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With so many suspension products on the market these days which is the best one? Well, it depends on the intended application. An all out drag car will require different chassis components then a street car or a road course car. Since the majority of my experience is with drag race and street suspensions, that is what I will outline.
Quad shocks are nothing more than a band-aid for a poorly designed factory lower control arm. Its actually the front lower control arm bushing that causes the problems. Without the quad shocks Mustangs wheel hop horribly. Change the lower control arms to some good aftermarket pieces and throw the quad shocks in the garbage.
K-members: 1979-1989 K-members were nearly the same. 1990 and up Mustangs had the lower control arm mount repositioned on the K-member to increase negative camber on suspension compression. The front struts top mounting position where also repositioned slightly rearward to improve static caster. Inline 6 cylinder k-members differ from 4 cylinder and V8 k-members due to the length of the engine. To swap a V8 into a inline 6 cylinder car you will need a 4 cylinder or V8 k-member.
Aftermarket K-members have many advantages. The first obvious advantage is roughly 25lbs in weight savings. Other advantages are increased header clearance and improved suspension geometry.
Subframe connectors: There are several choices in subframe connectors on the market. Some are bolt on, some are weld on and some are thru the floor design. The least desirable are the bolt on type for obvious reasons. The next choice would be the weld on type that connects the front and rear subframe on the underside of the car. A lot of these types of connectors are made of flimsy steel so if you elect to go this route make sure you stick with the good brands that make heavy duty pieces. The best choice is the thru floor design which is typically 2x2 or 2x3 square or rectangle tubing and solidly ties the front and rear subframes together. Some chassis shops will also add tubing to connect the subframe to the rocker panel area as well for additional support.
Rear control arms: Pretty much any aftermarket control arm is going to be better than the flimsy factory control arms. However, a non adjustable bolt on control arm has its limitations. Pinion angle and preload can not be adjusted so you are stuck with the factory settings which can be slightly altered with other than stock springs by changing the ride height. A non adjustable set of control arms will make a noticeable difference but an adjustable set of control arms will make a bigger difference and is a step in the right direction for making an efficient suspension. Adjustable lower control arms are nice for centering the wheel in the wheel well as well as positively aligning the rear end. Adjustable upper control arms can be either single or double adjustable. Double adjustable are much easier to work with because single adjustable control arms need to be removed to make adjustments. Using double adjustable uppers you can set your pinion angle and preload. Which control arms are the best is dependent on the individual application.
Pinion angle and preload: Pinion angle is the angle of the pinion in relationship to the Crankshaft Centerline OR the Driveshaft. To set pinion angle and preload you will need an angle finder that has a 360 degree face and uses gravity to pull the needle. These usually come with a magnetic base and are about 4" in diameter. You will need to have the car in full race trim with either you in the car or a stack of weights in the driver seat that weighs the same as you as well as fuel, nitrous bottle(s), etc. The car must also be sitting on the ground or on blocks to load the front and rear suspension and the car needs to be sitting at the same angle as it would be if it was on the ground. In other words, if the car sits level in full race trim on the ground with you in it, then it needs to be level when it is on blocks. Once you get that done then you can remove the bolt from the body side of the passenger side upper control arm and let the control arm hang on the rear end housing. If the body or axle housing moves sideways during this process you will need to start over. Put the angle finder on the front of the harmonic balancer and note the angle. Now you can put the angle finder on the flat portion of the pinion yoke and note the angle. Subtract the two measurements to get your pinion angle. Example, if you have -1 degree angle on the crank and +2 on the pinion the difference would be -3 which would be your pinion angle. Now you can adjust the driver side upper control arm to set pinion angle. Shortening the control arm will increase pinion angle while lengthening the control arm will decrease the pinion angle.
*With rubber bushings: Set Pinion Angle -3 degrees to -4
Anti roll devices: An anti roll device (or anti roll bar) is a device that attaches to the body of the car and to the rear end to minimize body roll. The body brackets allow the bar to move freely. There are connecting links that attach to the anti roll bar and to the rear end. These connecting links are adjustable. Once you have the anti roll bar mounted to the body and the connecting link tabs welded to the rear axle you can adjust the device. Like setting pinion angle and preload, to adjust the anti roll device you need to have the car race ready with the driver or weight of the driver in the driver seat. If you have coil overs, level the car side to side (with the weight of the driver in the driver seat) before adjusting the anti roll device. If you don’t have coil overs then you have to work with what you’ve got. Do not use drag type stock location springs with an anti roll device. Stock V8 Mustang springs work great if you don’t have coil overs. You can install the driver side connecting link or links as well as the passenger side. Set the links with zero preload to start with. Make a pass with the car and see how the chassis reacts. If the car steers left on the rear tires, add shorten the passenger link by a ¼ turn at a time until the car straightens out. If the car steers right on the rear tires, lengthen the passenger side link by ¼ turn at a time until the car straightens out. If the car doesn’t wheelie much or at all you probably can just leave it at zero preload unless you can feel the car pushing one direction or another when you leave the line.
