FIAT 128
There are three main areas to concentrate on, the engine (and transmission), the brakes and the suspension and then various other details. These three should be done together since they complement each other, not all of one and none of another !
1. The engine.
Before modifying the engine it is worthwhile filling it with a good quality synthetic oil and fitting new spark plugs. An engine oil additive may also be used.
The first improvements are relatively simple. The air filter can be replaced for an aftermarket item which will help the engine breathe more freely and the exhaust can be replaced for one which will restrict the exit of the gases less.
The main modification (outside of taking the engine apart) is to fit a better carburettor. Either a unit from a larger engined model, or you can buy a special inlet manifold to allow the fitment of other units. A camshaft will also provide a noticeable gain, especially if fitted in conjuction with the carburettor.
Other things to do should include fitting a cold air intake, a large diameter pipe (minimum 5cm) to provide air from outside the engine bay to the air filter. The exhaust manifold can also be lagged with thermal cloth or tape to keep the exhaust gases hotter (and thus reduce back pressure) and also to keep the underbonnet (and hence intake and fuel) temperatures lower.
The high tension leads can also be replaced with performance ones.
Further modifications require the machining of the cylinder headand/or cylinder block (which will not be dealt with here since it is not normally a DIY job) after which it may be worth fitting an oil cooler. If overheating is a problem due to the increased power output then a small hole can also be drilled through the plate in the thermostat.
Regarding the transmission the main requirement is to uprate the clutch to handle the increase in power and torque achieved though the engine modifications. Friction plates can be purchased with improved materials and heavier duty pressure plates are also available. Whilst doing this it is worthwhile lightening the flywheel.
2. The brakes.
Initially it is relatively easy to replace the brake discs with drilled and grooved items, and the pads for a harder compound. The latter should not be too hard (ie no race pads on the road) or they will not function effectively at the normal 'road' operating temperatures. Stainless steel braided flexible hoses will improve the pedal feel and reduce the chance of damage whilst DoT5 fluid (not silicon) will increase the temperature at which it can operate effectively. If the brakes are getting too hot the dustguards can be removed and/or ducts fitted, taking air from behind the front bumper.
If more serious braking is required the next modification would be to increase the disc size. It is possible to use larger discs with a bracket allowing use of the production callipers, or alloy four pot callipers can be fitted.
In order to improve the balance of the car under braking it is desireable to be able to adjust the balance of braking from front to rear (and vice versa). This can be accomplished by fitting a bias valve in the line to the rear brakes, usually in a position so that it can be reached from the drivers seat.
3. The suspension.
The easiest improvement,and the one which will probably bring the single most noticeable change, is to replace the dampers and springs. At the front, everything can be replaced, at the rear the suspension can be lowered by clamping the leaf spring. Top adjustable dampers are compromised, but are good for road and track day cars since it allows the suspension to be adjusted between these two, rather different, requirements. Coil over units add more adjustability and can be purchased outright, or can be made from standard dampers by welding a threaded sleeve to the standard tube.
There are then two other main suspension aims; to reduce the flexiblity in the suspension and to increase the stiffness of the car, both of which aim at more accurate control of the wheel movement. To reduce the flexibility it is possible to fit nylon bushes instead of the normal production rubber items, or if perfection is desired the suspension can be fitted with metallic bearings (rose joints / rod ends). Spherical bearing top mounts can also be used. To stiffen the car it is most popular to fit strut braces. These can be fitted to the front and rear. For more extreme cases a rollcage can be fitted.....
Into this category also fall the choice of wheels and tyres. With an increase in power it can be necessary to fit larger tyres (thus requiring larger wheels) but the temptation to fit the biggest possible should be resisted. Consideration should be given to fitting a wider tyre on the front (since they provide traction and steering) but keeping the standard, or a wider but not as wide as the front, tyre at the rear. This will improve the balance of the car.
4. other things.
Other modifications worth considering include fitment of a shift light (and rev limiter if there is not one as standard), higher power bulbs in the headlights (if you are going to go faster you need to see further) and installation of a quicker steering rack.
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