All Pro
Front Solid
Axle Swap
and
Rear Suspension
Last Update:  August 11, 2006
Now rather common, the Toyota solid axle swap, often referred too as "SAS", has been performed on '86-'95 IFS
Toyotas for a number of years.  It's long been perfected and is the ultimate modification for '86 and later Toyota
pick-ups and 4Runners as the remedy for the lack of travel from the independent front suspension.   Not long after I
purchased this truck, I dreamed of performing this swap.  But cost, time and skill level always hampered me.  It was
a
catastrophic breakage in a remote area that finally allowed me to justify this swap.   
Winter, 2002
The next major suspension modification was
the installation of a
long arm IFS kit, which
dramticly improved IFS articulation, but still
had it's limitations.  
Pictures, Pictures 2
Summer, 2000
The first modifications, back in 2000 were
31" tires and a rear Lockrite and 4.56 gears.
Otherwise the truck was stock.  
Pictures.
Spring, 2001
Later I added 33" tires with minimal lift.
Additional mods included 5.29 gears and
front Truetrac LSD.  
Picture, Picture 2
Summer, 2002
Solid Axle Swap, 35" tires, front Lockrite
(later replaced with a front ARB air locker)
IFS and Introduction
The Toyota IFS system, often gets a bad rap.  Sometimes unjustifiably.    People sometimes forget, that while the stock IFS system does have
limited travel, only about 5-7 total inches, the original Toyota torsion bar IFS system is one of the most durable ever designed.    When Toyota sat
down to design an all new IFS system for its trucks in the early 1980s, the primary requirement was that it be durable and as strong as the
previous solid axle systems.   In this regard, they largely succeeded, with some exceptions.   The steering was an all new design that was
mounted high and well protected.  To a large degree it was a major improvement over the previous solid push-pull steering.  The A-arms were
large, made of steel,  and heavy duty.  And the torsion bars were mounted up high, along the frame rails, impervious to off road obstacles.  One
area that Toyota did reduce the strength in the IFS system compared to the solid axle system was in the axle half shafts themselves.   They
designed larger and stronger outer CV birfield style joints (something not well known) than the solid axle birfields, but included smaller outer CV
joint studs.     

The reason for this appears to be a built in safety feature.   On the IFS, if the axle were fail at the outer CV, then the steering could adversely
affected an accident result.   Instead, they made the axle and the outer stub the weak point, while strengthening the outer CV joint.  Unfortunately,
for off road use, when larger than stock tires are added, this means that IFS axle breakage can occure.

When compared to even modern IFS systems, it was probably the best ever made in terms of pure off road durability.     While Toyota retained this
excellent torsion bar IFS system well beyond 1995 on overseas trucks, it did introduce a brand new design for the Tacoma.   For a number of
reasons, it fell a bit short compared to the original design, but that's another topic.  The original torsion bar IFS system worked so well, that it is
only now being phased out on the newly designed Toyota Hilux overseas.   It was a suspension design that remained in production, nearly
unchanged, for almost 20 years.  That says something.  So, don't completely discount the old Toyota IFS system.  

Ok, so enough about the IFS.   The bottom line is while it's a good system, it lacks one very important thing.   Wheel travel and articulation.   For
serious off roading, there is just no way to get around the lack of either.    That's where the solid front axle swap comes in.  

Toyota stopped producing the solid front axle Toyota pick-ups and 4Runners for the North American market in 1985.   However, most overseas
markets would continue to get solid front axle trucks (although not 4Runners) through 1997.   Because of this, factory solid axles are fairly
common overseas, but not so much here in the U.S.   Back in the early to mid 1990s, somebody figured out that it would relatively easy to simply
cut off the factory IFS system on '86 and later trucks and weld on a solid front axle.   The reason was that Toyota used the exact same frame width
on both solid axle and IFS trucks.   Because of that, once the IFS was cut off, one only needed to weld front and rear hangers and than simply bolt
on springs and the axle, then figured out the steering, and they were ready to go.      Some of the first SASs involved swapping the old solid axle
push-pull steering systems onto the IFS trucks.  This added significant complexity to the swap.   Someone then came up with one of the best parts
of the solid axle swap, a way to adapt the solid axle steering using the stock IFS steering box, while at the same time dramatically increasing the
steering strength, eliminating a significant amount of bumpsteer and moving the steering rods up high, out of the way.   By the late 1990s, kits
were being sold and the SAS craze begun.  

One of the first companies to successfully design and market SAS kits was All Pro Off Road of Helmet, California.    That's who I purchased my kit
from back in 2002.   Since then, a number of companies have gotten into the game.  Sometimes with better designs.   Overall, the cost, due to
competition, has come down significantly since I did my swap.

