Set Blasters to stun.....

Armed with my trusty Budget Blaster Mk2, I had been making good progress with cleaning and prepping many of the donor car parts for powder coating.

However, the change of my blasting media of choice from kiln-dried sand to aluminium oxide soon identified a major issue.  

The aluminium oxide media is far more abrasive than the sand; so abrasive that it actually blew its way through the nozzle of Budget Blaster.  I was starting to notice that it was taking a bit longer to clean off one of the rear hubs and then I spotted the hole in the nozzle...

The additional hole does not improve performance.....

OK I thought, I've managed to do quite a lot of sand blasting with the original nozzle so I'll just order another set of nozzles from a well-known mail-order company that offers next day delivery and that should see me set for a bit longer.  In the meantime, I'll just revert to Budget Blaster Mk1.

A great plan....for less than 5 minutes, by which time Budget Blaster Mk1 had bitten the dust as well.

RIP Budget Blaster Mk1...

Clearly, the nozzles were not going to survive very long with the aluminium oxide media and so I cancelled the order for another set of cheap nozzles and contemplated Plan B.

Plan B involved the purchase of a Clarke SB3 Grit Blasting Gun, the main lure of which was it came with a hardened steel nozzle!  There were fairly mixed reviews of this on the internet, but for £20 I was prepared to give it a go.

Clarke SB3 Grit Blast Gun - photo courtesy of MachineMart

Some of the reviews cited issues with media delivery and volume of media used.  I found one review that said to ensure the delivery tube was fixed facing forwards and to angle the gun downwards in use - which I did and had no problems in use.

However, the speed at which the gun uses blasting media is quite high.  The pot takes has a litre capacity so around 1-1.5kg of media.  My initial experiments with the gun managed to empty a full pot in a couple of minutes.  The results were impressive but clearly, some means of capturing and recycling blast media would be required otherwise 25kg was not going to last very long!

My solution was to buy a large tarpaulin and a cheap gazebo with sides, from the well-known internet auction site, to make a supersize blasting 'cabinet' by laying the tarpaulin on the floor and sitting the gazebo on top.  The theory being that the gazebo would help to contain the excess blast media and this could be swept off the tarpaulin and reused.

For the first full-scale test of this set-up, I reverted to using the kiln-dried sand since a) the damp bag that I bought previously had now dried out a bit and b) if the set-up failed I was only wasting a £3 bag of sand rather than expensive aluminium oxide.  

I have to say the results using the SB3 gun and sand were pretty amazing.  The gun is pretty effective and I managed to strip and clean some of the rear axle parts in less than 30 minutes.  It does go through the media at a phenomenal rate!  But the tarpaulin/gazebo combo did a reasonable job of containing the excess media and with some frequent sweeping up, I did manage to recycle a fair amount of the sand and finished with almost as much as I had started with!

Lifes a Beach - After 5 minutes of blasting...

Initial results...

A quick blast with the aluminium oxide should see these parts finished and ready for powder coating.

So a big thumbs up for Plan B (although unfortunately, the 'B' does not stand for budget...)

Differential - Part 3 - I'm a bit tied up at the moment

With the differential fitted and the problems with fitting the wishbone tie resolved, I decided to deviate slightly from the AK build manual instructions.

Rather than press on with installing the rear wishbones and hubs (well my hubs aren't ready in any case), I decided to install the rear differential tie bars.  I had seen from Richard's blog post that he had had some fun and games getting these fitted and I figured it would be easier without all the extra weight of the drivetrain if things needed to be jiggled about!

The AK-supplied tie bars are fixed between two chassis lugs and the upstand flanges on the wishbone tie; one on each side of the chassis.

I offered up the tie bars to the chassis lugs but despite trying both ends of both bars, they did not fit between the lugs.  I find this a bit surprising really; as the tie bars are supplied by AK and the lugs on the chassis are welded on by AK, I would expect the fit to be a bit better.  The difference is more than the thickness of the powder coat and would require some metal removal to allow bushings on tie bar end to fit between the lugs.

Nope - that isn't going to fit!

The simple solution used by many others to this issue has been to reach for the file and file down the ends of the tie bar bushing to fit.  But I don't like removing metal unnecessarily so I went for a different approach.

My plan was to ease the chassis lugs apart very slightly to allow the end of the tie bar to fit between them.  This was achieved using a long bolt passed through the chassis lugs with two nuts installed in between the lugs (with washers under the nuts to protect the powder coat).  Using a couple of spanners to tighten one nut and back off the other, this has the effect of spreading the lugs apart very slightly (I did this very carefully as I didn't want to bend the lugs, just ease them apart).

