"In order to retrofit a Jaguar independent rear suspension into a classic car, first you must find a Jaguar rear end assembly."

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Mustang IRS Page II:
The fallowing information is the second web article on installing a Jaguar IRS unit in to a 64.5-66 Mustang. This article covers: where to get a unit, what to look for, tare down in to key components, and cleaning. If you have not seen it yet I recommend looking at Page I of this series, which describes the reasons for making the upgrade and compares the Jaguar IRS unit to the original IRS unit ford designed for the early Mustang.

Finding and Building a Jaguar IRS Assembly:
In order to retrofit a Jaguar independent rear suspension into a classic Mustang, or any other car for that matter, first you must find a Jaguar rear end assembly. Since the best units for this purpose are from 1960-1987 various model jaguars, the unit WILL be used, more than 20 years old, and thus will need to be completely dissembled, cleaned and inspected so that parts such as bearings, seals, pads, rotors, or maybe even ring and pinion and carrier can be replaced.

Finding an IRS Unit:
If you live in an area with minimal population such as my home state of Montana, the simple act of finding a unit at a reasonable price can be challenging.  I called every junkyard in the seven major cities in the state and only found one Jaguar and it was too new.  I found several options two states over in Seattle, Washington, but it was still going to cost me $600.00 for the rear end assembly and then another $200 to have it shipped to me.  Prior to starting this project, I was under the impression that Jaguar rear end assemblies could be had for less than $300.00 so this information was most disheartening.  Not being one who takes no for an answer, I began looking on-line for a Jaguar forum because I knew most automotive forums have a classifieds section.  Such a forum, and corresponding classifieds section, put me in contact with  David Boger  of Everyday XJ, who parts out Jaguars.  From there, getting a rear end assembly became MUCH easier.  David had a wide range of choices including gear ratios from 3.54:1 all the way to 2.88:1, coming out of many different years of cars.  David sold me two units, the first cost $200, and that included him strapping it to a pallet and dropping it off at a local freight company (freight collect).
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The second unit also cost me $200.00 but David broke it down for me, (for an additional fee) so that it could be shipped FedEx ground in 3 large boxes.  Shipping it FedEx rather than truck freight reduced freight charges by over half, but eliminated the ability for me to get the cage on the second unit, fortunately I did not need it. The unit for the Mustang project has a gear ratio of 3.54:1 and came out of a 1972 XJ6.  Besides the gear ratio being ideal for my application, this unit was an excellent choice because it came from a car that had been a driver so the bearings and other greasable parts had been maintained.  In retrospect, getting a rear end with well maintained greaseable parts is IMHO far more important than the correct gear ratio because the gears can be changed out for any of the many gear set ratios available for the Dana 44 in the aftermarket, even though, as mentioned in the first article, the differential in a Jaguar IRS unit is not exactly a Dana 44.  NOTE when purchasing an assembly or removing one from a donor car, make sure to get the yoke from the end of the driveline that bolts to the differential.  A standard Ford u-joint fits in that yoke and will allow you to easily mate the Jaguar differential to the driveline in your car.

Choosing a Donor Car:
As mentioned in page 1 of the “Mustang IRS project”, the Jaguar rear end has remained mostly unchanged in all the various models of Jaguar from 1960-1987 with the exception of wheelbase width from hub to hub.  Because of this, most of the moving parts from the various years are interchangeable. When attempting to locate a unit, the easiest way to know what you are getting is to look at the model and year the assembly came out of.  The following is a basic list of what a given year and model of Jaguar will have for a rear end assembly, however, this list is just a guideline and probably not all-inclusive.
Track Width Gear Ratios
3.54:1 or 3.31:1


4.54:1 or 3.31:1

XJ6 & XJ12
XJ12 Ball bearing stub axles
XJ6 & XJ12
3.31:1 or 3.07:1
XJ6 & XJ12
3.07:1 or  2.88:1
1982-1987 XJ6 & XJ12 III 61.75” 2.88:1 XJ12

It is important to note that all the units from the 1969-1987 XJ6-XJ12 are basically the same except the differential axle bearings on the pre-1975 units use ball bearings rather than roller bearing.  These bearings are no longer made and the only way to replace them with the more modern roller bearings is to replace the differential axles with axles from a 1975 or newer assembly.  Fortunately, there is not much strain on these bearings and they can be completely dissembled and inspected.  Assuming no problems are found, they can be reassembled and used for many more years/miles.