One thing that makes the solid front axle stand above the IFS system is the ability to modify for strength.    In today's market there are few parts
designed to improve the strength of the IFS system.  The notable exception are some of the long A-arm kits available, one of which I ran on my
truck for a while.   But for the solid axle, a number of aftermarket parts to improve the steering, differential and axles exist.   Long thought to the
major weakness in an otherwise very strong axle design, the stock birfield joints are usually the first thing to break when extreme off roading,
followed by the axle shafts.   A number of  improvements have been made by
Longfield and others to the point where birfield and axle breakage is
almost a thing of the past.

Toyota designed beefier differentials in the mid 1980s when it came out a turbo 22RE and later V-6.  These diffs were limited to the rear axle, but
Toyota was kind enougth to use the same bolt patterns for the front and rear axle housings, so these stronger diffs are a direct bolt on modification
for the front end.  Even better, when Toyota came  up with a brand new high pinion front diff for it's Land Cruiser 80 series in 1990, it decided to  
forgo the old 9" Land Cruiser diff for an 8" diff that also just so happens to fit in the front mini-truck axles, but is much stronger.    

When combined with the latest offerings from Longfield with 30 spline birfields, the Toyota mini-truck axle can almost approach the strength of a
Dana 60, in a much smaller and lighter package.
The Parts
The SAS swap is not for the mechanically challenged.  It's not extremely difficult, but the most critical part of the swap is welding on the springs
mounts.   This absolutely has to be done by a professional using the proper welding equipment.   Your life literally depends on these welds,
because if they failed on the freeway, you will very likely die and take other motorists with you.  I was very fortunately that my Dad is a professional
welder by trade (now retired).  He performed a large amount of the work on the swap and his help was extremely appreciated.

The first thing to do was find a donor front axle.   These have been getting harder to find since they were last produced for the U.S. back in '85.  
Also, as they become more popular, people are swiping them up.   While any '79-'85 pick-up or 4Runner front axle will work, one thing to consider
is that '84-'85 axles are the strongest, because of a full length welded gusset that exists.  Prior axles had a shorter gusset and the earliest axles
had no gusset at all.  I've not heard of older axles breaking because of any lack of gusset, but it's something to consider.  If you can only find an
older axle, a gusset could always be fabricated later on.  Otherwise these axles are pretty much identical.   When sourcing from a wrecked truck,
avoid axles that were involved in major front end collisions as they may be bent. even unnoticeably.   My axle was sourced from an '85 4Runner.
Plan on completely rebuilding the axle, since you will have it out anyway.    Also consider the diff and gearing.   You will likely want to regear and
rebuild the diff.   In my case, I chose to have 5.29 gears installed along with a Lockrite locker in the original 4Runner diff.    However, later I
upgraded to a Land Cruiser 80 series high pinion diff and an ARB air locker, which worked much better.  More on that later.

Once the kit and axle are installed, you will very likely need to install a new front driveshaft.  One that can extended and droop much further than
either the stock SA or stock IFS driveshafts can.  This usually means a custom driveshaft.   

Below are the parts that I used as sourced from All Pro Off Road.   Not shown, are the Bilstien shocks I also purchased from them.
Spring hanger kit
High travel 3" or 4" springs
Axle U-bolt flip kit
Shock hoops
3/4" wheel spacer kit
Axle Rebuild Kit
Hi-Steer kit
Note:  This is not meant to be a step by step guide to performing an SAS.  But rather an overview of my experience.  
 