The patented Acme lug-spreader tool...

I am pleased to say that this actually worked!  Using this approach I managed to spread the lugs sufficiently to be able to tap the end of the tie bar in between the lugs - obviously, the presence of the bolt meant that it only just sat between the lugs.  Then it was a case of gently undoing the nuts on the make-shift lug spreader tool, without disturbing the tie bar.  Then the tie-bar could be gently tapped fully into the lugs and centred over the bolt hole.  To make sure these didn't slip out of position while fixing the differential ends I passed one of the AK-supplied 7/16" by 3" fixing bolts through each of the chassis mounts.

Using this approach I had the chassis ends of both tie bars installed in under an hour - result!

The other ends were much easier, in that the ends of both tie bars fitted between the upstand flanges on the wishbone tie - although the holes did not line up perfectly.  This was easily rectified by loosening the mounting bolts of the wishbone tie which gave enough play to allow the bolt holes to line up.  Again I passed a 7/16" by 3" bolt through each of the holes to hold it in place and tightened the wishbone tie bolts back up again.

First tie bar in place....

....both bars in place

After the fun and games I had had with fixing the wishbone tie, it was good to have a job that I was expecting to take some time only take a couple of hours!

I haven't yet tightened up all the nuts and bolts a) because I need to try and work out from the Haynes manual what all the relevant torque settings are, and b) in case I need to loosen any bits off again to facilitate installation of the rear wishbones and hubs.

I will also probably attempt to re-coat the wishbone tie; since I originally thought this was going to be a spare and I used it for my initial attempts at powder coating, there are some areas that are a bit patchy and thin.  Being the perfectionist that I am I want to get a better finish on this piece - it won't be seen (hidden behind the fuel tank) but I want to minimise the chances of any corrosion developing in future.

I will also probably replace the AK-supplied tie bar mounting bolts with some shorter ones; AK provides 3" long bolts which leaves a significant amount of protruding thread.  I reckon a 2 1/2" or even a 2 1/4" long bolt will look neater.

Now I need to crack on with cleaning up the rear hubs...

Engine Ordered!

So it appears I have just put down a deposit for my engine!


My plan for the engine is to use a Chevrolet LS3 engine with a Tremec TKO600 transmission. 

My original thought was to buy the engine and gearbox as a complete package from Brian at Roadcraft UK Ltd.  Brian had given me a quote based on the 430hp version of the GM LS3 Crate Engine with all ancillaries and ECU.

I would have preferred the 525hp version of the LS3 Crate Engine, but from reading on the various internet forums it seems there is no chance of this engine passing the IVA emissions test.

At the end of last year another AK Cobra Builder, Barry Boughton, had contacted me after reading my blog.  He recommended the name of a guy, Kyle Rushall, who had built his LS7 engine and also apparently built the engines for Apple and Rufus, the AK Demonstrator vehicles.  I've been in Apple and I can testify to the power the engine in that beast puts out!

Turns out that Kyle used to work at Tim Adams Racing Engines and has built quite a few engines for the Cobra community.  He is now working on his own and building engines for the GT and Drift scene amongst others.  

I made a mental note to drop him a line, but figured that getting a bespoke engine built was always going to be more expensive than buying a crate engine package and never really got round to it. Besides I was planning on spending the rest of 2019 getting the rolling chassis completed and didn't think I would be in a position to need the engine/transmission until early 2020 at best.

Anyway a few weeks ago I saw an advert on Fleabay for an LS7 engine; the price was out of my range but the seller was also offering LS3 engines.  I sent a message asking for prices and it turned out the seller was none other than Kyle Rushall himself!  

He suggested I give him a call to discuss options, which I did and we had a good chat through things.  Turns out he has built a few LS3 engines for Cobra builders now; the last one made over 560hp and passed the IVA test! Not only that but the price he quoted was not a million miles away from what Roadcraft UK was quoting.

Unfortunately, Kyle only has two LS3 cores left and is not expecting to get any more until late 2020.  So after some brief (?!) negotiating with my better half, I have altered by budget plans and put down a deposit to secure one of the remaining cores.

