Ford Mustang II Based IFS

This is the place for all Ford Mustang II based IFS information. Here you will find projects new and old as well as the old installation instructions from our kits, hints and tips on alignment and how to get the most of your Mustang II based installation. This page is a work in progress, check back regularly for updates.

 

Tech articles I have written regarding the construction and troubleshooting of the popular Ford Mustang II front suspension

I wrote an article on how to build your own Mustang II kit on the HAMB in September of 2005.

Build your own Mustang II kit

Here is that same article for you to use as a reference. 

Mustang II crossmember build up

I feel there are two different types of cross members available. I will group them into the Heidts style and the Fatman style. There are multiple manufacturers of both styles with the majority of them being the Heidts style. This is the one I am going to focus in on as the Fatman style has a few inherent problems and to correct them you end up with a Heidts style crossmember. The Fatman style crossmember does not support the frame rails and relies on frame rail torsional strength to hold the spring towers in place. 

Few guide lines here; Mustang II has a stock track width of 56″. If you use the brake rotors from a Ford Granada your track width will be 58″. I will go into brake conversions later, more importantly we need to establish if this is the right choice for you. If your car or truck is wider than 58″ it is possible to widen the track width, but with a loss of correct geometry and a degradation of handling ability. Widening the rack and pinion with rack extensions will wear the rack out faster because of the increased load. The farther the pivot from the support bushings the more strain is induced. 

This is also best suited for frames under 30″ wide overall. If you have a wider frame such as cars from the late thirties to early fifties like Buick, Oldsmobile and Cadillac that have a 58″ track width and a stock IFS but have a wide frame it may be necessary to build a new frame clip that narrows at the axle centerline. I have done several of these in the past with great success. And at that point you have the advantage of building some drop or rise in the frame to adjust the final ride height. 

STUFF YOU WILL NEED

There are some variances here, use your best judgment. 

Safety equipment is a must! Eye protection, ear protection, good welding gloves and a quality welding helmet.

You will need a 4’X 4’ sheet of either 3/16″ or 8 gauge steel. I prefer to use 10 gauge cold rolled. It is easier to work and lighter. It also requires you double up in the upper spring pocket, which makes the kit a little more complicated so I think for simplicity we will stick with the heavier material. Cold rolled steel is cleaner and stronger material, and more expensive. An alternative is to use pickled and oiled steel, PO. The main reason for this is the elimination of the hard mill scale, that black coating on the sheet. It is an impurity from hot rolling the sheet not unlike what happens to steel that you heat red hot with a torch and let it cool, it forms the same thing. That stuff is hard like wedding day dick and a bitch to grind off. When it comes to finishing your welds that scale will wipe the edge off your sanding discs almost immediately. 

You will need some tubing or pipe 3 ¼” in outer diameter. Two pieces about 2″ long is all you need.

You will need two beveled washers; I use the radius arm washers from F150’s 

Also handy will be heavy paper or poster board. Corrugated cardboard will work but is harder to cut cleanly. A compass, graphite pencil and a silver pencil or soapstone, straight edges and scissors to make your patterns from. 

You will need a way to cut the parts out of the sheet. If you’re really hearty you could use a jig saw but that is a butt load of work and noisy as hell for a long time. Most of this will be geared toward using an oxy/accetlelene torch. Once you have the parts cut out they will need to be finished. The best tool for this is an angle grinder with a sanding disc. I use a 4 ½” X 7/8″ 50 grit aluminum zirconium sanding discs. These discs are more expensive than aluminum oxide discs but last about three times longer. You will need about a dozen aluminum oxide discs or four zirconium discs.

A drill press will be handy but not necessary, a 3/8″ hand held drill motor will work but a ½” drill will be better. You are going to need a ½” and a 5/8″ drill bit. A die grinder with a carbide bit will be helpful for making the slots for the upper control arm slots, but if you don’t have one a handful of files will work.