Shocks and struts: Shocks and struts are a critical part of any suspension. In a drag race suspension front struts (or shocks) control the rise and fall of the front end, hence the terms 70/30, 90/10, etc. The first number in the ratio is the percentage of resistance for compression and the second number in the ratio is the percentage of resistance for extension. For example, a 70/30 strut has 70% compression resistance and 30% extension resistance. In a basic drag race set up, a 90/10 strut will do the trick. However, to get the most out of your chassis you will need an adjustable strut, preferable a double adjustable unit so you can adjust the compression and extension. Many variables effect what strut or shock will work on your particular vehicle. Tire size, transmission type, gear ratio, horsepower, weight, track conditions, clutch type, stall speed, etc. all have an effect on what the vehicle is going to want for strut and shock adjustment. A 90/10 might work on one car while another car might work better with a 70/30 or other ratio. You want the front to rise evenly and slowly but not so slow that it effects and traction. If the front end rise too fast the car could wheelie excessively. If the front end doesn’t rise fast enough there will be excessive tire spin. If the front end falls too quickly the rear suspension can unload causing tire spin. Bigger is not always better. It is very possible that a tighter extension rate will 60 foot better than a looser extension rate. A looser strut is not always the answer. You have to find the sweet spot for both compression and extension. This will probably take several test and tune passes but nobody said going fast was easy.
Rear Shocks: Ratios apply to rear shocks as well. A 50/50 rear shock has 50% compression resistance and 50% extension resistance. Again, adjustable shocks can make a big difference in chassis tuning.
Rear coilover shocks are another option and are a good way to add adjustability to the rear of a drag. Basically there are two versions, single adjustable and double adjustable. Single adjustable coil overs only allow one adjustment which is usually compression. I did have a set of QA1 rear coil overs once that seemed to adjust extension and compression with a single knob but extension and compression could not be adjusted separately. Double adjustable coil overs are more expensive than single adjustable coil overs but they offer adjustment of both compression and rebound independently of each other. Double adjustable is the way to go if your budget permits. Which ever style of coil over you choose, be sure to install them properly. Most coil overs are designed to be installed so when the vehicle is at the desired ride height the shock will be about 2/3 compressed.
Spring rates for coil over shocks:
With a coil over you want the lightest spring rate that will not coil bind so
that the spring can react quickly and allow the suspension to operate as
intended. Too stiff of a spring will hit the tires hard and then unload the
rear suspension causing tire spin. On a Mustang the spring rate will be in the
100 pound to 150 pound range depending on the weight of the car.
Swapping a tilt column into a 90-93 Mustang:
Removal of old steering column:
Installing the non air bag, tilt column:
The airbag has a built in back up power supply that takes
about 15 minutes to discharge after disconnecting the negative battery cable so
keep this in mind when handling an airbag steering wheel. As a safety
precaution you should disconnect the negative battery cable and wait at least 15
minutes before removing the airbag.
You can rebuild the traction lock using the factory type clutch packs or you can rebuild it using the heavy duty carbon clutch packs from 03-04 Cobras. When you rebuild the traction lock, it is a good time to install performance gears and an aluminum differential cover with bearing cap supports. It is also a great time to upgrade axles. You can upgrade from the stock 28 spline axles to 31 spline axles and keep your factory differential You will need to buy a set of 31 spline side spider gears and install them in place of the 28 spline side spider gears when doing this rebuild if you choose to upgrade to a 31 spline axle.
