RTOC RENAULT 5 GT TURBO BUYING GUIDE
This month the buying guide is on that cult Hot Hatch, the Renault 5 GT Turbo. Back in the late 80’s & early 90’s these cars were many young man’s dream and were slugging it out with Peugeot 205 & VW Golf GTI’s round every ring road & leisure park car park. There have been many buying guides for these cars over the years, giving differing recommendations on what’s right & wrong. However this time Performance French Cars have created this buying guide in conjunction with the Renault Turbo Owners Club (www.rtoc.org) to ensure that you are provided with the most accurate and comprehensive guide so far.
Over the last 25 years the Renault 5 GT Turbo has continued to appeal to many car enthusiasts from competing and winning in various racing series to road use engine and chassis tuning to styling modification from the sensible and practical to the ridiculously exaggerated with actual performance loss.
Many people remember the whole Ali-G big wheels & body kit scene which the RTOC believe tarnished the reputation of the 5 GT Turbo in the minds of many people. In more recent years though there has been a shift in restoring the cars back to factory fresh examples and Big Steve’s car pictured here was one of the first cars restored back in 2006.
HISTORY
The Renault 5 was launched in 1972 and spawned many performance versions from the Turbocharged Gordini, to the wide body Turbo in 1980 that won the 1981 Monte Carlo rally, the Turbo 2 in 1983 and the Maxi in 1985 of which only 20 were made. In total only 5007 T1, T2 and Maxi were made.
The second generation Supercinq (Super Five) was launched in 1985 and was styled by Marcello Gandini who had previously penned the Lamborghini Countach. The chassis was based on the Renault 9/11 models with McPherson strut front suspension and transverse engine and gearbox, but the Renault 5 styling trademarks were retained.
When the Supercinq was launched the GT Turbo was not offered for sale but was included in the brochure as the “Coupe” model. This Coupe model was described as being developed for racing only and not available for sale, but by 1986 the GT Turbo was launched with a price tag of £7,710. Producing 115bhp, it was fitted with a slightly different body kit to the one shown here.
In 1987 Renault made a number of small but significant changes and designated this the phase 2 model. Most obvious is the painted smoothed body kit that reduced the car's drag coefficient from 0.36 to 0.35, different wheels and seat cloth and a more comprehensive centre console. But under the bonnet were some reliability improvements to address some of the issues seen with the Phase 1 hot starting problems; an Anti Percolation Fan to cool the carburettor, and when the engine is off, to cool the turbo compressor and also intercooler when it’s thermostatically controlled diverter flap is open. Also a water cooled turbo charger and changed routing of the cooling system pipes. The power increased by 5 BHP to 120 BHP. In the ECU was moved from over the turbo, the heat from which slowly damaged it, to behind the bulkhead. In 1990/91 they re-routed the throttle cable to the carb and replaced the rubber steering column UJ with a metal UJ, provided cloth covered door cards, more sound proofing in the boot and a boot light. In late 1991 the 5 GT Turbo was discontinued make H reg the last available, though there are a few J and K reg's around these were ones kept in Dealerships and sold later.
There are approximately 3500 GT Turbo’s still registered with the DVLA and with the newest cars now 20 years old parts are becoming harder to source as Renault withdraw components from there dealership network. However due to the fanatical following and a number of specialists, there are few parts that are truly unobtainable.
Advice
Look at the cost of buying vs. the cost of making it / keeping it road worthy. Things which would almost write the car off: rotten floor, inner and outer sills, rotten windscreen surround as many panels are no longer available from Renault.
Brakes are fairly cheap and available but things like rear compensators are costly to replace.
Don't buy one unless you know what you are looking for or know someone who does as 90% of the time the car will need some amount of work be it mechanical or cosmetic.
What you look for when buying a 5 might be totally different to what other people look for if you know what you can put right yourself relatively cheaply and what spares are available.
Other things to add in: Or delete.
Check for inner edge front tyre wear, especially if lowered, as this increases camber, and can be caused if the tracking has not been adjusted.
