I’ve always been nervous when accelerating hard with my 14HU 3.27 Quaife setup, due to the known tendency of the 14HU to shed teeth, so I have swapped it out for an X300 15HU with worm drive limited slip differential and 3.73 ratio Dana 44 JK ring and pinion (fuel economy is not a priority….). Obviously this topic is not mainstream (!), but I thought I’d write it up for reference, in case I decide to do it again sometime.

When fitting an X300 15HU differential in place of the weak X100 14HU, many of the components are common, although there are some differences that need to be accommodated.

• I’ve not researched using differentials and brackets from earlier XJ40 or other models, although the basic 15HU housing is, I believe, very similar
• These comments apply to the AJ27 X100 with Mercedes transmission and two piece driveshaft. Whether they also apply unchanged to the X100 with ZF5 speed or ZF 6 speed needs validating.
• Options for the 15HU include:
  • Use ‘as is’, assuming it is a locking differential, and the ratio is as required (such as X300 XJR 3.27 ratio). Other ‘GKN/Salisbury’ ratios fitted include 2.88 (special carrier offset?), 3.58, and possibly 3.77. All use an 8.5 inch ring gear.
  • Convert to Dana44 ring (8.5 inch ring gear) and pinion, and use Dana44 19 spline locking carrier (not the more common 30 spline carrier) such as Auburn, Speedmaster, Eaton, etc.). This route provides many options on ratio (3.07, 3.31, 3.54, 3.73, 3.92, …, 5.89)
  • Convert to the stronger JK Dana44 (8.8 inch ring gear), also known as a Dana 44 big pinion conversion, and use Dana44 19 spline locking carrier (such as Auburn, Speedmaster, Eaton, etc.). Ratios are more limited, with easy to find options including 3.21, 3.73, 4.10, …, 5.38). Note the Dana 44 big pinion kits commonly available won’t work with the Salisbury housing as different bearings are required.

Baxtor covered all the key issues on using the first option above, with a X300 XJR 15HU in this thread, so I have tried to focus more on use of the JK ring and pinion, and some alternative approaches to fitment, although inevitably there is some repetition of the common issues. There is also some discussion around installing JK ring and pinion into a Salisbury Jaguar housing .

Components common to both X300 and X100 AJ27 XKR include:
• rear subframe bracket
• lower ‘batwing’ control arms
• pendulum assembly at pinion end of diff
• rear hub carriers
• half shafts
• mounting strut
• i.e. MNB2840AA, CAC77601, CAC4713, MNG2960AA, MNG2961AA, MMB2860AA, MNA3501AA, MNA3505AE, MJA3290AA, CAC4610, JLM21053, MJA2590BG, MJA2595AC, MNC2630AA, MNC2631AA, MJA3715AB, etc., ignoring revisions

Components that are different are:
1) wide mounting bracket (CBC1820 vs MJA2622AA)
2) wishbone tie, wishbone mounting bracket, and suspension mounting studs (CAC7623 vs MNC2717BA, etc.)
3) anti roll bar (MNA2500DA vs MJA3500DF, CBC4901 vs MJA2502DD, etc.))
4) driveshaft flange/pinion flange
5) The differential housing

Details on these different components are:

• 1) for the wide mounting bracket, the 15HU pinion is offset, whereas the 14HU is centered
  • the X300 bracket must be used
  • the exhaust hanger brackets are at a different offset, with the 14HU brackets being closer to the center line.
  • Offset pinion X300 bracket below, and centered 14HU bracket above. Perspective is a bit deceptive in this image (lower bracket seems larger, but is not), but you can see that the bracket designs are different, and the center hole for the pinion is offset on the lower bracket compared to the upper. Also, the different exhaust hanger bracket locations (position and mounting angle), can be seen. The X300 exhaust hangers can be unbolted and remounted in the correct position and angle (weld, rivet, bolt, etc.) with a bit of creativity.

