Toyota MR2 Roadster (ZZW30) 1999 - 2007
An alternative to the Mk2 Mazda MX5. The MR2 Roadster (also know as Mk3 MR2, MR-S & MR2 Spyder) was a monospec car, only coming with one engine choice and one trim level. The car came with a transverse mid-mounted 1.8l VVT-i, 4 cylinder engine (1ZZ-FED) producing 138hp transmitted to the rear wheels through a 5 or 6 speed gearbox (depending on the year) and a standard fit Torsen LSD. The car's kerb weight scraps in at just under a metric ton (Weight varies with year. Facelift cars are heavier and SMT cars a heavier still) so it's able to use it's modest power effectively. The only notable changes to the cars specifications happened with a facelift in 2003. Pre facelift cars had a 5 speed gearbox and came with 15x6" front wheels and 15x6.5" rear wheels. Facelifted cars came with a 6 speed gearbox which helped with motorway MPG. They also have different front and rear bumpers and lights and the rear wheels where changed to 16x7" to aid traction and stability. The facelift cars also got extra chassis bracing to improve handling. All years were available with a SMT gearbox which was the same manual gearbox as the standard car but with an automated clutch and gearchange via paddles behind the steering wheel.As a trackday car the MR2 is reasonable quick and capable. Although the chassis has a good natural balance on a track with standard tyre sizes (185/55/15 front, 205/50/15 or 215/45/16 rear) the car has a tendency to understeer. A square set up (eg. 195/50/15 tyres all round) will reduce the understeer and mean that the rear will be adjustable on the throttle. This has the added bonus of keeping things cheap. You could also increase the front and rear tyre widths in equal proportion (eg. 185mm to 195mm on the front and 215mm to 225mm on the rear). This will reduce the understeer but maintain rear traction, stability and safety however it could lead to problems with available tyre sizes and increased costs. There is also a possibility that you'll over tyre the rear for the car's power and weight making it less enjoyable.
The car will happily take anything from 14" to 17" wheels without rubbing. The hub fitment is 4x100 PCD and a 54.1mm centre bore (same as Mks. 1 & 2 MX5). The car will take offset of between ET+35 to ET+50 depending on the wheel/tyre width but between ET+40 to ET+45 will usually avoid any rubbing on the wheel arches. The car was designed to have wider wheels on the rear, up to 8 - 8.5" width without rubbing but the front is limited to 7 - 7.5".
The standard brakes are up to trackday work with minimal upgrades. Some Yellowstuff pads, braided hoses and Super Dot 4 brake fluid and you're ready to go. The front brake pads are common to the Mk7 Celica (ZZT230) and the Yaris (XP10) and the rear pads are the same as the Mk2 MR2 (SW20) so whilst the MR2 Roadster may not always be listed as a application for a trackday brake pad ones for these cars will fit. With the upgrades suggested the roadsters brake pedal will feel firm but progressive unlike the over servoed brake pedals in modern cars.
The standard suspension on the MR2 roadster is pretty good. It's comfortable but still offers great handling. Lowering spring conversions are very common with TTE (Toyota Team Europe) lowing springs often been the most coveted. Adjustable coilover kits are few and far between. The best European coilovers available are the KW Variant 3's but that reflected in the £1400+ price tag. The most commonly used coilovers are from BC Racing offer a range of coilovers for the Mk3 MR2 priced from £770 to £1000. They are highly regarded among MR2 Roadster owners although they're known to offer a less than comfortable ride quality. There are a great range of Japanese coilovers available but they are often very expensive and are less common in Europe and the UK. Other kits are available from Tien, Gaz, and Meister R. The car has both front and rear ARB's (Anti-Roll Bars) which are quite adequate for trackdays. When replacing suspension the rear drop links are usually destroyed and will need replacing at the same time.
Unlike and MX5 which has double wishbones all round the MR2 Roadster had McPherson struts all round with a conventional lower wishbone at the front and a three arm multi-link set up on the rear. The only aspect of the geometry that adjustable as standard is the toe angle. To get an adjustable camber angle either camber bolts, adjustable top mounts or in the case of the rear, adjustable length control arms will be needed in order to have a suspension that the geometry can be set up correctly.
As a topless car the MR2 Roadster's chassis can be a bit 'floppy'. Facelift cars have additional under body bracing over the pre-facelift cars and handle marginally better. Although not essential additional after market bracing will make the MR2's handling sharper. The first two ports of call should be a front upper strut brace and what's commonly called a midship under brace or breast plate. The rear of the car is considered to be stiff enough so any further bracing should be aimed at under the front of the car help make the steering sharper. Additional lower front bracing on 2004 onwards cars is more difficult because of the extra crash structure put there by Toyota.
The engine although sturdy and reliable is a bit characterless. Modifications to gain power in a naturally aspirated spec are often expensive whilst yielding little extra power. Most owners replace the heavy, restrictive exhaust manifold and back box for stainless steel items and replacing the air intake and panel air filter for less restrictive items. Other NA modifications include stage one camshafts and a mapped piggy back ECU. All these modifications together will see you a net increase of around 20hp.
Turbo conversions are common and although expensive (£3000 - £6000) often yield HP increase of between 60 to 100hp depending of spec. There was an sem-official turbo kit from TTE (Toyota Team Europe) which increased power to 182hp. There are/were many other turbo kits/conversions available including ones from Silverstone Performance and Thor Racing.
Engine conversions are less common than turbo kits but are still well known. The most common conversion is a swap to a 1.8l VVTL-i, 190hp (2ZZ-GE) from the Celica. It's the same engine that was used in the last generation of Lotus Elise and offers the high revving thrills that are usually reserved for a Honda Vtec engine. Although not a plug and play conversion it's a relatively straight forward and well know conversion. The next most common conversion is the 3S-GTE Turbo engine form the Mk2 MR2 and older Celica. This gives a great increase in power and reliability but increases weight considerably over the all alloy 1ZZ-FE engine. Other conversions are the K20C engine form a Honda S2000 and various Toyota V6 engines and the occasional V8 conversion.
As with any car there car common failure points to look out for. The biggest concern is what is know as pre-cat/ovelbore. This is an engine failure problem that's more applicable primarily to pre-facelift cars (later cars can suffer too but it's far less common). It starts with increased oil use that then gets into the exhaust manifold where the pre-catalytic converters (pre-cats) are located. The pre-cat material then breaks up gets back into the engine which cause excessive wear on the cylinder bore. One problem exacerbates the other and vice versa. This problem is usually terminal. Look for excessive oil usage or burning oil in the exhaust fumes. There should be none. You can also check the condition of the pre-cats by removing the O2 sensors in the manifold and looking at them they should be a fine honeycomb structure. MR2 owners often remove the pre-cats by gutting the manifold or getting an after market stainless steel manifold. The engine was redesigned for the facelift cars to prevent the problem. apparently the problem was only fully solved in cars made in 2006 or later. Follow the link for more information; MR2 Roadster Pre-cat Problem. Other common problems are rustly rear subframes and rusty brake discs (usually on the rear face through lack of use). Cabin rattles are very common. Otherwise as you'd expect from Toyota it's a very reliable car.
Comparisons to the Mazda MX5 are inevitable. Round a track a standard MR2 Roadster is probably faster than a standard Mk1 or Mk2 MX5 but tuning parts for an MX5 are much cheaper and far more abundant. The MR2 is not the easier option then but it's more unique and with it's mid-engined layout has the potential to be the faster and better car.