Exhaust, best for performance are the 2 1/4" or 2 1/2" full systems that are from the turbo backwards. No catalytic converter is required in these pre '91 cars. Such a free flowing exhaust lowers the back pressure after the turbo so the OE boost compensation system no longer works and may as well be removed and the holes plugged.
Clutch; heavy pedal with fierce bite = uprated clutch kit and no long release arm conversion. Cost is about £70?? Fitting costs £???
Play in steering? If the steering wheel has lateral or longitudinal play that would probably be the two column ball bearing bushes.
ECU over turbo? Is the Phase 1 layout and will damage the ECU leading to very uneven idle and pinking on lowish boost.
The turbo can jam due to oil burnt and set hard in it's bearings also causing no boost.
Dump Valve; they can leak leading to low boost.
OE actuator or weak actuator spring and bleed valve? Can lead to slow boost rise.
Harder springs and 15" wheels can lead to wheel bearing wearing out in only 12,000 miles.
OE anti percolation fan; noisy = worn. Unfused OE = fire risk if the fan jams.
White powder in tail pipe can mean over heating engine and possibly caused by blocked rad.
Some copper rads can leak. Bars leak can just block the rad and cause the engine to over heat.
Thinking out loud follows:
Big front discs are mainly for show but really for better cooling but can lead to poorer stopping as normally 20% of braking is from the rear tyres and bigger front discs lead to less pedal effort before the fronts lock so the rears are simply doing less.
Track lapping at race speeds with rock hard springs and shock settings and very sticky tyres means more weight transference and less rear braking.
With braided lines the pressure in the callipers is more immediate as there is no bulging like the rubber lines so the brake pedal travel is shorter to reach peak pressure. This means there can be locking of the front discs when applied suddenly compared to the OE lines. But there can be better pedal feel due to the reduction in sponginess.
Peak pressure in the callipers might be the same therefore also the same in the rears or it might be less if they just keep bulging until you run out of pedal travel.
ENGINE
The Renault 5 GT Turbo uses a heavily modified four cylinder, eight-valve “Cléon” (or C Series) 1397cc engine. The unit is of Pushrod OHV design that can trace it’s roots back to 1962. To cope with the rigours of turbo charging, it was fitted with hardened valve seats, compression ratio lowered 7.9:1 and heavier duty pistons with 13mm crown thickness. The engine utilised wet liners in a cast iron block which was a saving grace to many home modifiers meaning that if catastrophic engine damage occurred the entire piston & liner assemblies could be changed without even removing the engine from the car and the engine block did not become scrap.
Breather pipes; clean, with restrictors and working one way valves.
Mayo in header tank?
Low water in header tank?
Beige stains on hoses or engine? Could be leaking coolant.
Struggles to start?
water pump; leak / squeal = replace, half or whole.
CARBURETTOR
To control the air/fuel mix a Solex 32DIS single choke Carburettor is used rather than fuel injection so positively prehistoric compared to today’s modern cars which have sensors all over the car. This simple set up meant that the cars were easy to tune and increase the power by turning up the boost pressure. However if the carburettor was not tuned correctly the first you knew that something was wrong was that the Head Gasket failed. Thanks to the advance in wideband lambda sensor technology though it is easy to fit one and re-jet the carburettor to deliver the correct amount of fuel for the amount of boost pressure.
Group A and Group N are racing classes. The Group A Carb has a specially made taller venturi with a larger bore different jets and whilst some parts vendors in the 80’s / 90's may have sold an original group A carb there were only a handful of true Group spec carb’s in circulation. It soon became the case that they were selling a bored re-jetted standard carb and unknowing customers were wrongly called them, and re-selling them as, Group A. It’s safe to say that any Car advertised as having Group spec Carb means it’s just been re-jetted.
The re-jetting of the Carb requires a delicate touch and the knowledge of which parts to change/drill out otherwise you could end up over fuelling the engine which will not only give you poor fuel consumption but the fuel mixes with the oil and can rapidly wear the engine & turbo bearings and cause failure in a matter of weeks. A number of RTOC members have become very skilled in setting up the Carb’s and can tune them to give either big power or an increase in fuel consumption.