• 2) the wishbone tie, wishbone mounting bracket, and suspension mounting studs
  • Baxtor’s approach was to use the 14HU wishbone tie and wishbone mounting bracket, and turn down the 15HU mounting studs to fit, and then add spacers at the rear due to the longer protruding thread
  • An alternative is to use the X300 wishbone tie from an XJR/XJ Sport (note Vanden Plas etc. wishbone ties do not have the anti-roll bar mounts for the bushings, so can’t be used unless new brackets are added), the X300 wishbone mounting bracket (although the 14HU versions could presumably be drilled to the larger diameter), and the X300 mounting studs
  • As Baxtor noted, the mounting studs for the X300 are longer, engage deeper in the differential housing, and have a larger diameter into the wishbone tie. Below you can see that 14HU differential with attached mounting bracket and studs above, with 15HU bracket (Vanden Plas) and studs in front/below.

• The X300 XJR and non-XJR seem to use slightly different wishbone designs. The image shows a Vanden Plas 15HU wishbone tie in front (with no anti-roll bar brackets), and the 14HU wishbone tie at the back.
  

• One workaround is to add an anti-roll bar to an X300 wishbone tie, as shown here (ignore the red circle)

• An X300 XJR assembly with a wishbone tie that does have the anti-roll bar brackets is shown below

• The XJR wishbone tie stud washers have rubber gaskets, whereas the non-XJR use larger holes in the wishbone tie with ‘pilot’ washers.

• 3) The anti roll bar thickness is different (~15mm for X300 and ~17 mm for XKR non-R version), and the links are of a different design.(although mounting brackets are similar)
  • X100 anti-roll bar, bushings, and links should be used (unless a different rated roll bar is desired…)
  • The X100 anti-roll bar is shown below (poor picture, but you can see the drop link between the folds of the safety strap on the right)

• Below, the X300 anti-roll bar (when fitted…)

(continued in next post)

 

• 4) Driveshaft flange at pinion end
  • The X100 XKR/Mercedes driveshaft has a 4 bolt flange (circular pattern) at the pinion end, and a 3+3 bolt jurid coupling at the transmission output, with a two piece driveshaft in between including a center bearing aft of the slip joint.
    • Bolt circle diameter for the pinion flange appears to be about 3 1/8 inch or 79mm (TBC)
    • Pilot diameter appears to be about 2.375 inch

• The X300 has a 3+3 bolt jurid coupling at the 10 spline pinion.
• However, the 15HU pinion extended shaft for the Jurid centering cut be cut down, and the jurid mounting flange replaced with a suitable 10 spline Jaguar flange (per Baxtor – XJS 10 spline flange? ). I don’t have much information on the various Jaguar pinion flange bolt patterns
• Note that Baxtor needed to add a spacer between the flanges

• If using a Dana44 26 spline pinion then there is a larger challenge since the driveshaft flange is a 1300 series UJ, and 26 spline flanges are typically 1310 series. A 26 spline pinion yoke with ‘traditional’ Jaguar bolt pattern ( rectangle 2.0 x 2.375 ) is Spicer 2-1-1881X, and this will mate with a 1310 flange such as 2-2-329 (Male pilot 2.375 diameter, center of u-joint bore to Face of flange is smaller than 2-2-459) or 2-2-459 (Male pilot 2.375 diameter, Center of u-joint bore to Face of flange = 1.625 inches ). This still leaves the issue of connecting the 1310 flange to the 1300 driveshaft UJ. Options include a custom driveshaft, or maybe at a pinch using a 1310 UJ, and tack welding plus welding washers over the ends on the driveshaft 1300 yoke, since a 1310 will fit about flush when centered.
• Another alternative is to do something really fancy like post #168 of this thread, and get custom made 30 spline output shafts and 26 spline input flange for Jurid coupling, budget permitting….
• If using a JK pinion, then the requirements change again since it uses a 24 spline input flange, and typically this would use a 1350 series UJ. One option is to use Spicer 2006269/268 pinion companion flange, and Spicer 3-2-1879 yoke flange, although these are quite large, but it proved time consuming to find a matching pair and these do seem to work (4.25 in bolt circle, 4 x 1/2” holes, 2.6 in pilot). The challenge of connecting the 1300 series driveshaft to the 1350 yoke is then as above. One option is again to use a custom made rear driveshaft section with 1300 and 1350 fittings at the front and back respectively, and in this case it should be shortened by about 0.2 inches (center to center of UJs). This is the solution I used.
• Note that when connecting the driveshaft to the pinion, if using a greaseable UJ, then ensure that the grease fitting is under compression (being squashed) by the driveshaft rotation transferring torque to the pinon, and not under tension (being stretched) to minimize the change of the UJ failing.

