Opening the Differential

In an earlier post, I mentioned I had an issue opening the differential cover due to the two large bolts which support the tie bar. After some head scratching, Ian came up with a perfect tool for removing these stubborn bolts. What's more, on his holiday travels to Finland he even found such a tool in a local hardware store, something none of my local tool stores stocked. The magic tool is a 30 mm slogging spanner, or in other words, a spanner designed to be hit with a hammer.

Differential with slogging spanner on the righthand bolt.

With the spanner placed around these bolts and many many hits with a lump hammer, this bolt finally began to loosen. With the bolt's removed, it is no surprise why it was such a pain to remove, given the large smooth concave contact area.

Complaining over though, the bolts did come out and with that, the differential cover fell away and I can at last check the internals. Upon opening the differential I was initially surprised that there was no paper gasket between the main housing and the cover, but Dr Google informed me that this is normal and instead a silicon gasket is used. Must make sure to add this to one of my future shopping lists.

First view of the opened differential – nice and oily.

Close up of the crown wheel.

After rotating the main crown wheel and inspecting these teeth along with the internal gears, everything seems to be in good order. There was no excess play in the output shafts.

Having had a precursory look, the cover can be placed back on with the smaller bolts which I took out last time. I will keep the large bolts out for now and give them a good clean before putting them back on.

Rear subframe breakdown

The final major section to disassemble are all the parts which connect to the differential (or pumpkin in American). Having previously separated the IRS from the prop shaft, what remains to be removed are: the swing arms, two half shafts, opening up and checking the internal condition of the differential. 

The steps taken in this blog entry could not have been completed without two of my good friends Ian and Suvi Virtanen, who came up several times and spent the weekend helping out in the garage. Ian’s all rounded mechanical experience was, is and I'm sure will continue to be a massive help.

Half shafts

The half shafts are connected to the differential with four 11/16 nuts, through a thick spacer. To remove these nuts, I placed a spanner on the head of each bolt in turn, which I then wedged against the wooden pallet to stop the shaft from rotating. I then used my small upcycled breaker bar on the corresponding nut to loosen it. These did require a considerable amount of force for such a relatively small nut. With these nuts removed, as the bolts stay in place, the half shaft can be freed from the differential. In case the spacers (between half shaft and differential) are not symmetric, I decided to leave these in place on their respective sides by loosely putting back on the nuts. This should also help reduce the chance of me loosening them and the nuts.

Differential with one of the half shafts removed

The removed half shafts need to be further broken down into three components; differential mounting plate, half shafts, and splined hub ends. These three parts are connected together using two universal joints or UJ’s for short. Whilst the shafts go to AK for shortening, I need to retain either end for cleaning and painting.

Complete half shaft assembly prior to breakdown

Since I don’t have a hydraulic press or a large enough vice, the UJ are separated by brute force. The approach which Ian suggested was to place each UJ between a pair of sockets, one smaller than the central section and one larger. Then, with plenty of percussion persuasion, the joint cups began to slide within the gap. Unfortunately, there is not enough space between the shaft ends to separate the joint from its cup. Instead, the plan was to move one end of the UJ cap to its far extent and then use a drift or a sacrificial chisel to move the other end of the cap out by hitting it with a lump hammer. Similarly, you could also hit the UJ itself, depending on your future plans for them. With the two cups partially out, this created enough space between them for the joint itself to be removed.

Sockets used to drift out UJ cups

Repeating this process multiple times, all the UJ are finally removed. As I am not going to reuse these ball joints, I am not too worried about damaging the joint with the hammer or losing any of the needle bearings from within.

Separated UJ and differential mounting plate

Swing Arm Strip Down

Now the half shafts are removed and broken down, the remaining components connected to the differential can be removed. These are the square looking ring item around the front of the differential (apparently it’s called the Pendulum for some reason), the swing arms and the rear tie bar. These are all held together by some large bolts on the differential and another pair of fulcrum shafts.

