solid axle swap questions

so I recently acquired a 1988 f150 and was looking into sas my biggest question is ive read in multiple places that a lift of 4 inches or bigger is required is this true?

Yo strong918,

I do believe from what many others have done this sas that a 4 inch lift is needed, depending upon tire size.

FOLLOWING FOR A BRONCO, BUT SHOULD BE SAME FOR F150:

"...From 80-86 the bodies and fenders were more squared off and the fender openings are generally referred to as being larger than later models. Generally 33 inch tires will fit without rubbing issues except on the radius arms. Some rubbing may occur on the fenders under extreme flex but can be fixed with very minor trimming and if the rubbing occurs on the bumper it can be spaced out to fix this problem. A 4 inch lift can fit 35s with minor trimming but 33s are recommended to alleviate any rubbing issues. A 6 inch lift can fit up to 35 inch tires with minor rubbing if any. Skyjacker makes an 8 inch lift that can be used to fit up to 38 inch tires, but this puts a lot of strain on the TTB axle setup.

Another issue is whether to get radius arm drop brackets or to get extended radius arms. Extended radius arms can increase flex and offer better ground clearance, but also cost much more. Extended radius arms are also much stronger. Drop down brackets use the stock radius arms and do not offer as much flex or strength or ground clearance but are also much cheaper.

The stock sway bars can be reused with a lift if you absolutely think they are necessary. Many members believe that taking the stock sway bars off makes no difference in handling or body lean, but this modification does help the suspension flex properly. Unless you drive like Mario Andretti, this modification will be a good one for you.

Another question often asked is what is the difference between a kit and system when looking at suspension kits. A kit lifts the rear by the use of blocks or add-a-leafs or a combination of those. A system completely replaces the rear leaf springs and offers both better flex and better reliability. Using blocks for lift can be dangerous off road because they can easily break or slip out causing damage to the vehicle. Replacement leaf springs are a much better way to lift the rear of your vehicle.

Another question is whether to get a body lift or suspension lift. A body lift uses longer bolts and bushings of some type to lift the body off the frame. Generally this is not recommended over a suspension lift for off-roading, but it is a cheap alternative to fit bigger tires if necessary. One major disadvantages to body lifts is that the bolts are longer and this puts more strain on them and in extreme situations have been known to break. A suspension lift basically moves the axles away from the frame allowing for fitment of larger tires. This is usually better than a body lift because it also increases travel.

Driveshaft modification is generally not needed for lifts up to 6 inches, more than 6 inches of lift it is recommended that you lengthen your driveshafts to eliminate vibration and increased strain.

Here is a list I have compiled of the different lift heights and the companies that make them:

2 inch lift-coils and alignment cams only: Rancho, Superlift, Skyjacker, BDS, Rough Country

2.5 inch lift: Rough Country, Tuff country

3 inch lift: Rancho

4 inch lift: Skyjacker, Superlift, Rancho, BDS, **** Cepek, Rough Country, Tuff Country, Pro Comp, Trailmaster

6 inch lift: Skyjacker, Superlift, BDS, **** Cepek, Rough Country, Tuff Country, Pro Comp

8 inch lift: Skyjacker

Skyjacker, Superlift, Rancho, BDS, **** Cepek, Pro Comp, Trailmaster and Tough Country all make extended radius arms for the various lift sizes.

Body lifts are available from Performance Accessories in both 2 and 3 inch lift heights.

Another thing to keep in mind when doing a suspension lift is steering. If the stock geometry were to be kept in place, the increased angles would create excessive bumpsteer. To correct this, the steering geometry must be changed. The most common ways to change it are to use a drop pitman arm (either included in most kits or an option), to flip the tie rods to the top of the steering knuckles, to use Superlift's Superrunner steering system, or to use some combination.

Flipping the tie rods to the top of the knuckles works perfect for a 4" lift with the stock pitman arm. For a 6" lift, a drop pitman arm is also needed. In either case, a drop pitman arm will suffice by itself. Superlift's superrunner steering utilizes a drag link, 2 equal length tie rods (as opposed to the stock drag link/ tie rod combo), and adds an idler arm in addition to the drop pitman arm. It is designed for use with Superlift's suspension systems, but most others can be modified to accept it..." by Wespecially

Here is a 1/2 ton SAS (Solid Axle Swap) guide in what I THINK IS AN 86 F150 by 9.ford.5

Pics @ http://s87.photobucket.com/user/black_wolf_2006/media/Picture088.jpg.html?sort=3&o=12

"...ok here is the guide to a 1/2 ton solid axle swap, i will include all parts as well as costs to the best of my memory, as far as i know i did it on a fairly good dime. This swap replaces the stock 1/2 ton independent front suspension axle commonly known as TTB (Twin Traction Beam) with a solid or straight axle from an older 1/2 truck or bronco, most common donor vehicles are 78/79 model year but mine is a bit different

there IS metal fabrication/welding involved along with a fair amount of steering/suspension geometry

heres the parts list for my build keeping in mind very few builds are identical.

i used the 1975 axle, it came with drum brakes, i replaced those with disc brake setup from a 78 axle. I use the 75 axle because the housing is actually stronger than the 78, but the 78 is a more direct and straight forward build.