Let’s get started. To keep this simple I am going to be thinking of a car like a 1935-1940 Ford or 1949-1954 Chevy. These are about the simplest frames to deal with, each having their own quirks. Mostly we will concern ourselves with the construction of the crossmember and getting the geometry correct. 

Support the car off the ground and level it out as best possible. Tree stumps and large blocks of wood work fine. Good quality ratcheting jack stands are good too. I fabricated some non-adjustable stands about 20″ tall, makes it easier to roll around underneath on your creeper. Strip off the front old suspension; advertise it on the HAMB classifieds. Remove any existing cross members or brackets that are going to be in the way at the axle centerline. At this point I would leave the front fenders on, if you already removed them mock them back on. Take a tire near the size you intend on using and set it under the fender at the ride height you want. Notice for and aft placement, sometimes the stock location is not the best aesthetically. I try and sneak the wheels forward a bit on cars and trucks I intend on really slamming down look better to me. I would always err on placing them forward of the center of the fender well instead of rearward. Keep in mind scrub lines and usefulness. Hammering it flat out may look cool, but is hardly practical. I try and set at least four to five inches of ground clearance. Once you’re satisfied with the placement of the wheel(s) measure up from the ground to the center of the wheel this is your spindle center, and from the front edge of the door or other reference point for the for/aft axle centerline placement. At this point you can remove the sheet metal. 

Use a long straight edge and set it on top of the frame rails. Place it at the same for aft dimension for your axle centerline. Also if your spindle center is on the frame rail go ahead and mark where it is in relation to your axle center. The rack and pinion is going to be about three inches lower than your spindle center if you are using stock spindles. If your spindle center is higher than the top of the frame rail you may need to run dropped spindles. Generally the spindle center is two inches below the top of the frame rail for a standard installation. Two inch spindles will allow you more engine clearance if space is an issue. If not you can push the crossmember up into the frame, remember that you may need to raise the engine this same amount. That may involve installing a new transmission tunnel. If you intend on installing air bags and want to lay frame this may not be a bad idea. Otherwise it is a lot more work than I care to do, spindles are cheaper than my time to install a new floor tunnel.

Now that you have established where the crossmember will go, box your frame rails. For the Chevy guys with the top hat shaped frames, you will need to box the bottom of your frame. They only have thin sheet metal there and it is very prone to rusting through. Take some of your poster board and lay it up against the frame rail, trace and cut out. When you transfer the pattern onto your sheet of steel make the pattern slightly smaller than the frame. This will make it easier to weld and give the weld bead a place to go. IF the boxing plate is the same size as the frame rail or bigger you will not get a good solid weld and it will crack out. Finish grind and sand to your taste. 

Transfer your axle centerlines all the way around the frame rail using your long straight edge. They need to be parallel from side to side. Your frame rails may not be parallel to each other so dimensions made perpendicular to the frame rail may not be accurate. Measure 1 ¾” in front of and behind the axle centerline and mark the frame at these points. This is where the front and back plates are going to be at. Measure the inside of the frame rails at these points. These are going to be the outer edges of the vertical supports for your crossmember beam, draw these out on your cardboard. What you want to do is re-create a cross section of your frame rails. So go ahead and locate all four sides of the rail, top bottom and outsides. It is best you draw this out in the center of a large piece. Cardboard is cheap or free so use it up. Also locate where the spindle center is in relation to your frame rail. Now measure down from spindle centerline 3 ½” (stock spindle) or 5 ½” (dropped spindle) on both sides. This is going to be the vertical dimension (ref. drawing 1, dim. A) for your lower control arm mounts. These mounting holes are going to be equidistant from the center of the crossmember and 21 ¾” apart (dim. B) and the holes are ½” in diameter. You can draw the upper and lower parts of the main beam at this point making the lower control arm mounting holes the center of the beam. The beam should be about 3″ tall at the most. Now depending on what style rack and pinion you are going to use and what your needs are depends on where and if you drill holes for the rack and pinion. Most of the time we won’t drill them out just mark them for locating rack and pinion. For stock Mustang II rack and pinions, power or manual, the first hole is 2 1/8″ (dim. C) from the left (driver side US) and the second is 16″ to the right (passenger US) (dim. D). If you plan to use a power rack from a Fox chassis Mustang, Thunderbird the second hole (dim. D) is 15 ½” over. To finish the front and back plates draw your inside vertical supports from the top of the frame rail down to the main beam. The intersection points should be 18″+ apart (dim. F) for the best rack and pinion clearance. When you’re done it should look something like drawing one. 