This is becoming somewhat of a habit, but I again kept referring to another exploded diagram of the rear assembly to guide me through the process. 

Exploded diagram of the rear subframe Justjagsuk

The first part which Ian and myself removed was the Pendulum. The nuts holding this in place had already been removed by Simply Performance so it was just a case of leveraging this free. Unfortunately, the stiff bushes in the pendulum and the large contact patch on the diff bolts meant this required some long pry bars and considerable force to shift. We then discovered that the pendulum would not pass the plate on the input shaft, with the lower fulcrum shafts in place. 

The plan dynamically changed to pulling the rear tie bar and swing arm assembly in the other direction to separate it from the differential. As we removed this part we were greeted with a clunk as the pendulum also came free and fell onto the differential casing. We should have seen that coming, but no damage done. Now the pendulum easily slides over the input shaft bracket and away from the differential.

Differential after the removal of the swing arm and pendulum  

Swing arms connected to the tie bar with their fulcrum shafts

With the components removed from the differential, we had hoped to open it up and check its internals. Whilst the 6 smaller 1/2 inch mm bolts were easy to remove, there were two bottom bolts/shafts at the bottom which proved more troublesome. These two large bolts required a 30 mm spanner with a depth of approx. 100 mm. Even after a quick trip to Wicks to buy a large adjustable spanner and some percussions we could not shift these bolts. With these in place, we could not open the differential. A review of several other AK builder blogs (mainly Steve's AK blog), revealed the historical difficulty and some of the innovative solutions which others had used. Clearly, more tools and further research was required here so I will mark this as a problem for the future. 

Not wanting to stop, we continued to separate the swing arms from the tie bar and the fulcrum shafts. The fulcrum shafts, however, seemed to be rusted in place to either the tie bar or the swing arms. Due to the large horizontal void between the swing arm and shaft, it seems obvious to expect water to collect here, eventually rusting these parts together. Clearly, Jaguar either didn't see this or cared.

Having tackled a similar problem before at the front, the solution seemed obvious, cut them out! A quick phone call to AK, it was apparent that they no longer require the swing arms and so I was free to cut them up as I wished. Out came the angle grinder again and I began to cut slices into the swing arm to separate the fulcrum shaft from the swing arm. The second time around and with better access to the metal surfaces, this was an easy-ish job.

Cutting the fulcrums free from the swing arm

Partially removed lower fulcrum shaft

With all that said and done, I had two fulcrum shafts, two junk swing arms and a tie bar. A good weekend's work!

Front Suspension Breakdown

Having previously stripped down the front brakes, the final stage of dismantling the front subframe are the suspension components. I must confess that during this stage I did phone both Simply Performance and AK to check what I should be doing and how to do it. The solution involved the use of an angle grinder, so fun times ahead.

As with previous entries, I found a schematic on the just justjagsuk website very helpful as it explained how the components fitted together. This made pulling them apart easier - or at least I knew what to do, even if at first I wasn't able to...

Schematic of front suspension assembly from www.justjagsuk.com/catalogue

Front Wishbone Removal

A few nights before starting this process I did a precautionary spray of WD40 on all the nuts and bolts I could see, connecting suspension components together. A quick job that should hopefully make my life easier in the long run. Using my shorter upcycled breaker bar I loosened the M10 bolts which connect the two halves of the top wishbones together (through the top ball joint). This was so easy I couldn’t believe my luck so I carried on, easily loosen the top fulcrum shaft nut (19 mm) as well. The same story was true of the bolts connecting the bottom halves of the wishbone together as well. At this stage, I chose to only loosen all these bolts in case I needed the rigidity of the suspension when using a breaker bar. A trick I learned from pulling apart IRS splash shield as mentioned in my last post.

Front top and bottom wishbones connected to upright and subframe

Although I could loosen and remove the lower fulcrum nut (22 mm), I was not able to twist or remove the shaft itself. This does lead to the pointless hypothetical question, when does a bolt become a shaft??

