Rear Axle: Jaguar IRS for Avanti

[Springstreet]

Someone on the Forum installed a Jaguar IRS in his Avanti. Could you tell me which Jaguar (E Type, S Type, or XJ6 Series 1,2,or 3), gear ratio (3.54, 3.31 or 2.88), and width (52, 55, or 61.75"). Did it have the "locker" option? How did the track match the Avanti wheel wells? And finally, did you use their "cage" or did you have a crossbar fabricated? Thanks. (There is an old Jaguar upside down in a field down the road so I thought I should ask!)

[Dwight FitzSimons]

This installation was written up decades ago in the Avanti Owners' Association magazine. As I recall the article was detailed and with pictures. You might check their index of previous articles or their forum.
-Dwight

[swvalcon]

I know a lot of the street rod guy's are using xj6 stuff.

[Alan]

There are 2 or 3 ways of doing it. I was involved in a XJ6 swap done at Bob Pattons, Le Concourse with Bob and Vergil Rice. There is a thread on the Racing Stude site by Silver Hawk Dan that does it a different way.

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[Hawklover]

Carl Lange of Uniondale NY did this to his Avanti back in the day.......indeed Nate Altman consulted Carl about doing this to all Avanti 2's......Nate passed as the money was an issue. Carl was killed under his Coupe Express some years ago, his son Jeff owns the car now.

This installation was written up decades ago in the Avanti Owners' Association magazine. As I recall the article was detailed and with pictures. You might check their index of previous articles or their forum.
-Dwight

[Dwain G.]

Nick Berger frequents the Avanti forum. His '63 has an E-Type rear end I believe.

[Warren Webb]

I've seen Nick's car & it looks like it was made that way. Very well done.

[48skyliner]

The Jag rear suspension was a popular swap for hot rodders back in the 70s-80s, and some may still use it. The main drawbacks seem to be that it is really heavy, and in some installations the inboard brakes are a real pain for pad and rotor replacement, requiring a lot of disassembly.

My fabricator friend Sean O'Brien has done these swaps, and indeed we have a Jag rear suspension in my storage area. But as soon as we looked at the Nissan rear suspension, we immediately decided it was much better and easier to install. This of course depends on the width and the space available. The 240SX is the most narrow, has a 4x4.5 bolt pattern. The Skyline is somewhat wider, the Infiniti J30 about 1.5 inches wider than the Skyline, and the Q45 is even wider, all 3 having 5x4.5 bolt pattern,and all 3 having the heavier duty limited slip diff and big disc brakes. All four of these units are mounted on a subframe that attaches with 4 bolts, makes the installation pretty easy, all very similar except for the width. We used the Skyline unit in my 48 Champion and a J30 unit in a 68 Mustang, both purchased as complete suspension with brakes and limited slip diff for about $300. These diffs are good for at least 400hp. Smaller aftermarket coilover shocks were used because of space limitations.

http://www.pro-touring.com/threads/111428-68-Mustang-Convertible-Some-Unique-Upgrades

http://www.pro-touring.com/threads/111168-1948-Studebaker-Starlight-coupe-project

[Springstreet]

48 Skyliner, Very nice job, but I have no where near the skills of Sean. My parts car (LS-3 engine and tranny) was a 2006 GTO and it had a similar low mileage rear suspension ... BUT ... I didn't know how to deal with the extra width and the shock towers. Your idea of shorter coil overs would have helped deal with the shock mounts but I didn't want to flare out the Avanti fenders to deal with the wider GTO track. For the Avanti/Hawk frame, one of the Jaguar (XKE, S Type, XJ6) IRS's should be the right width (which one?) and with a prefabricated longitudinal frame support (I saw someone in England had made one) the Jag's heavy cage could be eliminated and maybe the whole assembly could actually be made bolt in. As for the not so accessible Jag inboard rotors, I like the looks (through the rims especially) and my Avanti is not a daily driver so it should not need rotor replacements. Thanks again for documenting all your work.