Before you start anything else dump some fresh gear oil in a container and soak the new clutch discs and steel plates while you disassemble everything. Now with the car on jack stands remove the wheels and pull the drums off. Put an oil catch can under the center of the rear end and remove nine of the ten bolts for the differential cover leaving the top one in place but loose. Pry the cover loose at the bottom and drain the majority of the. Then you can pull the cover off and the rest of the fluid will drain. While the rest of the fluid is draining scrape any gasket or sealant material off of the gasket surface of the axle housing and off of the differential cover. Be sure to wipe surfaces clean as well as the inside of the axle housing and the differential cover. Rotate the differential until the small retaining bolt for the differential center pin comes around. Take this bolt out and remove the pin. Now you can push the axles in toward the differential and remove the c-clips that hold the axles in. Once the c-clips are removed you can slide the axles out a few inches so you can work on the differential. Remove the S-spring. This may require the use of a hammer and/or screwdriver. Once you get the spring out you can rotate the differential either by hand or using the pinion to work the spider gears out. Take all four out and set them aside. Now you can pull the clutch packs and shims out. You can rebuild per the factory specs or you can remove a steel plate add an extra clutch disc which is going to create more friction area and will be better for performance applications. To do this stack the pack on each side as follows, clutch disc, steel plate, clutch disc, steel plate, clutch disc, steel plate, clutch disc and then the shim. You will either need to buy another rebuild kit (or two clutch discs separate if you can find them) or you can find the two best clutch discs out of your used clutch packs and reuse them. Chances are this configuration is going to be different from the way you took the parts out which is ok because the method listed above will give you a stronger traction lock. Now you can install the shims and clutch pack assembly and then the side spider gears. Its pretty self explanatory but the clutch packs have two tabs that will line up with two slots in the carrier. Line them up and everything will slide right in. Shimming can be kind of tricky. Some people use a micrometer to measure the clutch pack when they remove it and reshim it to that size which does work but the parts are wore so shimming it to the size that it was when removed is going to leave the clutch pack a bit loose. I like to tighten them up a bit. I usually put it together and take it apart a couple times until it feels tight enough for my liking. When the upper spider gears start to get hard to rotate back in, the clutch pack shimming is just about perfect. Do not use extra shims or a thicker shim in place of adding an extra clutch pack. All an extra shim will do is make the clutch packs wear out prematurely. Adding an extra clutch disc and removing a steel plate on each side increases friction surface without any added wear and tear. Now you can install the remaining two spider gears. To make this easy you can cheat and use an axle. Slide an axle in and then set the two remaining gears in place. When rotated into place you will want the hole in the center of the gear to line up with the hole in the differential so the pin can slide back thru them so plan accordingly when you set them in place. You can slide the center pin thru the gears to make sure they are lined up straight across from each other. Now rotate the axle (with the car in gear) until the gears are in place. You will probably have to use both hands so you can hold the gears in place while rotating the axle. Now you can install the center pin thru the differential and thru the gears to make sure they are lined up properly. It should slide in fairly easy. Then pull the pin back out. Now you can install the S-spring. This can be a bit difficult and will probably need some “convincing” with a hammer and a block of wood. An F150 spring is stiffer and will provide more force on the clutch packs but can also make the clutch packs to wear faster. Keep that in mind if you elect to go that route. Once you get the S-spring back in you can slide both axles back in, install the C-clips and then pull the axles back. Then install the center pin thru the differential and thru the gears. Install the pin bolt in and tighten. Now put the car in neutral and rotate an axle to make sure everything spins freely. Next lay a generous bead of silicone around the outside of the differential cover and install it. Tighten the bolts. After allowing the silicone to dry you can fill the differential with new gear oil and friction modifier thru the fill plug on the front side of the differential. When the gear oil runs out of the fill plug hole the differential is full. Clean the magnetic fill plug while you have it out. Then put the drums on and the wheels. Your done!
Factory Mustang Suspension Specs
Ford Racing Spring specs:
Fox body 5 lug conversion:
Basic front 5 lug conversion
The easiest and cheapest front conversion is to use factory 5 lug rotors. For 1979-1986 Mustangs and 1987-1993 4 cylinder Mustangs use 1983-1992 4 cylinder Ranger rotors. For 1987-1993 5 liter Mustangs use 1985-1991 Lincoln Mark VII rotors or 1984-1986 SVO Mustang rotors. Installation is as simple as taking the old rotors off and putting the new rotors on. There are several late 90s and newer factory wheels that will not work with this conversion because the rotor hub protrudes out past the rotor surface and interferes with the center of the wheel. Not only will the center caps not fit on the wheel when they are on the car but the wheels will also not mount flush to the rotor. Even though you may think the wheels are flush with the rotor after tightening the lug nuts, I assure you they are not. I'm speaking from experience. You will surely find out if you take the car for a drive... 1/2 wheel spacers (which I don't recommend) will remedy this problem or you can do the SN95 5 lug conversion instead.