• 5) Housings
  • The GKN/Salisbury 15HU housing and the Dana44 housing are fairly similar, but not identical, noting that a genuine Dana44 rear was actually used on a few XJSs. There are also differences between the Dana44 19 spline and 30 spline output shaft variants. And on top of this, the ‘JK’ Dana44 is not the same as the ‘standard’ Dana44 (or the Super Dana44, or any of the other variants….), noting that a popular modification is to put a JK ring and gear into a standard Dana44 housing, also known as a ‘big pinion’ conversion.
  • One of the key differences is in the bearings, which is summarized below.

• Obvious from above is that the JK pinion is much thicker and stronger, which when combined with the large 8.8 in ring gear results in a significantly stronger overall setup.
• Another difference is that the after market limited slip carriers mostly conform to the 30 spline spec for carrier bearing ID (1.795), so they use the larger bearing diameter even when supplied as 19 spline, in contrast to the OEM Jaguar carrier.
• I chose to use a Speedmaster Dana44 worm gear carrier with 19 spline outputs (PCE 204.1059) (similar in operation to a Quaife, etc.), mainly because it is predrilled for 3 different ring gear bolt sizes (3/8, 7/16, 1/2), which accommodated the ½ inch bolts that are used on the 3.73 JK ring gear I obtained. And the black friday deal was excellent. An alternative would be the Auburn Dana44 Grip-N-Loc 546085 if clutch style locking is preferred, but the bolt holes will have to be drilled out for a JK ring, as would the OEM Jaguar carrier. The difference in price between usual, and ‘on sale’ seems to be be massive (> 2X discount) in the aftermarket for these types of parts, so I you are not in a hurry I suggest waiting for your preferred carrier to go on sale. Both these carriers are for 3.73 and down carrier offset, so should work for ratios from stock Jaguar 3.07 up to 3.73, depending on what ratios can be found in the aftermarket.
• I installed the carrier in a housing from an X300 Vanden Plas, and re-used the mounting brackets from it as well. The wishbone tie and associated hardware came from an X300 XJR.
• Required bearings can be figured out fairly easily by looking at the bearings used on various known models using the different differentials (such as rock auto), and browsing a online bearing catalog (such as Timken) to cross reference using interior and exterior diameters, and bearing thicknesses. The bearings for JK ring and pinion when used with the Speedmaster carrier are:

• Comparing Salisbury and Dana44 bearings
  • Inner pinion 89410/89446 versus 31520/31594. Dimensions are the same, width is the same at 1.1563, Salisbury bearings have a higher load rating
  • Outer pinion 88043/88010 versus 02820/02872. ID and OD dimensions are different, same width of 0.875
• Then looking at the bearings required to install the JK pinion in the 15HU housing
  • Inner pinion 24720/24780 width is 0.875, which is 0.281 less than the 1.1563 OEM width
  • Outer pinion M88010/M88048 width is 0.875, which is the same as OEM
• This means a thick spacer is required behind the inner pinion race to make up for the much thinner inner pinion bearing.
• Various internet info ( unverified by me) suggests that both the Salisbury housing, and the Dana44 JK, have master housing dimension of 4.312 in (depth from carrier bearing center line to top of inner pinion bearing) and pinion depth of 2.625 in (depth from carrier bearing center line to top of pinion). This obviously would mean the larger JK ring gear is ~0.15 in closer to the top of the inner pinion bearing that the 15HU ring, so the bottom of the JK pinion is set lower than the 15HU pinion, if the pinion depths are the same for both.
• If (again unverified) the 15HU is similar to the earlier 4HA housing, then the inner pinion bearing is at a depth of 5.5 in (+/- 0.005). The 15HU bearing thickness is 1.1563, which allows for approximately 0.0317 additional for shimming adjustments to the 4.213 master housing dimension.
• Given the 0.281 in difference in bearing thickness between 15HU and JK, and the 0.0317 allowed for 15HU pinion depth adjustment, this implies total shim depth required to fit the JK inner pinion is 0.313, before accounting for depth adjustments.
• Note also that carrier bearing 25523/25590 has a total width of 1.0625 in. The Jaguar OEM carrier bearing is 25523/25577, which has a total width of 1.00 in, so a difference of 0.0625 per bearing. The after market 19 spline carriers have an OD of 1.795 (same as Dana44 30 spline carrier), instead of the OEM Jaguar 19 spline at 1.6875, so they are slightly stronger

