"Did you ever complete the IRS mustang project? Do you have any final pictures of the car and suspension you could send over?  I am enjoying your webpage and forum. Thinking about doing this for my 66."

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What ever happened to this project?
Short answer, I got the IRS “fully” mocked up and in the car. I have pulled the car on and off the lift dozens of times over the last 6 years but I never got things buttoned up enough for a true road test.

Long answer, for me the fun in doing this kind of project is the problem solving and design. Short of a road test, I got all the bugs worked out and the suspension 95% done (I need to rework my trailing arms and coil-over mounts, finish the sway bar mount and finish-weld the entire set up) The other issue is that there have been a lot more things in the last 6 years vying for my time. The biggest thing taking my garage time has been my 62 Galaxie. It has become a driver but once I got it on the road realized it needed some upgrades: a coil-over front suspension that I retrofit to the car, rack and pinion install that I built from scratch using a GM J-car rack, home made fan shroud and a bunch of little projects including eliminating the drone in my exhaust.

The good news is my interest is renewed and I am working on the Mustang again.
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Others have followed in my footsteps and finished their installations
One thing that was born from this project and series of web pages was www.IRSuspension.com Even when I wasn’t updating my webpage I was posting on the forum and sharing what I had been working on. From these pages and that forum several people took my basic concept, modified it to meet their needs and the following is three different Mustangs that have a working Jaguar IRS with a bolt in sub-frame based on the one I designed.  All this information and pictures came from forum members who posted what they had done.

Mustsed's Mustangs

IRSuspension.com Forum Post:
  Jaguar IRS install into 1967 Mustang Hardtop - Long 04/18/10

Beside being someone who is different and likes doing modifications to his car, I live in Turkey and our roads are not well suited for cars with straight axles. Either you have some kind of IRS our you have to drive slow on the roads here at the south coast of Turkey.
I started to research this IRS thing 1.5 years ago and told a buddy about it who has a "K" code 1967 Mustang Hardtop AND more money to spend then I do. Very soon we agreed that I DO it and he PAYS it(great).

I run across a 1986 Jaguar XJ12 rear end with 2.88:1 ratio and Power Lock. There is really not much info on that issue and Daze's page came to rescue. I've read his pages at least a few thousand times and created my idea of how to proceed. The first things where the standard shortening of the wishbones and half shafts beside rebuilding the bearings and joints. Meanwhile I ordered a set of 3.73:1 ratio Dana 44 gears to be installed into our Salisbury Differential & Carrier assembly.

All ebay sellers and informations on the net state that 3.73:1 gears fit into the numerical lower carriers which we believe to be true!?!?!.
The 2.88:1 IS numerical lower then the 3.73:1 so it fits but it didn't, I was forced to buy a THİCK gear 3.73:1 gear to make it work.
All this took some time and made a delay in the project time line but at the end I was able to put the IRS into the Mustang.

Lately, Daze started a post about the placement of the IRS and what degree it should have in relation to the transmission. I chooses a neutral "0" degree because of 1. the wishbone and 2. the reality that Jaguar put it in that way. The 1. point was that I didn't want the wheels to travel backwards while moving up and down.

At the end I was able to stuff that IRS under the 1967 and it works well there since almost a year now. Below are some pics of the install and should there arise any questions please ask.


The upper support bracket is made of 50x80mm with 3mm wall thickness tubing. It is heavy!! The round tubing for the trailing arms and support arms are heavy hydraulic tubing with at least 4mm wall thickness.

I don't have the equipment to measure the toe adjustments and I am certain there is some change but keep in mind that the 4 Jaguar shocks don't let the wheels move much on a light Mustang. The car in the pics has maybe 3" of travel on a bad road but not more.

The owner of the pictured car is very happy with the IRS and every time we talk about it, he mentions how great road grip he has now.

I am preparing my second Jaguar IRS to go into my own 1967 Mustang and will try to use some kind of Watt's link on the wishbones instead of the trailing arms. Shouldn't take to long to get there and theoretically it is possible to do this but this is another post.
There WAS a real big ISSUE with the exhaust routing. We had the exhaust made very late at night so we could attend a classic car meeting the next day. There are a lot of kinks in the pipe and the performance has gone down.

The owner is going to replace the whole system. He and the car are in another town so I don't know what and how they are going to do this

IRSuspension.com Forum Post:  Thanks Daze! 07/10/12

Thanks you very much for creating this forum, for sharing your knowladge and helping out people that are a way far away.