My luck had finally run out, however having loosened all the other wishbone bolts, I decided to completely remove all the wishbones parts that I could.  With the easy wishbones removed, the top ball joint remains in place as well as one half of the bottom wishbone, which connects to the fulcrum shaft and the upright via the bottom ball joint. 

Remaining front bottom wishbone and upright

Despite trying for an afternoon with a hammer and several sets of different pullers, I wasn’t able to separate either the top or bottom ball joint from the upright. Getting very fed up, I decided that I will tackle these joints when the bottom wishbone is off the subframe and I have easier and better access to them. This calm decision was taken much later having given up in the garage for that day.

After repeating the above process on the other side I ran into the same problem, with the ball joints and the fulcrum shaft, so it was time to tackle this obstacle. Initially, I tried hammering and prying on the shaft but with no joy, so went to do some research with the help of Dr Google. The two main methods I found from the internet were using a hammer (which hadn’t work) or using a blow torch to heat and expand the surrounding frame and then hit the shaft with a hammer. Given the amount of metal, I needed to heat up most mechanics used an oxyacetylene torch for this, which I didn’t have.

Fulcrum shaft rusted into the subframe

One solution which I came up with was to cut the shaft out from the subframe, although realising that I would need to be very careful, as this shaft is required for the kit. Another concern with this approach is that I didn’t actually have an angle grinder. Luckily, I was able to borrow a friends (massive credit to Andrew Young) brand new angle grinder, so many thanks to him. Also on a side note, congratulations to him and his wife on the birth of their first new child. 

Removal of Front Fulcrum Shafts

A quick phone call to AK, to check this approach and they said that they (and I) didn’t need the fulcrum shaft end of the bottom wishbone, so to make life/access easier I could cut this lose from the shaft. I therefore carefully cut two slices through the wishbone bushes and then chiseled the metal cutout and bushes free from the fulcrum shaft.  This meant I could drop the wishbone away from the fulcrum shaft, leaving just the fulcrum shaft to be removed from the stubborn front subframe.

With the loan of an angle grinder, I could start cutting up the frame. To avoid cutting into the shaft I cut some exploratory slices in the upturned subframe a few cm’s away from the shaft. Bending back this subframe metal, I found that, to my surprise, it was filled with foam. With the foam removed, I could see the shaft and so could begin cutting closer to it removing the metal as I went.

Initial cuts into front subframe to avoid cutting the fulcrum shaft

Whilst making these initial cuts, it was amazing how quickly the angle grinder began to look oily and dirty. I did carefully clean the angle grinder once finished with white spirit before returning it.

Borrowed angle grinder - what a tool!!!

Having cut away much of the metal which covers the fulcrum shaft I learned that there is a metal sleeve surrounding the shaft. This makes life more challenging and so more careful cutting required… joys

Fulcrum shaft still within a metal cylinder

The process that I went through here was to cut the fulcrum shaft and its sleeve out from the rest of the frame. Due to the concave angles which surround the bolt head, I had to cut a large section out from the subframe which included the shaft ends, and then cut this section down afterward at my bench. With the shaft and sleeve finally removed, I now had to separate them. My suspicion was that only the ends of the sleeves were rusted onto the shaft. If this is true, I only need to cut the ends of the sleeve away. For this, I made very careful slices into the sleeve along its length and then one circumferential cut. With these cuts, I could then chisel the sleeve away from the shaft. Repeating this process on both ends of the shaft, the sleeve did then slide away. Lucky it was just the ends that had been rusted.

By only cutting small depths at a time, both shafts were extracted and more importantly are re-usable. This saves me a few hundred quid on buying a new set. Given the faf that I had gone to achieve this, I had to take a photo of the shaft placed back into the cutout of the subframe.

Front Fulcrum shaft, finally liberated!

