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Jag IRS dimensions?
Nickp - 29/10/19 at 06:34 AM

Anyone got a Jag diff sat about (or in a car) that they can measure up please?
I'm after the total width of the diff including the discs if possible?

Thanks in advance,
Nick

r1_pete - 30/10/19 at 09:14 AM

They are 451mm between uj centres if that helps?

Nickp - 30/10/19 at 11:09 AM

quote:
Originally posted by r1_pete
They are 451mm between uj centres if that helps?


The UJ centre either side of the diff?
Where did you get that info please?

r1_pete - 30/10/19 at 01:48 PM

Yes, the uj yokes which bolt on with the discs.....

Believe it or not its something I remember from my 70s /80s hot rodding days, building irs crossmembers, and working out the suspension angles.

r1_pete - 30/10/19 at 02:04 PM

Found on the net, looking at the dims this is an XJ6 axle,

Jagarse
Jagarse

Nickp - 30/10/19 at 02:47 PM

Cheers that's a really helpful diagram and good memory sir!!

What I'm doing is looking to fit a Jag diff into my old Lotus Eclat, which is getting a Lexus V8. The original Salisbury axle / diff is not renowned for it's strength and the ratios are rubbish for the V8 too, either 3.7 or 4.1, I have the 4.1 unfortunately I'm hoping to retain the Lotus suspension / hubs etc, just replace the diff. The original width of the UJ centres is 26.75" on the Lotus. According to your diagram the Jag is 17.75, leaving me with a 9" shortfall. My initial idea was to get a pair of spacer / adaptors machined up for either side so they bolt to the discs on the Jag diff and the Lotus shaft bolts to them. I was hoping that the spacers would be smaller than this tbh.

r1_pete - 30/10/19 at 04:03 PM

Mmmm, the Jag diff is phenomenally heavy, the halfshafts also serve as the top wishbones so there is a lot of strength and weight built into the diff casting.

It might be worth looking at some of the big Triumph diffs, 2500pi, TR6 etc...

Nickp - 30/10/19 at 05:08 PM

quote:
Originally posted by r1_pete
Mmmm, the Jag diff is phenomenally heavy, the halfshafts also serve as the top wishbones so there is a lot of strength and weight built into the diff casting.

It might be worth looking at some of the big Triumph diffs, 2500pi, TR6 etc...


The Lotus is the same, using the driveshaft as the top wishbone and has inboard brakes, hence my thinking behind using the Jag diff.
Just weighed the Lotus axle / diff assembly and it's a full 50kg!! Is a Jag diff and brakes as much as that?
If I can get it mounted in there then I'll need to work out if it's best to use a spacer bolted to the disc or make extended driveshafts. The latter will move the pivot point of the 'top wishbone' (driveshaft) in by 4.5" affecting suspension geometry but a better solution than a spacer I reckon.

Simon - 30/10/19 at 08:23 PM

I was looking into using Jag IRS on toy car years ago and I'm sure the diff alone was 47kg. For better ratios I went to BMW and got a 2.28:1 shipped from Germany for £150. Never fitted it as sold car to pay for extension.

Anyway, found this thread which I'd recommend reading

http://locostbuilders.co.uk/viewthread.php?tid=48585