All Pro Off Road and other websites do have more indepth guides and instructions.
The Swap - Cutting off the IFS
This is what got me here in the first place.  The old WCOR upper A-arm, which literally supports the entire front end of the truck, snapped in two.   I
was barely able to get the truck off the trail and to a point where it could be towed home on a flatbed.   This particular long A-arm design was one of
the first from the early 1990s and cracked where the torsion bar bolts were mounted.   Current designs from
Chaos Fab and others, address this
issue.  But for me, I decided it was time to give up on the IFS and go the dark side.
The first part of installing an SAS kit is to cut off the original IFS.  One important thing to remember is that if you are having a hard time finding
somebody to weld the mounts on your truck, one option is to leave the IFS on the truck and drive it to a professional shop and have them weld the
front and rear spring mounts.   These mounts do not interefere with the IFS system, so once completed, you can drive home and essentially
perform the rest of the swap.    Cutting off the IFS parts can be done with a torch or saw.   The only other welding that remains is for the shock
hoops, but those can be done later.
In some cases, the entire IFS system is left intact, then torched off the truck as one piece.  This is much faster than unbolting, but it can also be
more dangerous.  In our case, we disassembled most of the IFS parts first, then torched off the mounts.   Be extremely careful not to torch off the
motor mounts which are an integral part of the upper IFS mounting bracket.   Once the mounts are torched off, the remainder can be ground off
with a grinder.  That's my Dad working on the truck.  
There's no turning back now.   This truck will never again see IFS.
These are what's left of my IFS.   Because I had a WCOR long A-arm kit, the parts may not be recognizable to some.   Most of these parts were
later sold off or thrown away.  I retained the sway-a-way torsion bars and the entire steering system and shock hoops in the event that I ever
purchase another IFS truck in the future.    These were good parts that could come in handy someday on a stock IFS system.
The Swap - The Front Axle
Bringing home the "new to me" 1985 4Runner front axle.   I also got the driveshaft.  Although I wouldn't use it on the truck, I did end up using it as a
core to High Angle Driveline who built my front driveshaft.   This front axle would be entirely rebuilt from the ground up.
Once I got the axle home, it was placed on a work bench  (This was a heavy sucker!)  to be torn down.   The first thing to come off was the diff and
axle shafts.    It would be sent out to have new gears and a Lockrite locker.  The 4Runner it came out of was an automatic, but the stock 4.30 gears
wouldn't do.  They would be discared for 5.29s and a Lockrite locker.   I eventually installed a brand new high pinion Land Cruiser 80 series diff
with 5.29 gears and an ARB locker.   The factory torque rod is not needed when doing an SAS, since we won't be doing a push-pull type steering.   
This will be cut off as will the front steering stabilizer tab.   The steering stabilizer will be located up higher and attached to the frame.
This view is one of the knuckles prior to removal.   The spindle has been removed as have the birfield joints and axles and the inside has been
cleaned of grease.    This views show the factory J-arm steering arms.    On stock solid axle Toyotas, these proved to be a weak point and would
occasionally break as they fatigued over time.    They'll be discared in favor of hi-steer arms and the hi-steer system  which is a world away
improvement over the stock solid axle push-pull J-arm steering.
This picture shows a good view of the solid machined steel steering A-arms.  These are some seriously beefy pieces that have almost no chance
of bending or breaking.   They come unpainted, so I decided to brighten them up a bit.    The other photo shows me pressing the new longer wheel
studs into the hub.   A 3/4" aluminum spacer will be added later to make the front end as wide as the rear.   Some have suggested that aluminum
wheel spacers are unsafe.   I've not had a problem in almost 4 years of using them.
The passenger side birfield and axle is being installed and repacked with grease.   I elected to initially keep the stock birfields and axles to get the
truck up and running.  But I later upgraded to Longfields.   Note the brand new All Pro steering arm that is part of the hi-steer system.   On the right,
the spindle and dustshield have been installed in preparation for the hub.    Here a special stud kit was utilized which made installing these parts
much easier than with the stock bolts.
The completed axle ready to install in the truck, minus a little painting.     The axle was completely rebuilt from hub to hub.  I highly recommend
performing this task before installing it in the truck.  It's much easier to work on it from the bench and the rebuild kit is relatively cheap.
Other parts that were installed, but not shown were vented Land Cruiser rotors from All Pro.   These rotors allow the stock IFS brake calipers to be
utilized.   My truck came with the heavy duty twin piston calipers and work very well. Some earlier IFS trucks have small calipers and you might want
to consider upgrading.  In the end, the braking system of this axle is now far better than it had before when it was on the '85 4Runner.
The Swap - Welding the Spring Mounts
In my opinion, the rear spring mount is the hardest part of the entire swap.   You have several options here.  One is to weld a spring mount on the
bottom of the frame.  Because this lifts the truck higher than desired, it's a method rarely used today.   Second is to copy the factory method of
putting a hole in the frame and welding in a tube for the spring hanger.    All Pro supplies a jig that allows you to drill or torch exactly where you are
supposed too. The jig fits inside the front cab body mount and works very well.   The main problem is that the frame is actually internally gusseted
in this location, rather than being just a hollow box frame, so it's not any easy thing to cut or torch through.   We elected to torch, but a hole saw is
really probably the cleanest method.