 

Other supplies needed include the following – this is my best recollection, so apologies for any errors, and I went through various different shim packs and other supplies before ending up with the optimum setup.

• red loctite
• Carrier shim kit, Dana44 19 spline such as Spicer 701004X
• For inner pinion shims, depending on preference (shimming behind race vs behind cone) :
  • source a solid spacer of about 0.25 in – I used sendcutsend to create a 0.25 in spacer/washer with OD 2.995 and ID 2.25
  • For behind the race/cup in the housing: Ratech 1113 is 5 pieces 2.25 ID 2.995 OD 0.020 – 0.074 range, Ratech 1133 is 5 pieces 2.25 ID 2.995 OD 0.020 – 0.052 range
  • behind bearing/cone, Spicer 701140x or 701140-1x
• Crush sleeve or solid spacer for JK pinion. Note a JK solid spacer will probably not work as stock, depending on the shimming behind the inner bearing race, but can be adapted using a different solid spacer, or shortening the stock solid spacer
• Input shaft oil seal - National 9316 (3.16 housing OD, 3.165 seal OD. 1.875 shaft, 0.695 width, neoprene, type 72)
• 7/8 – 14 nut and washer for pinion preload setup, and locking nut for final assembly
• Slinger (Spicer 42737)
• marking compound
• if using custom driveshaft with 1350 UJ
  • Spicer 2006269/268 pinion companion flange
  • Spicer 3-2-1879 yoke flange
• To refurbish the stub axles
  - Bearing SKF 6207 (JLM11527)
  - Oil seal SKF 18662 (JLM12138)
  - Retainer JLM615 (I used a short piece of schedule 40 1.5 inch gas pipe to press these on)
  - O-ring JLM621 ( AS568 o-ring 235 seems to match, and is what I used)
• Half shaft U-joints, JLM1388 (GKN U220 ?)
• Gear oil – conventional 80W90 is recommended for the worm drive locking carrier
• As extensively discussed in other threads, you will also need a solution for the TCM to use a different ratio – either a TCM (EGS51) reprogram, or a Canbus spoofing box, or similar.
• Also an ECU reflash is required if the ratio is changed by more than 20% (3.73/3.06 = ~ 22%) and a spoofing box is used, otherwise the ECU will likely disable cruise control operation. The typical 3.27 ratio change is 7%, so well inside the 20% limit. I can advise on specifics for the 2002 XKR if details are needed (probably applicable to any AJ27 XKR or XJR) – mods are obviously firmware specific to the target year/model, and require competent computing and soldering skills.

The basic procedure is as follows:

• Remove stub axles, carrier, and pinion. Note the stub axles seem to have a custom depth shim specific to the housing, so do not mix up the parts for the left and right sides.
• I recommended making setup bearings for the carrier, and pinion, especially if you don’t have a carrier bearing removal tool. I used a dremel flap wheel to hone out the internal diameter (ID) of bearings/cones, and a belt sander to reduce the outside diameter (OD) of races. Unfortunately none of the existing 15HU bearings can be used as everything changes, but you can use cheap ebay bearings to make setup units, and then use Timken/National etc. for the final installation.
• Re-install the carrier with setup bearings and shims to allow loose fit, tape a ¼ inch spacer to the ring gear (e.g. 4 pennies), and grind case as necessary to provide clearance. On my housing, there were only a couple of spots that required light grinding.
• Photo is miserably out of focus, but you can roughly see the two areas where grinding was necessary , on one rib to the left and above the pinion, and on the case directly above that.

