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How To Build A Rally Car

发表于 2009-6-9 03:21 | 显示全部楼层 |阅读模式

Ever wondered what it takes to turn a car taken off the production line into a competition car capable of challenging for the British Rally Championship? It's a huge task. Here the latest Evolution 2 version of the SEAT Cupra Sport Ibiza which Gwndaf Evans will drive this season goes from a bare shell and roll cage to the complete car ready for testing and the rally in Wales.

SEAT Ibizas are tough cars but look at the punishment Gwyndaf Evans or Harri Rovanpera gives his over hundreds of miles of rally stages and you wonder it survives, let alone wins. Watch one being up before the season and you start to understand. This particular car came off the SEAT production line near Barcelona like any other then the rallymen descend on it, preparing it for Harri Rovanpera's use in the 1997 F2 Rally Championship. The make over is incredibly thorough with the completely stripped shell fitted with a full roll cage. Yards of thick 48mm tensile chrome-moly steel completely surround driver and co-driver.

It serves two purposes, obviously to providing a survival cell that can wit***tand rolling the car off the side of a mountain, with impact bars strong enough to take high-speed slides into unyielding trees and rocks. Crew safety is just part of the story though; the cage connects all the crucial points of the car together, which in a race or rally car is basically all the suspension pick up points, and it keeps the shell in alignment whatever punishment it suffers.

Welding in a roll cage alone makes the car far stronger than the standard road car but rally cars need to go one stage further. The various panels that go to make a road car are just spot-welded together with small welds every two or three inches. Look at every panel join on this Ibiza and there's a continuous line of weld along each one. This seam welding, along with the roll cage produces a structure with a torsional stiffness of 26,500 lb/degree. That's several times stiffer than the normal road car, far more than the old Evo 1, and nearly as stiff as a BTCC Touring Car. This strength and stiffness is absolutely vital because rally cars have to survive as precision racing machines.

That precision starts in the factory in Spain where new suspension mounts to take the specialised components used are welded in with extraordinary accuracy on jigs. The aim is to have each point located exactly where the design engineer's computer has dictated, to within a quarter of a millimetre. Contrast that with a road car. Once the effect of looser production tolerances, coupled with the use of rubber mounting bushes, are taken into account accuracy may only be to within nearer 4mm.

It may not sound much but it's enough to make all the difference in handling. This way there's no slop, no compromise.

Regulations allow the designers to move the suspension mounting points within a sphere of 20mm, that is in and out, up or down. That means the rally cars have to keep, more or less, the sort of suspension found on the road cars but even if the basic specification is the same there's a world of difference, Take the Ibiza's rear suspension. On the road car it's a simple beam. On this year's Evolution 2 rally car it's a complicated system fabricated from aircraft quality light high tensile steel, with two trailing arms mounted on a beam so the rear suspension is fully independent. Those two arms are braced by 2 Panhard rods stretching across the car to give sideways location. Those rods are allowed even though they are not on the road car because they use location points that can be found on the standard car. Successful race car designers have to do everything the rules allow, an example of the ingenuity needed to win.

Why go independent at the rear? As Chief Mechanic John Down explains, "It gives fewer geometry changes over jumps, with less of the kick back through the car when it lands on one wheel, and it gives a better spread of heat through the tyres. You can even see the difference between the cars fitted with and without it on rallies just on the way they behave."

Even more important on these front-wheel drive only cars is the front suspension. Extremely strong fabricated wishbones (long for tarmac events to give more negative camber) are mounted to a vital component. The new crossmember, which holds suspension and steering rack in place, is quite different from the standard steel pressing. It's made in aircraft spec T45 steel, welded up and heat-treated to wit***tand the constant enormous shocks generated when the Evo 2 lands nosedown on its front wheels.

Look more closely and you'll see that those shocks are transmitted up directly into the roll cage so the whole structure is sharing the load.
How To Build A Rally Car.jpg
 楼主| 发表于 2009-6-9 03:21 | 显示全部楼层
Its one more indication of how much more advanced in this year's Evo 2 car compared with the Evo 1 which itself has brought SEAT so much success. The Evo 2 seems more like a tubular structure with a body around it while the Evo 1 was more like a shell stiffened by a roll cage. On to that new crossmember goes a new steering rack, with far fewer turns of the steering wheel lock to lock than standard, with most drivers liking two and a half. Power assistance is upped thanks to far greater hydraulic pressure from the power

steering pump and the amount of assist is tailored to each driver, usually at the beginning of the season, via different shims in the pump. In the SEAT team, as John Down explains, "Gwyndaf likes nice light steering while Barbara Armstrong likes much firmer steering."

