Differential - Part 2 - Being Granted Two Wish(bones)....

With the differential unit in place, next on the list was to install the rear wishbone tie. A simple task from looking at the AK Build Manual.  Well...not quite!

First up was to install the donor mounting bracket, which is simply slid over the main rear differential bolts.

Wishbone tie (top), Mounting Bracket (middle) and Compliance Buffers (bottom)

Mounting bracket installed...

I then applied copper grease liberally to the main rear diff bolts and installed the inner compliance buffers (the ones with the big hole which fits over the main bolts); these are installed with the flat edge towards the outside of the chassis.

Inboard Compliance Buffers installed...

All nice and straightforward so far!

Next on was the wishbone tie; this is installed with the side marked "Jaguar" facing towards the rear of the chassis.

Wishbone tie in place - I see a problem looming...

The outer compliance buffers are then installed again with the flat edge facing outwards.

Hang on!  There's no thread of main rear diff bolts protruding out of the assembly to get the M12 Nylocs onto! WTF!!

Bugger...!

After much head-scratching, drinking of tea, internet research, taking it all apart and reassembling (hoping for a different result), and a teeny bit of swearing, I was none the wiser and I still had no protruding thread onto which to attach a nut...

The problem it seemed was simple; the flange on the back of my compliance buffers seemed to be too thick/big to allow the buffer to sit tightly against the wishbone tie.

This doesn't look right...

Then I remembered something fellow builder Richard had said to me when he was round and I had shown him some of my first attempts at powder coating; which happened to me a couple of the metal compliance buffers.  Richard had said that his buffers/spacers were completely different; they were rubber with a metal insert.

So I had a closer look at the AK Build Manual and the buffers/spacers in the photo in the manual looked completely different from mine.

These are not my spacers! - Photo courtesy of AK Sportscars Ltd

Then I had a lightning bolt moment and I dug out the original wishbone tie that I had received from Simply Performance with my donor axles; remember the one that I had assumed was missing the inner bushes.

Well, guess what - the flange on the back of my metal buffers/spacers seated exactly into the recess in the wishbone tie where the inner bushes should have been fitted.

Fits like a glass slipper!

A quick email to Jon at AK and he confirmed that some of the Jag rear ends did come with a solidly mounted wishbone tie.  So it was a good job I kept the original wishbone tie and even better, I had decided to powder coat it as well! (Although the finish was not as good as the tie that I thought I was using - so I might need to consider recoating it at some point).

Armed with that knowledge, I tried reassembly with the original wishbone tie, and this time it all went together beautifully and I ended up with a goodly amount of thread from the main rear diff bolts sticking out to get the M12 Nylocs and washers onto.

Looking more promising...

Result!

So after several hours attempting a job that should literally have taken five minutes, I need a lie down...or a beer...or both!

Differential - Part 1 - Differential Equations

Having done as much as I can do for the time being on the front end build, it was time to start on the rear end build.

The first task was to press some new bushes into the newly powder-coated pendulum bracket.  The replacement bushes were ordered from SNG Barratt as follows:

More bits courtesy of SNG Barratt

To (hopefully) make the installation a little easier I left the pendulum bracket out in the sun for an hour or two to warm up nicely and put the new bushes in the freezer for a few hours.

Bushes and chips for tea?

I lightly greased the bush housings in the pendulum with copper grease and then pressed the new (cold) bushes into place using my 12T press and a suitably sized impact socket as a drift.  Note that one side of the bush housings on the pendulum has a bevelled edge which helps hold the new bush in position and guides it into the housing when starting to press it in.

Greased bore - note bevelled edge to ease bush insertion...

Pressing bushes into place

All bushes replaced

Next, it was time to unbox the rear differential unit.  The diff is a Salisbury Power Lock (limited-slip) unit with a 3.58 final ratio.  This was fully refurbished by Simply Performance when I purchased the donor axles and has sat in a large box occupying a large space on my garage floor ever since.  The unit is also bloody heavy and I needed some help from Sam to lift it out of the box and onto the cup of my 3T trolley jack.