Finally I did the "Subframed a la Daze" IRS build into a '68 Mustang hardtop. The installation went smooth and easy...

During the installation I noticed that I forgot my file with the Jaguar data at home (800 km away) so the best thing was to contact the nearest (8000 miles) gearhead which was Daze.  He send me the data the same day so I could continue to work on the car - Thanks again Daze!

Below are some pics of the car and the IRS. I have more pics but none of the entire setup.

Mustsed from Turkey

It's been quite a while since I started this thread and promissed more pics back then. Finally I got around to sort the pics and below are a few more.

I am in the process of installing my own Jaguar IRS with outboard brakes into my '67 Mustang. Have it all mocked up but the car sits way to high so I have to re-arrange the cage a bit. Will start a new post with that later.


I was comparing yours to mine and these are the differences I came up with, please let me know if I missed any:

different cross bar (between side rales) location. 
different pinion mount
different upper shock mount
the pinion support is solidly mounted to the frame rather than bushing mounted like mine
didn't have to notch the side rales 


I think that the idea of a "cage" mounted to the stock leaf mounts is a great idea and therefore needs to be credited to you Daze because I got it from you!

Yes there are some differences mainly because of time limitations and I only got 5 days to work on that car. Ford tolerances are more then I tought when using my own '67 as a jig for the cage. I had planned to mount a section of  U channel to the front leaf spring bolts and then use some bushings on the CM ends to hold it there. Have done them but no time to make it to the car again. So it will wait a bit more till they will bolt on the car. I can't remember from where I got the 3 upper shock mount bosses idea but they allow a bit of adjustability up there. 
I did the trailing arms at home and sent them to a mechanic who installed them but they will be replaced by threaded rods with adjustable joints that are sold by Kugel ($55 a piece - that hurts). . .

All in all he is very very happy with how the car handles and stays on the road as it never did before!!!!

The plates form a rectangle at the end of the lower control arm which stiffens up the mount boss / tube / fork triangle.

The preparation took a few months but the installation was not a big of a deal (except the variable meassurments on these Mustangs and the extra work that showed up because of this) and I think that it is worth every cent invested.


Chuwers' Mustang

IRSuspension.com Forum Post:  All credit to Daze - - His IRS concept on my '68 Mustang 02/03/17
Here she is today.

I mocked it up in wood first, then welded up the three main pieces; side rails and cross-member.
Here's where the cross member attaches to the side rails. Two sets of poly bushings and flanges, with a 5/8" Grade 8 bolt through 'em. The frame tubing is 1 1/2" x 2 1/2" by 0.188" wall.
Then, I bolt the front of the side rails through the forward leaf spring hard points, and swing up the rear. This shows the rear end swinging up into place, pivoting on the forward rail bushings.  Once in place, I use the original shackle links to pin the rear in place.
The spring adjustment details are shown here. At first run, I was about 2" too high, so I got shorter, stiffer springs, and now they're perfect. (IMPORTANT NOTE:, the '67 & '68 Mustang have 2" wider flange-to-flange distance on the original car, so shortening the LCA and half shafts is not necessary.)
Since I have welded in TCP Frame Connectors and stiffener, I have a convenient place to bolt in a pair of torque arms (Left Picture).  Then, added the anti-sway bar. If you notice, there's still about an inch left on the bolt where the original Jag radius arms attached. My future plan is to build Watts linkage style radius arms (going straight forward and aft to the chassis, with a pivot at that bolt) to react the loads at the LCA (Middle Picture). And then a view from the rear, up into the left side of the IRS (Right Picture).

By the wat, just for kicks, I had one of the local high school geniuses do this whole thing in CAD (Inventor), and made a few adaptations on the as-built. Here are my starting dimensions (elevation view).


The '67/'68 is two inches wider flange-to-flange than the '65/'66. I didn't shorten the LCA or half shafts. What I did need tho', was wheels as follows: 16"x8"x5.25" BS Torq Thrust.  Note the large backspacing. That pulled my rear wheels back in. Since the Jag IRS is a Chevy bolt pattern, and I wanted same wheels all around, I needed wheel adapters in the front, to go from Ford to Chevy. So, I got the 1" thk wheel adapters in front, and the high backspace wheels with Chevy bolt pattern all around.

It handles really well, altho' so far haven't really stressed it. I'm still working the "shake down cruise", or might I say "flight testing". It is totally stable, straight line under acceleration or braking. Feels tight and confident. Once I get 500 miles on her, I'll take her down to the skid pad, and maybe run an autocross or two, then report back.

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

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.

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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.