[karterfred88]

I was wondering if the anyone has tried a 2000-ish Mustang SVT/Cobra type conversion, a little less pricey than a Jag. It's 62" WMF to WMF and with the right backset wheels it might be doable.

http://www.ebay.com/itm/2003-2004-FORD-MUSTANG-COBRA-IRS-REAR-AXLE-3-55-DIFFERENTIAL-INDEPENDENT-03-04-/262361487277

[PackardV8]

IIRC, the XKE is the only Jag which can fit under an Avanti without narrowing the axles.

I was wondering if the anyone has tried a 2000-ish Mustang SVT/Cobra type conversion, a little less pricey than a Jag. It's 62" WMF to WMF and with the right backset wheels it might be doable.
http://www.ebay.com/itm/2003-2004-FO...-/262361487277

Not sure I'd agree the Mustang Cobra is less than a used XKE, but would agree the one above is probably a better value, as everything should be good to go and not needing rebuilding.

IIRC, most Studes are no more than 57" tread width, so the 62.5" hub to hub is the problem. As to the right backset wheels, JMHO, but I can't make the FWD-like wheels look right on an Avanti.

Great tech article on the H.A.M.B. "How to fit a Jag in anything"
http://www.jalopyjournal.com/forum/t...nything.77729/

jack vines

[karterfred88]

IIRC, the XKE is the only Jag which can fit under an Avanti without narrowing the axles.



Not sure I'd agree the Mustang Cobra is less than a used XKE, but would agree the one above is probably a better value, as everything should be good to go and not needing rebuilding.

IIRC, most Studes are no more than 57" tread width, so the 62.5" hub to hub is the problem. As to the right backset wheels, JMHO, but I can't make the FWD-like wheels look right on an Avanti.

jack vines

I understand, the new "way positive" set of the spokes looks wrong to me also. But seeing tubes, brackets and coils instead of leaf springs probably will look "wrong" too. I'm not sure where to even find a E Jag rear anymore, maybe a sedan rear but haven't seen any E-types available for a long time.

[Springstreet]

From what everyone has said: the XJ6 has a 58" track and 61 3/4" hub to hub width (XKE 50 - 52" and S Type 54 - 55") The XJ6 Series 1 1969-73 can have 3.54 gears, Series 2 1973-79 3.31 and the 1979-88 Series 3 2.88 ... with high bias power lock available (the 3 Series can be rebuilt with special seals). The Jaguar "cage" can be eliminated with a H.A.M.B. Snow White Jag IRS Cross member which costs about $315 and rubber mounts the Dana like differential, provides for mounting the upper shock/coils and could be welded to the Avanti frame (with some sort of end brackets to set height). My chromed 5 X 4.72 Hot Rod GTO 17 X 8 rims have a 6 1/2" backspace, so they add 5 inches which equals 66 3/4". The Avanti width is 70.4 so it sounds like I would be cutting it very close if I try to use the XJ6 inboard mounted brake unit IRS suspension.

[bezhawk]

Here's one near me.

http://stlouis.craigslist.org/pts/5534093352.html

[Xcalibur]

Springstreet, I have an early XKE rear-end in my '63 Avanti. They were almost "unobtainiums" back then; but are the best for Stude's because of their narrowness compared to the others--NOTHING needed shortened. I did a write up for Avanti Magazine not long after the install in the mid '90s and it's been in there serving quite well ever since.

I put my stock Dana/Spicer 44, 4.09, Twin-Trac unit in the Jag housing (as I recall it came with a 4.56!)--with a T-5 OD tranny it works quite well. Mine was mounted by fabbing an additional cross-member and a bunch of frame brackets for the half-dozen, required, locator rods (made from recycled, chromed, hydraulic rams from a rebuilding shop). It has adjustable Aldan shocks and adjustable coil-overs. In my opinion it is the best thing possible for handling, of far more use than all the "updates" usually done to the front suspension.

If you wish I can discus more thoroughly with you here (pm me) and/or send you pix.

Sorry, but I don't have a better picture on this computer. (just for giggles... that's the stock, front, sway-bar repurposed for the Jag rear--for the uber-purists, ya unnerstan, hehehe!)

Dwight, the Avanti Mag article from 20 years ago, or so, was mine. The one some years before that was by a Carl Lange who used the stock mounting "cage." I tried repeatedly to contact him but he never replied. As I recall now, it looked like the one Alan posted above (maybe the same pic) and as I recall now it set too high in the rear for that reason.