If you're sticking with your 4 lug wheels, AmericanMuscle will help you find the right ones with their selection of Mustang 4 lug wheels
Fox body SN95 front 5 lug conversion
One way to do this conversion is to order the Ford Racing M2300-K Cobra Brake Kit. Another way to do it is to use SN95 spindles from a parts car. SN95 assemblies are designed with improved geometry for better steering feel and the braking system provides better stopping power and less pedal fade. Steering response is greatly improved and bump-steer is reduced. In addition to that they use a sealed bearing instead of the old style two bearing and a dust cap that protrudes out past the rotor surface which somewhat limits your choice of wheels. With a 4 wheel disc conversion it will be necessary to convert to a 2 port master cylinder and an adjustable proportioning valve is recommended as well. Some of the master cylinders that will work are: 1994-1998 GT, 1993 Cobra and 1994-1995 Cobra. When using an aftermarket adjustable proportioning valve you will need to gut the factory piece. To do this, remove the 13/16" cap off the front of the factory valve and remove the internals except the rear spring and rod and then replace the cap.
If you don't use the Ford Racing M2300-K brake kit you will need left and right side spindles, hubs, rotors and calipers from either a 1994 or 1995 V6 or V8 Mustang. The assemblies are the same for the V6 and V8 so either model will work but it must be from a 1994 or 1995 because the front wheel track is about ¼" - ½" on the 1996 and later Mustangs which will cause the wheel to stick out too far. This can be remedied with the proper wheel offset. When getting the parts from a salvage yard make sure you also get the flexible brake hose and banjo bolt that attaches to the caliper. The fox body flexible brake hose mounting block will not mount to an SN95 caliper. You will also need adapters to connect them to the fox body steel brake lines. Another option is to use stainless steel braided brake lines for a fox body which will also mount to an SN95 caliper. You can get them from various performance parts companies such as Summit Racing. Either way you will need to use the SN95 banjo bolt to connect the hose to the caliper because the fox body banjo bolt will not thread into the SN95 caliper. Other parts you will need are new brake pads, a .330" spacer, new cotter pins, and four new copper washers for the banjo bolts. The spacer is necessary to mount the SN95 spindle on the fox body ball joint. The fox body ball joint is taller than the SN95 ball joint so you will not have enough threads to tighten the spindle to the ball joint. The Ford Racing M2300-K brake kit comes with these spacers. I'm not sure if any company sells just the spacer but I would think someone does since this is a fairly common swap. If you get your parts from a salvage yard or parts car and you can't find anyone that sells the required spacer, you will need to fabricate your own spacers. Some people cut tubing to length to use as a spacer while others have used hardened washers.
To disassemble the front you need to start by obviously putting the car on jack stands and taking the wheels off. Next remove the brake hose from the caliper. Be ready for a mess of brake fluid and don't get any on paint! Remove the caliper mounting bolts and then remove the caliper. Then remove the dust cap from the rotor along with the cotter pin, crown cap and the spindle nut. Slide the rotor assembly off. Use a floor jack and jack the bottom of the control arm just enough to preload the coil spring. Now you can take the sway bar end link off and also remove the cotter pins and nuts from the tie rod end and ball joint. Knock the tie rod end loose with a pickle fork and do the same for the ball joint. Then remove the bolts connecting the strut to the spindle. Now you can pull the spindle off and discard it. If you are installing lowering springs, now is a good time to do it. Repeat the process on the other side.
Now its time to install the new spindles. Place the SN95 spindle assembly on the ball joint and then slide the strut in place on the spindle. Install the bolts and nuts to mount the strut to the spindle and and tighten. Now install the ball joint nut and tighten. Now you can let the jack down and move it out of the way. Install and tighten the tie rod end and sway bar end link. Don't forget to install the cotter pins in the tie rod end and ball joint! The hard part is done. Now you can slide the rotor on and put the caliper on and then tighten the caliper mounting bolts. Use a new copper washer on each side of the brake hose and mount it to the caliper using the SN95 banjo bolts. After checking clearance for the hose you can tighten the banjo bolt. This side is done. Repeat the process on the other side and then bleed the brakes. Then you can put the wheels on.
After installation you will need an alignment before you can safely drive the car due to the differences in the SN95 spindles versus the fox body spindles. You will also want to check fender clearance and the clearance of the wheel to the lower control arm with the steering wheel fully turned in both directions. Wide wheels on 1987-1990 Mustangs will possibly run into clearance issues between the inner wheel weights and control arms. The solution to this problem is the steering limiters that Ford used from the factory on 1991-1993 Mustangs. The Ford part number is N804842-S. Also check brake hose clearance during up and down suspension travel and turning in both directions.