AXLE

--1975 dana 44 high pinion 3.50 gears from a 75 f150 4x4 including radius arms + brackets, and lower coil spring buckets

--1978 knuckles and spindles to replace the drum brake knuckles and spindles of the 75 model

i spent a grand total of $400 on this stuff because i had to buy 2 new spindles

heres a good tip, i used the radius arm brackets from the 75...use the ones from the 78, they help with pinion angle, rad arm angle, and are easier to mount.

BRAKES/HUB/ROTOR

--1978 brake calipers and hoses (the 75 axle had drum brakes, had to replace those) the TTB calipers WILL NOT fit

--i used the hub and rotor and lockout assemblies from the old TTB axle

--i also needed the caliper brackets from the 78 axle

i bought brand new calipers and hoses so this was about $150 total

SUSPENSION

--78 4" lift coil springs

--i kept the old TTB upper coil buckets but you can use the 78 buckets, this way you can locate them further forward for a better approach angle, or lower for more lift

--78 trac bar, modified, most people build them from DOM tubing

$250 total

STEERING

--1978 tie rod

--custom built drag link, a drag link from a 92-97 F350 4x4 will work, or build your steering

MISC

--4* C bushings for rad arms

--trac bar bushing kit

--rad arm bushing kit

$100

so that is roughly $900 not including the lift for the rear end which was another $800 LOL

now onto building the new axle BEFORE you start your swap. To do this swap you must lift the truck at LEAST 4 " via coil springs. Now that you have lifted it you need C bushings, to get the correct bushings while the axle is not attached to a truck is difficult, ask around, someone has lifted their SAS that much too and knows the proper C bushings to use. I lifted 4" and i used 4* offset C bushings to keep positive cater (a good thing). The proper caster measure is about 4* ( positive cater means the axle is rotated clockwise from horizontal when looking from the driver side) caster is measured from the flat spot on top of the knuckle. you want about 4* of positive caster so that your pinion angle will be at its best meaning you want the drive shaft and the pinion to be in as straight of a line as possible. different lift requires different C bushings to correct the caster and pinion angles...also you want your radius arms to be parallel with the ground to optimize movement, this is not a major issue but it does need to be decent, this is why from lifts over 6" you need either longer rad arms or drop brackets, since i used a 4" lift the stock brackets worked

now that you read and understand that you can move on, once you figure out all the bushings and get them, put the axle together (bolt everything you can onto it...rad arms, coil springs ect.)

removing the TTB...6 bolts, 30 minutes of work, self explanatory

no SAS is complete until the TTB is saluted on its way to the scrap pile

now hang the solid axle by the coil springs, once this is done place a jack under that axle and lift until the truck starts to come up off the stands you have it on...be careful with this, it can get squirrely fast, try to find a way to keep the axle under the truck, once the springs are at their compressed ride height, line up the rad arms and brackets on the frame, square everything up making sure the brackets are the same side to side. then mark the holes, drill and bolt them down, once the rad arms are bolted down the truck will stand on its own weight but keep a good eye on it and some jack stands under the frame just in case. now is a good time to mount your shocks and brake lines while the wheels are off. and bolt up the drive shaft, if the pinion yoke on the diff does not match fit your drive shaft just swap in the old one from the TTB

now you have to set up your steering and trac bar, the trac bar keeps the axle under the truck while steering/flexing suspension. the drag link of the steering and the trac bar have to be as close as possible in length and as close to parallel with each other as possible. just because you lifted doesnt mean you will need a drop pitman arm either, wait till after to see if you need one. before you measure everything make sure the axle is square and centered with the truck, then bolt up the tie rod and drag link, measure the length of the drag link and find a location for the bracket you will make that allows the trac bar to be as close to that length as possible, AND as close to the angle of the drag link as possible. then build the trac bar and bracket to suit. this is where the fab comes in, that end of the frame is boxed so most people just weld their brackets onto the frame, also to make the trac bar clear everything you will likely have to cut the front of the engine x-member off and reinforce it however you choose, i dont have to, mine works without cutting it up. install the trac bar and make sure everything is still square, centered and aligned.

then take it straight to an alignment shop and have them align it to 1978 F150 4x4 specs

then you TEST IT and ENJOY IT..."

SAS QUESTION

I read your guide and i was just asking if i would have to modify any thing on the drag link off of a 92-97 f350 or can i just bolt it up and for the trac bar do i need to make my own cus that is not a problem or was it better to just modify the one from the 78

I guess you could modify a 78 track bar, I used an aftermarket adustable one."

...

I do not know anyone that did a sas on 86 F Series with up to 33 inch tires that you can contact for results.

Hopefully others her will help.

GL!