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3/16/2014 11:01 am  #1


Help Identifying IRS

I need help identifying the Jag IRS I have. It has a tag with 43 over 13 which I believe means it has a 3.31 gear ratio. It had the drain plug in the bottom and had the number 8 stamped in the bottom as well.  It has 5 bolts retaining the bearing covers. It's also about 61 flange to flange. I'm pretty sure it's a mid 70's XJ6. Is there anyway to narrow down exactly what year it is? 

 

 

3/17/2014 9:20 am  #2


Re: Help Identifying IRS

Not easily and may not be important.  
What is important is what you plan on doing with it and the type of bearings on the side axles.  If you have a ball bearing on the stub axles, you have a Series I Jag rear.  Otherwise, you most likely have a Series II.  And none of this will matter until you go to rebuild, which you may not need to do right away.

If you remove the rear diff cover and have a posi unit, this came out of XJ12.  With those gears, that is what I'd lean to.  However, I have the same tag on my housing but had 3.54:1 gears.  Someone changed the somewhere along they.

Most importantly, if you don't have a lot of play in the gears and everything fits nice and tight, use it as it as!

When ordering parts, any place which is familiar with the Jag IRS will know the difference between a Series I or II.  Unless you are altering the width, I think (will let others chime in) all the other parts such as bearings, bushings, etc are all the same regardless of year.

What plans do you have for this?

 

3/17/2014 3:05 pm  #3


Re: Help Identifying IRS

303Radar wrote:

Not easily and may not be important.  
What is important is what you plan on doing with it and the type of bearings on the side axles.  If you have a ball bearing on the stub axles, you have a Series I Jag rear.  Otherwise, you most likely have a Series II.  And none of this will matter until you go to rebuild, which you may not need to do right away.

If you remove the rear diff cover and have a posi unit, this came out of XJ12.  With those gears, that is what I'd lean to.  However, I have the same tag on my housing but had 3.54:1 gears.  Someone changed the somewhere along they.

Most importantly, if you don't have a lot of play in the gears and everything fits nice and tight, use it as it as!

When ordering parts, any place which is familiar with the Jag IRS will know the difference between a Series I or II.  Unless you are altering the width, I think (will let others chime in) all the other parts such as bearings, bushings, etc are all the same regardless of year.

What plans do you have for this?

It's going to replace the Ford 8" rear end in my T-bucket. The differential is nice and tight and it turns easily. It doesn't appear any of the seals are leaking. I am missing the caliper bracket and the brake calipers. I may use a kit to move them to the rear. 

Any idea what Lubicant I should fill it with? 

     Thread Starter
 

3/18/2014 8:18 am  #4


Re: Help Identifying IRS

If you have a posi-unit, you'll need to use one with a posi additive.  I think most of the modern fluids will do a good job for what you need.
I don't know if you'll find much of a kit to move the calipers to the rear of the discs, if you do, can you post a link?  
If you don't, have fun with cardboard, razor blades, cut off wheels or band saw, and 5/16th or 3/8 inch plate.  Search the posts for Wilwood.  Not so much for their product as much as there was a post once identifying what was needed for Wilwood calipers.  Should be mostly the same work involved.

 

3/21/2014 3:25 pm  #5


Re: Help Identifying IRS

     Thread Starter
 

3/24/2014 8:49 am  #6


Re: Help Identifying IRS

If you have access to 3/8th inch plate, you could move the rotors to the rear pretty easily.  Another option for pads and rotor is EBC.  They emailed me the following:

303Radar wrote:

It is good to see there are performance braking options for the XJ rears.

I've been corresponding with EBC this week regarding their product offerings for the Jag IRS and keeping the rear brakes the coolest.

From their catalog (http://ebcbrakes.com/catalogs/), I came down to:
Rotors - GD239 (cross drilled & slotted) or USR239 (sport slotted)
Pads - Red (ceremic) DP3101c or Yellow (Ultra high friction) DP4101R

They recommended either the Red or Yellow pads and their dimpled & cross drilled rotors (GD239) for keeping the brakes the coolest.  Here is a pic to the part on Summit:
http://www.summitracing.com/parts/ebc-gd239/overview/

Here is their email back to me:
Based on what you’ve told me I would lean more towards the YellowStuff pads due to the fact that you will occasionally be using this car on the track. RedStuff pads are great for fast performance street driving but don’t have the 1200F+ degrees of heat fade resistance that the Yellow’s do. But If you don’t feel you need the extremely high heat fade resistance, go with the Reds. Both compounds will have similar heat dissipation and similar average friction ratings .48Mu friction for Reds and .50Mu friction for Yellows so your best bet for cooling is going to be the use of the GD rotors with either combination of pads.


 

 

 

3/24/2014 10:43 am  #7


Re: Help Identifying IRS

I can get 3/8 plate no problem. I'm doing all the brackets to fit the XJ rear into the T-bucket.

Is there a pattern somewhere I could make the brackets from?

This is the rear I have.


 

     Thread Starter
 

3/24/2014 11:12 am  #8


Re: Help Identifying IRS

Not that I'm aware of.  I would start with some cardboard, razor blade and patience.

 

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