Jag Jaguar IRS into a 46' International Harvester

great pic's!

 

Agreed!

 

Just read through your thread. I have front and rear 1980 Jag XJ6 in the 47 Caddy I am working on. A friend of ours in IL did the install and is very experienced in installing Jags in many of his street rods, as well as previously XK Jag install in my father's 32. So although I have not had it on the road yet, I'm confident in his work. There are pics in my build thread at...
http://www.jalopyjournal.com/forum/showthread.php?t=771329

I can email more pics if needed. Hopefully any visual of this install can assist on your build.

 

Thought I would update the thread. I've been working on my C5 Corvette lately. $$$ isn't plentiful so what extra I do have can only go towards 1 project at a time. But, I scored a cherry original Fulton Visor that has got me excited and focused back on the Harvester.
With that said, a little snail progress on the truck. Finally boxed in the rear of the frame where the Jag IRS will mount up. While it's not much, it opens the door for me to build up the crossmember for the rear and finally get the Jag setup mounted in the truck. Headed up this week to pick up some parts for the crossmember and order up all the other goodies for the rear suspension. More progress finally to come.

 

IronMaiden looks like you are on the right lines with your crossmember - here's my Snow White installation. I am using the factory cage completely stock and all the Metalastik body - or in my case frame - mounts from the original Jaguar cage. This is going under a fat fender rod with the gas tank mounted immediately behind the rear end, so nobody will see it anyway. I really lucked out as the radius arms sit dead center on my frame - so they will work as the factory intended. The only problem with this is the cage to differential bolts are too short. These are cone bolts and I have not yet found anybody who makes them in a longer length as they are a coarse thread - 1/2"-13 to be precise. I may have to get some wheel bolts machined to the correct thread. Should ride nice though....

 

Hey Weasel....

Not sure if you are complete with your install, and not to seem critical, but I'm just wondering a few things here that I see in your pictures. The entire weight, torque, and bounce forces are going to be transmitted through the red bushings. The old Jag stamped metal frame is being asked to take the cantilever effect from the shock mounts back to the pumpkin mount. As you are aware, the original metal frame mounts to the Jag chassis at the ends of the stamped housing. I would be slightly worried about rocking back and forth, too, about the pumpkin mount, causing potential metal fatigue in your Snow White crossmember at the point of the welds. I would be thinking about fabbing up some sort of bump stop arrangement that is in contact (under compression) full time between the Snow White shock mount location and the top of the stamped Jag housing to minimize the rotational forces that the center mount is going to be asked to take, at all four locations. Maybe you just aren't done with your concept. By the way, you might try finding a Fastenall store near you that could have something close (GRADE 8) that would work with the mount. When I installed mine, I erred on the mount angle, and had to cut it allllllll out and re-weld at the correct angle. I learned that it's best to get the engine/transmission mounted where it's going to be, then take your angle measurements so the rear end comes out at the correct tilt. See my sub-album "Building the frame"....

http://s28.photobucket.com/user/Pau...Mid May 2011/Building the Frame?sort=6&page=1

 

Hey '49 ford Coupe, thanks for the heads up. This is a work in progress/mock up only at the moment - the whole shebang will be mounted as per Jaguar factory with 1/4" plate outriggers - actually 'inriggers' with Vee receivers welded to the frame to allow the four Vee shaped Metalastik mounts on the outside of the cage to mate up exactly as per the stock Jaguar body, replicating the Jaguar geometry to a T. As for the diff mount bolts which bolt through the diff pad and cage to the threaded holes in the diff, as I mentioned these are specialty conical seat bolts and the Snow White diff pad has the cones machined into the holes of their mounting plate. Fastenal, McMaster Carr and every other specialty bolt supplier I have tried do not have high grade cone bolts in a coarse thread. I am therefore going to take some original megadollar factory 10.9 Ferrari long shank wheel bolts and have them machined to the correct thread length as they have sufficient meat on them to allow for machining to the correct size and already have conical seats....

 

COOL ! ! Looks like you've got it covered. I seriously considered doing it like you are doing, but what the heck, I chose to do a LOT more work for about the same outcome, but using only the jag mounts, and not the Snow White frame mount. Do you even need to use those bolts and center mount if you use the end mounts?