Cutting out the Ball Joints

The one remaining item of the front corner to disassemble was separating the upright from the bottom wishbone half. After earlier removing the four 1/2 inch bolts and failing to separate the lower ball joints with either the puller and hammer approach and because I had had such fun using the angle grinder, I decided to slice the bottom off from the ball joint and its casing. Having cut the largest part of the ball away, the upright came free from the bottom wishbone half. Of course, this does still leave part of the bottom ball joint (and the top ball joint) in the upright, however, as AK will be refurbishing the upright, I will leave these there for them ... an early Xmas present.

Bottom wishbone with ball joint casing cut off

Final Thoughts

Having completely disassembled the front subframe and the rear hubs removed, the pile of parts is starting to mount up. 

Parts removed from donor chassis thus far

Rear Hub Removal

With front hubs and brakes removed, I turned my attention to the rears. From the outset, this looks very similar to the front brakes, so should be easy. 

Rear corner assembly – before starting

Rear disc brake removal

The removal of the rear brake calipers and discs is almost identical to the front corners. Therefore only a summary of the steps is given below.

To remove the calipers undo the two allen headed bolts located at the back of the disc, which are contained within separate rubber tubes. With the calipers removed, the brake pads can easily be removed, or watch them fall out. The caliper carrier is fastened to the hub by two 15 mm bolts. The difference with the rear is that unlike the front these bolts have been wire locked together. Not sure why only the rears get this treatment, especially as the front brakes are more powerful. Now that the brake assembly is removed, the rear corner looks like this.

Image from the back of the IRS with the caliper carrier removed

Rear disc with the disc brake assembly removed

Not unsurprisingly the rear brake calipers are considerably smaller in size than the front brakes. They are however equally rusty and dirty, so will need a good clean. 

Both rear brake calipers and carriers

With the caliper carrier removed the disc can be removed by removing the grub screw. The grub screw on the near side was very difficult to remove, as the screwdriver head kept slipping. I did manage to get them out before totally stripping the head, but only just. These will certainly be replaced!

With the rear brake pads and discs removed, it is clear these are not in the same good condition as the front. As the images below show, there is significantly less meat on the pads and the discs have a very pronounced lip. Certainly, these will need to be replaced when building up the rear suspension on the AK chassis.

Rear brake disc and pad. Very little meat left

Notice the rim on the rear brake disc

Rear handbrake pads

Now that the rotors have been removed, I was slightly shocked to see that the handbrake is operated by internal drum brakes. Who would have thought that even in the 1990’s drum brakes were still used on Jaguars?

To remove the drum brakes first ensure that the self-adjuster at the top of the hub is fully screwed in. This reduces the tension placed on the pads making them 'easier' to remove. Then there are two NO. no. 5 allen headed clips which are held in place by a spring. These are removed by depressing the clip head and twisting free. With these removed and with a little more wiggling, the retaining springs holding the pads together can be unclipped. After removing one or both springs, the pads fall away from the hub. The last step is to detach the brake cable from the ‘fixing’ plate, by sliding out the middle pin. To avoid losing this small pin, I taped it back into the fixing bracket.

In hindsight, having removed the hub before tackling these drum brakes might have been easier, if possible...

Hub and IRS Removal

Now that all the brakes have been removed, the strip down of the hub and IRS really begins. For reference, I have referred to the following exploded diagram of the rear corner assembly which I found online.

Image from www.justjaguk.com/catalogue

To remove the hub there is a 27 mm nut which fastens the half shaft spline to the hub. These require some serious torque to remove. The near side nut required a week of regular WD40 spraying and then additional weight to resist the lifting of the differential when using the full extent of my up-cycled breaker bar.

With this nut loosened, but not fully removed, a good set of pullers is required to separate the half shaft from the IRS. Leaving the nut on ensures the whole assembly cannot fly off. This is another tip I remembered from Ed China.

Dirty rear hub removed from hub carrier

Luckily, all the races have stayed within the hub, which saved on the mess created. The only part which did fall off was the cogged wheel, which I believe is used by the ABS sensor to detect a differential wheel speed. This seems to be a press fit against the outside surface of the hub shaft and helps secure the hub within the IRS.