The rear 5 lug conversion is pretty simple. All you need is two drums and two driver side axles from a 1983-1992 4 cylinder or 3.0 liter Ranger or two passenger side axles from a 1986-1997 Ford Aerostar minivan. Or you can use one from each vehicle. They are all the same and measure 29 5/32" just like the Mustang axles. Mustangs use same length axles on each side where the Rangers and Aerostars use different length axles on each side. The 4 liter Rangers have 8.8 rear axles and use 10" drums where the Mustangs use 9" drums. I have not verified the length of the axles on 4 liter Rangers so I do not know if they are the correct length. The other Rangers and Aerostars are fairly common though so you should not have an issue finding the proper axles and drums. I personally would just buy the drums new at the auto parts store along with new brake shoes and a new hardware kit. While you are at the parts store pick up some gear lube and some RTV sealant. This conversion works on both 8.8 and 7.5 rear axles as the axle shafts are all 28 spline and are all the same diameter.
To remove the original axles, start by removing the brake drums. Then drain the gear oil out of the rear end by removing all of the differential cover bolts accept for the top bolt. Leave that bolt in but make sure it is pretty loose. With a catch can in place under the differential, pry the cover away and let the majority of the fluid drain. Then you can pull the cover off and the rest of the fluid will drain. Rotate the differential until the small retaining bolt for the differential center pin comes around. Take this bolt out and remove the pin. Now you can push the axles in toward the differential and remove the c-clips that hold the axles in. Once the c-clips are removed you can slide the axles out. Reassembly is just the opposite. Now would be a good time to install a set of performance oriented gears and rebuild the traction lock. When you are finished installing the 5 lug axles, lay a generous bead of silicone around the outside of the differential cover and install it. Tighten the bolts. After allowing the silicone to dry you can fill the differential with new gear oil and friction modifier thru the fill plug on the front side of the differential. When the gear oil runs out of the fill plug hole the differential is full. Clean the magnetic fill plug while you have it out. Then put the drums on and the wheels. Your done!
1979 and newer Mustang brake facts:
- 11"and smaller brakes fit under 15"+ wheels, 12" brakes require 16"+ wheels, and 13"+ brakes require a 17" or larger diameter wheels
- 1994-1998 Mustang rear axles are 3/4" wider on each side than a 79-93 Mustang.
- 1999 and newer Mustang rear axles are about 1 7/16" wider on each side than a 79-93 Mustang.
- 94 and newer Mustang 8.8 will bolt into a 79-93 Mustang but will require brake line adapters.
- Lincoln Mark7 LSC, SVO Mustang and Fox Body Saleens use a rear axle that is 1.25" wider per side than the 87-93 Mustangs.
- 94-95 spindles share the same track width as 79-93 spindles.
- 96 and up spindles have an 8mm wider track width.
- 79-93 Mustangs all use 9" drums with 7.5 and 8.8 rear axles.
- 4.0 liter Rangers use a wider 8.8 rear axle and 10" drums.
- Explorer 8.8 rear axles are 1" wider per side than a Ranger or Aerostar with a 7.5 rear axle.
- 1986 was the first year of the 8.8 rear axle in Mustangs
-7.5" and 8.8" axle shafts are the same diameter and are 28 spline.
The 1995 Ford Cobra R wheel comes in two different offsets, 24 mm and 36 mm. The original R58 Cobra R wheel has a 24 mm backspacing which is good for all four wheels of a 1994 and newer Mustang. The R58 Cobra R wheel fits in the front of a Fox body that has the Cobra brake upgrade but the rear of a Fox body Mustang with the M2300-K brake kit requires use the M179 Cobra R wheel which has a 36 mm backspace. The R58 and M179 wheels have been discontinued by Ford.