Even though IRS rear end assemblies are available in many Jaguar models, the best choices are the 1969-1987 XJ6-XJ12.  The simplest reasons are cost and availability. Depending on the year and model, an XKE is a $20,000- $100,000 car.  With these kind of car prices, it stands to reason that the rear end assembly out of an XKE is probably more valuable to the Jaguar community and, hence, will cost much more than the nearly identical unit out of an XJ6-XJ12, so why mess with an XKE. Not to mention, in populated areas, due to availability, purchasing an entire XJ6-XJ12 parts car may be cheaper than just the IRS assembly from a junkyard.   It is important to note that all the parts in the XJ6-XJ12 units all years up to 1987 are interchangeable, but some of the parts on the early XKE units are not interchangeable with the other models and years. 

Disassembly Advice:

Once you have your Jaguar IRS unit, next comes the task of disassembly and cleaning.  When it comes to a task like this, I have five important pieces of advice that aply to all rebuilding projects:

Get a GOOD Shop Manual:
I have a collection of shop manuals and have at least one for every type of vehicle I own. If some part on one of my cars came from a different vehicle, I locate and purchase a shop manual for the make and model of the donor vehicle as well.  I was able to purchase a CD on eBay for under $30.00 that was the full shop manuals for the various Jaguar makes and models in PDF format.  Any time I need to work on a specific section of the IRS assembly I can simply print out the pages I need. Having such a reference tool is important due to torque specification, tolerances, exploded views of assemblies and all the directions it gives in basic rebuilds and repairs.

Throwaway NOTHING:

As you begin to pull things apart you will find parts such as seals or small pieces that are so obviously worn out that you may have the urge to throw them away, DON’T DO IT!  The problem with prematurely discarding things is once you throw something away you no longer have it for a reference. When working on any rebuilding project, I always take things apart and after everything is back together, I then consider throwing out things that are no longer usable.  Having the original worn parts can often times make finding the replacement parts much easier, or in the case of not being able to find a part, having the original part is essential for fabricating a replacement.


As stated before you are rebuilding a used unit.  As parts are used, they often times get certain wear patterns.  That means that if a part comes from a specific place or side of the rear end assembly and is being reused, then it needs to go back where it came from.  Also, knowing the approximate starting location of a part can be a huge help during reassembly. Often times, these types of projects can last weeks or months, which makes remembering part location more challenging.  The easiest way to accommodate marking locations is to mark things as either driver’s side or passenger’s side.  A Sharpie marker and a good punch set can easily aid in this process.

Take LOTS of Pictures:

In today’s age of digital cameras, there is no reason (short of not having a digital camera) not to take many pictures during the disassembly process.  These pictures can be used later to ensure that things get reassembled correctly, not to mention they are wonderful to have if you want to create a web page documenting your work. :)  I like to take pictures of the complete assembly, as things come of, and an exploded view once all the parts are off, especially if there are several smaller parts that go together.

Find a GOOD forum:
The Internet IS an increasable tool for the restoration of cars and trucks all makes and models. Not only is it filled with tech articles just like this one, but it is also a wonderful place, through the many forums and message boards, to meet and exchange info, ideas and experiences with others from all over the world that have done or are in the process of doing similar things. One such Mustang forum “FYI Ford” put me in contact with an individual who had already put a Jaguar unit in his Mustang, another that had done the install in a street rod and their ideas and experiences have been a huge help. Also there is a wonderful Jaguar forum “Jag-Lovers” that is a good place to go if you have questions specific to the Jaguar parts you are working with. Keep in mind that some Jaguar owners are not happy that the IRS assemblies, from their favorite cars, are being used on other makes and models, so it is often times best to tread lightly and not take offense with the occasional poor comment.  If you take the time to understand and except the forum personality than all will be fine.  As a whole they have welcomed me with open arms.  Sometime after these pages launched I found there were lots of people out there interested in IRS so I created an IRS specific forum IRSuspension.com
Tools Needed:
  -  SAE wrenches and sockets
  -  Long Punch or 5/8” rod
  -  Snap ring pliers
  -  Wire brush
  -  Cleaning solvent
  -  Small compartment bins or cans
  -  Press
  -  Hub support  (home made)
  -  Needle bearing puller (home made)
  -  Digital calipers
  -  Notepad
  -  Sharpie
  -  Punch set or center punch
  -  Screwdriver


