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@addict Thanks for your interest.
There is a big improvement in spirited driving between an open diff, and an LSD.
Agreed.
Originally Posted by HermanWiegman
OEM Friction LSD:
there is no rebuild kit available ... have to buy a new rear axle from Jaguar.
Did not know this, that's disheartening, I had assumed clutch packs were available for purchase.
Originally Posted by HermanWiegman
What other concerns do you have?
None except how quickly can I get it and what are you targeting for pricing? Saw $1kUSD above but I think that's just for the Helical LSD portion, correct?
@addict@mcphill Parts Availability:
Yes, it is disheartening to realize that the OEM axle is a Jaguar-only item, and there are no known rebuild kits. (still looking)
So once the friction discs wear, you will need to purchase a rebuilt/new rear axle at the price of $2k to $7k (prices at SNG Barratt) www.sngbarratt.com/
Hence my motivation to find a long life, maintenance free alternative.
Estimating Prices:
Yes, the price of just the Helical LSD is about $1000 USD. I do not yet have firm quotes, but I suspect it to be about the same price as other 600 Nm rated rear diffs from these manufactures.
Pricing for a used Jaguar rear axle with the gear ratio of interest will fall into the $300 to $1000 range.
Then adding in some other materials and labor and shipping... (never mind installation and removal labor costs) comes to about $2500.
This is LESS than the OEM Jaguar replacement price, so things are looking up.
V8 eDiff:
Yes, the V8 has an electronically actuated LSD (as opposed to a speed or torque difference driven LSD). It has a motor to activating the clutch packs.
But the eDiff is still based on the DANA 44 / AdvanTEK rear axle architecture.
Below are comparative pictures of an eDiff axle from a V8 and a V6 axle. Note the obvious right hand cover with motor attached.
Something tells me that I could either:
1) alter the design of the V6 helical LSD carrier to match the extended cover, or
2) install the V6 helical LSD with some help from the old eDiff components, or
3) remove the 2.56:1 gears and fit them into a normal V6 rear axle + long half shaft from a V6 car
This could result in a reasonable replacement business as the V8 cars tend to wear out their rear diffs prematurely.
Any body want to donate a used V8 rear axle to the cause?
Jaguar DANA44AdvanTEK V6 rear axle
Jaguar DANA44Advantek V8 eDiff rear axle
Last edited by HermanWiegman; 05-17-2023 at 06:06 PM.
May 21, 2023 Update:
MFactory and I have signed off on a helical LSD carrier design and I have a quote from them for the first 10 to 30 pieces.
Who is interested in the below offer to purchase a smooth, maintenance free helical limited slip differential for their Jag?
(available for 3.15, 3.23, 3.31 gear ratios, fitment to other gear ratios are possible)
Good news:
The price quote was lower than I originally estimated, only $680 per helical LSD.
MFactory will also make the custom crown gear shims to fit the base helical LSD carrier to the various gear ratios. ($40/shim)
They will also make the longer bolts to fasten to the crown gear to the LSD carrier. ($1/bolt, qnt 10 needed)
Bad news:
There is none, We just have to submit an order for the first 10 pieces and give 50% down payment, then 50% upon completion.
Next Steps:
Collect funds from interested members and escrow the amount. Any one have experience doing this with web groups?
Once down payment is made, MFactory will build and release the first LSD and shim set to me for test fit, before releasing the remaining parts.
Final Product:
Procuring a helical LSD is only the first step in outfitting your Jag.
An axle rebuild process is necessary, and I am willing to rebuild rear axles for Forum members so the pre-loads and backlash are all within spec.
This process starts with a used rear axle with the desired gear ratio, and adds various new parts (helical LSD, seals, bearing, shims and c-clips), and some paintwork prep.
Does it make sense for all helical LSD's to come to me? or do individuals want to hold onto their own units until they are ready to build and swap in a rear axle?
Change Threads:
I may start a new thread about rear diff options available to Jaguar owners. (OEM new/used vs. Drexler, vs. MFactory)
That new thread would focus on the options available, rather than the whole sausage making process for a custom diff.
V8 eDiff: @mcphill I have three potential pathways to success on the V8 models. Did you want to invest a bit into finding a solution?
Addendum:
I am still in the design process with Quaife. It will take an other month to finalize their design.
They have a similar minimum order quantity of 10 units, but without a first article fit before release of the units.
This second supplier will likely be more expensive, and I am not sure they will manufacture the crownwheel shims and longer bolts.
Last edited by HermanWiegman; 05-22-2023 at 07:39 PM.
Reason: added some more target members
Who is interested in the below offer to purchase a smooth, maintenance free helical limited slip differential for their Jag?
