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3/01/2016 11:49 pm  #1

Narrowing my Jag XJ rear end.

My car (1938 Ford 7Y) is quite narrow, so although I want the tyres poking out a bit, the standard width XJ6 IRS I have will need to be narrowed by a total of 320mm (about 13"). This thread will show how I'm doing it.


3/01/2016 11:51 pm  #2

Re: Narrowing my Jag XJ rear end.

I reached the point of no return yesterday:

So having chewed through that, I thought I'd better sort out a way of getting them back together, and came up with this tool:

Which has a solid boss at one end, and a sliding sleeve at the other end, both machined to fit the holes at the ends of the arm.
When bolted together looks like this:

The ends will be set up level on the bench before I weld them together, but this will hold them solid and at the correct length whilst I weld.

     Thread Starter

3/06/2016 3:34 pm  #3

Re: Narrowing my Jag XJ rear end.

What were you planning on using for shock mounts now that you removed the originals?


3/10/2016 12:22 am  #4

Re: Narrowing my Jag XJ rear end.

So back with the IRS lower arms, these are now welded together and within a few thou of each other in length.
I cut the shock tubes from the original arms and smoothed them off ready to weld back in.

The tubes are welded back in exactly on the weld lines. As there will only be the front shock there will be a bracket which bolts between the shock and the lower hub pivot and takes the rose-joint for the radius arm, (more of that later). I've moved the shock mount further out for two reasons:
1. The spring will be more effective being closer to the hub, and as there is only one it probably needs all of the help it can get.
2. Aesthetics. I think it looks better like it is, and as they say if it looks right it probably is.

I'm quite happy with the result so far.
Hope that answers your question tyrellracing

     Thread Starter

3/13/2016 11:22 pm  #5

Re: Narrowing my Jag XJ rear end.

Narrowing the halfshafts:
I've only got a small-ish lathe to use, so had to come up with an plan that would work without me killing myself with flying shafts!
So stuck shaft 1 into the lathe and turned these two areas. The left-hand side is turned to 32mm, the centre to 28mm:

Then hack it into bite size lumps:

Then turn the short yoke internal diameter to a nice interference fit on 28mm:

Cut off the 32mm diameter revealing the 28mm internal bore, then press the yoke onto the shaft:

This took around 10 tons of pressure, so it's a proper interference fit. Not sure I needed to weld it, but I did anyway:

And here it is next to it's unmodified brother:

The other shaft will be shortened the same way.

     Thread Starter

3/18/2016 10:55 pm  #6

Re: Narrowing my Jag XJ rear end.

Just to prove it wasn't a fluke, here are all of the narrowed rear suspension components:

And here's the chassis that the narrowed IRS will be bolted to:

     Thread Starter

3/18/2016 11:38 pm  #7

Re: Narrowing my Jag XJ rear end.

I like the fact that you have moved the coil over attachments outboard.  This improves motion ratio as much as you could.  Nice work!

"'Cars are like primates. They need to squat to go.'—Carroll Smith"

4/04/2016 12:38 am  #8

Re: Narrowing my Jag XJ rear end.

Back at the rear axle, I realised I needed a rear lower tie-bracket to hold the two wishbone pivots together, so after a bit of head-scratching, cutting, drilling and grinding I ended up with these parts:

Which after welding together looked like this:

It's now a 4-function bracket:
1) It ties the wishbone pivots together and wraps underneath to pick up the bolt-holes on the underside of the pivot brackets.
2) The large aluminium boss in the middle is the parachute pick-up.
3) The two circular brackets on either end are for tie-downs to be hooked to (it will undoubtedly spend some of its time on a trailer).
4) it will provide a strong jacking point.

     Thread Starter

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