Breaking down the Jaguar IRS unit into its main pieces: cage, differential, disc brakes, half shafts, Lower Control Arms (LCAs), shocks and hubs, is relatively simple. Start by first making sure all fluids have been drained from the differential, and once this has been done, the unit can be flipped over so that it is sitting on the floor upside down. Now you can remove the bolts that attach the bottom plate to the cage and differential.  Once the plate is off, start at one end and remove nuts, washers and shafts attaching the LCA to the hub, taking care to separate out all the small pieces into bins (this applies to all small pieces further in the process, keeping parts separate and their location notated).  The shaft connecting the LCA to the hub will need to be driven out with a punch or rod. Repeat the process on the other side. NOTE once the shaft has been removed, the hub and half shaft will drop so make sure the hub is supported so that you can set it down rather than letting it fall and risk damaging it.  Next remove the nuts, washers, shaft and spacers attaching the shocks to the LCAs. Once again the shaft will need to be driven out. The only thing left holding the LCA is the nuts, washers and shaft that connect it to the cage and differential, and once said shaft and nuts have been removed, the LCAs can be lifted out.  NOTE between the LCA and the cage is a series of washers, spacers and seals, this is one of those times to either notate or photograph their location, also once the LCAs have been removed be sure to stamp them as DS or PS for drivers side or passengers side.  Such marks will be needed on all further parts that are removed.  DO NOT stamp any of the aluminum or machined surfaces because you can damage them.  To mark such parts simply clean off a small section and use a Sharpie.

IRS unit ready to be disassembled

Cage Plate removed to access LCAs

LCA stamped DS (Drivers Side)
Now that the LCAs are out, there is easy access to the four nuts holding the inner half shaft u-joint yokes to the disc brakes and differential axles.  Once these nuts have been removed, the half shafts can be pulled free of the assembly with the hub and set aside for further disassembly later. NOTE between the yoke and the disc brake rotor on each side is a series of shims that are used to adjust camber.  Make sure to remove them from the back of the yoke or from the front of the rotor and save them since they will be needed later.  The only thing left in the cage should be the differential with brake assembly and the four coil over shocks.  In order to remove the differential, you must first disconnect any e-brake bracketry and springs as well as brake hydraulic lines between the cage and differential.  Once these parts are disconnected, the differential and cage can be rolled over into the upright position with the cage on top.  Remove the four bolts that connect the differential to the cage and the cage can be lifted off leaving the differential and brakes as a stand-alone assembly.  Four bolts hold the coil over shocks to the cage and removing them completely empties the cage.

Half shafts/hub assemblies and LCAs

Unit with out LCAs and half shfts

Empty Cage

At this point, I set the differential assembly up on a workbench so that I could finish stripping it.  Each caliper is held on with two bolts and, once the calipers are removed, the rotors will slide off of the differential axles.  You can then either remove the five bolts on each side that hold the differential axles to the differential, or you can leave it as an assembly to be dealt with later in the differential rebuild/freshen up.  The only thing left to break down is the half shafts and hubs.  To remove the half shafts from the hub, remove the keeper pin, castle nut and washer from the end of the stub axle.  Now the splined shaft can be pressed out of the hub and ,once they are free, the unit has been broken down to all its key components. NOTE there is a specific thickness spacer between the wheel flange and the splined end of the half shaft.  That spacer is there to set hub bearing preload and may be different from the one in the other hub so I recommend measuring the thickness with a set of calipers and notating it to ensure the spacer is returned to its original location.  After talking to a Jaguar rear end expert, I learned that most of the time, even if you replace the bearings and races, the spacer(s) that come out of any given hub will usually be perfect to correctly set preload during reassembly. Each component is now ready for further breakdown.


Differential on a workbench so that I can clean and further  disassemble it.

use a pry bar to hold the flang so the castle nut can be loosened

machined seal plate and preload spacer from between hub & splined yoke
There is still further breakdown that can be done to the LCAs, hubs, and half shafts.  There are two sets of needle bearings and one zirk on each arm of the LCAs on the differential end.  The zirks can be removed by unscrewing them but the needle bearings will need to be pulled using a puller to avoid damaging them.  For this task, I built a puller by making two claws out of .125” thick .5” wide strap steel and by drilling a .25” hole in them and a .5” bolt so that a .25” bolt can be used to hold them together.  A section of pipe, a washer and a nut completed the tool.  To use it, I placed the bolt inside the bearing opening, positioned the claws, bolted them into place, slid the spacer and washer over the bolt and installed the nut.  Tightening down the nut pulls up on the bolt and claws and pulls the bearings.  This puller is the first of five tools and/or jigs that I have had to make to work on this project.  Now that the LCAs have been completely disassembled, work can now begin on the hub assemblies. 
Home made bearing puller