Shiny refurbished differential unit

The pendulum bracket is then fitted over the nose of the differential with the side marked "Jaguar" facing towards the front of the car.  The upper bushes of the bracket slide onto the shafts at the front of the diff; these had a generous application of copper grease prior to installation.

Pendulum Bracket in place

The rear upper differential bolts are M12 by 70 bolts which are supplied by AK, with M12 washers to sit under the bolt head and 35mm by 14mm washers which are used as spacers between the diff and the chassis.  I assume the 35mm diameter washers are supposed to fit into the recesses on the top of the diff unit but mine did not seem to sit properly and allow the M12 to pass through so I ended up having to flat off the bottom of the washers on the bench grinder.

Rear Diff Bolts and Spacer Washers - Photo courtesy of AK Sportscars Build Manual

"Modified" Spacer Washers

With some careful (skilful?) control of the jack, I managed to raise the differential unit up and slide it forward into position relatively easily (just remember to rotate the input yoke on the diff so that it passes through the aperture in the chassis first).

Then it was just a case of securing all the fasteners (M10x1.25 nuts on the diff nose studs, M16 Nylocs with 1.25" by 5/8" washers on the front diff studs and M12 Nylocs and M12 washers on the rear diff bolts) to hold the diff in place and allow removal of the jack.

Differential installed!

I haven't fully torqued up any of the fasteners at this stage, mainly as I haven't worked out which are the correct settings from the Jaguar XJ40 Haynes Manual yet.  However, from reading Richard's blog and the trouble he had getting the differential tie bar into place, I figured leaving the diff fasteners not fully tightened might allow some play to get the diff tie bars fitted.

Watch this space!

Front Axle Part 6 - Finally getting to the Hub of the matter...

I finally managed to find some time to make some progress on the actually build last weekend with the re-assembly and fitment of the front hubs.

I'd previously placed another order with SNG Barratt for the service parts needed as shown below.

Contents of Wheel Bearing Kit from SNG

Prior to attempting to install the new bearings I gave the hubs a final clean out to get rid of any final remnants of sand from the blasting prior to powder coating.  I read on the internet about masking off bearing recesses etc when sand blasting to avoid any contamination with blasting media.  Unfortunately I read that after I had sand blasted my hubs......And sure enough there were some traces of sand clinging to the cast areas in the middle of the hubs.  A final clean-out with some cotton buds soaked in WD40 and a blow out with the airgun and I think (hope) I managed to remove all traces of grit / sand that might lead to a very short bearing life!!

Cleaned out and grit free....(fingers crossed)

I recycled the old bearing races to use a drifts to assist in installing the new races.  Firstly I cut a slot in the old races using an angle grinder with a cutting disk so that the old races wouldn't get stuck in the bearing recesses - the slot allows the old race to be compressed slightly so it can be pulled out easily.

Old bearing races modified to assist with installation of new races

It was then a simple task of seating the new races into their respective housings and using the old race and a large hammer to gently tap the races into the hub until they were fully seated.

Inboard race prior to any gentle tapping....

Modified bearing drift...

Finally got the boy off the X-box to help out!

Inboard race fully installed and seated...

....followed by outboard bearing race.

With races installed it's time to get greasy!  Armed with a tub of high performance bearing grease and a large box of disposable gloves I set about packing the central part of the wheel hubs between the two bearing races with grease making sure I got plenty of grease in and any large air pockets out! 

Grease - does exactly what it says on the tin....

Having formed a large grease "dam" behind the bearing races, I packed the inboard roller bearings with grease, making sure to get all the spaces in the bearing cage as full of grease as I could manage.  The inboard bearings are then placed in their bearing races and the outer grease seals pressed into place (I used a large block of wood and the large hammer to press the seals in fully).

Hub cavity packed with grease

Inboard bearing cage greased and in place

The stub axle on the front uprights then got a generous coating of grease as well and then the hubs can be slid onto the stub axles.

