Heater Box

Got round to installing the heater box into the battery compartment- its all a bit tight but I do like the way all the space is utilised – makes for a really tidy installation. Disassemble the heater box and added a few M6 rivnuts for easy assembly  I fixed a bit of neoprene foam to the face of the heater panel before bolting up. Installation is no easy project.

I have also found that the outlet pipes do not line up with the holes I predrilled in the inner wing using the marks left by GD… Benefit of hindsight here, I wish I had not drilled these particular holes until I had trial fit the box, small matter I guess the pipes are going to come through a slot rather than a hole. With trial and error I found it necessary to fit the little elbow rubber pipe to the heater box “before installation”(after slightly shortening one leg) since it proved impossible to get at the bottom jubilee clip if you put the box in first. I cut both flanges off the face of the box since they also hinder installation and are unnecessary once you fit the rivnuts in the face. Some people recommend taking the motor off before assembly this may have helped but I found it would just go in without it off – once its tightly in place there is only approx. 20mm of space between the motor and the forward bulkhead.

The picture on the left is taken with a torch looking up to show how tight the fit is, since when trying to install the box whilst fully assembled, the two air outlets protrude about 40mm on the opposite face so it is necessary to get these into alignment (ie in their respective holes) as you roll the heater box assembly in place – otherwise the suggestion of removing the motor first may be a better option.

Side Vents

I have looked at a lot of Cobra Replicas and one of the features that always left me a little underwhelmed was the side vents. At the Stoneleigh show earlier this year I was interested to look around at all the variations of the side vents utilised by the different manufacturers. Some looked better than others but I felt they all looked a little thin and false. Others I am sure will love the look of the folded laser cut but to me it was just a little too obvious. One car that I thought stood out in the side vent department here was the demonstrator from XCS.xcs_427_side_vent_img_9593_optimized

I wasn’t convinced about the width of the louvers they seem a little large using only three blades instead of the more conventional 4 or 5? but I did like the craftsmanship and they looked as though they had been designed and installed for a high end sports car …. yes I was inspired ( Ok my wife thinks I’m sad ). Onwards with that inspiration I’m going to stick with a similar design but leave it at 5 blades as well as incorporating a slight curve on the blades…. After quite a few hours playing with paper cut-outs I’m finally in aluminium

fabrication and almost there. My final vents are going to be Red……    or maybe Black. Still undecided on final livery and theme but I’m happy with the shape, they will bolt through as the final version will have studs welded  in place of the 4 small holes on the rear corners. Red or Black??

 

 

 

Pedal Box

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Ive decided to make a new pedal box that carries the standard GM throttle pedal in normal location ie.  alongside the brake. The picture above shows the Standard GM fly by wire throttle (to the right) with its mounting bracket (middle) removed. The new throttle pedal frame (to the left) will accommodate the ls3 or any standard GM throttle pedal.

Getting everything dialled in geometrically was the main challenge here. Andy was kind enough to loan me one of the castings he presently uses as a starting point. Ive made quite a few changes including moving the pedal pivot point further towards the driver to minimise the thickness of the spacers needed on the rear of the bulkhead.C:UsersmkbulDesktopMarks COBRApedal boxPedal Box profiles

I also plan to cut in a footwell extension box on the accelerator side of the inner wing – similar to the engine side footwell extension molding provided by GD, but for the opposite side. I cut an area out with a hole saw just to the right of where the throttle pedal will be, then removed the foam inner wing filling and realised there is an extra 40mm of width to be gained here! more if I do the extension box in Aluminium and leave it without carpet. Ill get this new footwell extension fabricated over the next week or so and get some pictures taken. That will give me a generous 360mm across the footwell in the pedal area, which is pretty good and

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First prototype, I’ve incorporated some adjustment at the pedals for angle height and offset, and there is adjustment on the GM pedal. Think I’ll make some stainless steel pedals next week, more pics to follow. I want to get the pedal box installed soon so I can get the body back on and make progress with the power steering.

