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67-70 Mustang Suspension Modifications

 

Background

  My first car, purchased back in 1978, was a 67 Mustang convertible, which my father bought for me for $150. It was only $150 because it was missing the motor and transmission. I dropped a used 289 and 3-Speed in and drove it to high school during my Senior Year.

  In early 79 the shock towers began to crack. They cracked roughly on a horizontal plane parallel to the upper A-Frame. My father made me sell the car, because he was worried the ill-handling was dangerous. The frame cracks seemed to be a design issue that welding up would only temporarily repair.

  I sold the Convertible and then purchased a Fastback 1968 GT 390 4-Speed Mustang that actually handled worse than the convertible. Since then I have owned lots of Mustangs and learned the tricks to modifying the front suspension and frame structure. It is amazing how a couple of simple and inexpensive modifications can make the Mustang drive like a totally different car. Most of what I learned came after I bought a 1970 Boss 302 (in 1981), which drove radically better than any other Mustang I had driven.

  Below is a list of changes that I recommend making to your Mustang to improve handling performance and the life of the chassis. Changes are listed in order of both importance and difficulty.

Export Tower Brace

  Most everyone that works on a Mustang is familiar with the Export Tower Brace used on Shelby Mustangs. These were available from Ford for many years. They have been obsolete from Ford for some time now, but there are reproductions available at most Mustang Specialty shops.  All export braces are not created equal.  Many of the foreign reproductions are lighter weight and also have recesses that are not as deep as the Ford units.  One of the things that makes me cringe the most is looking at an otherwise beautiful Mustang, and then seeing an incorrect poorly made reproduction export brace installed. Make sure you purchase an original Ford or a concours Scott Drake unit.  Sanco Specialties is a Scott Drake Dealer and can provide you a correct one.  Cost is $70.00 plus shipping.

  Below is a picture of a NOS Ford Export brace that has been powder coated. The recess between the ridges on a Ford brace is a full 3/8" deep. A Ford Brace is .130" thick.

 

 

I list the export brace as the first modification. The export brace is useful as a tool to assist you in making the more critical changes by keeping the top of the towers aligned.

 

Tower Welding

 

In 1967 Ford began installing the 390 Big Block in the Mustang. The basic front structure was insufficient to support the torque and weight of the 390. The improvement made to the 67 frame to support the 390 was a simple one. The 390 (S Code) cars had the inner shock tower flange welded to the main shock tower. This simple change adds great strength to the Mustang front end and significantly reduces movement/flex of the towers. If your car is in good shape and shows no sign of cracks or the inner flange separating from the tower, just weld it up as is. Most cars need some work before welding them up. It can be done with the engine in place, but I recommend pulling the engine to get easy access to all of the areas that need welding.

Rework is usually required before welding the flange to the tower. In most cases there is a 1/4 inch or so gap between the flange and the tower. Many cars will also have some level of cracking. (I purchased a 1970 Fastback with a 351 Cleveland and the towers were cracked so badly that the flange was laying against the heads of the engine on both sides.) If you have a big gap and or cracking go ahead and remove the engine, it will be easier in the long run.

Below is a picture of my 67 GT 390 Mustang Left Shock Tower after straightening and welding.

 

Lowered Upper A-Arms

Relocating the upper control arms on 67 - 70 Mustangs have 3 significant advantages.

  1. The first advantage is that lowering the mounting location brings the A-Arm closer to the frame rail, to a location that is stronger and reduces the amount of leverage that the A-Arm has on the tower.
  2. The second advantage is the resulting change in suspension geometry. The angle of the A-Arm is reduced when it is lowered. This means that there is less camber change during suspension travel.  Range of motion with arm in stock location results in first positive camber, then negetave camber as suspension compreses.  This results in excellent tire wear, for normal driving, but instability under hard cornering.  Dropping the arm results in more negative camber as the suspension compresses, resulting in stable performance during hard cornering. 
  3. The third advantage is a reduction in ride height, roughly half the amount the arm is lowered.

  Lowering the A-Arms is simple (if you forget about all the hard work involved in safely removing the springs and A-Arms). Just drill 2 new mounting holes 1 inch below the existing holes. Draw a straight line that horizontally intersects the center of both of the existing holes. Then, draw line @ 90 degrees, down from the center of each hole. Now drill 2 new 17/32's holes 1 inch below the center of the original holes. Re-Install the upper A-Arm in the new holes. Below is a drawing that shows hole relocation and a picture of my 67 Mustang tower after completion of the A-Arm Relocation.

