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Thread: Jag IRS Differential cases and stub axle seals

  1. #1
    Join Date
    Jan 2003
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    Castries, , Saint Lucia.
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    Jag IRS Differential cases and stub axle seals

    Hi again -

    I finally got the drive axles and lower arms from the "new" 3.31 IRS assembly shortened to spec. The machinist did a really nice job beefing up and balancing the shafts and I'm just waiting on the new U-joints to arrive so I can start reassembling.


    I went back and forth on which differential I was going to use and had settled on the 3.31 because it just looked that much better and in better condition once I got it degreased and power washed. Both are Powerlock units and I figured that the 3.31 ratio would work a bit better in 4th gear since I rarely shift into 5th in normal driving on our hilly, twisty roads.

    Once I opened up the case though, the old fluid was very milky and there were bits of thin, rusted slivers of metal in the bottom which I figured could be from the clutch pack. The assembly turns smoothly with no play or noise, but it looks like it has been waterlogged and I decided to set it aside for a future full rebuild project.

    So now I've disassembled the old 3.54 unit and cleaned a bit of the gunk off of it. The fluid is clear and clean and it turns smoothly and silently with only a very tiny bit of play at the pinion. The only glaring issue is a leaky stub axle seal on one side.

    The cases are both markedly different - there's a lot of conflicting information out there on positively identifying the series and vintage, but due to the botttom drain plugs on both, I know that they are both Salisbury units. The brake calipers appear interchangeable and both bolt in from the diff case outward, but the stub axle flanges and the cases themselves are different. I've attached some pics in the hope that some of the gurus here can ID the 3.54 unit so I can order the correct axle seals.

    Below are the flanges side by side. 3.54 case on the left is gold below all the other stuff and the 3.31 on the right is originally red.


    Here are the two cases. First the gold 3.54 with the reinforcing fins.


    Next is the 3.31 case with solid bars instead of fins.



    I've done a lot of checking around the various sites and forums for info, videos and photos, but I'm still not 100% sure what exactly I'm dealing with. I'd really appreciate any help in establishing what seals I need for the 3.54 case.

    Just to add to the confusion, here's a screenshot from the JH Engineering page that says the series one has the ball bearings and the series 2 has the tapered rollers. Also by their account both of my axle flanges, though different, have the tabs for the calipers which indicate series 2, but the 3.54 case is finned, which indicates series 1.



    The brake rotors and calipers are interchangeable between the two.

    I've also posted this over at Club Cobra.
    Tropical Buzz

  2. #2
    Join Date
    Jan 2003
    Location
    Castries, , Saint Lucia.
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    139
    Update: One of the members on CC posted a link to a Mike Bontoft article about the various IRS series and I'm now pretty sure about what I'm dealing with. Looks like I will need to do a full rebuild of the newer 3.31 differential.
    Here's the link to the article FYI:
    http://www.firstcoastcobraclub.com/v....php?f=1&t=198
    Tropical Buzz

  3. #3
    Buzz- about 18 years ago I had an older cobra and the rear end leaked where the short stub axle attached to housing. The original seal had a flange around the outside. Took it to a federal mogle bearing dealer and he matched it up with a seal but without the flange and worked perfect. The 60-63 XKE series I rear ends are only ones with seven holes around the stub axle bearing sleeve. 64-67 series II have five holes. There is a company that sell most of rear end parts is Concours West Industries ((360)-274-3376. www.cwiinc.com (that's 2 i's). I've got a brochure that identifies the different rear ends. Can scan but not sure how to post on this website. Make sure you use high strength bolts and all metal lock nuts.
    Bob

  4. #4
    Join Date
    Jan 2003
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    Castries, , Saint Lucia.
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    Thanks Bob. Things are actually looking up. Contrary to all of the information I got on the web, the older 3.54:1 differential that was originally in the car has tapered roller bearings on the output shafts and the "newer" 3.31 unit has the less desirable ball bearings. The innards of the 3.31 are a mess while the 3.54 is pristine inside. The big problem that I ran into after establishing this is that the new brake calipers I had ordered wouldn't bolt onto the 3.54 case, so I had to choose between buying all new brakes (return shipping and import duties make exchange impractical) or swapping the 3.54 internals into the 3.31 case.