After a couple of modifications… Final Model

 

A few changes but Im finally happy with the whole box. I have made the actual pedal faces removable so I can modify this part easily once installed, which will allow a bit of fine tuning of the pedal geometry without the need to remove the majority of the pedal box from the car.Before I fit the pedal box I have to decide what to do with the cut out in the right side of the footwell.

This sequence of photos shows the cut out in right hand of footwell and the 40mm extra width that can be achieved by this butchery! The final photo shows the cut out glassed back in – I used some West System Epoxy resin and glass sheet to overlap the edges then coated with a black pigment resin gelcoat (or flowcoat). This way the structural integrity of this side panel is probably improved rather than weakened. I did consider making a fabricated panel to fit into the cutout but in the end i think the glass-up is the better solution. once it dries tomorrow ill fit the pedals for the final time.

 

 

body on and off

To be honest I’ve had the body on and off a few times now. I was a bit premature getting it on in September as I still had things to do in the footwells such as fit the heater unit and pedal box etc, all which seemed a bit easier if I took the body off again but now ive got my little hanging brackets off the 4 poster its all reasonably easy – just gotta make sure I never lower it too much or crunch! and I would be unhappy.

Good news on first the first body fit all mounting brackets seemed to line up quite nicely just needs a little pull forwards to keep it up tight to the chassis at the engine bulkhead. tried a few bolts in for location but then decided not to fully bolt it up since I was sure to take the whole thing off again.

 

Preparing body for lift on

Underbody sealing. After general sanding of the underside wheel arches etc. I have finally applied the body underseal. I have used the 3M 2-pack product sealer code 3M-08800

I have used this product before and really like the way it goes on and stays on. It comes in a foil bag which has a sealed part for the catalyst which must be torn then agitated before applied with a special spray nozzle. It dries to a really nice finish which is slightly soft to touch but not the least bit tacky. it took 12 No. 250ml packs to complete.

 

I have fitted the doors, bonnet and boot lid all without too much drama. I did find the doors quite a task to get right with several small adjustments needed before everything works nicely. The slots on the hinge brackets appear to be too far forward so the bolts end up tight at the end of the slot, even then the door gap at the A post was too tight on both doors. Eventually I used some shims behind the fixed hinge mount in the A post pillar to move the whole assembly rearwards. It only needs a couple of mm and all was good. With the door seals in place the doors close with a pleasant thud.

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I need to remember to cut the hole for the gear lever…. Not long now and the car will be ready to lift on the rolling chassis. Josh my son made me a few brackets today for the 4 post lift to hold the car body so I can do the body on/off trick singlehanded with the push of a button. cant wait to try it out over the next couple of days – the brackets work really well – they are lined with a thick neoprene and sit nicely into the wheel arch.20160901_150922

OK I know its unorthodox but it seems to work great – ill know better when I drop it on the chassis maybe tomorrow! Perhaps ill take the car off the top first so I can see a little better.

