Racecars - Building a car for competition May 06, 2020, 08:57:48 PM A big shout to TomRich for putting this together.We were talking the other day, and decided we’d try and put together some information on what is involved in turning a humble Golf into a car which is happy to go racing.This is not going to cover all bases, it is not going to give a hugely in depth or deeply technical run down of everything that is possible, and some things won’t be covered at all, but hopefully it will be mildly interesting or at least informative for people who have thought about doing this or just wondered what is involved.We’re going to skip the first step where you either dismantle your chosen complete car or collect a bodyshell, and we'll also skip any component, part, tool or kit purchases you need to make. Just straight into the work itself in a series of posts starting at the ground up. The pictures are compiled from various cars we’ve had around, so when it changes colour repeatedly don’t worry!An important note before starting, please understand what’s meant by a racecar here, we mean competition cars.We are not talking about cars that may see a one off track day, though fair play to these folks :thumbs: Nor are not talking about cars which go quickly on the road and have a few fruity bits fitted to them, also fair play :cool: And definitely not ‘race inspired’ show field clutter. If that's your thing, go grab a pumpkin spiced Latte or something :bout ye: No disrespect to anyone or their pride and joy, if it’s your car and you enjoy it then more power to ya, but we’re talking cars which are built for the purpose of getting the kind of stick you can only give a car on track. Even people calling occasional track cars 'racecars' is irritating, so just cool it on all that crap and enjoy what you're doing without any misrepresentation. Preemptive rant over.More importantly than that, it is incredibly important to look into what series or events are available to your chosen car, looking at the regulations of those series (and others) to see which way to go and making a plan which will work and trying to stick to it. Don't get sucked into trying to build a BTCC car on an individuals budget. Getting out and having fun in a lesser spec’d car, and improving on it later, is more valuable than going to town and spending years in the garage… ask me how I know. Seat time is king! :thumbs: Some series like the Production GTI Championship is very conservative with what you’re allowed to change on the car, leading to great racing and (fairly) evenly matched cars. Some like the Classic VW Challenge give more scope for modifications and have some very serious cars in the field, organiser Ken Larks Corrado for example, and some like the Scottish Saloon championship and Pembrey’s Welsh Sports & Saloons championship are incredibly liberal letting you run big turbo’d 20v’s and slicks and whatnot and even featuring ex-BTCC cars on occasion :shock: As said we'll be starting at the beginning, so the first post will be on the car itself in the most basic state.Thanks,TomThe ShellIt’s always a good idea to kick things off with the bodyshell itself. In a perfect world, you’d have a brand new pre-production shell, which you’d have had pulled off the production line before the seat belt brackets and so on, underseal, all those things have been put on, you’d send it off for acid dipping to get the coating off the metals, your staff would weigh it, crack the computer design and simulated testing, complete the fab work, moulding and final assembly in some insanely rapid time frame and you’d forget about it until turning up to pre-season testing without a care in the world to get busy behind the wheel. BUT we’re assuming for the sake of this thread, and real life, that your build starts like most of ours.So in stark contrast to the above, you pick up a shell which has seemed like a winner to you, the best you can find for the money you have or simply all that is available, and you’ll hopefully have a fairly solid starting point to get cracking on with. Prepare to spend the next few days / weeks / months covered in metal dust, sucking in toxic fumes, burning yourselves, and generally being a badass.First things first, get yourself a clean slate. Get rid of all that bitumen, sound deadening, underseal, all those things that make your road car a nice pleasant place to be. In some pics, it is already removed, but all locations are outlined whether they’re there or missing.Interior wise, there are individual patches on the rear panelInside the rear quarter panels rearward of the rear turretsInside the rear quarter panels behind the interior rear quarter cardsInside the front doorsOn both of the interior surfaces of the front wheel wellsAnd on the shifter tunnelThese are easily removed with a wallpaper scraper and a heat gun. It is handy to sharpen one side of the wallpaper scraper *slightly* with a sharpening stone, a belt sander or something along those lines, but leave the other side, which will meet the panels while scraping, to avoid skagging the metalwork or making the bottom of the scraper an uneven surface which will make your life harder. As far as the amount of heat required, you’ll get an eye for it very quickly. Do small areas at a time as it cools quickly, heat the area moderately, it doesn’t need to smoke or bubble, you just need to warm it up a touch, get that portion out of the way and move on.The firewall’s interior side is also covered in these, so they've gotta get it too. On top of this, both the front and middle sections of the floor pan are covered in a bitumen kind of coating, which is deceptively weighty once it’s all clumped together.This comes off better without heat for the most part, as when it’s cold it chips and isn’t stuck as rigorously as the individual pads, so with a good sharp scraper and moderate force at the right angle you can take it all off without much grief. It’s worth