Jag Jaguar IRS into a 46' International Harvester

Might I suggest that you PM Langy here on the HAMB. He has fitted a number of Jag rears to all sorts and would be able to advise you on the pinion angle.

P.

 

Hi Im glad you're asking for lots of info for newbe's -im learning at the same time.

 

stick your head under a laden jag IRS and take a measurement on the shocks centre to centre remove the shocks from your suspension and replace with a flat bar drilled on the new centres this will similate the compressed height of the springs and giveyou a very good idea of the ride height without trying to compress the springs .this is what i used on my corvette set up

 

this might help someone (DIAGRAMS) http://www.uk-hotrods.co.uk/v2/tech/jag_rear/tech_jag.php

 

I suggest that the pinion angle match the angle of the motor and trans. The pinion angle in a Jag IRS doesn't change under load ( not enough to worry about anyway) like a leaf sprung rear. Hence, no need to compensate for it.


An apart from that WTF does it matter if the pinion is offset to the right?

 

Slag Kustom.......the pics in your post show using 'radius rods' to help control the hub carrier with the rods going straight forward to their attach points on the frame. The geometry of that system is incorrect for the Jag suspension. On the Jag rear end, the control arms move in a verticle motion....with the radius rod pivoting at the frame it will move in an arc at the hub carrier and try to "pull" the hub carrier in an arc when it is not normally moving in that way. That will cause a binding in the lower control arms inner pivots and will try to move the wheels into a toe-in position.

When adding arms in the manner you have shown, the forward pivots have to be inboard and in longitudinal alignment with the lower control arm inner pivots to avoid adversely loading the rear suspenion. I realize the original Jag arms bolt to the body/frame ahead of the hub carrier, BUT, they are mounted in very soft rubber bushings that absorb the induced misalignment. Though it is simple to fabricate and looks good, it appears there is no such "give" in the system pictured and will not function correctly.

As for all the debate about pinion angle, it seems pretty obvious the Jag has 0 degress at the pinion flange as installed by the factory. Any change from that changes the rear geometry unless the control arm pivots are also moved to compensate. It seems to me that if either end of the driveshaft would be fitted with a double Carden joint (aka CV joint) it should eliminate any driveline problem resulting from the engine trans centerline at 3 degrees or so.

Also, someone mentioned in their post that "since the Jag rear end isn't attached to the suspension the pinion would not rise on acceleration....." That is not true. The pinion's (and housing's) tendency to rise upon initial acceleration is the pinion gear trying to "climb" the ring gear because the ring gear resists movement because it is connected to the tires through the axle shafts, IRS or not. However, In Jags and Vettes, the differential carrier is held more rigidly in place because of how it is mounted and THAT resists upward movement of the pinion as compared to a solid ("live") rear axle system.

Ray

 

Re solid mounted diff head.
This is by far the best solution to have for the front end of the rods.
The distance apart should be the same as the pivot points by the diff head.
The bars should be about 1 metre (40") long.
Any torsional twisting incurred is taken up here.
Having them parallel to the chassis rails will in time fail due to incorrect geometry.
Unless of course you use the original Jag system completely. eg all rubber mounted in the cage.

 

Can't get it any better but you get the idea I hope.




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A link here to info and drawings on setting up the jag rear.

http://www.uk-hotrods.co.uk/v2/tech/jag_rear/tech_jag.php

 

That's what I was looking for. Thanks.

 

I took a shot at clearing up the image LIFESTYLZ posted with photoshop. Not sure how to post it full size though.

Ken

 

Hey thanks.
I'm still trying to access the original off the Oz govt website.

 

Hi, I've been following this thread, as I'm also about to fit my Jag IRS (currently tacked in place). I have been collecting info off the net for a while now.
Initially I was going to run the radius rods straight forward to a pivot point under the chassis rails (like in the original Jag), until I saw the info in this thread and started doing more homework.
It does appear that if you are hard mounting the diff to the chassis, you have to tri-angulate the rods. I have attached some pics and some instructions from www.snowwhiteltd.com on their Jag crossmember.

Steve

 

Dakota, any more pics of that last one? It looks to be cage mounted.....

 

Lol that's mine, under my 34 Chevy. It's still in the cage because I have only tacked it in position to get the ride height/rake right. There is a piece of steel conduit tacked in as well to stabilize it while being rolled around.
I'm going to take the entire thing out of the cage and mount it to a plate fixed to 2 cross-members (see sketch).
I will also be closing off the ends of the chassis rails at the back. Still working on some ideas.
Steve

 

I'm about to drop mine out of the Jag to put in the F1 frame, I'll take a few pictures before I do. I was thinking of using the two piece drive shaft. I did some measurements with the frame level and the Jag pinion angle is zero degrees, as is the bottom of the front Xmember. I think this thread has given me the information I need, thanks for starting it Iron Maiden and good luck on your project.

 

Thanks. I wish I was done so it was a bit more complete. $$$$ is the hangup. I am waiting on a set of Centerline Champ 500's from a friend of mine. Once I have those I can get this finished. I removed the coil-overs from the rear and fabbed up some spacers to hold the rear in the loaded position. I need to remove the front springs and fab something to sit the front down as well. Then setting up the IRS should be a snap. Stay tuned and please either post your install photos and info on this thread or start one of your own so we can see. Thanks for posting about the stock Jag being level in the front and no pinion angle in the back. Let us know about the drive shaft. I'm curious if they build in some angles in the two piece shaft to correct the motor/trans angle and the pinion 0 degree setup.?????

 

In the past I have used a two piece drive shaft to split the difference between odd angles and minimize torsional vibrations by raising or lowering the carrier bearing, don't know if this is right but it seemed to work.

 

The two shafts in the jag are put in in perfect alignment, both horizontally and vertically.

 

Why two pieces then? If they are perfectly in line, why the extra joints?

 

Here's a pic of the Jag shaft(s).
I still have the it somewhere in my workshop.

 

My guess would be they didn't want one long one as it would flex too much.
They are only about 2" dia from memory.

 

In removing the parts from mine it looks to be just the over built nature of the beasts. Here are some reference pictures I took today before starting disassembly, More in my album.

 

Mike, thanks.
That is how I set up my front and rear.

 

I removed the 4 coilovers from the IRS and fabbed up some quick spacers to hold it in the loaded position. I think ; ) My spacers are 10.5" center to center.



Lower control arms are pretty much flat and level. Shafts slightly angled up. The shafts, right behind the hub carriers, and the notch of the cage between the rubber mounts are pretty close. Maybe 3". I didn't measure yet.

 

The lower arms are supposed to angle down. The axles are supposed to be straight.

 

Seems to be differing opinions on this too.
But I looked under my mates stock Jag and, yes, the half shafts are definitely level with the lower control arms angled down from the diff head.
It would alter the camber only I would think.

 

Is there anything 100% on installing these things??? Debate after debate!
http://www.uk-hotrods.co.uk/v2/tech/jag_rear/tech_jag.php

Guess I will modify the spacers I made.

 

That's the way I've been schooled to do it. Axles parallel to the ground.

 

Like the pinion angle, I've seen and read it both ways. The link I posted above shows it the way I have it. No big deal, I will just add a little length to the spacers I made to raise it up a tad. It will also give the axles more space between the cage for suspension travel. That was the reason I posted the pictures and mentioned it. Just didn't seem right ; ) Thanks for putting me back on track.