Engine bay bulkhead

Light at the end of the tunnel! The gelcoat repair work has been quite a monotonous task. I quite enjoyed doing the flash lines and general polishing stuff since after a bit of practice I was starting to get a reasonable technique and a finish that i was quite happy with. The more complicated areas however proved to be a real challenge that I hadn’t been expecting. Areas of the gelcoat where quite thin and the glass strand/mat layers could be seen on the surface in some places, to make matters worse the thinnest area of gelcoat was right on the front of the car around the radiator opening in front of the bonnet. I sought advice down many avenues and the conclusion was pretty much all the same – that’s not gonna be easy to fix!…. and it wasn’t! One thing I now understand about gelcoat is it wasn’t designed to be used in air and especially not in very fine layers. Gelcoat is supposed to be laid up in a mould. The side that you eventually see is therefore immediately sealed from the air as it is applied to the mould. The opposite side (the open to the air side) is designed (chemically) to remain tacky or soft for a considerable time, this is to allow a chemical bond to take place between it and the following layups of gelcoat or resin and matts. Thus when you are using gel coat to do small thin cover up repairs it is technically not being used the way it was chemically engineered. The way to solve this is to cover up the repairs as you apply them with a thin polyester film, this works very well for very small spot repairs on flat or external curved areas but does not provide a solution for larger areas or internal radius areas. Flow coat can also be used since flow coat is essentially gelcoat with a bit of wax added. The wax is designed/intended to come to the surface during the set and form a seal from the air and thus allow the cure, however flow coat is again not suitable for very fine layer application. In the end after numerous attempts and almost giving up ( surrendering to a paint job) I found (actually it was Kevin’s idea) a technique that worked. A combination of help from an old friend, who is good with an airbrush,(thanks Kevin – I shall be buying that man a beer or two) and trusty old youtube where I found the best method of covering thinly applied layers of gelcoat  – basically  -Wait an hour then paint over with PVA.  Kevin would paint over the repair areas with several very fine layers of acetone thinned gelcoat using an airbrush, this allowed the repair to sit very smooth and be feathered off at the edges which would mean minimal sanding afterwards(the minimal sanding is the essential bit to aim for). Then after approx an hour or once the coats had dried sufficiently to just quicky paint over the whole area with general duty PVA ( a water based adhesive widely available from any builders merchants, plasterers use it before skimming ceilings and walls to enhance the bond) but here its not being used to help with any bonding, its merely being used to completely seal the surface from the air which allows it to cure as if it were face down in a mould.. Then next morning the pva simply washes off with warm/hot water and light sanding can commence. (1200 or 1500 grit) before compound polish.20160727_153239

Used the same technique on the dreaded bulkhead.

At last now I can get on – the body under seal will be going on in the next few days and I can be planning the body on to chassis soon. Back to the real car building stuff hooray!

 

 

 

Garage Meet

Got to meet a few local cobra owners last Sunday. Malcolm Tommy John and Bob came over to meet up in their cobras to offer some guidance it was good to see a few complete cars together, thanks for the visit and the inspiration. I should have taken a few more pictures but managed to get this one of Tommys AK cobra on the drive together with my part built GD, what a terrific job Tommy from Newcastle has done a really smart looking car – ticks all the boxes. I was lucky enough to get taken for a spin along the coast road – that thing sure does shift – it certainly goes as quick as it looks. Thanks for the ride!

garage meet

Tommy’s car has a Chevy v8 producing a fantastic v8 rumble and awesome amounts of torque – it seemed almost too quick – what secrets did he have under the bonnet.

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I’m sure that’s cheating……

 

 

Power Steering

Well I know it wont be everyone’s cup of tea but i believe a car of this caliber deserves to have power steering so I’m going to have a go at putting something together. The tidy choice seems to be to go for a fully electronic version or EPAS – a lot of cars have this now and it has several advantages. No messy hydraulics, ecu controlled and mappable to provide the correct balance of assist (no or little assistance at high speed, full assistance at low speed), compact and dare i say, relatively easy to install. There are quite a few choices out there either new or second hand new systems are quite pricey and will run from a few thousand pounds. A very popular choice for several years has been those from Vauxhalls corsa range – they have been used on all sorts of conversions kit cars and rally cars etc., so there is a fair bit of knowledge out there on how the system works. I found a particularly helpful write up at.http://www.super7thheaven.co.uk/blog/corsa-c-electric-power-steering-epas/                                                                                                                                               This covers a great deal of the background on the ecu and maps etc – all very helpful stuff, and not the sort of info you will find in a Haynes manual – or from a Vauxhall technician for that matter.

Electronic Control

It seems the majority of the units get fitted with simplified dial in electronics that either set the amount of assistance by dialing a knob or use other methods of timing such as allows power assist for first 20 seconds after engine start or after pushing a button. Most of these systems look like a compromise on how the system is supposed to work so I’m aiming at a properly speed related self adjusting system.