A common problem with the 5GTT is poor idling and this is usually down to a blocked idling jet, however it is possible for the base of the Carb to be warped and the throttle spindly seals to be ovalised and leaking air. The RTOC recommend that if the your car is running poorly that you re-build the Carb and ensure that everything is cleaned and working correctly. They sell a uniquely comprehensive re-build kit through their on-line shop and have informative and helpful re-build guides on their website.
TURBO
The GTT was originally fitted with a Garrett T2 Turbo and would run approximately 7 psi of boost and is a good mix of power and low Turbo-lag. It is possible to increase the boost pressure of the T2 Turbo to 14 psi at the manifold but that is the maximum the standard Carb & Cam can handle. This roughly equates to a 0-60 of 6.5 seconds in good weather conditions.
The next level of turbo would be a T25 or T28 enabling you to increase the boost pressure to circa 25 psi. Becoming a favourite is a Tomcat spec turbo, not an actual Tomcat turbo from and old Rover.
The downside with ever larger turbos is the ever greater lag between planting the loud pedal and the torque happening. For greater cost is a VNT turbo that spools much more quickly but still offers the large turbo benefits of lower back pressure and higher boost.
For road use you don't have to accept the off boost performance drop if you spend enough money and have a VNT together with a higher compression engine with redesigned combustion chambers and perhaps only 18psi boost and very careful tuning you get the best of both worlds with a much more linear torque delivery of 230ft lbs and still as much as 240bhp.
COOLING SYSTEM
Any increase in the boost pressure/performance of the car puts more load into the cooling system which unless it is properly maintained will lead to the car overheating and again possible head gasket issues. The RTOC state that the standard cooling system is more than up to the job as long as it is properly maintained. If the car seems to be running too hot it is recommended that the cooling system is fully flushed out with just water as some engine flushes have been known to block the waterways in the Turbo. The cooling fan should cut in as the gauge reaches the 3rd of 4 marks. Some people remove the Thermostats in the Top Radiator Hose near the water pump to help the cars run cooler but this can make the oil too cool to protect the engine as the Oil Cooler in the Radiator will be too cold. Better is to use a low temperature radiator fan switch.
GEARBOX
The GT turbo gearbox is of the JB series. Phase 1's were numbered 014 and the Phase 2's were 032 and are fairly robust. They utilise an electronic Speedo pickup which can be prone to connection problems and means that the speedometer does not run or record the mileage. You should check that the gearbox shifts smoothly & you can not hear any strange rumbling or whining during a test drive. A symptom of a tired gearbox is the fact that the car jumps out of 2nd, 3rd or 5th gear which means the unit is worn. Don’t be fobbed off by the seller telling you that “they all do that” and all it needs is a change of the engine mounts or adjustment of the gear linkage rod, you will probably need a replacement gearbox or a rebuild.
Another problem which can happen to the JB series gearbox is that a large circlip on the passenger side of the unit can snap and the differential just spins leaving you without any drive. Thankfully it’s relatively easy to change and, as they fit all JB series gearboxes, cheap to buy direct from Renault.
The 5GTT uses a JB3 and has the longest gears. Whilst it’s fine for plenty more then the original 120ft lbs, it can be a limiting factor for higher torque 5GTT’s. The bearings can fail after some time in moderately high powered cars. The JC5 box of the Clio has different bearings but may last no better than the GTT. If torque is high and traction is sufficient then it's the gears that break instead, and instantly. 1st gear is especially poor and the crown wheel can brake up and punch its way out of the casing. 1st gear would be a lot better if it was not made from brittle cast iron. Its not uncommon to have the diff pop out of place if the retaining circlip becomes unseated (sometimes tack welding this into place can fix that. Upgrading to a JC5 casing and bolt-in diff would be better.
JB5 is a 5 speed gearbox found on the NA's 5’s. It has a shorter case (bell housing to end cap) and narrower gears; much less strong than a JB3. JC5 is the Williams/172/182 unit and is the preferred gearbox, ratio's aside, because they nearly all come with a 4.07 final drive, which is a bit short for a typical GTT revving to 6500rpm. Put the final drive from the GTT's JB3 into a JC5 and you're onto a winner.