Now the fun! Cut out your patterns and transfer them to your plate. I center punch through the pattern to locate the control arm holes and rack mounting holes. Use soapstone or other heat resistant marking device. Fire up the old blue wrench and get cutting (or jig sawing for you HE-MEN) I leave a little extra material when cutting with a torch, even with a straight edge guide the line I cut can be a little jagged. Once you’ve cut your pieces out clamp them down, or in a vise and grab the angle grinder and grind down to your lines, make them all smooth and clean. Then drill out the lower control arm attachment holes to ½”. 

Now you will need a pair of tubes 3 3/8″ long with a ½” bore or larger and a pair of 1/2′” bolts or all thread and some nuts and bolt the two pieces together. Starting to look like something isn’t it! Check it for fit in your frame; it should fit up nicely with out too much gap to the frame rails. Once satisfied with this part cut two pieces of plate for the top and bottom about 18″ X 3 ½” and two for the inside vertical of the crossmember. Clean up your edges of any slag or grinder dirt and tack the bottom into place. I recommend making some internal gusseting near where the rack and pinion bolts will be if you plan on mounting the rack straight to the crossmember and not rotating it back. These will act like a crush sleeve and keep over zealous wrenching from collapsing the crossmember. Tack welds the top three plates into place. Now suit up and weld that sucker together.

Sit back and enjoy a cold beverage and admire your work. 

When the crossmember cools down, grind off the ugly and finish to your taste.

Now lets tack that into the frame. The frame should be level at this point. Slide the crossmember into place and center it on you axle center line marks. The crossmember should also be level. Check to make sure the frame is square by cross measuring (diagonal) from holes in the frame and double check to make sure the crossmember is where it is supposed to be. Weld it down.

At this point you should have a main body crossmember installed into your frame. You will need to locate the rack and pinion next. Depending on how far you pushed the main beam up is going to determine whether or not you will need to create C-notches for rack boot clearance. For our purposes I am going to assume that anyone attempting this will purchase tubular A-frame style lower control arms from someone like TCI or Heidts. Both of these kits will relocate the forward control arm bushing in front of the main crossmember. To make things last we need to push the rack and pinion forward for better clearance against that bushing. 

The rack and pinion center is going to be 3″ forward (Drawing 2, dim. G) Of the front of the crossmember. And the height is 1 ½” above the lower control arm mount (dim. H). this is the actual rack shaft inside the rack and pinion not any of the attaching hardware. The reason for this is to eliminate any bump steer we may incur. We can rotate the rack body pinion shaft any which way (forward if you’re a sicko and are doing this on something like an Econoline Van)

If you do not have a 2″ radius of clearance around the rack and pinion center you will have to create a C-notch. What I do create these is to use a section of 3″ or bigger schedule 40 pipe. I cut the pipe about ½” wider than the frame rail. This gives me a better place to weld to (fillet) and there is no clean up and sanding for hours. Plus I think it looks cool. (Drawing 3).

Let’s not worry about actually mounting the rack until later. I would like to have the engine in place, and idea of what the exhaust is going to be and where the steering column will come through the fire wall so that we can determine the best routing for the steering shaft. 

If you have purchased a set of tubular arms, now would be a good time to install the lower arms. I really don’t like the mounting kits that come with these things. They put the entire load into the crossmember. You have a spring pressure trying to rip the mounts down, and you have resistance from the tire being accelerated by the frame creating a rear rotation of the arm. Not to mention shock loads from the adverse road conditions we like to plow through. 