A well lubricated shaft........(sorry...)

The outboard bearings were then packed with grease as above and pushed into their bearing races.  The D-washers from the original donor car were then placed over the end of the stub axle and a new locknut screwed onto the end.

Outboard bearing race inserted in place

D-washer and lock nut in place

The recommended procedure is then to tighten the locknut to 16Nm / 12 ft-lbs to seat the hub onto the stub axle and then while rotating the hub assembly in the forward direction tighten further to 27Nm / 20 ft-lbs.  The locknut is then slackened off half a turn and then retightened hand tight only.  The assembly was finished off with a new locknut retainer and split pin.

All torqued up with new nut retainer and lockpin installed

That's the front end finished for the moment, pending installation of the brakes.  Time for some rear end action now!

Completed hub assembly

Stoneleigh Kit Car Show - 2019

My son and I  took a quick trip up to Stoneleigh for the National Kit Car Show over the first May bank holiday weekend.

The last year seems to have zipped by; at last year's show we were still doing research before buying our cobra kit and now we are on the early stages of the build.

The show was much busier than last year and it was good to see the AK stand getting lots of visitors!

The main purpose of the visit was to get some thoughts and ideas around future details of the build; colours, dashboard layouts, lights, wheels etc etc.

Unfortunately the visit opened up some very clear differences between my son and I!  I am tending towards quick-lift jacks rather than over-riders, he is thinking full bumpers and over-riders.  I wanted a classic wooden steering wheel, he wants a modern black wheel.  I was thinking classic gauges in the cockpit, he found some horrible digital colour changing gauges (no way!).

It's a good job we have plenty of time before having to make some of these choices!!!!

Lights....modern?...

...or classic P700 style...?

Classic oxblood cockpit...

Nice grey leather cockpit...

Or black...?  (No wooden steering wheels in sight!!)

We also had a good wander through the trade stands and picked up some essentials including some abrasive disks, a new set of automatic wire-strippers, a new sign for the garage, some more powder-coating powder and a TIG welder.  OK the TIG welder wasn't an essential but I am a sucker for a bargain and it was a show special, half price at £100!

Retail therapy....

Of course the welder turned out to maybe not such a bargain after all and when I got it home and opened it up it has a strange blue plug on the end of the power lead.  Apparently they don't fit a standard 13A socket......and it requires a 32A supply.....and my garage only has a 16A supply.......

Oh well - time to call the electrician!!

Can't get that into a normal socket!!!

Front Axle Part 5 - Front Hub Refurb

In between the fun and games of assembling the front suspension, I have been pressing on with cleaning up the front hubs ready for reassembly.

First step was a good clean-up with a nylon brush and a bucket of Gunk degreaser to remove all the loose crud and old grease from inside the hubs.

Step 1 - Degreasing

This was given a rinse off with water, dried off with a towel and then to prevent any (further) flash rusting of the machined surfaces, I put the hubs in the oven for 30mins to dry off any last traces of water.

Dinner doesn't look very appetising....

I then set to work with a variety of steel wire brushes in a rotary drill.  I bought a couple of twist knotted steel wire brushes from Screwfix which were very effective at removing a lot of the surface rust.

HEALTH AND SAFETY TIP 1 - again an obvious one, but when using wire brushes in power tools, always ensure the work piece is secured in a vice or work bench and keep two hands on the power tool (especially if the trigger lock is on).  If you hold the work piece with one hand, there is a danger that the brush can snag on part of the work piece and kick back onto the hand holding the piece.  I was wearing gloves but the twisted knot brush still managed to give the end of my thumb a good stinging!

Steel Brush 1 - Glove 0

After a good session with the wire brushes, the hubs had cleaned up quite nicely.

After wire brushing

There was still quite a lot of rust engrained in the cast surface, especially on the back face of the hub, so I broke out the Budget Blaster and spent a couple more hours cleaning up the hubs.  Have to say I was very happy with the results.

