Steering - Part 3 - Steering Column Preparation

The steering column for the AK427 is provided by a BMW E34 unit (which comes from any BMW 5 Series from 1987 to 1996).  I acquired a used unit from the well-known internet auction site when I ordered my kit.  You must ensure the column is complete, including the lower extension piece and the bolt that holds the steering wheel in place.  My column did not include the plastic cowling and I did have to search around to get both the top and bottom sections; I ended up buying them separately.

BMW E34 Steering Column

The ignition barrel and steering lock mechanism need to be removed from the original column as they will not be needed in the final set-up.  The ignition barrel supposedly can be removed by "simply" inserting a stiff wire or narrow probe (I used a 1mm allen key) down the small hole on the face of the ignition barrel to depress a spring-loaded key that locates the barrel in place.  I spent a joyful hour trying to get that to work before I resorted to drilling a small hole into the side of the barrel and using a small screwdriver to depress the key and remove the barrel (which took less than 5 minutes).

To remove the barrel, insert a pin into this hole...

..

...although drilling a small hole here...

...and inserting a small screwdriver...

...is far quicker!

The rest of the ignition barrel mechanism is removed by grinding down the sides of a small boss on the bottom of the ignition housing until it is possible to grip the pin in the middle of the boss with some pliers and pull it out.  The rest of the mechanism can then be easily extracted.

Grind down the boss to expose this pin...

...pull the pin out...

...and pull out the last bit of the ignition barrel.

This still leaves the steering lock mechanism in the barrel.  The easiest way I have found to remove this is to undo the two security bolts holding a plate onto the top of the barrel housing.  I cut a slot in the top of each one using a dremel and used an impact screwdriver to undo them.  This allows the ignition barrel housing to be removed from the steering column and exposes the steering lock mechanism, which can then be levered out and removed.

Two security bolts on top of the ignition barrel housing...

...in the process of removal...

...which then exposes the steering lock mechanism...

...allowing all the components to be removed.

The BMW column mounts need to be modified to fit the AK body.  This involves trimming the top mounting plate of the column and cutting off the left-hand leg of the column mount.  

The top mounting plate needs to be trimmed...

...to leave around 40mm left protruding...

...and the left-hand leg of the column mounting...

...is removed entirely.

The last "modification" required is to remove the large nut from the end of the lower column section.  From Russ Howell's video series, I know that this nut can clash with the side of the pedal box and that AK had advised the nut is not really needed and can be dispensed with.  Easier said than done, as the nut on my column was stuck fast and no amount of leverage and gentle persuasion could budge it.  I resorted to cutting a slot in the side of the nut with an angle grinder and using a cold chisel to split the nut off the shaft.

The large nut on the lower section of the column...

...needed some minor surgery to aid its removal.

I gave the exposed metal parts of the column a couple of coats of black Smoothrite before reassembly and bought a new rubber steering joint for between the upper and lower column sections.  The column is now ready for installation! 

The modified steering column ready to fit!

Handbrake - Part 2 - Installing a Linear Particle Accelerator

The normal handbrake set-up on the AK Cobra is a cable-operated system, utilising an XJS handbrake lever in the cockpit, operating a lever mounted above the differential unit that in turn pulls on the handbrake cables connected to each rear hub.

The original AK handbrake set-up, whereby the cable simply pulled directly on the actuator lever, did appear to have a reputation for not being very efficient (based on a read of several internet forums).  AK has addressed this and modified the set-up with the cable operating the lever via a pulley set-up to provide twice the pulling power.  Improved, but still a bit touch and go come IVA / MOT test time.

AK Handbrake Modification (from AK Build Manual)

I decided to make a couple of further modifications to the system myself to improve the handbrake performance.

The first modification involves the XJS handbrake lever.  I obtained the lever from Simply Performance at the same time as my donor axles.  The photos below show the lever before and after modification...

XJS Handbrake Lever before initial modification...

...and after modification!

