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Front Suspension

Do It Yourself Alignment Article, click here

Front End Alignment Specs:

(GL) "Align it to 1 degree neg camber, 4 degrees pos caster, 0 toe. I am assuming you are using 17" tires. Tire pressures should be 23psi front and 27psi rear on a good gauge."  - Solid axle car.


Street Car:
3 degree caster :  -1/2 degree camber :  1/16th degree total toe in.
Coupe and IRS Street Cars:
    Front:    Caster  3 :  Camber  -1 :  Toe 1/16" Total
    Rear:     Camber  -1 : Toe  1/16" Total

Camber Simplified

Camber is the tilt of the tire as viewed from the front of the car. If the top of the tires lean toward the center of the car then you have negative camber. If the top of the tire tilts out away from the center of the car then you have positive camber.

Adjusting camber can have a dramatic effect on the cornering of your car. Most oval track racers run negative camber on the right side of the car and positive camber on the left. Optimum camber settings will result in more speed and ideal tire wear.

Camber is measured with a caster camber gauge and is usually easily adjusted with shims or adjustable upper a-arms. Always check the toe when making camber or caster adjustments.

The amount of static camber that you should run is a result of testing, pyrometer measurements, front suspension geometry and discussions with your car builder. Remember that poor camber settings will cause excessive tire wear. Camber settings set to extremes can reduce the braking ability of the car.

Caster Simplified

To understand caster you need to picture an imaginary line that runs from through the upper ball joint and extends through the lower ball joint. From the side view the imaginary line will tilt forward or backward. The tilting of this imaginary line is defined as caster.

Caster is measured in degrees by using a caster camber gauge. If the imaginary line described above tilts towards the back of the car, at the top, then you will have positive caster. If the imaginary line tilts forward then you would have negative caster.

Positive caster provides the directional stability in your racecar. Too much positive caster will make the steering effort difficult. Power steering will allow you to run more positive caster. Negative caster requires less steering effort but can cause the car to wander down the straightaway.

For oval track racing most racers run more positive caster on the right side tire than on the left. The caster split helps pull the car down into the turn, helps the car turn in the center and helps it stay hooked up on exit.

How much caster should you run? The amount and split depends on the type of car and track conditions. The details should be worked out with your car builder and through testing.

Toe Simplified

Toe is the pointing in or pointing out of the front wheels as viewed from the top of the car. If the front wheels point in, toward the engine, at the front edge of the wheels then you have toe in. If the front wheels point out at the front edge then you have toe out.

In general, racecars are set with a small amount of toe out. The toe out provides directional stability. Toe out pulls on the tie rods taking out the tiny clearances that are built into the tie rod ends. Depending on the type of car typical toe readings are 1/16" to " out for tracks under mile in length.

Toe should be checked often as any contact with other cars or retaining walls is likely to change your toe setting. Changes in ride height can have an effect on toe as well.

Toe can be set with a pair of toe plates that are rested on the sidewalls of the tires. A tape is placed on the toe plates in front of the tire and an additional tape behind the tire. When using toe plates a smaller tape reading on the back tape indicates toe out.

For a very precise reading you can scribe a line in each front tire. Use a tire scribe and spin each of the front tires to get your straight line. You can then measure between the two scribed lines with a tape measure or with a toe bar. As with toe plates, a smaller measurement at the backside of the tire indicates toe out.

Some racers use a toe bar to measure the toe that lies against the sidewall on one side of the racecar. On the other side, this toe bar extends past the sidewall by a few inches. A tape is used to measure from the toe bar back to the sidewall. When this system is used a smaller tape reading at the front of the tire indicates toe out. You will notice that this is opposite the two other methods described above.

Setting Toe Properly

You will get better more consistent results adjusting your toe in settings if you go the extra mile to eliminate variables. You must first decide which technique that you plan to use to take the measurements. Each technique offers different benefits and drawbacks. The methods discussed here will be the Toe Plate method, Toe Bar Method and Tire Scribe Method. If you understand each toe setting technique you will be assured of repeatable results.

Before you begin taking measurements you must insure that the car is race ready. Ride heights set, weight percentages correct, driver weight accounted for, bump steer set, camber and caster set, Ackerman set, air pressure set, stagger correct....you get the idea. You should also inspect the steering components and replace any that are worn or bent. Center up the steering before you begin. Center the drag link or rack so that the inner control pivots and inner tie rods are centered to each other. Tie rod lengths should be adjusted to match you lower control points if possible.

String the right side of the car to line up the right front to the right rear. By lining up the right side and starting with the right front in line with the right rear you will eliminate any Ackerman effect that is in the car. If the wheels are turned away from straight when you take your toe measurement the Ackerman effect can add toe out that will not be present when the wheels are straight ahead. Take the time to string the right side and you will get more precise results. Make sure to settle the car and roll it forward just before taking a reading. By rolling forward the caster in the car will pull the front wheels take any clearance in your suspension components all in one direction. Be sure not to let the car roll back after you have rolled it forward. By rolling the car forward each time you will get more accurate repeatable results.  Be sure to roll the car back then forward after each adjustment to relieve any pressure in the tire and suspension components.