Blasted vs Brushed

Unfortunately I left the hubs for a couple of weeks between sand blasting and coating and when I went back to them a fair amount of surface rust had reappeared.  I assume there must be some salt residue in the sand I used for the cleaning process that reacted with the freshly cleaned metal surface which caused this (I have other parts that have been cleaned up / polished with wire brush and flap wheels alone that have not shown any further signs of rusting over the same period).  Still another going over with the wire brush and another couple of hours on the sand blaster got them back to their prior glory!

HEALTH AND SAFETY TIP 2 - never ignore your previous health and safety advice.  Rather stupidly I did the same thing again but this time was not so lucky with the wire brush catching on my glove and running up my arm until it found some bare skin to abrade....

Come back - its only a flesh wound..!!

Having re-cleaned both the hubs it was time to have a go at powder coating them!

For cast parts, particularly cast iron and aluminium parts, it is recommended to preheat the parts prior to coating to "outgas" or "degas" them.  The cast surface  can trap contaminants which, when heated, "outgas" and can cause porosity problems or lack of adhesion to coatings.

Firstly I masked off all the bits of the hub that I did not want to coat using high temperature masking tape.  The hub was then suspended from the oven shelf from my "specialist powder coating oven" using stainless steel wire wrapped around a couple of the wheel studs and secured with a couple of old nuts.

Masking Tape Applied...

Suspended from oven shelf (Note Project Powdercoating Stand in use)

The hubs were then put in the oven at around 230 degrees C for 30-40 mins before being removed and allowed to cool.  I then gave the hubs a good clean with Eastwood PrePrep to remove any last traces of grease and contaminants, gave them a final wipeover with a tack-rag and let them dry for few minutes.

Then it was time to powder coat!

The oven was preheated to 230 degrees C.  I hooked the powder coating gun up to my compressor, with the regulator set to around 6-7psi at free flow.  The ground clip from the powder coating gun was clipped to the hub and I attached a pot of gloss black powder to the gun.

As it was quite a still day, I risked attempting to coat the hubs outside.  Generally this worked OK, although the powder is very fine and even the slightest breeze would make coating very difficult.  The theory is that the powder coating gun kit provides a static charge to the powder within the gun with the effect that the charged powder is attracted to the grounded part that you are coating.

Theory seemed to be correct and I managed to coat most of hub quite quickly with a good covering of powder.  It can be difficult to get powder into intricate shapes and recesses due to something called the Faraday Cage effect (one for the electro physicists reading....) which causes some issues with the charged powder getting into these areas.  I had a couple of issues particularly with the ABS ring on the rear of the hub and some of the areas on the rear of the wheel studs.  I managed to get powder onto these by removing the deflector from the end of the gun and "misting" the area at a slightly lower air pressure.

Powder coated and ready for curing..

With the hub coated it was time to gently place it into the oven (without knocking any of the powder off) to be cured.  Once hub was in oven the temperature was turned down to 200 degrees C (which is the curing temperature for the gloss black I was using - different powders have different curing temperatures and times).

As the part starts to heat up, the powder starts to flow out - that is you can start to see it changing from the matt powder to a glossy finish.  After the powder has flowed out across the whole part, that is the point at which the curing time is started.

The hubs being quite a large and heavy part took quite some time to heat up to the point where the powder had glossed over everywhere - around 30 minutes.  This was not helped by the oven that I have bought only having the option to use the top heating element or the bottom element individually and not both at the same time - hence when using the top element (as I was), the top surface of the hub had started to flow out, well before the bottom surface had.

Top of hub has started to flow out (glossy) while bottom is still slightly matt

When the powder had flowed out across the whole hub, the timer was set for 20 minutes after which it was removed from the oven and left to cool

Freshly cooked hub....

Once the hub had fully cooled, I unhooked it from the oven shelf and removed all traces of the masking tape.  To prevent any further rusting before fitting the hubs to the stub axles, I gave all the exposed metal surfaces a wipe with some WD40 which will hopefully protect them.

Have to say I am actually pretty pleased with the results.  

Back face of powder coated hub....

....and the front face