Pullerinstalled in the LCA bearing

Spacers, washer, and tightening nut

Bearing removed

The hub has many bearings and seals at both the LCA mounting point and at the wheel flange.  Before removing any of the bearings and seals, I recommend removing the zirk on the bottom of the hub between the two LCA mounting points.  Failure to do so may result in accidentally snapping the zirk off while working on the other parts of the hub. To remove the LCA bearing components from the hub, start by popping out the washer and spacer.  Under that you will find a cloth seal that needs to be pulled out and then the bearing retainer under it needs to pried out or taped out from the other side. Once the retainer has been removed, the bearing and bearing shim will come loose, and  below the bearing is the bearing race retainer and corrisponding race. The last things too be removed are a spacer tubes and shims from the middle of the hub.  Both tubes and all shims will need to be removed before flipping the hub over and repeating the process on the other side.

In order to press out the wheel flange, a “hub support” needs to be built (home made tool # 2).  I made mine by drilling two holes, one on each end, through two 12” long pieces of steel and then running bolts through the holes.  The hub is then placed in between the two pieces of steel and the nuts on the connecting bolts are snugged down.  Each end of the “hub support” can then be placed on a block of wood to allow clearance to press out the hub.  NOTE I recommend using wood blocks rather than metal to support the hub because the hub is made of aluminum and, if the wheel flange is stuck, you have less of a chance of damaging the hub if the “hub support” is blocked up on something softer than aluminum.  Once I had the hub correctly positioned, I placed a piece of pipe on the inside end of the wheel flanges and a washer on top of it and pressed out the flange. The outer bearing and seal will come out with the wheel flange and can be pulled off by hand.  The inner bearing and seal can now also be pulled.  The only parts left in the main body of the hub are the inner and outer wheel bearing races.  These will need to be knocked out carefully using a punch.  NOTE make sure you are careful and that the hub is sitting on a wooden surface such as a work bench, rather than a stone or metal surface, because once again the hub is made of aluminum and can easily be damaged. The last part to be removed from the hub is the grease service hole cap, which can be popped out with a screwdriver.
Hub support tool. when using it hand tighten the  nuts.  Never us a wrench because cranking them down with a wrench could result in damaging the hub.  Also as previously mentoned us woden block to support the tool when pressing out the weel flang.

Place a pipe spacer on the flang to press it out

Hub greaser plug needs to be removed from the hub

Hub and hub support blocked up on in the press to press out the wheel flang

Exploded vew of the parts that go in the hub

The only thing left to disassemble is the half-shafts.  These each breakdown into three pieces connected by two u-joints.  NOTE the retaining clips that hold the u-joints into place are not typical u-joint spring clips, but rather snap rings, and a set of snap ring pliers is required to remove them. Once the snap rings are out, the u-joints can be pressed out separating the three pieces.

Now that everything is disassembled except the brake calipers and differential, all of the parts can be cleaned.  I recommend a good parts washer, a wire brush, a putty knife, lots of elbow grease and a blast cabinet if you have one. NOTE if a part is marked with a Sharpie, make sure you clean it by itself and then remark it since Sharpie marks wash off with most solvents.   Once I have the bulk of dirt and grease scraped off of any given part, I like using paint thinner as a metal cleaner.  It quickly cuts through the grease and is not as pungent or caustic as many of the commercially available parts cleaner fluids. NOTE paint thinner will eat or dry out most seals, plastics, and/or other rubber parts, so do not use it to clean them.  Also, paint thinner is highly flammable, so make sure you are not using it near open flames, grinding sparks or welding.  In the next article, page III, we will look at narrowing of the LCAs and half shafts as well as converting the Jaguar bolt pattern to a Ford bolt pattern.

Want more information about putting a Jaguar IRS in a classic Mustang??  Check out Page I, Page III, Page IV, Page V Page VI and Page VII of this project.

BUT if you can't wait to see what a Jaguar IRS looks like under a classic Mustang check out Mustang IRS Success Stories

Disclaimer on Daze Tech Tips
      I am not an expert in this field. I have performed these modifications myself with very good results. I am passing along restoration and performance tips for the purpose of education.  If you are concerned about reliability or safety issues, I do not recommend that you or any other individual perform these changes or attempt to modify your cars from stock configuration except under your own volition.  I do not assume nor accept any liability for the use of this information or how it is applied.

2013 DazeCars
The words / logos for Ford, Jaguar, Mustang, Galaxie, etc are used for descriptive and reference purposes only. DazeCars is neither affiliated with Jaguar Land Rover North America LLC, Ford Motor Company nor the manufacturers/distributors of Ford or Jaguar automobiles.