Everywhere you look on this production based class the end result is far removed from any road-going car. John Down again "About the only thing you could buy off the shelf in the parts department would be the glass and headlights." Everything else is different or modified. Take the rear wings; surely they look different? You're right, they are flared to cove the wider track and far larger wheels and are made of lighter gauge steel.

The engine is production based but that gives quite the wrong impression. Although it has to be the same two litres and remain normally aspirated rather than turbocharged it's still quite different from the 16valve 1984cc 150bhp unit found in the Ibiza Cupra Sport road car. The standard block and head have to be retained but the head is reworked with larger inlet and exhaust ports, along with larger valves made in titanium.

Crankshaft and connecting rods are new, and made out of very high strength steel. The rods are also as light as possible, as are the pistons to minimise the reciprocating weight spinning around and help the engine rev as quickly as possible to 9000rpm. Naturally the camshaft timing is nowhere near that on the standard car.

As an example of how much work goes into the engines, the sump alone takes 40 hours to build up. It's full of very complicated baffling to stop the oil draining away from the pump in violent cornering because even a split second's lack of pressure ruins the engine. Race engineers would prefer dry sumping where the oil is pumped around from a separate tank but these cars have to stay closer to road car design.

Other features are just as far away from the production car, such as the £2700 worth of carbon clutch and associated flywheel, or the two rail fuel injection system which can switch from four to eight injectors to produce maximum power. It's no surprise these engines need frequent attention and SEAT are regularly air freighted to the specialist engine builders Mader back in Switzerland for an expensive rebuild, typically after two rallies and a test session.

These engines are extremely valuable assets and they've protected by water-to-oil heat exchangers rather than conventional radiators alone to keep temperatures as steady as possible. Rally teams run two different engine specifications, one with more outright power, (something beyond 270bhp, but no one gives away precise figures in this business), for fast tarmac events where the car might be geared for 125mph. The gravel spec engine in contrast will have less power but more torque, with the car geared for a lower maximum nearer 110mph.

To give the drivers the best chance to exploit all this power the standard five speed gearbox is thrown out and replaced by a Hewland six-speed sequential unit closer in spirit to a motorbike gearbox and the driver only has to move the lever one way to change gear at lightning speed.

It's the interior of the Ibiza which really brings home just how different these cars are, All the standard interior and trim is junked. Extra mouldings are made up to supplement the standard left-hand-drive dashboard moulding to take a huge array of equipment.

There's a large bank of relays on the right, the trip fuses (which the co-driver can reset in a split second when on the go), radio, and trip meter. The driver's given additional information too - a digital rev counter reading beyond 9000rpm.

As Gwyndaf and Barbara will be almost always be too busy to look at that, shifting close to full power with right foot to the floor, there's a reminder light mounted on top of the dash. That indicates when the engine is at full power in each gear and it's time to shift, while there's another to show when the gearbox is in neutral (again as with a motorbike, and vital with a sequential type gearshift for the mechanics as well as the driver). There's even a display to indicate which of the six gears is in use.

As you watch the car take shape in the SEAT Cupra Sport workshop it looks bullet proof but many of these components won't be around long at all, strong as they appear. They are 'lifed' as in the aircraft world, in other words used only for a certain time and then changed regardless of apparent condition because the risk of failure is too great. Driveshafts will only be used once despite being over £1000 each. In the same case with the steering and suspension joints while other parts not automatically lifed are X-rayed and crack tested as a precaution.

With a modern rally car nothing is left to chance but the designers, engineers and mechanics can only do so much. Then it's down to the driver and navigator.


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发表于 2009-6-9 04:07 | 显示全部楼层
发表于 2009-6-9 08:19 | 显示全部楼层
发表于 2009-6-9 09:25 | 显示全部楼层

Ever wondered what it takes to turn a car taken off the production line into a competition car capable of challenging for the British Rally Championship? It's a huge task. Here the lates ...
WRC 发表于 2009-6-9 03:21




它有两个目的,显然是为了提供一个生存的细胞,可以机智*** tand滚动的这辆车一侧山区,与影响酒吧强大到足以采取高速陷入不屈树和石头。乘员安全只是故事的一部分虽然;笼连接的关键点,所有的汽车一起,这在一个种族或拉力赛车基本上是所有暂停拿起点,并保持一致的shell它受到任何惩罚。

焊接在防滚架单独使汽车远远优于标准公路汽车拉力赛车,但需要去一个阶段。各个小组的进入,使公路赛车只是点焊连同小焊缝每两年或三年英寸。看看每个小组参加关于这一伊维萨和有一个不断线沿线的每一个焊缝。这焊缝,连同防滚架生产结构,抗扭刚度二点六五〇万英镑/度。这几次严厉高于正常公路汽车,远远超过旧埃沃莫1 ,几乎僵硬作为膀胱癌房车。这种强度和刚度是绝对重要的,因为拉力赛车的生存精密赛车机器。