• Setup of the differential is per usual procedures. Remembering the (estimated/guessed) nominal 0.313 in of total shimming required to set the pinion depth, I started with approx. 0.260 in of shims behind inner pinion race (see picture of 0.250 spacer, which measured 0.247, below, plus 10 thou shim), and approx 0.050 behind pinion inner bearing/cone, adjusted for 2.625 pinion depth, and then adjusted from there for backlash (using JK spec) and pattern.

• Torque specs and preload specs are as per Dana44 JK (ring bolts, pre-load, backlash, pinion nut) or Dana44/Salisbury (carrier caps).
• I used a solid spacer for preload, since I ended up taking things apart multiple times to adjust final pattern, and I had to shorten the solid spacer a little to get it into the adjustment range of the supplied shim pack.
• This is also a good time to replace all the rear suspension bushings, etc.
• Despite the driveshaft shop balancing the custom driveshaft including the rear flange, it was badly out of balance. The very large flanges certainly don’t help here, and are probably the culprit. Since I own an oscilloscope, I was able to balance the driveshaft on the car using the accelerometer and phototransistor method (ADXL335 and TCRT5000 in my case, cost < $30). See picture below before balancing – light blue is the rotation alignment mark on the driveshaft, yellow is the accelerometer on the diff mount, pink is the center bearing mount, dark blue is the transmission mount. Finding smaller suitable flanges might be something to consider when going the custom driveshaft route.

 

Chirpy, Unbelievable amount of effort to document this.
Many, many thanks.
wj

 

Great work!

 

I am very thankful for the information Chirpy provided here. I am in the process of conducting a similar upgrade on an x308 VP with the ZF5hp24 transmission. I bought the 15hu differential and Speedmaster 19 spline LSD carrier. I am working on the ring and pinion now. One thing I didn't hear him talk about much was installing the mixed gear ratio. These cars seem to be very fussy about changing gear ratios. I think the Mercedes transmission is a little more forgiving. Any information someone could share on that would be great. I know some have used the Canbus to fool the TCM but it gets complicated and expensive. I bought a 3.21 ratio JK ring and pinion hoping it wont give me problems. I don't understand how some people are using 3.73 gears and getting away with it.

 

Chirpy helped me out with the "spoof" some time ago. 3.27 HU15 in my 2000 XKR, has never missed beat but as you stated, MB box is a whole different animal to the ZF.
Before l found Chirpy l was planning a laser cut of wheel reluctors with suitable change in segments, l never actually tested this method.

 

buried in my ramblings was this bullet point

• As extensively discussed in other threads, you will also need a solution for the TCM to use a different ratio – either a TCM (EGS51) reprogram, or a Canbus spoofing box, or similar.

this alluded to the following link, and was also discussed in Baxtor's 15HU thread:
and the github link here

I don't know of anyone that has tried the canbus ABS wheel speed modification approach with the 5HP24 yet, although I would optimistically guess that it would probably work.
Certainly the Mercedes TCM (Siemens EGS51 for the XKR) is not tolerant of a ratio change, and needs intervention for a 3.06 to 3.27 ratio change (and obviously larger like 3.73), or will trigger a 'gearbox fault' on the instrument pack display and put the transmission into limp mode.
(I would assume the 'second gear skip through' technique to bypass the ratio checking is unique to the Mercedes, so likely not applicable to the ZF (Bosch?) TCM)
So whilst I am cheering you on with your project, I am guessing there is a significant chance you will run into similar issues with the TCM even with the 3.21 ratio, and need to either make an electronic solution like I did, or create a mechanical one like Baxtor suggests, or maybe there is someone that has a reprogram service for the ZF TCM.
On the mechanical side, at least with outfits like SendCutSend and similar, it is a lot cheaper to get laser cut custom projects than it used to be. I use FreeCAD for design, and have had great results in various projects with laser cutting and sheet metal bending.

 

Fred Drift, but I've often thought that kind of solution would be the easiest way to get round monitors not setting on cars in jurisdictions which require all monitors set in their annual inspection. Instead of being wired in between the ECU and TCM, the box would be spliced in at the OBD connector to the appropriate bus and would intercept/report whatever emissions information is required.