eyeing up where there are seams and joins in panels etc as well so as not to keep smashing a scraper into the OEM seat crossmember or similar.There is a big sound proofing mat, seemingly made of clothes from the holocaust blended with some leftover disgusting felt stuff and a black rubbery backing. There is some under the carpets, some covering the firewall / bulkhead, and some with the rubber backing stuck directly to the inside of the roof and the metalwork beneath the dashboard.After this, the actual body is properly exposed. What may have looked like a very solid car may now not look like it did with a thick coating of tar, but hopefully it’s all okay. Identifying, assessing and sorting out any corrosion, holes or anything structural makes sense at this point. A good straight base is invaluable, so take care of anything that needs taking care of so your work later isn’t wasted on a rust bucket.The next logical step in our opinion is to bin the unused brackets and mountings that you will no longer be needed. Off the top of my head, the washer bottle bracket in the bay, moving to the inside the rear seat base, the rear seat upper brackets on the rear suspension turrets, the rear seat belt mounting bolt plate in the C Pillars and behind the rear turrets.With some of these, such as the front seat crossmember and the front seat rails, your best approach is to cut off the bulk with a mix of angle grinder, air saw and even tin snips to minimise the amount of grinding back you need to do afterwards. The reason for my opinion on this, is due to the shear volume of spot welds attaching them. Cutting the bulk off and grinding then flap disc-ing down the remainder is much quicker.So once you’re left with this, for example, just grind out what’s left until this skin is thin enough to lift, just don’t prise skins apart with force, as you’ll just bend the one you’re keeping and make a mess.With others, like the washer bottle bracket, rear seat belt upper bracket (pictured), the easiest approach is to drill out the handful of spot welds which attach this ‘skin’ to the panel beneath it, as they're much less concentrated than on the areas covered before.Seam sealer and the rubberized stone chip stuff is the final hurdle in terms of now-unnecessary crap stuck to your shell. There’s a mountain of this, seam sealer all around the engine bay, on many of the panel joins in and under the car, coating all four wheel wells and the entire underside of the car. This definitely shouldn’t be any kind of priority, but if seam welding or going full bore to keep weight down you’ll find yourself doing this at some point, at least to some extent. Same old heat gun and scraper job here with the wire wheel on a drill or preferably angle grinder and a rag with paint thinner or panel wipe to finish up the job.It’s worth remembering the panels themselves have a little weight to give up as well, the inner skins of the doors for example, but before getting too keen on cutting things up this is one of those check and check again moments for your rulebook. Interestingly, the MSA excludes bolt-off panels from its definition of “bodyshell” in its regulations, so that’s nice By this point, hopefully you’ll end up with a nice bare shell, with the factory weight and provisions for a nice quiet car well and truly having gone out the window.Roll CageThe next thing to address is the lack of anything resembling a climbing frame. A well built roll cage can save your life, and a badly built one can kill you, or at the least not help if needed. A lot of the time it doesn’t come to this, and of course that’s a good thing, but with things like roll cages, seat mounts, brakes and whatnot, it pays to think in this way as if things do go wrong and luck isn’t on your side, it can be this serious, and you can’t race or party if you’re dead. There are countless videos on Youtube from British circuits in ‘regular’ tin top racers, it is a very real concern.It’s important to check the regulations again here, most series in the UK simply reference the MSA’s Competitor Safety section, which gives all the information you need to build a compliant cage. Read, re-read and keep it handy whilst building :thumbs:The basics, and I mean basics, are that mounting feet must be 3mm thick steel and cover an area of 120cm2. The cage should be as close as possible to the pillars etc and follow them properly. All mandatory tubes which must be present in any cage - the Main Hoop, the A Pillar bars, the Windscreen bar, the rear Upper Stays and the one mandatory Diagonal, which can be set across either the rear Upper Stays or across the Main Hoop - must all be made from 45mm O/D seamless tube with a 2.5mm wall thickness. Optional tubes, such as rear lower stays, harness bars, etc, can be made of 38mm OD 2.5mm thick or 40mm OD 2.0mm thick tube, which can save a little weight but sometimes it saves money and keeps things simple to just use 45mm OD 2.5mm thick tube across the board. Specs vary for T45 tube compared to steel, but it’s all in the Competitor Safety section.It’s also worth noting, some cages do not comply to these regulations but are still legal. As an example, the Safety Devices Mk2 Golf cage was designed, originally built and then homologated and certificated when regs were more lax. This means the tubing is 38mm OD throughout, so while if you made your own cage like this, or modified one of these cages, you would not pass scrutineering, as an off the shelf item from Safety Devices with the certificate they provide it is still legal for competition now, even after the regulations have been updated. Never black and white, always check and re-check, always do your own research and always ask (MSA, a local scrutineer, etc) if you are unsure.Here’s an example of a weld in cage, kept basic to keep weight down, going for a full bore WRC looking cage will look very nice but there’s already upwards of 60kg of weight in a basic cage, so