Couple of Minor Jobs - Part 1

 I had a few minor things that I needed to go back and sort out before I totally forgot them and it was too late!

The first was to set the front camber.  

I omitted to do this when I initially assembled the front suspension as a) ideally the front discs need to be installed as it gives a surface against which to measure the camber angle and b) because I didn't read the manual properly and didn't notice that it was something I needed to do!!  (setting front camber is only applicable to the AK Gen 3 chassis).

Unfortunately, the operation required some disassembly of the front suspension; namely the removal of the front shock absorbers so that the top wishbones could be set horizontal.  I also had to remove the front brake callipers to make access to the shock absorber mounting bolts and the upper ball joint mounting bolts slightly easier.

Once the top wishbones were set horizontal I placed a digital level vertically on the front face of the brake disc (handily my level is magnetic so it held itself in place!).  I then loosened the upper ball joint mounting bolts and then gently tapped the top of the axle upright so that I got an angle reading on my digital level of between 0.5 and 0.75 degrees negative camber (i.e. slightly inwards at the top).

I managed to get about 0.65/0.70 degrees on both sides.  I couldn't seem to get the angle to be any much less as the balljoint mounting bolts were at the extreme extent of the slots in the wishbones.  However, the readings were within the AK specified range so all was good.

0.65 degrees of negative camber achieved!

I could then retorque the balljoint mounting bolts and reinstall shock absorbers and retorque the mounting bolts (I needed to use new nuts for the shock absorber mounting bolts as the nylon inserts on the original one looked a bit chewed up upon removal).  Finally, the brake callipers could be reinstalled and I was right back to where I started around 90 minutes previously!!

As the front suspension is now officially completed, I rounded things off by installing the dust caps onto the front hubs.  As with many parts on this project that will never be seen, I had powder-coated them in my favourite shade of metallic red.  I put a slight smear of copper grease around the edge of this to facilitate future removal, should it be required, and then tapped the caps into place with a soft-faced mallet.

Nice shiny dust cap!

The second job was to replace the differential nose nuts.  These were M10x1.25 Nyloc nuts but when I had installed these and eventually torqued them to the correct specification, I was not happy with the extent of the studs protruding from the nuts.  They only just engaged with the nylon insert in the nuts and I was concerned that this was insufficient engagement to prevent the nuts from working loose during service.

Minimal engagement of stud within Nylon insert in nuts

My plan to overcome this concern was to safety-wire lock the nuts to prevent any possible loosening under vibration.  I had tried drilling the original Nyloc nuts to allow safety lock wire to pass through them.  I bought a jig which was supposed to hold the nuts and then facilitate the drilling of a 2mm diameter hole through two facets of the nuts.  This was next to useless, there was too much play in the assembly and in most cases, I just ended up drilling a slot across the corner of the nuts.

I managed to find some nuts which were pre-drilled for safety wire from RaceTi online.  These had the added advantage of being made from titanium so provided added lightness to the build!  

It was a fairly quick task to remove the old Nyloc nuts, replace them with the much lighter titanium items and then torque to the correct specification.  I then wire-locked these nuts in two pairs to prevent them from loosening using stainless steel safety lock wire.

M10x1.25 Titanium Nut - drilled for lockwire.  Photo courtesy of RaceTi

Typical Locking Arrangement for pair of bolts/nuts

The first pair of nuts safety wired...

...followed by the second pair. Job done!

With those items crossed off the list, I could get back onto the main build jobs!

Brakes - Part 2 - Front

I'm planning to run 16" rims on Project Snake so I went with the smaller option of the AK Big Brake Upgrade kits which is suitable for 15"-17" rims.  The kit includes two vented front discs (335mm diameter by 32mm thick), two bells for the front discs (discs and bells came pre-assembled), two 6-pot calipers for the front, and two 4-pot calipers for the rear. The kit uses the standard Jaguar rear discs.  I also elected to upgrade the brake pads supplied with the kit from EBC Green Stuff pads to Ferodo pads.