 

Interesting thread looking forward to following this one.

 

I agree you need the 4 outer stock Jag rubber mounts. I would think it would work fine with the Snow White mount in the center and the 4 stock Jag cage mounts. I'm thinking it would be just like Jag had it but with reduced rear steer that was built into the Jag suspension. I was gonna keep it in the cage as well. My frame falls right into the Cage mounts but my tank is gonna be under the cab so you can see the rear from behind. Keep posting pics of your install.
Also, is that an aftermarket cover or is that an XJ12 rear with the good gear ratio?

 

So I have come across a 70's posi/gear set. He's not sure of the year or what it came out of other than it's a series 1 suspension. The guy has the 3.54 gears and posi unit for sale as well as the 19 spline stub axles. I don't think I need the stub axles so what is fair for the posi unit and gears? It's in the shop right now having the internals swapped to a 30 spline setup. He said it looks like it was recently rebuilt as there are still marking for checking the gear contact. He is gonna send me pics when the swap is done.
Any advice on what is a fair price. Not much in the searches I did.
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Here's the photo of the diff before he took it to the shop for the rebuild.

 

As I've learned over my long long life, the value of anything is a balance between what a willing seller wants for the item, and what a willing buyer is willing to pay.

 

The 3.54 centersection is worth $2-300 in good shape if it's a posi unit, which were pretty rare in the sedans. The later XJS six-cylinder cars used this ratio w/posi and a OD trans, so that may be what he has. It will interchange, although check for the caliper mounts as the 93-96 cars had the brakes moved outboard.

Jag used 2.88 gears in nearly everything though the 80s (with that bastard carrier/ring gear that prevents gear swaps), you have to go older/newer to find anything else. All the XKE/XJS/V12 cars got posi, the six sedans didn't as a general rule.

And that finned rear cover is '89-up OEM and is designed for a electronic speedometer sensor, but you need the special Jag carrier to make it work.

 

Well, he's selling the the ring/pinion gears and the posi unit only. As well as the stub axles. From my research, the stub axles from the series 1 units made with the 3.54's, used ball bearings which is an oddity and usually replaced with later year stub axles which don't use the ball bearing bearings. Just what I read. I have a last year series 3 setup so will just use my stubs. His initial asking price was 600 shipped but said he is negotiable. I was gonna offer 400 shipped and go as high as 450. At the same time, if that's too high then I don't want to over pay.

 

$600 is pretty steep IMO.... For not much more you could probably pick up a complete '93-96 rear complete with the better brakes....

 

Well, I for 1, wouldn't touch a '93-'96 rear with my money.
But good luck to those who go that way.

 

Just got offered a 93 rear end so I hear stay away from them, please tell me why and what would ratio of it. Car was a 6cyl. Thanks last thing I want is lemon.

 

The 90's xjs 3.54 rear ends in 6cyl or v12 are low bias power lock. They have very little slip limiting function. Jaguar made this change to improve driving dynamics and there was a TSB on the subject. I discovered this first hand when buying a 3:54 power lock from a 1995 xjs to replace my 1970's 3:31 power lock IRS. I wanted the later IRS for the much larger outboard brakes. First trip out of the garage I could tell something was wrong...there was no grip, lots of wheel spin and it acted like a open diff. I figued it needed a rebuild and when I set out to order parts, I discovered the low bias issue. I replaced the whole carrier with a Auburn locker. Great success...but then I got axel tramp which I solved today with some additional trailing arms but that's a whole other story.

I'd wouldnt stay away from it...pick it up for the right price. The later IRS with outboard brakes are much much better. The brakes are lighter and easier & cheaper to service, the low bias issue is solveable, the 3.54 ratio is great, they tend to be less leaky because the seals dont get baked by the inboard brakes, the hub carrier is reinforced and not prone to cracking like the early hubs are.

 

I should have clarified the '93-96' comment. Jag used two similar-but-different rear IRS units. The Series 1-3 sedans, XKE, and XJS all used the 'first generation' type (and can be identified by the 'cage' and four shocks/springs). These used common parts and are the units used for rods.

