do we have a clear count of how many are confirmed thus far? [I'm in for one]

 

@addict

Purchase Commitments:
I only have clear purchase commitments from two forum members (you and me), and "interest" from about 3 others.
But several forum members, who have championed my helical diff development efforts in the past, have not weighed in yet.
Sometimes you have to wait a few weeks to cycle through everyone's attention. (vacations, work, life gets in the way sometimes).
I can start putting out Personal Messages to these members.... other wise we split the $6800 investment in two and recoup our investment over time.

There was very little interest from the XF/XE/F-Pace forums, and I didn't get any hits from the British Jag Forum. So interest at this time is slow.
I think as the V6 and V8 models age, there will be renewed interest to address the rear axles, so I am willing to take a chance.

V8 eDiff Investigation:
We also have @mcphill looking at a used V8 eDiff to see what can be done to fix/repair/rebuild/modify that unit.
Don't know where that journey will take us.
One solution could be to fit the V8 car with a V6 style rear axle with helical LSD (plus a V6 driveshaft on the left side of car).
This would make the proposed helical solution a real slam dunk.

 

I’m in on the helical. I already have @ used V6S diff sitting in a box.

 

Update: helical torque biasing differential batch purchase.

So far, we are up to 5 firm commitments (and 3 strong interest).
@HermanWiegman , @addict , @lizzardo , @Unhingd , @Dan Wink
We would ideally have 10 commitment, then we can make the 50% down payment to initiate the order, then 50% upon completion in 6-8 weeks.
I will offer to be the "holding pen" for the helical diffs, or you can individually opt to have them shipped to you for safe keeping (30 lbs, small box)
I will also offer a rebuild service and core exchange so we can keep the rebuilds going to cover everyone's axle swap.

A lists of costs for a rebuilt rear axle:
new helical diff from MFactory $680
some ratios need a crown wheel shim +$45 and longer bolts +$10
all rebuilt rear axles get new bearings +$72
all rebuilt rear axles get new seals +$70
and some shims and c-clips +$80
my labor and re-shim process +$375
paint option (media blast + refinish) +$100
TOTAL about $1422 for parts & labor

then add in some shipping costs back and forth for $60-$100
and outlay of a refundable core charge (may not apply to some of you with existing spare axles)
and maybe some lift time and labor at your local garage/repair facility to help with the swap.

Any other questions?

 

Rear Differential Removal and Installation Process

The Jaguar Method
I have reviewed the rear differential removal process as published in the Jaguar service instructions.
There are some cumbersome steps where the rear suspension subframe needs to be lowered by 10 cm (4 inches) to gain access to two of the differential's mounting bolts.
These bolts are crammed up against the cargo/spare tire bulkhead.
Then the rear axle needs to be removed while still supporting the rear suspension subframe... very awkward.

The Simplified Method
I am proposing an alternate method where two holes are drilled in the cargo/spare tire bulkhead to access the bolts from inside the trunk.
These trunk access ports would eliminate the need for lowering the suspension cross member and potentially saving a few hours of labor, never mind the risk to ourselves.

Otherwise this looks like a "big job" that requires two service persons working together.


differential mounting bolts

 

Rear Differential Removal and Installation Process - Continued
I hope the members don't mind me barfing up all of my little homework assignments into this thread... it is getting a bit long in the tooth.
I found an other simplification that reduces the number of steps and labor time for a rear differential swap.
Don't worry, I will summarize all of these tips in a single doc for the benefit of those doing rear axle swaps.

The Jaguar Method
Calls for the removal of the half shafts from the car, as if they were going to be inspected or replaced with new.
This requires some brutal work to get the splined half shafts out of a LocTite joint with the wheel hubs.

The Simplified Method
This method assumes the half shafts are not in need of replacing and are in good working order.
So we only have to "pull" them out of the rear differential by ~8 cm... meaning there is no need to loosen the LocTite joint to the wheel hubs.
Just loosen up the upper and lower control arms and "flop" the axle and wheel hub out of the way.


Rear axle nut which is normally discarded after removal.

half shaft and wheel hub assembly connected to the upper / lower control arms.

 

Rear Differential Removal and Installation Process - Continued
After inspecting my 2017 F-Type Premium V6...
I don't think we need any heroics to remove the rear differential from the vehicle, making it a process which any common mechanic can do.

The OEM Jaguar method called for the lowering of the rear suspension frame in order to remove the two rearward facing retention bolts for the differential.
This is unnecessary as our mission is to release the differential, and there seems to be enough room to loosen the bolts and drop the differential.
(the bolts will remain in the suspension frame, with insufficient room for removal)

Once I have a rebuilt rear diff ready for my F-Type, I hope to document the swap process and take pictures along the way so others can benefit.

 

this will be a great asset to the community! fingers crossed we can keep pushing this project forward!

 

Update: Quaife production quote

The folks at Quaife in Berkshire UK got back to me with a quote for the production of their automatic torque biasing (ATB) rear differentials for our DANA 44 / AdvanTEK equipped Jaguars.

