In some of the earlier Jaguar diffs, the case had to be slightly deformed, or squeezed in one direction to expand it in the other, in order to remove or reinstall the ring gear. I even saw this process described in a Dana or Dana Spicer manual. There is a special tool for this that attached to the cover mounting holes, if I recall correctly, but I also found numerous DIY solutions online. As it turned out, I didn't have to do it on our XJ40, but you might consider whether that might be possible on your X350 diff.

Cheers,

Don

 

Maybe try what Don B suggests in post #21 on the 4.2 diff case? IF it can be "stretched" by a shade under 1/4 inch it might be possible to install the Ford 8.8" LSD?

 

Thanks Jackra, I think I might try. Although rolling burnouts are fun, it would be great to be able to power out of corners without the intrusive TC ruining the fun.

My indie thinks the job is possible and he's also rebuilt AM LSDs which should help him.

 

I am not so interested in rolling burnouts as I am in the powering out of corners without the TC issue as you stated.

Also if trying the "stretching method" obviously try the stretch before buying the Ford LSD.

 

I believe a LSD would be also most useful when driving in very slippery conditions (snow, ice, turns or climbing in winter).
Unless the XJ is not used in winter...

 

I think so too paydase, approaching 500hp in rainy Wales on summer tyres is an interesting combination!

 

This is all very strange...

I wrote an email to Tom Lenthall asking to buy a QDF3W, same as I did last time. So far I got no answer, maybe this is the reason why...

EDIT

I just got a reply from Tom right this minute, he says he can still supply them.

There was some funny sales arrangement in the past with this QDF3W diff (I mean when I bought one 4-5 years ago) In the UK the official distributors were only Racing Green Cars, and TL Jaguar (Tom Lenthall). Norman Durban was also involved as well. But you could only buy from those two places.

Then Paramount was offering them for sale. And then others were offering them as well...

And now, it seems Quaife is giving up on this model, and sold off all their stock?

This is the first time I ever heard of the version QDF3W37 too...

 

Up until about 8 weeks ago several Ebay vendors advertised the QDF3W for sale.
Now none except Motorsport-Tools does.

The vendors that used to advertise did not stock the item but apparently sourced it elsewhere and I assumed it was from Quaife direct.

Anyway when I get the QDF3W37 I will soon find out whether I have wasted yet more money.

If I find that it does fit there will only be 4 units left as per the Motorsport-Tools Ebay listing.

 

Just looked at a 2007 XKR differential for sale on Ebay and it looks the same as mine plus the numbers on the casing are the same.

So maybe a hopeful sign?

What was curious tho is the fact that Motor-Tools did have a listing for the Quaife in question about 8 weeks ago but was listed as no longer
in stock. That was the UK Ebay site.

 

Tom Lenthall just replied to me, he can supply the QDF3W...

 

The casing is exactly the same part, the only difference between the diff in a 4.2L X150 XKR and an X350 XJR is the gear ratios, rest is the same.

 

Does it have any letters after QDF3W.

This is what I have ordered : QDF3W-MST-37

 

I don't know, but here's what Tom has said, paraphrased...

Quaife cancelled the exlusive distribution agreements for the Jaguar LSD's
So any Quaife reseller could sell them.
However Quaife does not keep stock, it's make-to-order and only produced in batches
So a reseller would have to buy a batch and keep them in their own stock

This would be why you get a "not available" from some places, they do not have them in stock and do not want to buy a batch quantity in for just one sale.

Tom said he has the QDF3W in his stock right now.

No idea what the other numbers or letters mean...

 

It's the final drive of the diff which is different, if I am not mistaken:
3.31:1 for the XKR (X150 from 2006 on)
2.87:1 for the XJR and SV8 (X350 and X358)

The gear ratios of the ZF 6HP26 look to be the same:
4.17:1
2.34:1
1.52:1
1.14:1
0.87:1
0.69:1

 

Just for future reference to anyone else who decides to do this swap/upgrade, Tijoe did some comparisons between the Gen1 & Gen2 axles on another (related) forum

 

I contacted Tom, following the infos from Cambo.
Tom confirms that he can provide the QDF3W unit (in principle he commissioned them only for the XKR) and that he would make small adjustments to it in order that it can be fitted to the X350 (SV8 or XJR).
I have asked him what these mods would be, maybe related to the different final drive.
So jackra, maybe you will have to make a small tuning or your unit.
I am very tempted and may also bite the bullet...

 

I don't understand why the waters get muddied with statements like "small adjustments needed"...

The QDF3W bolts straight in to the diff of the X350 XJR.

When I got my diff from Tom, it was sealed up in the heatshrinked plastic as it left the Quaife factory....



And bolted straight in...





No modification, no adjustment, it just goes straight in.

The only difference between an X150 XKR diff and the X350 XJR diff is the gear ratio.

Actually if you take a diff from a 3.0L X350 XJ6 (not sold in North America, but everywhere else in the world) the diff is identical to the one from the XKR, same ratio, same part number in the bloody JEPC even... ditto for a 3.0L auto S-Type...





Same part numbers...

The diff in the X350 and the X150 (and X202) is the same, just different ratios depending on the engine.

 

Thx for the comment and further info, Cambo.
I just reproduced what he wrote to me (why indeed would ne need to muddy waters?), hence my request to him for clarification

 

Ok got the email I was suspecting that I would get from Motorsport-Tools.

They say the QDF3W that I ordered will not be in until the end of July.

I suspect I will get another email around that time to the effect it will never ship.

So what would be the price shipped from Tom Lenthal? Can you help Cambo?

Just sent email to Tom Lenthal.

John

 

John,
Price from Tom is £895 + UK VAT + shipment.
He also can provide a bearing and seal kit at £200 + UK VAT.

I also copy his answer to my last message (he did not reply to my question wrt the "small adjustments" but commented on his price when compared to the offer of Motorsport-tools):
"I would recommend sending your diff to atransmission / diff specialist for the components to be fitted. It's nota normal job for your average mechanic. I know my prices are a littlemore expensive but then you get the benefit of my experience. The Quaifediff centre will fit straight into your housing and comes with the usual Quaife warranty."

So I'm hesitating, it's a 2k+ bill in the end, if done by a specialised shop, but it seems attractive for you if you want the associated performance.
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