(available for 3.15, 3.23, 3.31 gear ratios, fitment to other gear ratios are possible)
phenomenal! still extremely interested. If I currently had a 3.15 but wanted to move to a 3.31 with the LSD, would that pose any logistical issues?
Originally Posted by HermanWiegman
Good news:
The price quote was lower than I originally estimated, only $680 per helical LSD.
Great news!
Originally Posted by HermanWiegman
Bad news:
There is none, We just have to submit an order for the first 10 pieces and give 50% down payment, then 50% upon completion.
Great! 50% down is completely reasonable.
Originally Posted by HermanWiegman
Next Steps:
Collect funds from interested members and escrow the amount. Any one have experience doing this with web groups?
Once down payment is made, MFactory will build and release the first LSD and shim set to me for test fit, before releasing the remaining parts.
No experience but happy to lean on the collective knowledge here and send payment wherever / whenever necessary.
Originally Posted by HermanWiegman
Final Product:
Does it make sense for all helical LSD's to come to me? or do individuals want to hold onto their own units until they are ready to build and swap in a rear axle?
in my opinion, it is probably easiest for them all to go to you pending rebuild -- saves on shipping costs.
Originally Posted by HermanWiegman
Change Threads:
I may start a new thread about rear diff options available to Jaguar owners. (OEM new/used vs. Drexler, vs. MFactory)
That new thread would focus on the options available, rather than the whole sausage making process for a custom diff.
my vote would be to stay in this thread for now until there's a finished first run -- keep all the knowledge / data in one place. Then once the first group has been successful, migrate to a new thread with all the finalized components.
Changing Gears:
Changing from one gear ratio (say 3.15 to 3.31) requires two steps..
1) procure a rear axle with the desired gear ratio,
2) then up fit it with the new helical LSD.
Note: this does not work if your car is an AWD model. The car would have to have a similar gear ratio in the rear as is found in the front (same tire diameter?)
Naming Game:
I may stop calling the new diff a "helical LSD" as it is more accurately a "helical Torque biasing differential"
The "LSD" moniker is more associated with friction disc based, axle locking or axle speed matching differentials.
Existing Solution?!
Last night I saw Tom Lenthall's YouTube post on a Jaguar "helical Torque biasing differential" for the XK and XJ V8 cars.
Some of the earlier V8 Jaguars with 31 spline axle shafts seem to be compatible with the later AdvanTEK rear axles found in the F-Type/F-Pace/XF/XE.
I just got off the phone with Tom in the UK and will see if Quaife may already have a solution. I pinged my contact at Quaife to see if it covers all of my key dimensions.
Otherwise their ATB diff would require moderate redesign to cover all of the gear ratios that I want to cover.
Nope... the earlier Jag's are not compatible with the newer AdvanTEK rear axles on the modern Jag cars.
The earlier Jags have either 25 or 28 spline shafts... (not 31)
The earlier Jags have different axle bearing sizes...
So no easy answer there.
The per piece pricing at Quaife is about $1200 USD ... so the MFactory path is still the best solution.
Changing Gears:
Changing from one gear ratio (say 3.15 to 3.31) requires two steps..
1) procure a rear axle with the desired gear ratio,
2) then up fit it with the new helical LSD.
got it -- and since you will be rebuilding diffs, we could work on sourcing a used rear axle in the correct ration, right?
Originally Posted by HermanWiegman
Note: this does not work if your car is an AWD model. The car would have to have a similar gear ratio in the rear as is found in the front (same tire diameter?)
understood -- I have an early RWD car so no issues there.
Originally Posted by HermanWiegman
Existing Solution?!
Last night I saw Tom Lenthall's YouTube post on a Jaguar "helical Torque biasing differential" for the XK and XJ V8 cars.
I pinged my contact at Quaife to see if it covers all of my key dimensions.
Otherwise their ATB diff would require moderate redesign to cover all of the gear ratios that I want to cover.
this could be sweet -- Tom Lenthall did incredible work on Harry Metcalf's Jag
got it -- and since you will be rebuilding diffs, we could work on sourcing a used rear axle in the correct ration, right?
Correct. I previously outlined two ways to up grade your Jaguar.
1) by removing the Jag's rear axle and sending that in for "rebuild" .. then installing it back into your Jag (lots of car down time)
2) by procuring a used axle with the desired gear ratio for "rebuild" .. install it into your Jag, then ship back your Jag's original axle as a "core" (more shipping, but less down time)
Note: I have a few cores (rear axles) on hand in my garage, so maybe I could stay ahead of the game and just send out a rebuilt unit upon request, and then ask for the customer's axle in return (same box).
