Archive for the ‘ Gearbox & Drivetrain ’ Category

Air shifter/ engine mount

Due to the unfortunate misplacement of our original engine/ air shifter brackets, we were forced to re-design and manufacture.
This being said we took the opportunity to improve upon our previous design. Initially we had a large block of aluminum water-jet cut to a rough profile, and then further machined for lightening and mounting points.

I’ll let the pictures do the talking.

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Geartronics Air-shift system in place!

The first of the engine bay accessories to go onto the car! The Geartronics electronic air shifter system is now in place!

The air actuator used for the pulling and pushing of the Sadev gear box’s input shaft, was integrated into the rear bell housing mount. It’s made from 4mm thick laser cut steel plate and has been webbed with reinforcement plates to provide plenty of rigidity for when the actuator is under load.

A small mounting plate was fabricated and TIG welded onto the chassis to retain the air valves used to control the air between the pump, reservoir tank, and air actuator. Small rubber grommets where used between the Valve bodies and the mount so that harmful chassis vibrations will be dampened.

The reservoir canister has been rigidly mounted to the chassis via a fabricated aluminium mount. Small tabs where welded onto the rear subframe of the lotus to accommodate the mount, then small and light riv-nut threads where inserted for quick release. The tank is held in place with 2 large jubilee clips wrapped in shrink wrap so that the canister won’t be scratched.

All 3 accessories have been located as close as possible to each other to maintain a constant pressure for quicker, crisper shifts.

For any more information on the Geartronics air shifter system, check out their website.

Engine mounted!

It’s been quite some time since our last update. Project N2 is back on it’s feet and getting nearer and nearer to tearing around all the famous race tracks the world has to offer.

In order for any drive train related accessories to be put in place (ie: air shifter system, oil/ coolant tanks, drive shafts, etc.), the engine and gearbox needed to be mounted. Using a series of levels, scales, and inclinometers, numerous surfaces of the engine where picked and related to the chassis to locate the engine in the optimal location.
Once the engine was set in it’s final orientation, engine mounts where designed using the latest 3D Computer Aided Design software, laser cut, then TIG welded together.
Rubber bushing inserts where chosen to support the engine as they will allow for the stiffness the engine will require under load, but will also offer some “give” so that the vibrations of the chassis and drive train don’t effect the inner workings of the engine and related equipment. The standard S2 Exige engine mount has been left in place for now as it’s a hydraulic dampening mount which will also allow the engine some “give” under vibration. This isn’t to say that it won’t be replaced in the future by a superior design.

ULTRALIGHT FLYWHEEL!

Here’s a couple of pics of our one-off flywheel, weighing in at 2.1kg.  It is made in one-piece with integrated ring gear teeth and is designed to take a twin-plate 5.5″ race clutch.  Using a super-light flywheel helps the engine speed up more easily during downchanges.  Not only is it super-light, it has a very low moment of inertia which means the majority of the weight is concentrated in the centre, the reason for wanting to use a small clutch.  When the weight is at the outer edge (or a larger diameter clutch is used), the flywheel assembly will not want to change speed quickly.  This kind of very light flywheel with small diameter clutch will really have a benefit when combined with the paddle shift change sequential box.

Drive Transfer Shafts Made

We have designed custom specification differential output shafts and a transfer shaft to suit our engine and gearbox installation.  These shafts arrived with the gearbox and were made by Sadev in France.  Bolting onto these will be GKN tripode joints and custom length driveshafts.

Sadev Gearbox Has Arrived…

Our Sadev ST-90 has arrived

GEARBOX & DRIVETRAIN

We have decided to use the Sadev ST90-14 fully sequential straight cut dog ‘box which is well suited to the Lotus chassis, can handle the power (just) and is compact enough to fit .  We will be able to change individual gear ratios for different circuits which will be a real benefit, for example Monza will need very different gearing to say Brands Hatch Indy.

Designing our own installation was the only solution, everything other than the gearbox itself is our own design.  We have designed the driveshafts to use Tripode joints as they run cooler at higher angles and use less power than the Lobro type, the short shafts that the Exige uses mean they run at high angles.

We will be fitting the gearbox with a pneumatic gear change system operated by paddles behind the steering wheel.  This is a closed loop system, where the ECU waits for the gear to drive fully home before bringing the power back in.  The gearbox can even be driven in fully automatic mode, as well as safeguarding against accidental downshifts (he downshifts can be stacked up, only shifting when the road speed allows).

We have had a super-light flywheel made which weights 2.1kg, which is fitted with a twin-plate Tilton 5.5″ race clutch.  This assembly is not only significantly lighter than the stock flywheel and clutch assembly, but has a much lower moment of inertia, both helping the engine ‘spin up’ during down-changes.  The clutch is operated by a concentric hydraulic slave cylinder which runs around the gearbox input shaft, rather than the external slave cylinder systems which flex and are heavier.  However, with the paddle shift system hopefully we won’t be using the clutch much.

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