V8 XJ8 Differential - any use?

[jonbillings]

Does anyone know the ratios of the 1998 4.0 litre XJ8 V8 diff, I was wondering if I could use one in a Dax? (on the back of a Muncie M21 & 350 SBC)
Are the same mounting/size as the XJS ones we all use?
Do I need the prop as well?
Advice for the experts/ those who know appreciated.

Thanks

Jon

[kdavies3]

I think you may need help from Russell Ram here.
I don't think it will fit the standard Dax Chassis, not sure about the new De-Dion one which uses XJ40 running gear.

http://animatedgif.net/flags/-flags-uncat/Wales.gif

Kev Davies
Dax, 383ci Chevy Stroker, Tremec TKO
South Wales

:tu

[tom]

Hi Jon

don't know anything about your dif,but i tried to fit a muncie 4sp to a dax chassis and found that the shifter mechanism fouled on the backbone brace. Consequently i bought a tremec and have a muncie sitting in the back of the shed collecting dust.

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regards

[jonbillings]

We must have something different somewhere - I have been driving my Muncie/Chevy/Dax for 3 years! Mine fitted OK with no problems.

Jon

I'm growing older but not up
My metabolic rate is pleasantly stuck
So let the winds of change blow over my head
I'd rather die while I'm living than live while I'm dead

[russell_ram]

Jon,

the short answer to your question is - NO.

The more complicated answer is still NO. XJ and XJS series that we normally use are DANA 14HU series units - you know, the ones with the four tapered bolts into the mounting face on the top.

The XJ40 cars have a 14HU series unit which is similar to the older 4HUs with most of the internals being interchangable. However, the mounting system for these is VERY different in that they are mounted of rubber bushes on the diff nose and rear.

Powerlok complicates matters slightly more. The 4HU units are controlled by belville washers, the plate stack arrangement, and cross pin ramps that stiffen up the diff increasingly the more speed difference ratio there is between the two output shafts. The 14HU PLok is not as good and is 'fixed' slip controlled by the belville washer stiffness and plate stack alone - it does not increase with increasing slip. Further more, the 14HU quickly loses its initial 'lock torque' as the plates wear, the 4HU compensates for this because of it's ability to increase slip torque the more slip there is. You could, however, retro fit a 4HU PL unit into a 14HU case.

XK8 diff is a DANA 15HU unit. NO commonality to either 4 or 14HU, but similar mounting system to 14HU (ie the wrong one). The gears are smaller and generally it's not as strong as a 4 or 14 unit, which were vastly over engineered for the Jaguar application ( but not in some of their other applications).

Finally, no powerlok option available in the 15HU XK8 unit. Replaced by 'clever' engine ECU/ABS controlled traction control.

Stick with the standard 4HU/14HU units (I think most kits will accomodate either these days).

Russ

[jonbillings]

Many thanks for a very detailed reply - most useful. I have been offered the XK8 one at a good price and had thought it might be a possible upgrade from my current one (2.88(I think LSD) - as I wanted to get a more useable low down ratio with a Muncie M21 - this saves me making a mistake!
If anyone wants an XK8 diff - I know where there is one............

Excellent use of the forum - thanks again.

Jon


I'm growing older but not up
My metabolic rate is pleasantly stuck
So let the winds of change blow over my head
I'd rather die while I'm living than live while I'm dead

[russell_ram]

Jon,

you're very welcome

Russ