They came out with the 'second generation' IRS in 1984 for the XJ40 sedans, and also used it in the later X300 and X308 sedans. This is the one you DON'T want. No longer 'caged', and very few parts interchange; although the outer uprights with their outboard disc brakes will fit the earlier units. These units are a real PITA to swap into anything.

When looking for a 'donor', you have to know the players.... Note that these are US-spec cars (excluding the handful of six-cylinder/manual trans cars imported in the mid-80s).

The series 3 sedans were built until '92, the XJS to '96. The six-cylinder sedans got non-posi rears, while everything else had posi (including the V12 sedans). Gear ratios before '81 varied, with 3.03 and 3.31 being common for the V12s and 3.54s in the sedans (and supposedly these carriers would accept Dana 44 gears with a bit of monkey motion). In '82 when the XJS resumed production (there was no '81 model), all V12 models got 2.88 gears with the oddball carrier that would only use the Jag-specific gears. This ratio was also common for the six-cylinder cars as Jag was searching for mileage. In '92 Jag started bringing six-cylinder XJS cars to the US, and 3.03, 3.31, and 3.54 ratios/w posi reappeared in those until the XJS was discontinued in '96. Jag moved the inboard brakes outboard in '93, a desirable option.

That design Jag suspension was used for 35 years, so there's lots of 'em out there. Rebuild parts are relatively cheap if needed (for the later front suspension too), certainly less than buying a 'new' Ford 8/9 inch or a M2 conversion.

Dead Jags aren't all that hard to find, and you can usually get them cheap. Bad motors means repair costs will be more than the car is worth, so they're really only worth scrap prices....

 

The one i'm looking at has inboard brakes so it could be a 92'.

 

That may not be a 1992 IRS. On the XJS, starting in 1988 they had provisions for ABS sensors on the top of the hub carriers. In the back ground I can see clearly a mid 1980's XJ sedan with no rear axel and sedan wheels stacked so I'm guessing thats where its from. If the sedan was a v12 then it would be power lok but V12 sedans in the 80's are super rare and a very limited number were sold in canada until 1992. It appears to be 80's 2:88 and if it's from that 6cyl sedan its open diff not power lok.

 

My friend had the car and maybe somebody put a different year differential in it. From the pics does it look like a desirable year.

 

Anyone

 

I am of the understanding that the XJS went to the outboard brakes and 3.54 ratio in mid 1993 with the introduction of the 1994 model year. The carrier has a different casting with mounts for the handbrake cables, so it is readily identifiable by this. Most were solid disc but a very few of the 1996 last year of production had vented discs....

 

If it has inboard brakes then it's good to go.

 

Here is the one I plan using in my next project.
Early diff with late model outboard brakes and hubs...

 

Do the inboard disc brakes wear fast or something? Seems like I read a lot about them being an issue. Rear brakes on any car/truck I've had have always had long service life. It's the front's that wear quickly. I turned the bed of my truck into a tilt bed so that I can tilt it up, sit on the crossmember just in front of the Jag rear, and do a brake job when required. Hopefully years down the road once the truck is built and driving.

 

The issue with the inboard brakes are....

They tend to get contaminated with oil from the diff. The heat cycling from the rotors caused them seals to harden and leak. Then oil drips right on to the disc. Also any oil leaking from the engine tend to drift back on to the inboard brakes. Once the pads get oiled up their performance suffers greatly.

They are difficult to maintain. Installing new pads is easy but changing the rotors requires major disassembly.

With no wheel as a heat sync and exhaust running close by they tend to overheat and become ineffective.

 

For road use there is no appreciable technical advantage in using the inboard brake setup. Inboard brakes came from racing where they were used to reduce unsprung weight. The disadvantages for road use far outweigh any notional benefit. You can modify an inboard brake rear end by using XK8 hub carriers and brakes - through about 2002 I think. Easier still is to use the half shafts as well - if you have a 61-3/4" wide rear end. The only thing you cannot do is mount the outboard brake versions hand brake cable brackets to the diff as the late XJS style diff (the ones with the good, non low bias Powrlok and the 3.54 ratio) has mounting ears as part of the diff casting....

 

and the park/E brake setup on the in board IRS is junk compared with the newer setup...