 

The specification for my AK LS3 550 includes

 

• LS3 Pistons - hot washed and checked
• Mahle High Performance Piston Rings
• Custom Camshaft (not too aggressive grind - but guaranteed to pass IVA / MOT)
• Competition Cams reduced travel Hydraulic Lifters
• Competition Cams Rocker Trunnion Upgrade (with needle roller bearings)
• LS3 Conrods
• ARP High Performance Big End Bolts
• Clevite Big End Bearings
• Clevite Mains Bearings
• MLS Head Gaskets
• Double Valve Springs
• Melling Oil Pump
• Uprated Water Pump
• New Front Damper
• New F-body Oil Pan (to fit AK Chassis)
• New LS3 Intake with 42 lb per hour Injectors
• One Piece Manley Pushrods
• New Gaskets
• New Sensors
• New Oil Seals
• Fly-by-Wire Throttle Body
• Custom Corvette Front End (Power Steering Pump, Alternator, Idler and Custom Tensioner)
• Canems ECU and Wiring Loom
• Dyno Run and Set-up

 

Kyle is a busy man and engine won't be ready until later this year, which is fine for me as I still have a way to go to get rolling chassis completed.

I'll have one of those please! (Photo courtesy of Kyle Rushall)

 

 

 

 

 

 

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....

Powder Coating Fest - Part 2

In between getting on with the assembly of the front and rear axles, I have been continuing to clean and powder coat many of the donor parts in readiness for reassembly.

The budget sandblaster has been busy - now powered by my new 3hp /100-litre air compressor, which was a present to myself for a recent major milestone birthday.

Bigger is better!

I also have also tried out some different blasting media.  

I was quite happy with the results using the Wickes Kiln Dried Sand; well at least with the first bag I had bought.  When I bought the second bag, the sand was more like builders sand, quite soft and slightly damp, and just clogged in the nozzle of the blaster.

So I splashed out on 25kg of Fine Glass Grit from Amazon and 25kg of Fine Aluminium Oxide from Frost.

I have had some great results with the aluminium oxide.  It strips paint, rust and clag off in next to no time.  It's far more brutal than the sand, both on the metal parts and on exposed skin!  

Aluminium Oxide blasting media

The glass grit is a more gentle blasting media and is good for removing light rust and cleaning up the machined surfaces of some of the donor parts.

Fine Glass Grit blasting media

HEALTH AND SAFETY TIP - As with the sand it is important to wear eye protection but I found it necessary to upgrade to a full set of enclosed safety goggles (after learning the hard way that aluminium oxide grit is very sharp and will find its way into your eyes while just wearing an ordinary pair of safety glasses).  Also with both the aluminium oxide and glass grit, I would recommend a good quality dust mask; both media have a lot of very fine particles which I have no doubt are not good for the respiratory passages.

The pictures below show one of the rear stub axles before and after blasting.  The aluminium oxide cleaned off all the old paint in less than 10 minutes (the kiln dried sand would have taken over an hour) and then I used the glass grit to clean up the splined shaft and threaded end of the shaft.

Prior to a good gunking!

Post gunk...(zip ties used to identify parts from offside driveshaft)

After 20 mins of the budget blaster with Aluminium Oxide / Glass Grit media

After my problems with the front hubs and the development of further rust/corrosion between blasting and powder coating, I decided to try out Eastwood's After Blast Metal Prep.  

A gallon of SlartyAfterBlast...

This stuff is supposed to clean and degrease freshly blasted metal and also contains phosphoric acid to etch the metal surface and leave a zinc phosphate coating to prevent flash rusting and give a good surface to aid adhesion of paint or powder coat.  It's not cheap, at £45 a gallon from Frost, but if it does the job and saves me sandblasting everything twice, then I guess it will be worth it.

I bought a cheap spray bottle and used it to spray the parts with the After Blast.  The instructions say to leave it for 2-5mins and then to wipe off with a clean cloth to remove any excess contaminants and excess spray.

The inboard Drive Shaft Saddle after After Blast treatment...

A couple of tips for using this stuff:

1) Do make sure any excess liquid is wiped off - if it's allowed to sit on the part it  develops into large blobs of zinc phosphate coating

2) Avoid machined surfaces - since the spray etches the surface of the metal you want to avoid getting any spray on these surfaces and it will change the surface texture (i.e it's no longer smooth and machined!)

I made these mistakes the first time round on one of the inboard driveshaft saddles and ended up having to clean up the areas with a brass wire wheel in the angry end of the drill.

But the stuff does seem to work - I blasted the inboard driveshaft saddle a couple of weeks ago and no further rusting / corrosion had developed by the time I got round to powder coating.

Below are a few pictures of various parts in preparation and after powder coating.  

Rear Hub and Stub Axle prior to blasting

The backside of the Rear Hub after blasting...

...And the front face

Hub getting an After Blast bath (avoiding the machined surfaces)

Inboard Driveshaft Saddle fresh out of the oven

Freshly coated Hub and Drive Shaft ends

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!