The front calipers are not a massive difference in size from the original Jag twin-pot items, althoigh they are a lot slimmer and in fact, the brake pads are practically the same size as the Jag originals.  However, with three pistons per side, the braking pressure will be more evenly applied to the pads (and to both pads) providing superior stopping power.  The other massive difference is in weight.  The original cast iron calipers weigh in at a hefty 5.2kg.  The AK items, being billet, are a svelt 1.9kg, which provides a huge benefit through the reduction in the unsprung mass of the car leading to better handling on the far-from-smooth UK roads!

Gratuitous Brake Porn...

Looks far more attractive than the original...

...with 3.3kg of added lightness and 6 pistons of (stopping) power!

New pads (bottom) are similar in size to the originals (top)

Original front disc dwarfed by new shiny monster disc!

The kit comes with some new brackets and bolts to fix onto the front uprights onto which the calipers are attached.  I fitted these and torqued up the mounting bolts to 100Nm/74ft-lb.  The new discs were placed over the studs on the front hubs and secured with a new retaining screw (P/N SF605047 from British Parts UK).

New caliper mounting block and bolts...

...installed onto front upright

Before installing the calipers, the brake pads need to be installed (technically this can be done later as the pads install from the outer side of the caliper).  This required removing two threaded pins, allowing the pads to be slid into place.  The pins and spring clip were then reinstalled, the caliper placed over the front disc and then secured to the mounting block with two Allen-headed bolts.

It is recommended that a smear of copper grease is applied to the rear of the brake pads to prevent brake squeal.  This is something I have made a note to do later.  I have not removed the protective coating from the brake discs yet as I don't want them to start flash rusting while I finish off the rest of the car.  So the calipers will need to come off again at some point.  For that reason, I also haven't torqued up the caliper mounting bolts to their final spec - 60Nm (44lb-ft).

Starting to look more like a proper car!!

 

Brakes - Part 1 - Decision Time

My original intentions for the brakes on Project Snake were always to refurbish and reuse the original brakes from the donor car.  As Jon at AK told me "if they are good enough to stop a 2.5tonne Jag, they're good enough for a 1.4tonne Cobra".

When I sourced the donor parts from Simply Performance, they suggested that getting the biggest brakes possible from the outset would be the best path to take.  I wanted vented discs on both the front and the rear and Ben at Simply Performance suggested using a car with the larger XJ twin-pot calipers at the front.  Seemed like a good suggestion at the time and that is what I went with.

So the brake discs and calipers I got with the donor vehicle are summarised below.

The eagle-eyed amongst you will spot that the rear disc diameter is larger than the front, which is unusual.  Usually, under heavy braking and weight transfer towards the front end of the car, it is the front brakes that do more work in bringing the car to a halt, and hence traditionally they are larger.  I assume that the use of the twin-pot caliper at the front provides enhanced braking performance over the larger disc / single-pot caliper arrangement at the rear and allows a slightly smaller disc to be used. But who knows what was in the mind of those engineers at Jaguar?

It seems however that those twin-pot front calipers are a bit of an enigma.  Whichever of the usual Jaguar part suppliers I looked at to try and find service parts for these calipers, they didn't seem to exist.  Even typing my donor car VIN number into various parts websites still kept on bringing up the single-pot caliper.

Twin-pot Front Caliper

Single Pot Rear Caliper

Disc Thickness (Thicker Front on Left)

Disc Diameter (Smaller Front on Left)

Front disc 10mm smaller diameter than Rear...?!

I contacted Ben at Simply Performance and he suggested that maybe if I measured the piston diameter in the caliper then I might be able to find suitable replacement piston/seal kits from another caliper option.  No joy there; the diameter of the twin-pot pistons is smaller than any of the other standard front (or rear) pistons in the various calipers over the years.

I did find a couple of places online that claimed to be able to refurbish the calipers, but given my failure to find any semblance of service parts for these unicorn calipers, I wasn't convinced.  I did eventually discover that Ward Engineering in Colchester, which is a specialist in the supply of reconditioned Jaguar axles and brakes, did offer a reconditioning service for the twin-pot calipers.  However, by then, my plans had taken a slight change.

Switching from an LS3 engine to an LS7 with close to 660hp got me thinking that, despite Jon's adage above, rapid and stable deceleration was going to be a top priority.  The oddity of the smaller diameter front discs compared to the rear on my donor vehicle was also starting to perturb me; I didn't want any unexpected twitchiness under heavy braking.