Use the sleeve supplied with your kit that fits inside the crossmember. You may have to drill the crossmember out to 5/8″ as suggested by the control arm manufacturer. Weld the crossmember sleeve into place. Do not install the rear sleeve and gusset at this time. Put the control arm into place using the supplied hardware. This will allow you to measure the hole location for the rear support pieces (drawing 4) and determine overall shape. Again I always make test pieces out of cardboard first and then transfer them to steel after I am positive the will fit. Once you have all four parts cut I would install them and tack weld them into place. It is also a good idea to “box” the brackets in a similar manner to the crossmember. Remove the lower control arm and weld it up. You will want to get new hardware for mounting the control arm in this manner. Two bolts approximately 3″ long for the rear and two bolts approximately 5 ½” to 6″ long. These will be easier to remove and reinstall at a later date than the extra long bolt that comes with the kit. 

On to the spring pockets.

We need to create the basic upper shock mount first. This is where we need the 2″ long pieces of 3 ¼” OD pipe or tubing and those beveled washers. Weld the washers to the top of the pipe to make a sort of a cone. This is where the shock it going to mount into and what is going to locate the upper end of the spring. Set them aside to let them cool. 

Using some cardboard to make a pattern again, you are going to need two of every thing from here on out. Refer to drawing 5 to get an idea. Start off with a centerline on your paper. Draw a 3¼” circle; this is where the last piece you made will fit into. Second, draw a radius around that circle of 2 ¾””. This is going to be the outer edge of the spring pocket. Next draw a line perpendicular to the centerline 2 ½” (dim. I) away from the center of the 3 ¼” hole. And another line 3 ½” (dim. J) from the same hole. Next draw a parallel line to the centerline at 2″ (dim. K) and another on the opposite side of the centerline at 3″ (dim. L). The intersections of these newly drawn lines will be the adjusting slot hole locations. 

The next drawing (6) shows the outer shape of our spring pocket/adjuster plate. 

Dimension M = 2 7/8″

Dimension N = 3 7/8″

Dimension O = 4 ½”

Dimension P = 1 ½”

From that you should be able to play connect the dots and end up with something that looks similar to drawing 6. Cut it out and cut two of them and sand them to shape. Once that is done drill out the four holes per part for the adjusters to ½”. Now it is time to break out the files or die grinders and make the holes into slots. 

After we have cut out our adjuster plates we need to put a slight bend in them. On the “P” dimension in drawing 6 needs to be about a 10 degree bend. Make sure you mark them for a left and right side. Clamp each one into a vise or table by the slotted side and give the ring a whack with a hammer. I prefer the use of a brake over this method but it does work. 

At this point take the cones you made earlier and they should fit inside the large hole you cut in the adjuster plates. Install them as in drawing 7 about half in half out. You can weld them into place. 

We’re getting close guys! Now we need to start mocking up the spring pocket locations and figuring anti-dive. Let’s keep it simple for now and just use factory Pinto dimensions. Mustang II V-8 had more angle and a lot more front weight bias. That would be fine on a pickup but not all that necessary. If you have a good idea on where your center of mass is on your vehicle you can adjust the upper angle to match it. What you want is for the upper and lower control arm mounting planes to intersect at the center of mass, viewed from the side of the vehicle. You can change the dimensions I give to suit your needs if you’re a little more experienced with this. Otherwise stick to the program.

The spring pocket and shock mount need to line up on axle centerline. This keeps the spring square over the lower control arm. The adjuster slots need to be parallel to each other and parallel to the ground. They are also 28″ center to center (dim. Q) (Drawing 8) I use a piece of angle iron 30″ long with ½” holes drilled at 28″ and bolt the spring pockets to the angle. Then mock the spring pockets over the crossmember. I use scrap iron, wood or what ever lying around and cross measure to make sure they stay centered. Refer to drawing 9 to see the relation. Dimension R is 9″ and dimension S is 8 ½”. Once you have the spring/adjuster plates mocked into place cut a couple of pieces of steel that will serve as the upright inside of the spring pocket. Heavily shaded area of drawing 9. Tack weld them together. 