bear that in mind.If you choose to fit a weld in roll cage as opposed to a bolt in (which will still require proper welding of mounting plates to be legal and effective) you can increase the rigidity of the chassis even further. Often these are gusseted to additional points on the car besides the tubes mounting locations, most noticeably the A Pillars, and frequently there are additional tubes passing through the firewall to fully tie the front suspension turrets into the rest of the roll cages structure. This is obviously very good for very stiff suspension, very sticky tyres and a healthy dose more power in an aging shell.There’s loads more to this, but this is simply an overview for the sake of this thread.Seam WeldingSeam welding is a good place to go once the cage is in. This is tricky, as generally it’s dirty ‘car metal’. You need to be committed when you fire the welder up, as bits will blow through and you don’t want to leave holes, so get stuck in. The best way we’ve found is to wire wheel the areas that are getting your attention, blow torch them briefly to get the sealant to run out from between the skins, let it cool, wire wheel it again and that will minimise how much runs out when you start welding, but you’re bound to get some, so keep it in mind. You wouldn’t want to do more than an inch on to an inch off, so inch welded, inch skipped, inch welded, and so on. A lot of people say an inch every two inches, but either way I find it useful to map this out with a Sharpie before starting as I lose track once I start otherwise, and a massive irregularity can look a bit odd if you’re concerned about that. We weld 20mm, skip 40mm, peachy.We never go further forward than the front suspension turrets, or further rearward than the rear suspension turrets, so you still have some form of worthwhile crumple in the shell in a big impact. Think about it this way, what good is it going to do stiffening up areas of the car that have no bearing on handling or anything anyway, if it has a cost. And that cost will be more force transmitted to YOU in a big smash after hitting something at pace. Not cool.Seam welding is fairly time consuming and with a proper weld in cage, there’s a fair question over whether it’s worthwhile for an individual building a car for clubman use. If you have the time to kill between buying parts, feel like you should give it a go, or just plain think “if the pro’s have it, there must be something to it, so I want it” then by all means crack on. I’ve done it on mine for all three of those reasons. But likewise, there are fast cars competing without any noticeable seam welding and others with just key areas like suspension turret-to-shell joins for example seam welded, rather than doing every join on the car outright.Seat tubesMounting your seat is as important as anything else. I’ve seen a seat come out simply under acceleration on a trackday, I’ve seen a seat pull it’s mounting bolts through their mounting points in a crash, and you don’t want this happening when it’s your ass that’s planted in the seat in question. Typically, seat tubes are welded in, with spreader plates at either end and brackets coming off them forwards or rearwards to put the seat where it’s wanted. Once fully welded in, these are bombproof. Most kits have brackets with floating nuts to allow different width seats to be fitted and allow a small margin for error in bolt holes, and most side mounts which bolt to these to then bolt to the seat have numerous holes in them to allow for angle changes to the seat and movement forwards and backwards to suit a shorter or taller driver in the future, within reason. An important note here is to use properly sized washers on the bolts from the seat tube to the side mount, to stop them pulling through, and also to use a washer on the bolts from the side mount to the seat itself.Interior and safetyMoving onto the actual parts and whatnot for a moment, obviously all this info is out there too, so I’ll keep it relatively brief. Starting with the seat a seat which should be a fixed bucket with a suitable harness, so a 5 or 6 Point with a proper buckle. You can’t really release road car style seatbelt buckles if you’re upside down with your weight tensioning the belt, so that’s why those are illegal for race use. Both the seat and harness need to be FIA approved items and also in date, as they’re lifed for about 5 Years from the date of manufacture. For the steering wheel, it pays to have a proper (not eBay crap) quick release boss kit to aid in getting out of the car over the seat and door bars. Remember GTI International the other year when a mickey quick release boss let go? Yeah, you don’t want that at 130 odd :thumbs: Then it comes down to an extinguisher, battery kill and the rest of the things you need, i.e. dash, clocks, pedals / pedal box, shifter, the usuals really. The extinguisher will be regulated by the MSA with regard to size and is also a lifed item. The killswitch should be wired properly so it doesn’t let the car run on with power from the alternator, but as said this is an overview and wiring diagrams are easy to come by. Both the extinguisher and kill switch need to be operable by the driver in their normally seated position with the harness fastened and also by a Marshal outside the car, so you will run pull cables, or wiring if electrically operated, to the scuttle panel to activate these as well as having them within reach of the driver. The battery kill needs to isolate all circuits on the vehicle, excluding the extinguisher system if it’s electrically activated, and the extinguisher needs to be the correct extinguishant, properly charged and at least 2.25 litre capacity with lines to a nozzle for the engine bay and the interior of the car.Again there is way too much going on to cover an entire interior and all the parts it is made up of in detail, so please take this as a basic run down to spark your own research.