• ATB differential unit pricing of £940.50 each (about 1200 USD each)
  • A purchase of 5 or more units will receive a 10 % discount (about 1080 USD each)
  • A purchase of 10 or more units will receive a 20 % discount (about 960 USD each)
• Crown Gear Shim pricing of about £65.00 each (about 85 USD)
  • no quantity discount
• Long Crown Gear Bolts pricing of about £15.95 each, (about 20 USD)
  • no quantity discount
• additional costs for shipping and VAT.

Note: the 3.23 and 3.31 ratios need the crown gear shim and longer bolts.
Note: the crown gear requires a quantity of 10 long bolts... so about $200 in bolts. (I will confirm this)
Note: the above does not cover the rebuild process of the rear differential (bearings, bearing shims, seals, rebuild labor, paint, etc.. ) see post #84 /page5/#post2647224

I am interested in this quote, as it has two nice aspects:

1. seems more natural to have our Jags be supported by Quaife in the UK, who already make differentials for the earlier Jags.
2. The quote has no minimum order quantity which is nice,

But the pricing is about 2x more than the quote from MFactory in Taiwan.

What are your opinions?
@addict @lizzardo @Unhingd @Dan Wink @spinningcog @Naif Kasheqri@randyb

 

All three points are valid. On the first, Quaife also has good reputation, a long history, and I don't see them going away. On the second, if the people committed to the lower-priced unit stay in, we're at the level we can get that first tier of discount.

The third point makes a difference, but less so that would seem on its face. The core parts are more, but bearings, shims, labor and other ancilliaries are the same, and the R&R of the diff is also the same. I'm not looking at it as "double the cost for the main part" but instead "maybe $7-800 more for the whole job." There might be duty to pay on arrival. I had to cough up some extra for the brake rotors from the UK, but overall, I'd still be in if this is the way it goes.

 

You said VAT is not included - that's for our EU readers? No VAT due for US recipients.

 

I have no opposition to the good folks at MFactory but I agree with the above points -- Quaife is a well respect diff builder and has been around the block with Jag for years now. Between the two, I'd prefer Quaife but I'd be happy with MFactory as well. I'm not bothered by the change in price and the lack of a minimum order is nice.

 

We will be a "bigger fish" with MFactory, they are US based, and they are cheaper... Only downside I see is the minimum order quantity. I suspect they may negotiate if you tell them what Quaife offered.

 

@mcphill
The team at MFactory that I am working with on the LSD development is actually based out of Taiwan.
The sales team for our effort is lead out of Hong Kong.
MFactory has a sales and small R&D department in California that supports some automotive testing, but no production capability.

With the geo-political climate in Asia changing, it may be prudent to consider alternative sourcing.
But Quaife in the the UK is also struggling with full Brexit mode, and we need to deal with import rules and taxes.

Other firms who build helical LSD's are larger and generally do not support enthusiast lead design commissioning.
So we have fewer options than a larger buyer of LSD's. (qnt > 30 units per year)

 

My bad. I was reading their website and got the impression they were US Based. Actually founded in Dubai with heavy Asian sourcing. That said, they do have some impressive credentials, and qualifications. I would not be concerned with the quality of what they produce.

 

Persuade Biden to give us the trade deal we want!

 

VAT and Import Duties:
I did some digging on the topic of VAT and import duties from the UK to the US.... egged on by @scm
As it turns out the US and UK have a "continuity agreement" which does not apply import duties to things like car parts.
You can use the SimplyDuty.com web site to check out other countries.


Engagement Note:
Looks like I will inform the Quaife sales team of the Forum's preference to order the helical differentials from them.
I will ask about their payment terms, and any "final sign off" of the design before money exchanges hands.

Moving:
I will be moving from Vermont to Rhode Island over the next month, so I will be packing up my tools and parts, and then setting up a new garage work shop.
Also I will be reducing my work hours to 2 days / week, so I will have more time.

 

@HermanWiegman sorry for the delay in getting back to you, been on a large roadtrip testing out a German.

doesn't sound anywhere near as good as the jag but its quite the car

hips

That sounds great, let us know what Quaife says! Congrats on the new work schedule!

 

Has the Quaife sales team given us any feedback on this part yet? Would love to keep the ball rolling forward on this.

Hope the move is going well!

 

First off, Happy Independence Day for those who are state side.

Update:
@addict Quaife UK just released the preliminary drawings for the Helical Torque Biasing rear differential for our Jaguar Spicer/Dana 44 AdvanTEK rear axles.
The drawings had a few minor corrections which I addressed, and so we may soon initiate the order for the first 5 ~ 6 units. Estimated 1 week from today.

Moving:
I am 2 weeks away from listing my VT house, and setting up a new garage work space in RI.

To Blast, or Not To Blast:
What are your thoughts about building up a media blasting cabinet to refinish the exterior of these differential cases?
Do folks like the gloss black or want other custom colors? (then media blasting is necessary)
or should I just focus on the rebuild, pre-load, and shimming process? and pay the $50+ bucks to media blast when needed?



Preliminary drawings for the QDF8W helical ATB with comments - July 6, 2023