    The good news is that with a little bit of grinding on the case to accomodate the longer bolts, I was able to get the new calipers to fit and everything lines up perfectly. Now all I need to do is rebuild the stub axles with new bearings and seals and bolt on the new lower arms and axles. The parking brakes I got with the 3.31 assembly are in good condition for cleaning up and rebuilding; then it will be refreshing the coil-overs and running new brake lines with a remote bleeder system (bleeder screws relocated under the rear bumper) similar to this setup: http://www.fossewayperformance.co.uk...ed-easy-bleed/

    EDITED for correction - calipers initially couldn't bolt to 3.54 series 1 case
    Last edited by Buzz; March 20th, 2018 at 04:10 AM. Reason: Correction
    Tropical Buzz

  5. #5
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    Gadsden, Al , USA.
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    How is the body work coming along, looked like the rear was pretty bad.

  6. #6
    Join Date
    Jan 2003
    Location
    Castries, , Saint Lucia.
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    Actually, its far better than it looked in the initial photos from the crash scene. A 12" X 3" chunk of fiberglass was broken off the lower rear valance, some cracks in the left rear fender, left front headlight torn out, crack at inner left front wheelwell body mount bolt and assorted scuffing /scratches in other areas. Doors, hood and trunk still perfectly aligned and functional. Windshield undamaged, rear brake line severed, engine/transmission fully functional. Left rear trailing arm bracket sheared off lower control arm, and of course the bent left lower control arm and broken hub carrier. Once the rear suspension and brakes - including park brake and lines - are done, I'm installing a new steering column and rack, modifying the lower radiator bracket and installing a new cooling fan. Headers need to be modified for improved footbox clearance, then a full refresh of the electrical system including a battery cutoff switch and a grounding terminal bar in the engine compartment/firewall area. Next will be new gauges, switches, lights, mirrors, windwings, etc. and a refurbished soft top before final sorting.

    Update - Here's a pic of the cleaned up 3.54:1 differential with the new brakes and rotors fitted. The "newer" 3:31 series 2 unit has the less desirable ball bearings in the outputs and given the dodgy condition of the rest of the internals, I decided to set it aside completely.

    Next, I had to address the brake issue; and while some online sources claim the calipers are interchangeable between series' 1 and 2, there just wasn't enough space behind the horseshoe-shaped mounting brackets to allow the longer mounting bolts to get started. I realized that I could bolt the calipers to the brackets and then bolt the assembly onto the bearing caps, but since the mounting bolts for the brackets also attach the bearing caps to the case, concerns about future servicing of the calipers on the car with everything safety wired, etc. made this a less than desirable option.

    So out came the trusty Dremel, and with a bit of clearancing on the case in four spots to allow the longer mounting bolts to get started, I was happily able to attach the brakes properly without any compromises or MacGyverisms. Now, with everything bolted up tight and no shims installed, the rotors look eyeball-centered in the calipers - subject of course to measurement and adjustment on final assembly. It all comes back apart for the stub axle rebuilds as soon as the bearings and seals, etc. arrive.




    In the mean time, I'll focus on the routing of the new brake lines and fabbing-up of a remote rear brake bleeder system to make that task a lot less cussworthy down the road. I'm looking at this setup from Fosseway Performance, but since It's designed for the stock differential cage, it might be just as easy to make it from scratch with my choice of location for the bleeder screws.


    I also need to rebuild the parking brake setup, and my previous experience with those has me considering the installation of a hydraulic line-lock switch as a backup. :CRY:
    Last edited by Buzz; March 21st, 2018 at 02:32 AM.
    Tropical Buzz

  7. #7
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    Gadsden, Al , USA.
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    You might not be able to bleed all the air out with the bleeder lower than the caliper.

  8. #8
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    Castries, , Saint Lucia.
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    Good point - I never thought of that. Using regular clear tubing coming down into a catch container with normal bleed screws its easy to see the bubbles in the tube and closing the bleeder keeps them from reentering the system. With this setup whatever is in the remote lines up to the bleeder screws remains a part of the hydraulic system. Hmmm.
    Tropical Buzz

  9. #9
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    If you use a vacuum bleeder it will work but not if plan on manual bleeding.

  10. #10
    Join Date
    Jan 2003
    Location
    Castries, , Saint Lucia.
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    I did some scouting on the Jaguar forums and users of this system say that although it looks like there should be an issue with air trapped in the high part of the remote loop, they work fine in practice. I already have a bench bleeder and a vacuum bleeder kit in my basket at Summit, so I think I'll order them and give it a try.
    Tropical Buzz

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