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Information and notes on Ford 8.8" axle swap for Jeep Applications.
  1. What should I know before purchasing a Ford 8.8" for my Jeep

Q: What should I know before purchasing a Ford 8.8" for my Jeep


There is a vast amount of information and questions that go along with a custom axle so we will do our best to answer most of them here for your reference. We will start with the options or the drop down tabs listed online.



LOCKER OPTION: You have a choice of lockers. If you would like something not listed we can still install it in your axle, but we do not stock it. Any option not listed in the drop down box will require a few more days lead time.

POSI OPTION: If you think a Positraction/Limited slip fits your needs better than a locker we have some options. Again, if you would like something else we can install it. However, it is not a stocked item and may require a few additional days lead time. All items listed in the drop down box are in stock. The factory limited slip is a good, cheap option for traction. We rebuild them using the most efficient clutch stacking to give you better performance and longevity over the stock setup. If you choose a used factory unit non-rebuilt we do not inspect clutches, only the spider gears, as these are visible from the outside.

ADPATER FLANGE/YOKE OPTION: The stock Ford 8.8 uses a flange style yoke, while your jeep uses a conventional style u-joint yoke. In order for your driveshaft to bolt up you will need to purchase a new U-bolt style conventional yoke or you will require an adapter flange. The U-bolt style yokes are American made forged yokes and are of the highest quality available. This eliminates extra pieces in your already short driveshaft and gives you a new yoke versus used components. It also will give you 3/8” more driveshaft length.

BRAKE OPTIONS: We offer new brakes to you at a very low cost and put them on for free. The prices listed should be the same or lower then what you would pay at your local auto parts store. Remember, the base axle comes with used brake parts and although sometimes they are in good condition, your axle will look so much better with new brake components. We do highly recommend new e-brake shoes as moisture gets trapped inside the rotor and will cause the stock shoes to rot. It is difficult to install the e-brake shoes with the shafts installed so if we are replacing parts inside the diff now is the perfect time to install the shoes. If you choose the used brake option we will make an attempt to give you good used parts but they are used. We will not change e-brake shoes for other used parts, only new. You may be contacted, when your axle is ready to be built, in order to discuss additional brake parts that may be required.

DRIVESHAFT STYLE: The answer to this option will determine the pinion angle your 8.8 is set at during assembly. We will go further into this later.

ADD EBRAKE CABLES: If you want a functioning e-brake with your new disc brake set-up. These cables are required and will swap right in.

ADD DIFF COVER: We have 2 aftermarket options for differential covers. The SOLID covers are heavy duty cast pieces, carry a lifetime warranty, and are of great quality at a very affordable price. Our second option is the 1/4" bent and welded steel cover. Fifty dollars off your 8.8 if you mention this. These are also great covers with a lifetime warranty. Both covers will offer you ample protection and give you additional fluid capacity. For the money the SOLID covers are a great value. The steel covers are very useful if you need to weld to the cover for any reason (hydraulic assist ram mount, 4 link truss with cover tie-in, etc.). ***Please always fill Ford 8.8 through factory fill plug in front of differential not through an aftermarket cover fill plug.***

FINISH: We have 2 Paint options - Flat Black and Rustoleum Hammered Finish. The flat black gives a nice, clean look and is functional. The Hammered Finish is more glossy and will be more rust preventative.

FACTORY GEARS: We have 4 factory ratio options available: 3.07, 3.55, 3.73, and 4.10. The 3.07 and the 4.10’s are getting difficult to source so you may want to call on availability on these two ratios. By choosing the factory ratio, you will be getting a used gear set. If you do not purchase the "Freshen Up" option we do not inspect the gear. However if the gear turns out to be in poor quality we will ship you a good used replacement gear. We do not cover any labor related to swapping the gear set.

FRESHEN UP FACTORY GEARS: If you choose the used gear option then please consider this option as well. We will totally disassemble the axle. Install new differential bearings, new axle bearings, check the axle shafts for run out, inspect spider gears, and ensure the ring and pinion is in good condition. The only thing we do not inspect is the clutches in a used limited slip if that was an option chosen.