When taking toe measurements that utilize the side wall it is a good idea to spin each front tire and mark the high spots on the side wall with a piece of chalk. Jack up the car and spin the RF wheel. Hold a piece of chalk on a jack stand about 1/8" away from the sidewall. Spin the tire and see if the chalk hits anywhere on the sidewall. If the chalk does not leave a mark then move the chalk gradually closer until you get marks on the high spots. Then find the uniform spots on the side wall and orient the tire so that those points will touch the Toe bar or toe plate when the car is on the ground. Lower the car and repeat the process on the other side.

Toe Plate Method: Toe plates offer fast and easy measurement of the front end alignment. When using toe plates be sure to have the toe plates resting flat on the ground and centered on the tire. You should always be sure to have the toe plates flat against the side wall. Make sure that the plate is up against the side wall evenly on both sides. Air up the tires so that there is not a bulge at the bottom of the tire in the center due to under inflation. Go the extra mile and mark the high spots of the side wall with chalk. Use a tape measure to check the back of the tire and the front between toe plates. The toe plate method should give you a smaller number at the back of the tire if you want to have toe out. Remember that any bent wheels or imperfections in the side wall will affect your settings.

Toe Bar Method: When using a toe bar make sure that the toe bar is held in the same place on the side wall each time on both sides of the car. Make sure that the toe bar is straight up and that equal pressure is place both front and back. Chalk the wheels and take your measurements. Measure the difference from the toe bar to the side wall on the back and on the front. To have toe out you will need to see a larger measurement on the back side of the tire. This is opposite of the toe plate and Tire Scribe measurement techniques. Any wheel run out or side wall imperfections will have an effect on your readings.

Tire Scribe Method: Start by scribing a line in each front tire. By spinning the tire and scribing a line with a tire scribe you will take out any variables to to bent wheels or side wall wobbles. Measure the front and back of the tire. A smaller number at the back side of the tire will produce toe out.

Regardless of the method used you should use care to adjust the tire rods equally so as to keep the geometry of the front end correct. Be sure to tighten all jamb nuts and other steering components as well as visually inspecting the steering system. All three methods can give you good results if you take your time and eliminate as many variables as possible.

Front Lower Control Arms:

[Olli] Question: "I have asked this question before but never really got a straight answer. Can I use front lower control arms besides the Ford ones or FFR's?? I ask this because my build will be at a stand still in a very short time. The Ford ones will not be available until mid to late November and FFR are kind of pricey and most likely in a backorder situation anyway ( like that would be a surprise ).

So what is it , yes or no??"


[M] "I believe the answer is NO. This is due to the use of the coil overs in the FFR suspension."

[DC] "Short answer? YES!!! Details and photos to follow! Want a hint? Control arms, front or rear, upper or lower, or coil over shocks, can't tell if they are sitting in a Mustang or a FFR Roadster. They just sit there, iron dumb, waiting to do their job. Get my drift? Folks forget the primary objective of Factory Five. USE MUSTANG RUNNING GEAR!!! Some folks think ALL of the parts on their roadsters have to come in a spanky white box with a cool logo. Remember, the stock FFR's use STOCK stang arms and shocks, and the corresponding pickup points. Kinda' opens up a whole new perspective, doesn't it?"

[2Fast] "Actually, the short answer is NO, you can not use other brands of lower control arms without major modifications BECAUSE they do not have mounting points for the coil overs. I ordered the FFR tubular lowers, and got them shipped quickly. My donor arms were a mess, with torn boots on the ball joints. Replacing the ball joints and bushings would cost about as much as the new Ford Motorsports control arms so that was my first choice. But NOBODY has them. I called all over the country to everyone who advertised in any of the Mustang magazines. Same story, national backorder from Ford. Maybe they will be available in November. Yeah, right. I think the reason that Ford doesn't have any is because they ran out of the leftovers from the Fox mustangs, and they won't / can't make any more. At least not without jacking up the price.
At this point the incremental cost of the FFR arms over the Ford Motorsport control arms didn't seem too bad, and besides, they do look pretty cool. So if you want some old donor arms that need ball joints I'll give you mine, but I would recommend getting a set from FFR. And if you do, make sure they send you the instructions to go with them. I didn't get any, but I figured this is pretty simple, it should be obvious. Wrong! Hint, the coil overs go on upside down with the FFR arms."