With the hub removed, I foolishly undid the IRS fulcrum shaft. This nut came loose relatively easily using the large breaker bar and the shaft itself came out with some persuasion. With the IRS away from the swing arm, the handbrake cable can now be removed. This is held in place by a semi-round plastic clip which sits just behind the hole for the handbrake cable. By rotating this clip, so its cut out is facing upwards you can gently pull this clip off.  Now the cable should just pull out from the IRS.

Inside view of the rear hub carrier

I then planned to remove the splash shield. This is fastened to the IRS with 4 no. 8 Allen headed bolts. These are obscured when the hub was fitted. However, there is a small cut out in the hub, which I assume is there to gain access to these bolts, but it is far too small for my sockets. I found the best way to remove them was to put the IRS back onto the lower swing arm, which prevented any rotational movement as I used my smaller breaker bar with an Allen key slotted inside to loosen them. With these four bolts removed the shield falls off from the IRS.

Removal of the rear splash shield

Now the shield is off, I can again remove the IRS from the swing arm. Having separated the major components from the rear swing arm, my work on this corner is done for now.

The layout of the disassembled rear corner

I will tackle the further breakdown of the half shafts and the hub carrier later.

Front Hub Strip Down

The first part to strip down from the heap of Jaguar parts, will be the removal of the front disc brakes and hubs. This is a very exciting first step echoed by the immortal phrase ‘How hard can this be?’. 

Brake discs and Calipers 

From an initial inspection, the front brakes look to be in reasonable condition with plenty of ‘meat’ left on the brake pads and the discs don’t appear to have much of a lip at the rim. These might be a candidate for saving… will have a closer look later. 

Image of front disc and pad after removal 

The front brakes are removed in two stages. First, there are two no. 7 Allen (Hex) key headed screws contained within a rubber tube behind each caliper. To access these, pop off the plastic cover from the rubber tube with a screwdriver and then with the Allen wrench these bolts are relatively easy to remove. By then pulling the caliper towards you and pressing the inboard brake pad to the rotor, you can push the brake piston back into its housing creating enough space to remove the caliper from the rotor. Of course, it’s obvious (with hindsight), that because the brake lines have been cut, when you squeeze the brake piston, brake fluid will come out of the brake line. I only realized this when I spotted an oil patch on the floor, luckily, I had put some newspaper down. 

Image of removed calipers 

With the calipers removed, the next step is to wiggle out the brake pads away from the caliper carrier. This leaves the rotors exposed with the caliper carriers as shown below. 

Front hub minus the brake pads and caliper

The next step is to remove the caliper carriers, which are each fastened by two 17 mm bolts through to the front upright (threaded holes). These bolts required a few goes with WD40 and a breaker bar. As a home DIYer, my choice of breaker bar went through several iterations. 

I have a breaker bar which came in my Halfords socket set, but it is not the longest at 180 mm and so struggles to shift some of these bolts. Definitely room for improvement in regards to length, in order to gain greater torque to remove the more stubborn nuts/bolts. A quick look online found a selection of breaker bars with a maximum length of 700 mm. Whilst I considered buying one, I thought I would try making my own, at least for the short term. I began with a spare piece of wood found in my garage and taped it to my breaker bar. This did work, but with limited results. I then spotted my old bench-press bar (2.2 m in length), which turns out to be a hollow tube that my breaker bar fits inside. Perfect! With my up-cycled breaker bar, removing these few bolts was straightforward. What was it Archimedes said? "With a lever, I will move the whole world" 

Original wooden breaker bar 

Comparison of an up-cycled breaker bar with the wooden breaker bar 

Up-cycled breaker bar being used to remove caliper carrier bolts 

The last part of the brake disassembly is to remove the rotor. This is simply by the removal of the small 'grub' screw found on the front of the disc. With this screw removed, the rotor then slides past the wheel studs. 

