GD427 in action

GD427 in action

Saturday, 30 April 2011

Gearshift and Intake Clearance

I cut two more holes today in preperation for the body going on. The first was the hole to give clearance for the gearshift. The tremec box I'm using has a short stub shaft which would foul the tunnel so a hole has to be cut before the body can go on. This poses a problem as until the body is on you can't use this as a guide on where to cut the hole. I'm sure there's a few different ways to overcome this, I chose to use the body mounting holes as reference points and as close as I could, transfered the measurements from them to the gearshift from the chassis onto the body. I used various pieces of wood, clamps, spirit levels and tape measures, the proof of the pudding is in the eating so we'll have to wait until the body is on to see how accurate I was.

The Dremel with a radius cutting tool doing it's thing...!

Ta daaa...

The other hole I cut was to give clearance to the air intake tube which runs from the engine forward to the air filter. There's not quite enough clearance as the tube disapears beneath the nose of the car so a small section has to be cut away firstly from the lip around the bonnet opening and then a section from the piece which holds the bonnet hinge fixings.

The cable you can see just pushes up out of the way.

Not a bad fit, of course it may need a bit more work once the body is on but should only require a little fettling.

This is the view from underneath showing how the GD air filter mounts inside the nose cose

Sunday, 24 April 2011

First hot run

No major progress today, had a bit of a lazy one.

I did however start the engine again but this time let it run, varying the revs a little, trying not to alienate the neighbours too much on a sunny Easter Sunday afternoon, until the fan came on at just a smidge under 90 degrees on the gauge. This was mainly because I just wanted to hear the engine again but more importantly, when I filled the radiator last time it was with just water an no antifreeze. Now I know it's unlikely to freeze at this time of year but I had a niggling worry about missing out on the anti-corrosive properties so I drained the water and refilled with a water/antifreeze mix and then of course had to start the engine to make sure it was all nicely circulated. :-) I was quite pleased to see the radiator come on. I wondered whether I'd have to recalibrate the gauge as it's running off the ECU rather than directly from a sender but it seems OK.

The other thing I did last week was to spray the side sills matt black, this part is kinda under the car and looks like it should be hidden rather than polished. Here's a quick picture to illustrate.

Saturday, 23 April 2011

Testing hydraulics

I noticed a small pool of fluid sitting on a chassis cross member which appeared to be coming from a brake union. As the brake system isn't under any pressure this had me a little confused. Having bought a rolling chassis it led me to consider if any of the brake fittings had been tested before I took delivery. Common sense would tell you even if they had it made sense to check them myself so I set about mocking up the pedal box asssembly in order to apply some pressure to the system. You'll see from the pictures, I basically made a wooden frame to mount the pedal box and master cylinder and then used the supplied pipes and fittings in a tempoarary fashion to connect it all up to the chassis.

Once it was all connected and I'd bled the fluid through the system I tested it with a few pumps and finally held the pedal down for as long as my leg muscles would stand. There were a few leaks, nothing horrendous and a quick tweak with the spanner was all that was needed. I used a Gunson's Easibleed to bleed the fluid through the system and it worked flawlessly, thoroughly recommended.

Sunday, 17 April 2011

Battery Tray & Stainless Mesh

Decided to fit the battery tray today. Considering it's hidden away under the battery and behind a wheel arch compartment cover I probably needn't have gone to the trouble of spraying it but well.... in for a penny ! Oh and it's made of stainless steel as well so it isn't going to rust, Hmm, I suppose I could have polished it instead !

I also fitted the stainless steel mesh into the oil cooler and brake duct vents. This is purely cosmetic and does look rather nice when finished. I made a template of the opening and then added 5 mm all the way round and used this to form the mesh around before "glueing" it in place with Sikaflex. I should have kept and used the blanks which I cut out from the openings originally which would have saved me some time.

Body on soon !

Saturday, 9 April 2011

Guess what I did today... :-)

I must admit, the first attempt didn't go so well, I hadn't put enough fuel in the tank so whilst it started it was very rough and wouldn't idle, hence the "jaunty" angle of the tank in the video to make sure the fuel level was high enough on that side so the pump wasn't sucking air. This was the very next try though...


In this next clip you can see the box I made with the basic electrical connections to start the engine, along with the accelerator pedal.


Thursday, 7 April 2011

Electrical musings

The Tremec T56 gearbox comes with a reverse lockout solenoid designed to prevent you accidentally selecting reverse during forward motion. On a modern vehicle this is controlled by the ECU which effectively locks the car out of reverse once the vehicle speed exceeds a certain value say, 3mph. There has to be a failsafe in case of a malfunction so in fact the lockout can be overcome with a bit of brute force against the spring loaded plunger. The ECU I’m using doesn’t have provision for this functionality so I’m left with either using a bit of force each time I want reverse or rig something else up. I’ve decided to go with the “rig something else up” option although I understand many choose to use brute force or even take the mechanism off altogether. The problem with removing it comes with the reverse selection being across to the right and forward which could potentially lead to problems from an enthusiastic shift from fourth to fifth if you miss the gate and crash into reverse. The other option is to mount a switch somewhere that needs to be pressed before you select reverse but this option doesn't really appeal. The spring is quite stiff and so as an experiment i’ve temporarily wired the solenoid and powered it direct and it does make shifting into reverse so much easier so I think it’s something worth pursuing.

Another aspect I’ve come across in relation to the engine management system is the use of a Neutral Safety Switch (NSS), again a modern “gadget” to ensure that you’re either in neutral with an auto box or have the clutch depressed in a manual before you can start the engine. Again, it can be overcome, the ecu provides an output which must be grounded to allow the engine to start, you could just permanently ground the wire but I’ve decided to make use of it and fit a switch to the clutch pedal requiring the clutch to be depressed (grounding the wire) before the engine will start thus avoiding the accidental lurch forward when you’ve forgotton you left it in gear.

This is where it gets interesting, I’ve going to try and power the reverse lockout solenoid on the gearbox from the brake light switch on the brake pedal and ground it through the safety switch on the clutch pedal. This will mean it’s only possible to select reverse (without brute force) whilst the brakes are on (providing power) and the clutch is depressed (providing an earth) which is generally a good position to be in before you put the car in reverse! I guess there’s still a possibility of a mis-shift whilst changing down and on the brakes but in this scenario I’ll be shifting away from the reverse position i.e. right to left. The other benefit is that by grounding the solenoid through the switch on the clutch, it won’t keep being activated each time you brake during normal driving. There’s a little bit of figuring out to do with the wiring, I don’t know yet the output voltage from the ECU for the NSS and don’t want to risk the solenoid trying to earth itself back through the ECU so I’ll have to fit some diodes in place to limit the direction of the current. Once I’ve got it all figured out I’ll post some more details