The second modification involved the purchase of an electronic handbrake kit from Hollin Applications Ltd.  This kit was developed for the Motability market in the UK but seems to have gained popularity with many Cobra builders over recent years. The kit includes a linear actuator, an electronic controller and a simple switch.  The controller enables the pull / push force on the actuator to be adjusted up to a maximum of 800N or 80kg in old money.  It also meets the IVA requirement of preventing the handbrake from being released unless the ignition is switched on (it does also have the problem that the handbrake can't be released if the battery goes flat - but we will cross that bridge later).  The switch is a bit basic and will do for initial testing, but it will be replaced with something to match the other interior switchgear (when I decide what that will be...)

Linear Actuator

A bracket of some description is needed to mount the actuator to the rear chassis cross-member.  Since I made the decision to go with the Hollins kit, AK has actually started using them in their factory builds and has started selling an electronic handbrake kit including a mounting bracket.  However, I felt the price they were asking for the bracket alone was a bit steep and as I enjoy spending valuable time that I haven't got, making unnecessary bits for this build, I decided to make my own...

Fortunately, I got a bit of a headstart via Steve Sutton's build blog which referenced a solution by another builder Michael de Kok, who had included the details of the bracket he had fabricated for his own Cobra electronic handbrake install.  So, giving credit where it is due, I have borrowed the same design.

I completely forgot to take any photos of the fabrication process, so thankfully you can all just see the final bracket before and after powder coating!

Final bracket before coating (don't be too harsh on my welding)...

...and after powder coating

I fitted the handbrake actuator to the bracket using a long M6 bolt with a couple of spacers that I machined from some offcut of steel bar.

The actuator is installed into the bracket.

I then drilled and tapped some holes in the rear cross-member and fixed the bracket/actuator to the cross-member with some M8x1.25 bolts and spring washers.

The handbrake actuator & bracket are fixed to the rear cross-member.

I also needed to replace the operating lever from the item that AK supplied.  I fabricated a new lever from a 5mm thick steel plate with a small section of steel channel welded on the end.  The channel end needed to be reworked with some light grinder action to prevent the lever from fouling on the chassis at full throw.

New handbrake operating lever

I trial-assembled all the bits and wired up the control board temporarily to test out the operation.  Thankfully it all seemed to work OK with the actuator shutting down at extension once the load from the handbrake cables started coming on; the control box is preset from Hollins at 50kN load.

The final assembly involved powder-coating the operating lever, making up a couple of nylon spacer washers and bolting it all back together with copious amounts of copper grease.

Final handbrake assembly

Rear Axle Reassembly - Part 11 - Finally completed

Once my new half shaft spacers had arrived I could get on and (hopefully) complete the rear axle assembly.

Upon removing the spacers from the packaging, I was disappointed to find that they were both made from steel, and not some more exotic metal, as the price I paid for them might have suggested.

Could a golden spacer lie within...No!

I installed both spacers (4mm on offside / 7mm on nearside) and a single rear camber shim on each side initially.  It actually turned out that I needed just the single 4mm spacer on the offside and the 7mm spacer plus two shims on the nearside to get a camber setting of 0.3 degrees negative on both sides.

Spacer in place on differential output flange

Oh look - those shims do fit after all...

0.3 degrees negative on that side...

...and 0.3 degrees negative on the other side.  Job done!

With that done, I could remove all the 7/16" nuts from the half shafts for the last time and replace them with 7/16" Nylocs.  These were torqued up to 90Nm / 66lbf ft.

The next job was to remove the original drive nuts from the hub end of the half shafts and replace them with new items.  The Jaguar service manual recommends that the splined end of the half shaft within the rear hub is covered in thread lock over 30-50% of the radial area.  I used Loctite 270 and covered the rear part of the splined section before reassembly.  As well as a new drive nut I also replaced the conical washer with a new item.  

Today's thread lock is Loctite 270...