I just hope it isn't illegal to think about that kind of thing.

 

Thank you so much for your input here Chirpy. I know you have hands on experience dealing with this upgrade and modifications. It seems like these issues shouldn't be so complicated when it comes to gear ratio upgrades. It would have made life a lot easier if Jaguar simply would have left some room for an easy programing change in the software where you could switch from one ratio to the other instead of trying to invent ways to defeat a system that locks you into what ever idea Jaguar had intended with no other reasonable options. Did they not really ever think that people wouldn't want to change the gear ratios? This is a Jaguar and by the very nature of Jaguar history you would think they would understand the answer. Looking at the 3.08 and 3.21 gear ratios it's like a 4% ratio change. I'm not even at the 3.27 gear ratio that was designed for some of their cars notably the 3.2L engine. I would certainly think it could handle that small change with going into limp mode which by itself seems to be an idea that Jaguar seems to be in love with because any kind of small issue going on with this car triggers limp mode. I have to say prior to buying this car I have never even owned one that had a limp mode let alone one that gets triggered as easy as this one. That issue alone creates a reliability problem for many. How does one travel thousands of miles in a car when they worry that limp mode may activate and suddenly your having a panic attack? I have more threads that I am about to introduce to discuss these issue but as a person who has been a engineer and mechanic all my life I am seeing red flags everywhere when it comes to Jaguars.

 

The problem I see with changing the wheel speed sensor is that it's not the wheel speed sensor that is the issue. Secondly if you do change the wheel speed sensor but cutting a new impulse encoder by either increasing or decreasing those it's going to have an effect on your speedometer that won't read correctly.
So as I understand this there is a direct correlation between the transmission speed sensor and the wheel sensor and that this information is processed at the TCM or maybe the ECM which also receives this information. That information is then compared to what the actual reading is and what it thinks the actual reading should be and depending on what it detects it will either determine the information is correct or that the information is faulty due to a miscalculation or a number it doesn't recognize.
To me the issue really needs dealt with at the transmission speed sensor and this is where the can bus interceptor can pick up those pulse codes and then repeat them to the receiver such as the TCM. We are basically altering the actual pulse codes and then sending them a artificial pulse code that is modified by some can bus receiver/transmitter to match what the TCM or ECM expects to receive so that way it doesn't go into limp mode.
So as I have explained this and people can correct me if I am wrong here because I don't claim to be an expert here I am just explain it the way I understand it. A change in the wheel encoders won't really solve this problem. Now I have to say there could be a pulse encoder on the transmission that could be changed and maybe even fabricated but that would also require a possible rebuilding of the transmission and I don't even know if this is possible and I haven't read any threads to indicate this is what someone has done.
Getting back to a can bus interceptor device again we are altering the pulse codes. So if for example we know we have increased our gear ratio by say (example 15% from a 3.08 to a 3.54) then we program the interceptor to add 15% more pulse codes to whatever pulse it is sending from the Transmission speed sensor. Whatever the difference between the original 3.08 ratio is changed to must be calculated by a percentage and then have that percentage of pulses added to the output of the interceptor so that the TCM receives what it thinks it should receive. This is the electronic method for resolving this issue as I know it. The mechanical method or the changing of the encoders does not appear to be a viable option which is why I haven't really seen or heard anyone doing it.

 

@Texas Jagman: Looking forward to that discussion, although my personal view is that it's a bit unfair to put these issues at Jaguar's door, when they just took what OEMs like ZF and Mercedes supplied them. Reading forums on BMW and Mercedes owners paying large sums to get programmers to help with their ratio changes, and/or trying to load various TCM firmware with 'wrong' car profiles to get their transmission mods to work suggests to me a much wider industry trend.

@dibbit: You had me scratching my head thinking who the heck is Fred Drift :-) Probably better to get 'Fred' to start a new 'thread' on Gedankenexperiments regarding those concepts, and hope the thought police allow such dangerous musings to be aired in public. After all, no-one seems to mind Schroedinger being mean to cats in an abstract way. I confess I looked into this at a deeper level on the AJ27, but the complexity of the state machine implementations regarding the various monitors is quite challenging to analyze.