 

 

  Sanco Specialties makes a stainless steel template to take the guess work out of dropping your a-arms.  This template includes 2 drop locations, 1 inch for stock street driving & 1 3/4 drop for Spirited driving.  This template is available for $12.95 as direct purchase or through ebay.  See below:

 

Template TemplateAlign Info

Ball Joint Wedge Kit  

Lowering the A-Arm more than 1 inch puts the upper ball joint at an angle that has the potential to cause it to bind at extreme compression.  To remedy this a "wedge" was designed by the early racers to put the joint at an angle that assures no binding will occur.  Sanco Specialties makes these for the earlier 4-bolt style A-Arm.  Available on ebay or direct for $99.00 for the set.

Wedge Kit wedge installed

Weld-In Tower Reinforcement

 

  The biggest strength improvement you can make to your 67-70 Mustang front end is to weld in reinforcements to the inside of your shock towers. These reinforcements are welded in underneath the Upper A-Arm and triangulate the structure from the A-Arm mounting location to each side of the frame. This adds metal and superior strength where it is most needed, at the mounting point of the A-Arm. This modification is outlined in the Boss 302 Chassis Modification book that was put out by Ford and Autolite back in 1970. This modification was added to Boss 302 Trans Am racers to strengthen their front ends for the abuse of road racing. From an engineering standpoint this is by far the best mod you can possibly make to your front towers to make them rigid and survive.

  The recommended thickness for these is .106 inches. You can make these yourself out of sheet metal or you can by them from me on ebay (user fwsanco of course I recommend buying them from me). They are not difficult to make, just get some thin cardboard and start cutting templates until you get the right fit. It may take you several tries, and you have to have the front end all apart before you start. Once you have made a nice template, it will work on both sides by flipping it over. Now locate some material between .105 and .125" and start cutting.

  Like the other jobs the hardest part is getting everything disassembled. This job will also include lots of cleaning since the top of the frame rail is likely full of dirt and grease. Clean everything and weld in the reinforcement. The reinforcement should lie in at a 45-degree angle. Make sure you leave clearance for the webbing on the bottom of the A-Arm at full travel. If you did the above A-Arm lowering mod, there will not be much extra room.

  Below are pictures of the reinforcement.  You can fab one yourself, or purchase them from us on ebay or directly for a mere $32.50 for a pair.

  NOTE: If you purchased a Shock Tower Reinforcement plate, minor grinding/fitting will be required to match it to your shock tower. There are minor differences in all of these towers, especially after 40 years of use.

 

 

 

Granada & Scott Drake Upper A-Arms

  Everyone talks about installing Granada Disc Brakes on 67-70 Mustangs but you don't hear much about using Granada upper control arms. Back in the 80's my brother had a couple of wrecked Granada's he was fixing up when he discovered the interchangeability of Granada parts with Mustangs. I use Granada Upper A-Arms on most of my cars because I've seen too many Mustangs with holes cut in the towers to get to the grease fittings, or because you can hear the car squeaking down the road.

  This is a pretty simple trick, just install new performance bushings on the pivot shaft of the A-Arm. Then after applying the proper torque to the nut, cut all but 1 or 2 of the protruding threads off of the shaft. Now your Granada A-Arm will fit in your Mustang tower.

  Granada stuff is now getting very difficult to find.  Recently I have switched to the new top quality Scott Drake A-Arms with thier 90 degree extended grease zerk.  These arms are configured like the 1970 A-Arm with 3 bolt ball joint and work very well.

 

 

1965 to 1967's Need Torque Boxes!!!

 One thing often overlooked in early Mustangs is the torque boxes.  As horspower and abuse of Mustangs increased, Ford started making them better and stronger.  65 & 66 Mustangs had no front torque boxes.  Many believe the front end was better on 65/66 because the towers didn't crack, truth is the frame wasn't strong enough to cause the towers to crack, it would just flex instead.  In 1967, a torque box was added to the left front, and in 68, one was added to the right front.  Torque boxes did a great job of tying the front frame rails to the  engine bay and rockers, making the whole platform stiffer.  So the good part is, 1968 torque boxes will fit right into 65 to 67 Mustangs.  There are lots of Torque boxes out there on the market.  I recommend spending the extra $$ and buying the Dynacorn 2 part boxes.  Many of the cheap ones come welded together, and are impossible to correctly install that way.  If you have difficulty finding them contact us, we usually have them in stock.  

Conventional Modifications

 

I will not go into the standard front suspension modifications such as spring rates, shocks, sway bars etc. There are plenty of experts out there to help you with those.

 

Boss 302 Rear Staggered Shock System

 

I manufacture a rear suspension staggered shock set up that is nearly identical to the one installed in all Boss 302 Mustangs at the factory. Please go to my staggered shock web site for more information by clicking on the picture below.

Stagger

 

For More Information contact:

Forrest & Karen Sanco

12 Hickory Crossing Lane

Argyle, TX 76226

Email: sanco@flash.net

Phone: 940-594-7259

 

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