There would also be a core charge added to the original purchase. @Unhingd recommends a core charge that is on the order of 50% of the purchase price to help force return of the used item.
Otherwise customers are not motivated to send parts back.
Originally Posted by addict
this could be sweet -- Tom Lenthall did incredible work on Harry Metcalf's Jag
Yes, some serious V12 car envy going on right now.
I think the spark and induction upgrades on the old V12 were expensive, but the results were great!
Do you also watch the Retropower series? They did an XJC a while back and are now doing two E-types.
Jaguar's OEM LSD:
Several of you have PM'd me about developing a rebuild kit for the Jaguar friction LSD, found on the F-Type V6S cars.
I did have a used LSD in my garage (40 k miles from a 2016 model), so now was the time to tear into it.
parts sequence for the Jag OEM LSD
Lesson #1
This thing is filthy. I'm talking gobs of black crud in all the corners. (see photos)
Now I am inspecting every part for wear, due to the amount of friction material floating around. Lesson #2
This thing ran hot. There is some metal bluing in places, indicating >300 *C hot spots.
Perhaps this unit was driven hard, but Friction based LSD do produce heat during LSD activation, and some heat during normal cornering (due to pre-load). Lesson #3
The friction discs look fancy, but they fail.
The friction material looked like carbon fiber, and it was less than 0.2 mm thick per plate.
Apparently they were stuck to the metal backing plates with an adhesive... which fails. (see photos) Lesson #4
The center cups had a non-aggressive, high angle shaft interfaces that were symmetric, which supports soft LSD engagement in both accel and decel.
This should be pretty good for street and occasional track driving, no fancy angles or asymmetry in this unit. Lesson #5
The preload was modest, and the clamping force wasn't too high.
Perhaps this was due to the worn friction discs, plus the one disk missing it's carbon fiber surfaces on one side.
I will remeasure the pre-load after it gets rebuilt (if I ever find suitable clutch discs).
Summary:
I would classify this LSD unit as 2-way, non-aggressive LSD, with moderate pre-load. (appropriate for a Jaguar)
I think operating these LSD's could be satisfactory long term solution, but only with frequent oil changes (of the correct type).
The challenge is finding the appropriate rebuild kit or friction discs and rebuilding the unit every 50~75k miles.
I still feel that a maintenance free helical torque biasing unit would be much easier to work with, clean running, cooler operating, and uses simple GL-5 oil.
The challenge is gathering ~10 enthusiasts to split the initial production run.
LSD carrier Tophat removed, showing bellville washer first plate set friction or clutch plate with carbon fiber the differential spur gear carrier loose friction material differential spur gears removed from carrier cup
Well, once I had the friction discs out, I might as well find a replacement.... so I spent the last few hours looking at web images of LSD clutch discs. Mind-numbing stuff.
But I did find a pretty compelling match: Porsche 993, 996, 997 Carrera 4/S/4S/RS rear LSD rebuild kit.
Or more accurately, I found a graphically scaled match. The actual parts may be several mm too big or too thick, but at least the proportions seem right.
Anybody got a rescalerator?
Jaguar to Porsche shape and scale comparison
Pricing:
These Porsche rebuild kits are a bit pricy, about $550 for a few discs and Belleville washers.
This is about the same price as a new helical torque biasing LSD. Something to consider.
but yeah I'm not interested in rebuilding the rear diff if there's a superior option available. I think we could get the 10 required for the initial order quite easily.
@randyb If you have an F-Type, or F-Pace, or XF/XE or some other late model, I hope to make a path to a helical LSD.
Otherwise, there are a few paths to friction based LSD’s for XK8 and later XKR models, and some of the AdvanTEK rear axle cars.
What Jag do you want to convert? And what sub-model do you have?
I will try to make a map for those involved.
BUt the leading path (as echoed by @addict is to join a group of members making a batch of MFactory helical LSD’s)
Rebuild Kit for Jaguar F-Type V6S LSD's
Ask and you shall receive. If you are trying to keep a V6 S LSD working, you can now get a rebuild kit.
Nenad Radenkovic at Racing Diffs LTD confirmed the fitment of part number RD4062
This kit normally fits the Porsche Carrera 993 / 996 / 997 LSD.
The metal plates and clutch discs are of different thicknesses than the Jaguar OEM parts, but the overall stack up is the same overall thickness, so it should work fine.
In the mean time, we are still looking to gather up 10 enthusiasts to purchase the first batch of helical torque biasing rear differentials from MFactory for $680.
This helical solution will be maintenance free and smoother operation than the friction LSD.
05-17-2023, 11:10 AM