Factory Wheels with a 4 lug 4.25 inch bolt pattern:
- 1995 - 1999 Ford Contour
- 1983 - 1994 Ford Tempo
- 1974 - 1993 Ford Mustang
- 1980 - 1990 Ford Escort/EXP
- 1980 - 1988 Ford Thunderbird
- 1983 - 1985 Ford LTD II
- 1981 - 1983 Ford Granada
- 1981 - 1983 Ford Maverick
- 1978 - 1983 Ford Fairmont
- 1975 - 1980 Ford Pinto
- 1995 - 1996 Mercury Mystique
- 1983 - 1994 Mercury Topaz
- 1981 - 1988 Mercury Cougar
- 1980 - 1986 Mercury Cougar XR-7
- 1981 - 1988 Mercury Marquis
- 1981 - 1988 Mercury Montego
- 1981 - 1988 Mercury Lynx
- 1974 - 1986 Mercury Capri
- 1978 - 1985 Mercury Zephyr
- 1989 - 1990 Toyota Van
Ford rear axle information:
*Ford rear axle widths*
- 65-66 Mustang 57.25 inches
- 67-70 Mustang 59.25 inches
- 71-73 Mustang 61.25 inches
- 77-81 Lincoln Versailles 58.50 inches
- 67-73 Torino, Ranchero, Fairlane 9" 59.25 inches to 61.25 inches
- 57-59 Ranchero and station wagon rears, 57.25 inches (narrowest 9" housing)
- 66-77 Bronco 9", 58 inches but has 5-on-5 1/2 inch diameter bolt circle
- 77-81 Granada, 58 inches
- 67-71 Comet, Cougar, Fairlane, 59.25 inches
- 71-73 Mustang, 61.25 inches
- 64 Falcon 58 inches
- 67 Fairlane 63.50 inches (coil springs)
- 72 Ford Van 3/4 ton 68 inches
- 79-93 Mustang 7.5 and 8.8 57 inches
- Lincoln Mark7 LSC, SVO Mustang and Fox Body Saleens use a 59.5 inch wide rear axle
- 94-98 Mustangs use a 58.5 inch wide rear axle
- 99 and newer Mustangs use a 59 7/8 inch wide rear axle
Where To Find 9":
- 67-73 medium and big block Mustangs and Cougars
- 66-71 Fairlanes, Torinos, Montegos, Comets, and other Ford intermediates with big blocks
- 57-59 V8 Fords and Mercurys
- 77-81 Lincoln Versailles & Trucks
Type Of 9" Housings, how to recognize them and other info:
- 67-73 Mustang/Cougar - light duty, thinnest housing material, small axle bearings, 28 and 31 splines
- 57-68 passenger car and 1/2 ton truck - medium duty, stronger than Mustang type, 28 and 31 splines
- Ranchero/Torino - heavy duty thick wall housing, 3.25 inch diameter axle tubes with flat tops
- 69-77 Galaxies (coils), Lincolns (coils), and late pickups (leaf)- 3.25 inch diameter all the way to the backing plate, coil housings have upper control arm mount
- 1957 - no dimples, flat center band up the center of the rear cover, bottom drain plug
- 58-59 - two dimples on back of housing, flat center band, some had drain holes
- 60-67 - two dimples, flat center band, oil level hole in back cover
- 63-77 Lincoln, LTD, Thunderbirds had 9.375 inch centers, housings were cut away at the gasket surface for ring gear clearance, one curved rib at the front top portion of differential, strong but no gears
- 28 spline axles cannot be shortened and resplined (they're tapered)
- 72 and earlier 31 spline axles have the ability to be shortened
- 73 and later 9" (cars) have a 5-on-5 bolt circle and the axles cannot be shortened
67-73 Mustang axles identified by wheel flange:
- oval hole - 28 splines
- two large holes and counter sunk center - 31 splines
- 5 on 5 lug pattern is a truck pattern
- A 9" complete rear axle is approximately 35 pounds heavier than an 8.8 rear axle with approximately the same components
- It is common to find a 9" in a old Falcon or Comet that has had a HIPO SMALL block with 31 splines and a locker
- If the case has two verticle RIBS ,from top to middle of case it is a good iron type
- If in the very center of the case there is the letter "N" than this is a nodular iron case which is the strongest factory case produced by Ford
- The ranger truck works good with a 9" from a 64 to 71 Falcon, Comet, some 65 to 69 Mustangs or 64 to 67 Ranchero V8 cars
A common question for people who change axle gearing is "What speedometer gear do I need to go with my new gears?". Here's a simple calculator to help solve the problem. Enter the data from your drive line setup and hit 'Calculate'.
Here's the part numbers for the various driven gears:
The 23 tooth driven gears are known for being short lived. The teeth are thin diameter is too small so it creates a bad mesh with the drive gear.
The drive gear on the AOD transmissions is integrally machined into the output shaft. This means that you'd have to replace the entire output shaft to change your drive gear to obtain the correct drive/driven gear ratios. This is pretty expensive and impractical. In this situation, you're better off obtaining a speedometer correction box to correct the speedometer readings.