Update of work done this month the the GT
I thought it best I do a summary of the work undertaken on the GT, but one has to remember its not actually me doing this, I am far to posh to get my hands dirty. The work is all down to Retropower
Starting with the subframe; First up it was check and re-check that we are happy that the angles of the uprights are not bent as we first thought after it was modified to take the engine. The old Vauxhall Books do include some drawings with dimensions, and utilising these, confirmed that things are within tolerances so work wasn’t wasted. A few minor alterations to fittings were done otherwise it was built up with the steering rack and made ready to fit to the car.
The steering rack is a custom job, utilising half a Ford Escort Long nose rack and half a Viva rack, the internals are Escort (so has potential for a quick rack) and the outer arms modified to accept the normal Viva Arms (so it mounts to the hubs as per normal. Some potential for bump steer exists but we will deal with that when we track the suspension, some spaces to the steering arms from the tie bars should sort it out.
Next was to fit the custom sump to the engine, the normal sump didn’t fit so a modified sump was created, which bolted on and gave clearance for the subframe, steering and rear mounted roll bar, and maintain capacity where possible. This then enable the engine to be mounted to the subframe ready for the gearbox to be fitted.
The gearbox is a Toyota W58, it mounts to the engine with a special bell housing from a Lotus Excel. The clutch consists of an Esprit Turbo flywheel & clutch cover, the friction plate is from a Toyota HiLux (w57 gearbox) and a small spacer to hold the release bearing at the correct distance from the cover completes the setup. A small hardened sleeve needed to be added to the input shaft of the gearbox so it mated the flywheel spigot bearing correctly, and a small adjustment of the boss in the fiction plate were needed to make things fit.
There are two types of crankshafts used in the lotus engines, one has a countersunk at flywheel end and allows the friction plate boss more room, alas the crankshaft in the Esprit engine didn’t have a countersunk end and this causes the boss of the clutch cover to rub against the flywheel bolts. Spinning it down so it was shorter cured this. The boss itself is quiet long and the loss of length doesn’t create a power loss issue going forward. In hindsight swapping the crank for a countersunk version would have been a good idea but this was unknown at the time.
Next the gearbox was mated onto the engine and bolted into place, the whole unit was then hoisted into the car and secured. You can see in the first image heat wrap around the top header pipe, as it runs close to the chassis rail. The chassis rail was also wrapped in heat reflective foil.
Here is the engine now sat in place. Missing is the rear roll bar, the brake callipers and brake lines, these will be down at a later date.
From above it looks almost like a factory fit.
Moving to the back of the GT, we have the rear axle. This axle is a Reliant Scimitar 4HA but modified to use the existing mounts on the floor, and not modify the shell to take the axle (which is a common way of mounting these axles). Its been rebuilt and now features a Jag 3.77:1 open diff unit (NO LSD for me as I just am not going to need a LSD for the things this car is going to do). To which the hubs have been modified to take disc brakes (no drums) and changed from 114.5mm PCD to 101.6mm PCD as per Viva.
A issue has appeared with the brake callipers that wasn’t foreseen to start with. A good friend runs a 4HA axle using he same discs as this GT, and he uses 13″ wheels, although he is using a different calliper to the ones on the GT (Astra Mk5 Bosch). With these callipers on the axle I cannot fit my 13″ Alloys. Some comparison are needed as to the alloys wheels we are both respectively using. The Cosmic Alloys I have for the car may well be small internal Diameter and cause this fitting issue. Until I get to try the Alloys off Lily I will know know the answer.
A hell of a lot of work in a very short space of time, and it now opens the door to a whole load more challenges for me to ponder over, and a load of odd jobs I can get on with myself (finish off building the front doors). For now thats it for 2014, 2015 will kick off with cures for the wheels, fitment of electric steering and a custom bias pedal box. I cannot wait.