Once the hole is cut, a tube is slid through the frame, then welded in place.   Early on, I'm sure folks questioned if this would weaken the frame by
cutting a hole here, but after many thousands of SAS swaps and years of the most extreme off roading imaginable, I've never of heard of single
frame failure at this location of the frame.    Not only is this probably the beefiest part of the whole frame, but it's also exactly where Toyota mounted
it's spring hanger on '85 and earlier trucks.
Next, we have to install the front spring mount.   In current kits there are a different thoughts on how this mount should be designed.   Most kits use
a solid steel squarebar with spring mounts on each end.  The entire single piece is then welded to the bottom of the very front crossmember.  The
difference in modern kits is how much lift is built into these designs.   This original All Pro design has about 1.5-2" of lift.  As it would turn out, more
lift than I cared to have.   Other kits reduce the lift to around 1/2" or so.    The thing to keep in mind is that on IFS trucks, the part that the spring
mounts are going to be welded too is lower than a comparable stock solid axle truck.  So, the built in lift, even without springs is going to
significant.   Lining up the new front mount was not too difficult.   All Pro supplies a jig for this too, by simply lining up the mount with two holes
present on front crossmember and temporarily bolting it in place.   We decided to clamp the mount on, then test fit the springs before tact welding
the mount on and then later finish welding.
Finally testing the fit of the spring and axles before tact welding the front hanger.  This step may not be necessary, but we wanted to be really sure
it was going to work before welding the front mount.   You might notice the springs are actually mounted backwards.  We figured out this problem
later and fixed it.  One interesting aspect of the front hanger from All Pro was that it was designed to move the spring forward about 1/2 inch to
allow for longer than stock springs to be mounted and to help locate the axle further forward, for better clearance.
Finish welding the front spring mount to the front cross member.  This is probably to the most critical weld of the entire project and should be done
by someone who really knows what they are doing.   There is a slight gap between the spring mount connecting squarebar and the front cross
member.  To fill this, we inserted smalll pieces of steel and then stitch welded across in both the front and rear.

You do not want this piece breaking off, so I can't implore enough, if you're not an experienced welder, do not do this part yourself.
The Swap - Shock Hoops and Steering
The shock hoops from All Pro are weld on pieces.  Where they are welded depends on where the axle is located.  In our case, it would move
forward about 1.5 to 2 inches.   So the hoops were mounted as far forward on the frame as they could fit.   Note how the springs shown are
mounted backwards accidently.   But we fixed this later.   The steering is now installed.  This was the easiest part of all, as it was a matter of
simply bolting it all up.   All Pro supplied a custom pitman arm that would fit the Land Cruiser 80 series tie rod ends that we used on the steering
system.
My Dad helping install the final parts, including the steering stabilizer.   Soon, it would be ready for it's first test drive.   The front driveline was
sourced from High Angle Drivelines of Colorado.   Initially, it had U-joints on each end, no CV joint, but it included a very long 12" splined shaft and
could droop at extreme angles, which is what I needed with my initial set up.    The drawback was that it vibrated like crazy.   Later, I installed an
high pinion Land Cruiser diff.  This allowed me to modify the front driveshaft with a CV joint, since the droop angles wouldn't be as extreme.   This
smoothed out the vibrations and now I can nearly drive at highway speeds in 4WD with hardly any vibration from the front driveshaft.
First Impressions
Photo on the left is with the old and short lived 33" tires.  Two photos on the right are with the then brand new 35" Goodyear MTRs.   This was back
in 2002.   As you probably know, my truck looks a little different now.

As with any major project there are always bugs to be worked out.   For such a major modification as swapping out an entire front suspension,
things went rather smoothly.   However, there were some small things to be fixed.   First of all, the front lift was higher than I expected.   The rear
would have to be lifted to compensate.  I had assumed the All Pro springs would sag over time, but they didn't.   

Inititally, the total front lift was well over 7".  Far more than I wanted.    I later traded the 4" springs for a set of 3" All Pro springs, then removed
several leafs and got the front lift down a more reasonable, although still high, 5.5 inches.    For the rear, I had custom Alcan springs with 4" of lift
built in.  Along with my longer shackles and an additional add-a-leaf, I got the rear level with the front.
I also modified the front fenders for more clearance.  As it turns out, this may not have been necessary, but I'll never have to worry about hitting the
fenders.  Besides, I think they look better anyway.  The left view is the stock fender, the three right views are the cut fenders.
Rear Springs
Initially, to quickly fill the void of needing at least 4" lift springs, I went with a cheap set of Superlift springs, then added add-a-leafs as needed to
even out the ride hieght.   In the end, articulation was OK, but the rear end always sagged due to the tremendous weight I carried in the rear.  i
would need new springs.   So, I called
Alcan and had them make me a custom set of 4" springs, based on my weight and needs.   instead of
buying stock length springs, I ordered springs that were 56" long, then relocated the front rear spring mounts forward about 5".   The longer
springs ride better and they flex a heck of a lot better than stock springs.   They did a wonderful job and the customer service was fantastic.    I still
had to add an add-a-leaf in the rear, but the new springs have performed admirably.
Longfield Birfield joints
When I ordered my new Longfield birfield joints, the choices were a stock, but heat and cold treated birfield joint with a ring welded at the end of
the bell to increase strength.   This was the original Lonfield design.  Or, I could have gone with an all new Longfield that did not utilize a ring, but
instead used a smaller cage so that the bell could be cast thicker.    I never much liked the that design and instead elected go with the original
ringed Longfield.   Today, there's a much better design out from Longfield, if you really want a bullet proof birfield and axle set up.  But for me, and
my relatively moderate off roading, these have proven to work just fine.