The next part involves making the “wrap” around the outer spring pocket. The best way I have fount to do this is to make a cardboard pattern. One from the front of the spring pocket and one from the rear and tape them together. (Drawing 10) and double check your fit. Once satisfied with the fit cut a pair out of steel and start bending the steel around the outer edge of the spring pocket. This is one of the hardest things about building one of these crossmembers, and I think it is one of the hardest to explain. It is something that I have had to do a number of times before I get one to fit perfectly. You may consider building the outer wrap in two pieces and welding the seam where they meet. 

Sorry if the drawings are getting crude, my eyes are starting to bug out.

Ok folks I think we may be near finished. Once you have the outer wrap figured out go ahead and weld that sucker down tight to the frame. If you have a frame that is wider than 28″ you may need to create a C-notch for spring clearance. I know some small ones are needed on 1941-1948 Fords; otherwise the springs will contact the frame. If you plan on installing airbags you may need even bigger notches for clearance. 

After everything cools down from your welding spree bolt on the upper control arms and spindles. Leave out the springs for now; they’re just a pain in the ass while you’re setting things up. 

If you have your mock up engine, grab it and set it into place. You will need a rear sump oil pan in most all situations to clear the rack and pinion and crossmember. I fabricate a steel U to cradle the oil pan and rest on the crossmember. It makes things much easier and safer than blocks of wood under the oil pan but isn’t necessary. If you have the headers or manifolds you intend on using put them on too. We need to determine where everything is first then we can install the rack. 

You cannot change the rack and pinion centerline, PERIOD. Refer to drawing 2 dimensions again to remind yourself where the rack is supposed to be. Now with the rack mocked into place, use some ¾” dowel rod of a broomstick to simulate the best routing of your steering shaft through your maze of engine components. It may be necessary to use three steering universal joints. Got it where it will work the best? Good! Now see where the rack mounting bolts are. If you’re lucky all you have to do is drill out the crossmember on your previously indicated marks on the crossmember and install. Because we moved the rack forward to clear aftermarket control arms you may need a stack of 5/8″ SAE washers between the bushings and the crossmember to get the proper spacing. 

If you have rotated the pinion shaft back for better clearance, say to avoid engine mounts, you will need to build some brackets to weld to the front of the crossmember. I think you have seen them on just about every aftermarket crossmember available. The easiest way to do this is to get a piece of heavy wall (.156″) 2″ or 3″ wide by what ever box tubing and cut a slice at the same angle that you need. (refer drawing 11) I find it easiest if I weld a 5/8″ nut to the inside of this bracket before I weld it to the crossmember as getting a wrench in there is nearly impossible. Bolt the brackets to the rack with appropriate hardware, usually grade 8 coarse thread stuff. Line up the brackets with the marks you made on the crossmember, minding of course the rack and pinion centerline (drawing 2) and tack weld them into place. Attach the tie rod ends to the spindles if you have everything. Center your rack and pinion by turning the pinion lock to lock counting the turns. Divide the number of turns in half and turn the rack back from full lock that same number of turns. You should be able to move the spindle up and down with little or no toe change and nothing should bind. If you are getting toe change re check your dimensions. If you absolutely need to, raise or lower the rack vertically and re-tack weld and then re check for toe change. A little change is normal, usually around ¼”. If you have more than that there may be something wrong with your rack or you have some dimension off somewhere. 

Once you are sure everything is correct do any final welding you may have not done.

I think that wraps the major construction up. I will screw with tuning a finished front suspension later. I’m tired. Thanks guys!

 

I will be editing this and adding new pictures in the near future. I am considering a service whereby you input your frame dimensions and can have us CNC Plasma cut your parts.

If this sounds like something you might be interested in, please leave some feedback.