 150 pounds of winch and bumper on the front of my truck, I
have experienced no bottom out, like I did with the stock bars. I have also been able to crank the bars
with no sag whatsoever. I would highly recommend these bars to anyone who experiences bottoming
out with a heavy winch and bumper.
|This picture shows what the nut and
bolt looks like. Note the length of the
nut. This is the problem. Because it is
so long and grabs so many threads,
when it siezes, it really siezes and can be
a real headache to get out. Note how
the many of the threads on this bolt
were stripped during removal. When I
removed the 2nd bolt, I had to snap it in
A new nut and bolt set from Toyota is
around $10 per side.