[DC] "Sorry dude, the answer is still yes, you can go aftermarket. Unless, of course, picking up a welder and mounting a coil over tab is now classified as major surgery. If this still isn't sinking in, pick up the newest issue of 5.0 magazine, there are 8 or so companies, with phone numbers and addresses, all selling tubular arms and K members. Call'em, e-mail 'em or write 'em. Don't ask if their parts fit A FFR. Ask how the arms attach, and if they will attach to a Mustang K member. I did. The answer, from all except for Griggs, was YES! Go get your Pegasus or Hoerr racing catalogs and check out all of the mounting tabs the REAL RACERS buy to build their cars. Oh, you can't weld? Gee whiz, take the arm to a welder 5 minutes and 20 bucks later, tubular arms for less than $300 bucks, not waiting weeks and weeks for $480 dollar arms. Granted, mine don't have the trippple coool 5 on the coil over mount, but I ain't waiting on them either. Like I said, THINK OUTSIDE THE BOX!! These cars are waaaayy more Mustang than Roadsters'. Ralph has a set that can be used, junkyards are loaded with wrecks you could scrounge up a set and rebuild them. This stuff doesn't have to come from the Factory brand new to be used. That's why the parts houses are stuffed to the gunnels with REPLACEMENT parts. You can rebuild used arms for around $100 bucks."

[2fast] "One of the reasons that I picked FFR is because I don't HAVE to do any welding. I hope to someday attain your level of expertise, but at this time I am not comfortable welding on suspension components. So I guess I would just say that you can't use other aftermarket arms "out of the box".

And I like the box thing. Call up your favorite Mustang parts supplier, give them the old credit card number, and a few days later you get a box of parts. Which is how I got the FFR arms in about 1 week. No waiting weeks and weeks.

PS I didn't say the incremental cost was small, although it looked a lot better to me when I told them to keep the seats that were backordered for a $246 credit which was applied to the cost of the FFR arms."

[MJ] "Before I did all the research I should have about 3 months ago (2 months prior to receiving my car), I purchased a set of D&D lower tubular control arms.. When I picked up the car a month ago, the FF lowers were on backorder. So, last sat, I took a ride to a friends shop (wire mesh fabrication), and brought the arms with me, along with some dimensions for the shock mount holes in respect to the pivot bolts and ball joint. 2 hours later I had a set of D&D's, with two vertical stock steel pieces and a shock mount hole right on the $$$$ Oh, and speaking of money.. I saved about $280"

94-95 and 96-98 differences

Question: [AD] "I told FFR that I was going to use the late model front spindles so I could use the bigger brakes and get 5 lug ( I got IRS coming as well).

Any problem with using 96 to 98 spindles? Will they match to the changes that FFR has to make to use the 94 spindles (as I specified 94 to them) or are these 2 types basically the same thing?"


[AD] "Turns out you are ok with using the 96-98 spindles according to Jim at Factory Five."

[RR] "Works fine, just make sure you swap for the IFS comp brackets with the kit. Or it will cost ya $129 later"

[CV] "The difference between the 94/95 & 96/98 spindles is the wider width of the spindles. The 96/98 spindles will make the width about 3/8 of an inch wider per side over the 94/95 spindles."


Question: [Ef] "I have the stock mustang front lower a-arms with the OEM bushings. My Roadster will have the FFR rear upper & lower arms with heim joint. I haven't decided on using the rear sway bar.. I probably will not. I will be installing my stock mustang Front A-arms but I need to replace the bushings. Can anyone recommend the bushings I need? I was looking at the poly's that summit offers. Also FMS has HD bushing replacements available now. They look like they're rubber though. I have read that you need to match the front w/ the rear.. Any help would be appreciated..."



[SL] "EYE, Energy Suspension makes 'em for front lower control arms (1989-1993) Pt#ES43132R $39.90/set, (1994-1998) Pt#ES43144R $59.95/set. http://www.holcomania.com"

About Vintage Performance

Our goal at Vintage Performance Motorcars is to offer products that complement the FFR IRS Roadster. When Craig decided to build an IRS roadster for road racing, he quickly came to the conclusion that their were a few items that were needed but unavailable. First, was the poly bushings for the IRS spindles. He refused to reuse the old rubber ones, it just didn't seem right. We were the FIRST to sell them over a year ago, before VPM was even an idea. Second, was the sway bars. Since Craig's roadster would be seeing street use, he didn't want to go with super heavy spring rates. A sway bar will control the body roll, without a harsh ride. Our latest idea is the machined aluminum differential bushings. Since the rear mount is solid, the front mount should also be solid. Plus they look cool, a must for a show car. You can find more information on our website. www.vintageperformancemotorcars.com.

Polyurethane IRS Spindle Bushings $89.00
Machined Aluminum Differential Bushings $59.00
IRS Sway Bar Kit $399.00
Front Roadster Sway Bar Kit $399.00

Ball Joints

What is the part number for the FFR lower front control arm?

NAPA p/n 260-1043


Go back to the FFR FAQ


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