In the photos, the two left photos show the three Toyota birfields.   From left to right, the stock original birfield, the Longfield and IFS outer CV joint.   
What is not well known is that the IFS CV is actually quite a bit bigger in both the cage and bell area than the solid axle birfields as can been seen.  
But there's no way to adapt it to fit inside the solid axle knuckle and in any case, the stub shaft is actually smaller than solid axle birfield, making it
a moot point.  Toyota designed the IFS to make the birfield stub shaft and the axle the breaking point, rather than the joint itself, for steering safety
reasons.

The two left photos show the difference between the Longfield (left) and the stock birfield (right).  The ring that is welded on is then ground down.  It
makes the birfield longer, but this doesn't affect how it fits inside the knuckle.    One drawback of the ring is that the cage can now no longer be
removed if the birfield were to ever break.    Also, some have complained that the ring limits steering.  In reality, the steering is the same as stock,
which is fine with me.  But some have elected to turn the bumpstops to allow for greater steering angle on the trail, and thus the newer Longfield
design works well for them.
High Pinion  Front Diff
After having problems with the front diff, because of the low angle driveline vibrating and seriously disliking the behavor of the front Lockrite locker
when in 4 wheel drive, I decided I needed a major change.  That would be an entirely new front diff.   It would solves several problems at once.  I
had
Leonard's Off Road  build me a brand new Land Cruiser 80 series front high pinion diff with 5.29 gears and an ARB air locker.
Once I installed it, I found that I could install a CV joint to the front diff and almost eliminate all front driveline vibration.  I also found that with an
open diff, with the locker turned off, I could drive in 4WD at speed as if I was in a stock vehicle with no quirkly behavior from the front end.  I couldn't
be happier.  In the end, I find that I rarely engage the ARB locker at all, but it's handy to have just in case.
Front Range Off Road Land Cruiser Pitman Arm
With the axle moved forward more than stock, I found that the pitman arm was hitting the front tie rod.  It could prove dangerous if it bent or broke
either the tie rod or pitman arm.    This is a common problem on SAS trucks with the axle moved forward.  A common, but complicated solution is
to relocate the steering box forward.   I didn't want to do that, so I had
Front Range Off Road to build me a custom Pitman arm using a Land
Cruiser 80 series arm, that is then cut and drilled.   So far, it's worked perfectly.   Unfortunately, I've heard they no longer offer these, probably due
to lack of demand and increase cost for a brand new LC80 Pitman arm.     There are a number of custom designed, brand new, cast, machined
and forged pitman arms that can fill this need today.
Bud Built Rear Traction Bar
After dealing with rear wheel hop for years, I decided to give the Bud Built rear traction bar a try.  Not wanting to weld it, I was happy to find that Bud
offers a bolt on version.    What I like most about this design is that it's specifically designed not to hang down like some of the more common
"show" traction bars.   With the excellent clearance, there's no worry of banging it on obstacles.   It's reduced the wheel hop significantly.
Update:  Lowered SAS lift
In May 2006, I lowered the lift by 1.5-2" by dearching the front springs.   Total suspension lift is now only 4" and it's great.   The truck is more stable
and rides great.  I then swapped out the 35" MTRs for 33x12.5-15 MTR tires.  For more information, see my write up on how I
Lowered my SAS lift & went to 33s.
THE END
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Note about technical content on this site:
This site contains technical information regarding certain vehicle modifications.  I cannot be held liable for any damage or injury resulting from
modifications made to another vehicle related to this website.  Modifications described on this website are only shown here for demonstration purposes only.   I
highly recommend that you seek a second opinion or further information, if you are unsure about any repairs, service or modification that you are performing on
your vehicle.
Modifications regarding suspension, steering or other critical safety related components of a vehicle should be done by a professional or experienced person.  
The legality of certain
modifications vary widely by state and country, so be sure to check your local laws.
First Impressions