...applied over the rear of the splined section

New conical washer and drive nut (note the red insert)

The drive nuts need to be tightened up to a whopping 225lbf ft / 305Nm of torque.  I tightened them up initially using my air spanner.  I then used a large pry bar against the wheel studs and braced against the floor to stop the hub from rotating and dug out the largest of the torque wrenches from my tool arsenal.

Top tip - push the wrench down rather than trying to pull it up or side on otherwise you may end up pulling the chassis off the axle stands.  Also, try and position yourself away from the pry bar.  Mine ended up bending like a banana and if it were to break free from the wheel studs, it will cause serious damage!

Drive nut installed and tightened to ridiculous torque level!

The last step was to install the rear shock absorbers.  These are fitted in place with 7/16" x 4.5" bolts, M12 washers and 7/16" Nylocs in the top mounts and 7/16" x 2.5" bolts, M12 washers and 7/16" Nylocs in the bottom mounts.  AK only appear to supply a single M12 washer per bolt so I splashed out and added an extra washer to have one under the bolt head and one under the nut on all mounts.

Shiney new shock absorber - fitted so adjuster knob is at the bottom and facing inboard.

Mounting bolts - these were given a liberal smear of copper grease before installation

Rear Shock Absorber installed

The final step was to torque down the shock absorber mounting bolts to 38Nm (28 lbf ft) for the upper mounts and 64Nm (47lbf ft) for the lower mounts.  And that is the rear axle finally completed!

Rear Axle Reassembly - Part 10 - Shafts and Shims Shocker

 Finally, I am at the last stage of getting the rear axle/suspension back together and be warned this stage is a right PITA.

The first job on the list was to set the rear camber.  This requires setting the top most point of each of the rear hubs to be 150mm below the top of the rear chassis rail, checking the vertical angle of the face of the rear hubs and adjusting (by inserting shims between the differential output flange and the inboard half shaft flange) until the camber of the rear hub is between 0 and 0.5 degrees negative camber.

There now follows a moment of monumental stupidity which I am amazed I am prepared to admit to on such a globally viewed forum.

There are a couple of options for shimming out the half shafts on a Jaguar rear axle.

• Spacers of a specific thickness.  Jaguar used spacers of between 3.5 and 7.5mm thickness with Part Number CBC4806xx, where xx is the spacer thickness (e.g. 35 for the 3.5mm spacer).  Although these are only made out of steel, at the price they cost, you would think they were made out of gold!
• Rear camber shims with Part Number C16621#.  These are 0.020" (approx 0.5mm) thick and cost less than £1 each

I went with the second and cheaper option and ordered 16 shims from SNG Barratt hoping that would be a sufficient number (giving me up to 4mm of shim on each side).

16 Rear Camber Shims for less than £20...

I jacked up the first rear hub until it was 150mm below the top of the chassis rail.  I did this by clamping a spirit level to the top of the chassis rail and setting an adjustable set square on top, with the ruler set to give a depth of 150mm below the bottom of the spirit level.  The hub was then jacked up until it just touched the bottom of the ruler.

Setting height of hub to correct level

I then checked the vertical angle of the hub using a digital spirit level set vertically across the edges of the centre spigot on the hub.  The first reading was 89.25 degrees (i.e 0.75 degrees of negative camber), slightly too high, so some shimming was required.

I found an article on one of the online Jaguar forums that suggested that each 0.5mm shim would adjust the camber angle by around 0.25 degrees. So theoretically I only needed to add one shim.  In reality, I needed to add a few more as, without any shims in place, there is a small flange on the back of the inboard half shaft that bears onto the differential output shaft flange, such that at the point where the bolts pass through there is a gap between the two of around 3.5 to 4mm.  Until that gap is filled, the rear camber shims won't actually have any effect at all.

So I undid the nuts on the inboard half-shaft, which is a bit of a pain as you have to get it in exactly the right spot to get a 7/16" socket in through the U-joints and then you have to turn the differential by hand to line up each nut for removal (and of course repeat the process when you put the nuts back on).