为什么要独立的后方?作为首席机械师约翰向下解释说, “它使较少几何变化跳跃,以较少的球回的汽车通过时,一个车轮的土地上,它提供了更好的传播热量通过轮胎。您甚至可以看到的区别车辆之间的安装和它的集会只是他们的方式行事。 “

更重要的就这些前轮驱动的汽车是唯一的前悬挂。极强的捏造叉(长期的停机坪活动提供更多的负面拱)是安装在一个重要组成部分。新crossmember ,拥有悬挂和转向齿条到位,是完全不同的标准钢紧迫。这是在飞机规格T45钢,焊接和热处理即*** tand不断产生巨大的冲击时,埃沃莫2土地nosedown其前轮。



参与人数 1速道米 +30 收起 理由
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发表于 2009-6-9 09:26 | 显示全部楼层
Its one more indication of how much more advanced in this year's Evo 2 car compared with the Evo 1 which itself has brought SEAT so much success. The Evo 2 seems more like a tubular structure with a b ...
WRC 发表于 2009-6-9 03:21


转向泵和数额的援助是针对每个驱动器,通常是在本赛季开始,通过不同的垫片的泵。在座椅团队,约翰跌解释说: “好轻Gwyndaf喜欢芭芭拉阿姆斯特朗指导,同时更坚定的指导喜欢。 ”

你看看世界各地生产的基础上这一类的最终结果是远离任何道路正在进行汽车。约翰再次“只有一件事情你可以购买现成的零件部将玻璃和车灯。 ”一切是不同的或修改。采取尾翼;肯定他们期待有什么不同吗?你说得对,他们是来湾爆发更广泛的跟踪和大得多车轮和作出的打火机衡量钢铁。

发动机生产基础,但是,让不少的错误印象。虽然它必须是相同的2升,并保持自然吸气,而不是涡轮增压它仍然不同于16valve 1984cc 150bhp单位发现在伊维萨Cupra体育路车。标准块和头部都必须保留,但头部是返工与较大的进气口和排气口,同时取得更大的阀门钛。

曲轴,连杆是新的,并提出了非常高强度钢。棒也轻如可能,而活塞队,以减低体重往复旋转,并帮助周围的发动机转速尽快9000rpm 。当然,凸轮轴时机远不说,标准的汽车。


其他功能也同样远离汽车的生产,如£ 2700元的碳离合器及相关飞轮,或两个共轨燃油喷射系统,可以切换4至8喷嘴产生最大功率。这是毫不奇怪这些发动机需要经常注意和所在地定期空运的专家引擎建设者马德在瑞士昂贵的重建,通常在两个集会和测试会议。

这些发动机是极其宝贵的财富和他们所保护的水,以油换热器,而不是传统的散热器仅保持温度不变的。拉力车队运行两个不同的引擎规格,一个更直接权力, (一些超越270bhp ,但没有人给出了确切的数字在此业务) ,为快速跑道事件的车可能是针对一百二十五英里每小时。砾石引擎相反将有更低的功耗,但更大的扭矩,与汽车面向较低最高接近一百一英里每小时。



有一个大的银行的权利继电器,行程保险丝(其中领航员可以重置在一瞬间的时候去) ,广播和访问米。司机提供更多的资料太-数字转速超过9000rpm反读。

作为Gwyndaf和芭芭拉将几乎总是太忙看的是,转移接近全功率与右脚在地上,有一个提醒轻安装在顶部的破折号。这表明当发动机在全功率在每一个齿轮,它的时间来转变,同时还有另一个显示当变速箱是中立的(又与一辆摩托车,和重要的序贯式换档的机械,以及司机) 。甚至还有一个显示说明其六个齿轮正在使用中。

当你看到赛车形成西亚特Cupra在体育研讨会看起来防弹但其中许多部件就不会再长了,强大的,因为它们出现。他们是' lifed '在世界的飞机,换言之,只用于特定的时间,然后明显改变,不论条件,因为失败的风险太大。传动轴将只能使用一次,尽管超过£ 1000年每个。在同一案件中的指导和中止关节,而其他部分不会自动lifed是X光检查,裂纹检测,以防万一。



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KANON + 15 奖励!


发表于 2009-6-9 09:28 | 显示全部楼层
发表于 2009-6-9 10:44 | 显示全部楼层
发表于 2009-6-9 13:35 | 显示全部楼层
hebin 发表于 2009-6-9 09:28

发表于 2009-6-10 17:21 | 显示全部楼层
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