A few companies seem to do their own variants of aftermarket kits but essentially rely on the stock Vauxhall Corsa B or C column. example below.

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The good thing is the units are still readily available and can be purchased for as little as £50 or £60. Try to get a good low mileage one if possible and it seems the tilt steering version will be an advantage to gain a bit of “inclination” on the steering wheel – more of that later.

Geometry

The biggest challenge will be getting the geometry correct and making sure it has a substantially engineered bracket system to attach to the car. (power steering can exert a lot of torque to its mounting points. I’m sure the GD monocoque shell will be more than man enough to handle it but the bracket that transfers it to the shell will have to be equal to the task. Keith A was incredibly helpful in providing me with some accurate dims to ascertain the standard position of the steering splined shaft, kindly removing his steering wheel and checking a few dimensions for me – great photos and great help – its gonna save me a lot of head scratching. With his photos and dimensions i can be pretty certain of the desired X Y and Z position of the steering wheel.

Keiths photos and dimsl

I firstly roughed up the position of the steering column into the body shell by a bit of temporary joinery work acting as support battens and props. Once I had the column in the correct position I can take a few measurements to make up the final bracketry. It soon becomes apparent that i wont be able to use the GD windscreen support cross bracket as it slightly interferes with electronics on the column, but that’s not a bad thing as it allows me to beef up the cross over assembly that will be transferring the power assistance loads.

It will be getting some additional fixtures to the body work around the gearbox tunnel as it develops… more pics and details to follow…

 

 

flashlines

3rd June began working on the flashlines. after a few hours of this I realise you have to be pretty meticulous with the sandpaper steps – I thought I was being very careful as I went through the grades but each time I finished the fine machine polish/cutting stage I could see micro scratches left by my less than perfect sanding operation.

  • Step 1    Mask up and scrape off as much excess as possible without adding further scratches. I used a thick blue masking tape to mask and a variety of scrapers.
  • Step 2    Sanding, I started with 800 then 1000 then 1500 grit, I was generally wet sanding with lots of water and I eventually realised its very important to thoroughly dry off between sanding layers and check for micro scratches, by the time you get to 15oo I needed to aim at having a smooth matt finish with no sign of micro scratches caused by the heavier grades used in the earlier steps. only then move on to the machine polishing. I’m half way down one side of the car by the time I’ve figured this out… maybe I’ll know what I’m doing by the time I finish.
  • Step 3   Machine cut/polish, I’m using two steps here firstly 3m green top fast cut(50417), followed by 3m blue top ultrafina (50383). After my first attempt I achieved an excellent shine but could see lots of micro scratches (they become more visible at this stage) .Obviously I hadn’t carried out step 2 correctly. I went back at it with 1500 grit and ensured I got rid of the scratches, once you know what you are looking for with these very fine scratches and are able to get rid of them with the 1500 grade, it all becomes much easier to achieve (it still aint easy though!).

For the machine polishing I’m using a small 3″ detail air polisher but I’m sure any polisher would work, I think its mostly important that you use the correct mop/sponge head for each grade and also don’t go too slow or too fast I guess I’m working somewhere in the 1200 to 1500 rpm area. only use as little compound as necessary, once polishing the compound should gradually disappear, if it doesn’t then I’m probably applying too much. I also found it best to concentrate on a small area at a time maybe no more than two sq feet or even less. I plan to do final polishing/wax with a larger mop head over the complete car once I get everything to this stage.20160605_094923 Prepare to get wet and messy… I found this little scraper from one of those vibrating tool sets (Aldi) ideal for stage 1 it has a slightly curved scrape edge which means its difficult to scratch other parts when scraping off the excess flash lines, although I also used a variety of fine files. Mainly using the 3m green top and blue top for stage 3 and the little Kobe polisher from Cromwell tools, the green sponge mop is for the green cap “Fast Cut” and the black (very soft)sponge top left of picture is used for the “Ultrafina” blue top.