Front corner with the brake rotor removed 

To avoid losing the wheel nuts and the small grub screw I put them back on the front subframe. 

Hub disassembly 

After removing all the front brake parts, the hub is now exposed and is the next culprit to be removed. To guide me through this process I found an illustrative schematic of how this component is put together from the internet, shown below. 

Schematic of the front hub from http://www.justjagsuk.com 

So the first step is to use a flat head screwdriver to prise off the central hub cover. This is the dented, doomed part in the previous photo above. 

These next steps get very messy, due to the packing grease in the hub. With the doomed cover off there is a 15/16 nut, secured with a castellated cover and a split pin. The split pin unfolds easily with needle nose pliers and slides out. The castellated cover then slides off and lastly the nut below un-screws relatively easily. 

Front hub split pin and nut – Image from AK manual 

Now the hub assembly slides off, in my case, with very little force. As it comes off, a range of spacers and races will probably fall to the floor. Whilst I might not use them again, I will keep them safe so if I do replace them I know what I am looking for. 

Front hub removed

Behind the hub and its bearings, there is even more grease and a few more bearings within the cupped shaped housing. This casing is fastened to the main upright by three small TORX no.T30 headed bolts. With the vast amount of grease that packed this area, there is no need for WD40. 

Even after removing these bolts the housing and back plate did not come off easily. It was held in place with an oil seal, which as its name should suggest, is a tight fit and holds the housing in place. To remove the housing and backplate, I found it helpful to place a medium pry bar down between the hub housing and the plate and gently wiggle the housing off. As the housing comes off it brings with it the oil seal. This then allows the back plate to fall off the front corner exposing the front upright with its wishbones and ball joints. 

Front upright after brake and hub removal 

Having tackled the front breaks and hubs, next onto the rear to do the same.

Chassis Donor Parts Arrive

To ensure I have all the dirty donor part jobs out of the way before the chassis and body arrive in October I suppose I should start looking for donor parts.

The traditional first place to look for donor parts is generally to scourer the classified ads for a donor car and liberate the required parts. It would though, leave me with an almost complete car, which is now considerably more difficult to move and dispose of owing to the fact I would have removed both axles for the Cobra. However, there is an argument to be said for continuing with the break down of the car and sell off the remaining pieces. Although as my aim is to build a Cobra, I would rather spend my time doing this rather than hours and hours stripping and selling Jag parts.

Luckily there is a common solution, which is to purchase just the required donor car parts from a breakers yard. AK recommended two specialized Jag breakers, Simply Performance and Black country Jags, which were hence my first port of call. Having contacted both companies and obtained quotes for their donor car kits, I decided to go for Simply Performance. This was not the cheapest of the two options, but I found them by far the most helpful when I was asking my initial stupid questions.  They were also able to effortlessly accommodate my desired delivery date and take a few photos for me of the donor car.

Photo of donor car taken by Simply Performance

Two weeks after paying just over a thousand pounds, the donor parts had been stripped from the original car, shipped to my address and are now sitting on the floor in my garage. Whilst to most this looks like a pile of scrap metal an ties, to me it’s the start of a new AK Cobra.   

Photo of donor car taken by Simply Performance

Photo of donor parts being delivered

Photo of donor parts as delivered

The donor parts included in the Simply Performance kit are: the front and rear subframe from an XJ40, handbrake assemble from an XJS, V5 documentation for donor car (required for age related registration later) and 4 slave wheels to use with the car. So whilst they are not all the donor parts I require, it’s a good start.

Photo of donor parts with covered removed

After removing the protective black cover, you can see in the photos how the parts are shipped. Whilst the wheels might not look secure sitting like that on top of the subframes, they are well held down with ropes. Taking the wheels off, I get my first look at the required subframe.

Donor subframes ready for stripping

XJS hand brake handle

Over the coming entries I will strip these down to the parts required for the AK Cobra.