REMAN UNIT W/ NEW GEARS: If you choose the "Reman" option with new gears, you will receive new gears, new differential bearings, new axle bearing and seals, spider gears inspected (if applicable), shafts checked for runout, and the labor to set up your new high quality ring and pinion properly for years of service. This option is covered by our five year warranty parts and labor warranty on all replaced parts. Our Warranty Policy will be covered in more detail below.

SHAFTS: You have three options for shafts 1. Good used shafts: these shafts are inspected for runout and for pitting around the bearing surface. Typically the used shafts will give years of service and take serious abuse off road. We believe that they will hold up to 35 inch tires with little issue. 2. Aftermarket 1541H axle shaft: This is a high quality aftermarket shaft made of a stronger alloy then the stock shafts. It is not chromoly, however, they are induction hardened (a heat treat process that insures long life and strength). Currently there are no aftermarket c-clip chromoly shafts on the market. These are the best c-clip axles available. 3. Yukon now has the Super 8.8 Kit: This is a great kit that offers 4340 chromoly induction hardened shafts as well as upgrading your wheel bearings to Set 20 bearings. These are the same bearings that are used in the big bearing 9” housings commonly found in heavy duty semi float axles. Each bearing is rated to support the entire weight of you jeep. These shafts have a lifetime warranty and do away with the C-clips as the axle retention method. The shafts are now bolt in assemblies similar to other heavy duty semi float axles. This kit will also widen your axle by 1.5 inches over stock. If a full spool is chosen this option is required. We believe these shafts will hold up to a 37 inch tire with little issue. If you would like to run a tire bigger than a 38” we have Dana 60 and other options available.

SUSPENSION LIFT: This option combined with the D-shaft option will determine the angle we set your pinion which affects the trac bar placement and your link geometry. The stock pinion angle of a TJ is around 6 degrees this means your spring perches are at zero and your pinion is pointing 6 degrees above zero. If you lift your jeep above 3 inches the lift manufacturer will likely include a trac bar relocation bracket. As you lift the frame of the vehicle the trac bar effectively gets shorter and out of alignment ideally the trac bar should be within factory spec to control body roll and to keep the axle centered. There are 2 common trac bar relocation brackets one is 2 ¾ inches higher than stock the other one is 3 inches above stock and is bent forward towards the front of the vehicle. The forward mount trac bar brackets are typically include in the 4 inch plus kits with adjustable upper control arms. The adjustable upper control arm lifts are designed for use with a CV driveshaft. With a CV driveshaft your pinion angle needs to be about 1 degree lower than your driveshaft angle. On a 4 inch lift w/ CV driveshaft the pinion angle is usually between 17-19 degrees. With a stock axle you would need to rotate the pinion angle 10-12 degrees up. This will roll your trac bar bracket backwards and the stock mounting location will now place your trac bar on your gas tank skid, roll your shock mounts underneath your axle. It will affect your spring perch mounts and control arms as well. The bent forward trac bar mount will move the trac bar bracket off the gas tank skid typically but leave the rest of your geometry off of factory spec. In order for you not to have to get an adjustable trac bar and uppers and keep your stock geometry we set your pinion angle as close as possible to what it should be with your current suspension and driveshaft set-up. We error on the low side for a few reasons. If you already have adjustable uppers they can be the same length totally collapsed as stock uppers so if we set your angle to high you would not be able to rotate it down. Secondly if you do not have adjustable uppers and pinion angle is slightly low there is a good possibility you won’t have any noticeable vibrations with a CV driveshaft and will not require adjustable uppers. If you do not have an SYE (Slip yoke eliminator kit w/ CV driveshaft) but anticipate installing one in the near future depending on your lift we recommend splitting the difference in the angles. This way you will probably have light vibrations without a slip yoke shaft and then when you upgrade to CV Shaft you will only need to rotate the pinion angle a few degrees and not disrupt your geometry as dramatically.