So when the UK taxman gave me a very unexpected but very well received tax rebate, my mind was made up.  It was time to buy an AK Big Brake Upgrade Kit!

Powder Coating Fest - Part 3

Having had some reasonably successful results powder coating various donor parts, using either satin black or gloss black powder, I thought it was time to funk things up a bit.

At the 2019 Stoneleigh Kit Car Show, I was looking at the various powder coat colours on the ElectroStaticMagic stand.  I had been contemplating coating a few pieces in either a candy blue or red which would be similar colours to the anodised aeroquip style hose fittings that we plan to use for plumbing Project Snake.

My original thought was to go for a blue candy colour but they didn't have any in stock at the Stoneleigh show so I went for candy red instead (always one for sticking to a plan).  The candy powder is applied over the High Gloss Chrome powder and I picked up 1/4kg of that at the same time.

The first pieces I decided to apply to funk treatment to were the front axle dust caps.  These got the usual wire brushing, sandblasting and Afterblast treatment prior to coating.

Dust Caps - after initial clean...

...after sand blasting

...and after application of Afterblast

The instructions for appying the candy powder coat require an initial coating with the High Chrome powder, which is then cured for 30mins at 180 degrees and then allowed to cool to ambient temperature.  The red candy powder is then applied over the High Chrome and cured for 10mins at 180 degrees.

The dust caps were given a once over with the Eastwood Prepaint Prep and a wipe over with a tack rag and then the High Chrome powder was applied.  This goes on as a flat medium grey colour.

High Chrome powder applied

These were then brought up to temperature in the oven and cured for the recommended 30mins.  The finish of the High Chrome is very good.  The powder cures to an almost chrome-like finish (as the name suggests....).  If leaving the parts as the Chrome finish it is recommended to gloss clear coat the parts to prevent the powder dulling with time.  I reckon this would give the parts a really good shine and, on a well-prepped surface (unlike my battered and bruised dust caps), I think at first glance it would be hard to differentiate the finish from a real chromed part.

Shiny Dust Caps - shame about the dimples...

I can see my face in this one!

Its like looking in a battered mirror....

Next step was to apply the red candy powder.  I did this the day after applying the High Chrome so obviously the parts had cooled completely.  I gave them another wipe over with Prepaint Prep and a tack rag and then tried to apply the red candy powder.  

Note the word 'tried'.  This proved quite tricky.  The second coat of powder didn't want to adhere to the parts at all.  I'm not sure whether I wasn't getting a good ground contact (because of the first coat), although I had scraped a bit of the coating off on the inside where I had placed the hanging/ground wire, but the powder went on in a very patchy manner and when I tried to fill in the gaps, the powder that had coated the part just seemed to blow off.

I ended up blowing all the powder off with an airgun, re-cleaning the parts and trying again.  The second time I turned the air pressure on the powder coating gun down a bit (to around 4psi) and trying to 'fog' the parts in powder.  This did achieve a better coverage (although not a very economic use of powder and everything in the garage now has a slight red tinge to it....) although care was still needed not to blow the powder off in places.

Eventually managed to get parts completely covered...

These were then popped in the oven at 180degrees / Gas mark 4 for 10mins after the parts had reached curing temperature.  I was quite pleased with the results.  The final colour is quite a deep red and so is more like the colour of 'Ruby' (the AK demonstrator that is current inspiration for this project) which is fine assuming we don't change our mind on the final colour!!

Close inspection of the final pieces did show some areas where the coating was a bit patchy, but only if you look closely (and the dust caps will eventually be hidden anyway - which begs the question why did I bother...).  

Freshly cured Candy Red dust caps...

Final result - some minor blemishes!!

Still, it was a good experiment for some parts which might be more visible and so buoyed by the initial success I attempted to powder coat the rear wishbone spacer tubes.

These needed a good session with the angle grinder and some flap wheels to clean off the surface pitting caused by my leaving them too long in a citric acid de-rusting bath previously.  After an intensive session with 40, 80 and then 120 grit flap wheels, the tubes cleaned up quite nicely.

After some flappy wheel treatment...

These then got a final sandblast, spray with Afterblast and a clean up before powder coating with the High Chrome.  As before these were cured at 180 degrees for 30mins.