With the half-shaft eased away from the differential flange bolts I could slide on a couple of shims, tighten it all back up and recheck the camber.  Except I couldn't because the hole pattern in my shims did not match the bolt pattern on my differential output flange; two of the holes matched up, but two were way out.

Cue much swearing...

In order not to waste the whole afternoon, I rummaged around in my box of leftover donor parts and found the two original (thick) half shaft spacers.  So I decided to install those just to try and get an idea of what thickness of shimming I was going to need.  After a frustrating and knuckle scraping afternoon of removing and reinstalling the half-shafts on both sides (several times), I had concluded that I was going to need around 4-4.5mm of shims on the offside and 7-7.5mm of shims on the nearside.

Later that afternoon I logged onto the SNG Barratt website to check out spacer options again.  This time I entered the VIN number for my donor vehicle and surprisingly the rear camber shims that I had already bought, did not come up as an option.  The only options were for the fixed-thickness spacers made of gold.  Clearly, I thought, the rear camber shims are for a different year model which has a different bolt pattern.

Annoyingly the spacers were also all on Special Order from SNG.  However, I found them in stock at Jaguar and Landrover Classic Parts.  I decided to order a 4mm and a 7mm spacer and then if necessary I could cut up the rear camber shims in such a way as to make one spacer out of two (or more) if additional thickness was needed.  BTW these two spacers cost over £100...

While I was waiting for the new spacers to arrive, I decided one evening to try and work out the best way to section up my original shims to try and make up a single shim from bits of others.  

It was then that my moment of stupidity hit me right between the eyes...

Why would they change the bolt pattern...

...Oh wait - they didn't...Doh!

Still...on the plus side, with needing nearly 12mm in total of shimming, I didn't have enough rear camber shims in any case plus its probably better to have a solid spacer rather than a large number of the thinner shims, particularly on the side needing nearly 8mm of shim (which would be 16 of the rear camber shims).

So maybe it has all worked out for the best!

Differential - Part 5 - We need to torque!

 There were a couple of small jobs that I needed to do to complete the installation of the rear differential.

The first was to cut down the 7/16UNF bolts securing the tie bars to the differential and the chassis.  The threaded length of these bolts is much greater than actually required and the protruding length looks a bit odd (to me anyway).

The second was to actually torque up all the various differential mounting bolts.  I didn't do this at the time of the original installation as, quite simply, I couldn't find the details for the necessary torque settings.

An offensive amount of bolt sticky-outedness...

I reckoned about 10mm off the end of the tie bar bolts should suffice.  Before cutting I wound a 7/16UNF die onto the bolt a) so that I could make sure the threads were intact after cutting and b) it made a handy brace to help support the bolts in the vice while cutting!

Die used to help keep bolt in place while cutting

I cut down the bolts with a hacksaw and then reinstalled them into the tie bar mounts, with a further liberal application of copper grease, adding a 7/16 washer on each end and 7/16UNF Nyloc nuts.  The final result was far more pleasing to my eye!

Much better - no unnecessary protrusion!

Now to finish tighten up all the differential mounting bolts.  You would have thought it would have been a relatively simple task to find all the necessary torque specifications, but oddly enough it took me a fair bit of searching before I was sure I had the right values.  This is complicated slightly by the fact that the AK mounting arrangement for the differential is of course not quite the same as the original Jaguar arrangement but my research was also hampered by the various Jaguar service manuals not calling any of the parts/bolt descriptions by anything remotely helpful!

I finally stumbled across a version of the Jaguar XJ40 Workshop Manual on the Jaguar UK forum.  This has a very handy series of diagrams at the front which show the various assemblies throughout the car and the necessary torque settings.  I almost missed this as I initially scrolled straight to the Final Drive Chapter (where of course everything was not called what I expected it to be).  Fortunately, I spotted this section as I was trying to refind the index!

The necessary specifications are as follows:

I was then able to finally tighten all the differential mounting bolts to the required specification and mark them as tightened with my favourite shade of blue nail varnish.

All torqued up and ready to go!