**** As with any custom suspension and axle packages we cannot guarantee that you will not need adjustable Uppers and a trac bar to completely center and get your pinion angle perfect. Every suspension system is different, however we make every feasible effort to make these bolt in to complete stock components or aftermarket parts***


Further Notes:

COT: Continuous output torque rating
MOT: Maximum output torque rating
Dana 35 rear axle COT: 870 MOT: 3480
Dana 44 rear axle COT: 1100 MOT: 4460
Ford 8.8 28spline COT: 1250 MOT: 4600
Ford 8.8 31spline COT: 1360 MOT: 5100
Dana60 semifloat COT: 1500 MOT: 5500

Ford 8.8 WMS is 59 5/8 - Stock TJ is 60.5

Pinion Offset of a D35 TJ is .75 and the pinion offset on a Ford 8.8 is 2.75

SHIPPING AND HANDLING: We charge a flat $200 dollar fee for palletizing and shipping your axle. If you provide a commercial address for us to ship the axle we will charge you actual shipping charges and no handling fee which is typically less than $200. The $200 dollar fee does not include lift gate service. The axle weighs 260Lbs so they can be unloaded by two people from a freight truck. If you require lift gate service or cannot have anyone available to assist the driver for unload a $60 dollar lift gate fee can be added at your request.  

WARRANTY: Our NEW or REMAN differential units carry a 5 year warranty on all new parts i.e. bearings, ring and pinion, shafts. This is a parts and labor warranty. Used shafts are not covered. Used Spider gears or case assemblies are not covered though we will provide good used replacement parts in the event of a failure. Axle housings or brackets destroyed do to abuse: ECGS is not liable for damage caused by excessive use though we will work with the customer on a replacement unit. All aftermarket lockers and Positractions carry the manufacturer’s warranty only. Used or Rebuilt positractions carry no warranty. In the event of a failure the customer will be required to ship the axle or differential to our location at their expense and we will repair and ship back free of charge. If the failure was a manufacturing defect ECGS will reimburse the customers shipping expense. Lack of oil will not be covered under warranty or improper break in, abuse of components is not covered, if there is a ring and pinion failure do to excessive abuse we will replace free of charge but we will not reimburse the shipping cost to our facility. In special circumstances ECGS will aid customer in having a repair done outside our facility, after which time all warranty claims are void. In short we guarantee that this axle will be set up to the highest quality specifications in our control. .

INSTALLATION: The Ford 8.8 axles are a bolt in axle, the brake lines are already plumbed for you to connect your center axle brake line. Please check all connection points for brake lines to insure they are tight before bleeding brakes, these fittings are often left loose for you to finish exact routing and insure the break lines do not rub any components. Your factory breather was mounted in conjunction with the center brake line mount, breather is now just under the track bar mount and a mounting stud is provided for your center brake line. Installation requires Installing springs, connecting control arms, trac bar, sway bar, bleeding brakes and adding gear oil. It will also require the installation of the adapter flange to your driveshaft, if purchased instead of a u-bolt style yoke.


GEAR OIL: THESE AXLES ARE SHIPPED WITH ASSEMBLY LUBE ONLY. FAILURE TO ADD GEAR OIL WILL CAUSE IMMEDIATE FAILURE AND BE VERY EVIDENT. ALWAYS FILL FROM FACTORY FILL HOLE NOT AFTERMARKET COVER FILL HOLE. We recommend Lucas 85w/140 gear oil, Lucas 80w/90 gear oil is also acceptable. We do not recommend synthetic fluids. IF you have a factory limited slip or any clutch style limited slip a limited slip additive will need to be added. TRANS-X makes a good additive that is available at any auto parts store and we also have it available for purchase.


QUESTIONS COMMENTS AND CONCERNS: If you have further questions and require assistance in purchasing or installation do not hesitate to call us we make every attempt to answer the phone from 8AM- 6PM M-F or later Eastern Standard time. We are also available via email customerservice@eastcoastgearsupply.com  We understand that this is a large purchase and will make every attempt to insure the process is as smooth as possible.