Chrome coated spacer tubes

Having scoured the internet for some tips on applying the candy powders, I found a couple of tips on various forums, which suggested that, rather than trying to apply the candy powder to a cooled part, it should be preheated to around 65-75 degrees to aid adhesion of the second coat. 

This technique made a big difference and the candy powder seemed to adhere much more readily to the chrome coat, although there were some areas that needed a bit more persuasion than others. 

However, after curing and cooling, I was a bit disappointed with the results.  The candy coat was still quite thin and patchy in places and where I had obviously not managed to remove all the surface blemishes from the tubes with the grinder/flap wheel combo, the powder had concentrated around these giving some very obvious dark spots on the coating.

Patchy coating...

...and dark spots

I know these tubes (and the dust caps) will be hidden from sight once the car is finished, but I still want these bits to be the best finish that they can be.  So at some point soon, I will probably attempt to redo them all.

Powder Coating Fest! - Part 1

With the good weather at the end of May / beginning of June I was expecting to be able to get some more garage time and progress the build.  However my wife had other plans and I received a long list of jobs for the garden and around the house.....

Still I did manage to find some time to get a few of the donor parts powder coated ready to compete the front end build and commence fitting of the differential unit.

First part to be coated was the second front hub.  This was tackled in exactly the same manner as the first hub (Front Axle Part 5 - Front Hub Refurb), although the overall process went much quicker second time round now that I had a better idea of what I was doing!  As with the first hub, I needed to spend a couple of hours reblasting and cleaning up the hub to remove the flash rust that had formed after the first clean.  Thankfully this process was achieved without further personal injury!

Second hub coated in glossy black

Now I could turn my attention to some of the parts to allow me to start on the rear axle rebuild and installation of the diff.  First piece to be tackled was the wishbone tie. 

Followers of this blog will recall that I had to obtain a second wishbone tie as the original one was missing a couple of the bushes and that these particular bushes are not available as a replacement part.  I spent a lot of time cleaning up the original wishbone tie, as well as the replacement, and now the reason for that effort can be revealed!!

Since the bushes can not be replaced, I was worried about damaging them while pressing them out to enable the wishbone tie to be powder coated.  I was also concerned that trying to powder coat the wishbone tie with the bushes in-situ would result in the bushes melting during the curing process!  Jon at AK had assured me that I could powder coat with the bushes in place, but I was still a bit nervous and decided to do a trial run on the original tie.

I followed the same process as for the hubs, pre-heat to "degas", degrease and clean, coat and cure.  The test was pretty successful although as a result I did make a few adjustments to the process.

Wishbone Tie - test

The wishbone tie is a pretty substantial lump of metal and during curing took around 50 minutes for the surface to get up to temperature.  Although the bushes didn't melt as I had feared, during the pre-bake and curing there was a pretty distinct smell of hot rubber; as result, for the actual tie, I lowered the temperature for the pre-bake to 200 degrees C and used Satin Black powder from ElectrostaticMagic which only requires 10 minute curing time at the lower temperature of 180 degrees C.  

Wishbone Tie - Final Result

Wishbone Tie - close-up of finish

Next up was the rear pendulum bracket - another substantial chunk of metal casting!  Although I have obtained new bushes for this part, I coated it with the satin black powder to match the wishbone tie.  In fact I did all the parts for the rear diff in satin black.  The process for all these parts was as previously described.

More sweeping of the drive required...

Pendulum after blasting and cleaning

Powder coated and reading for curing

Fresh out of the oven..

After cooling and removal of masking tape

Close-up of finish

Next up was the rear diff mounting bracket and the compliance buffers (which for the PowerLok differential are solid metal spacers as opposed to the rubber ones for the normal differential units).  The donor rear bracket was quite corroded and very pitted in places.  It needed some considerable work with the sand blaster, the angle grinder / flappy wheel combo and a dremel to get it cleaned up.  I still couldn't quite remove all the pitting though and final finish was not as great as I would have hoped.

Rear Bracket after some initial grinder / flappy wheel action...

Pitting needed a lot of grinding to remove...

After blasting and some treatment with the angry end of the Dremel

Coated parts for rear diff mounting

Some pitting still visible on final coated bracket

So with all those parts coated I am now in a position to finish off the front hubs and start mounting the rear differential.  Just need a wet weekend now then....