Print and Go Back ESPN.com: Rally-Moto X [Print without images]

Thursday, July 25, 2013
Updated: August 1, 11:09 PM ET
Thirteen signs of a broken rallycross car

By Jen Horsey
XGames.com

Rallycross cars take a lot of abuse and sometimes it's hard to tell from the grandstands what's really the problem.

A bumper hanging off as a car flies over a jump looks dramatic, but the driver probably doesn't even notice it. A seemingly innocuous puff of blue smoke from a tailpipe in practice could be an early sign the car won't make the final.

Here is a list of an unlucky 13 things that I'm looking for when I go check out the cars in the pits before a race -- and from the commentary box during competition -- and what they mean for your favorite drivers:

Dave Mirra
Dave Mirra races on at GRC Round 5 at Bristol Motor Speedway despite part of his bumper hanging off.

1. Body damage
Unless the car has taken a really hard hit that impacts a mechanical component or crunches body panels into the wheel wells where they can interfere with turning or cut a tire, body damage only looks bad. The cars are built tough and most of the important components are tucked away where they aren't likely to be damaged in a hit. Wheel imprints on doors, bumpers hanging off and crumpled fenders aren't going to affect the handling of the car. As far as the race mechanics are concerned, those cosmetic problems are the reason duct tape was invented.

2. Blue tire smoke
When a driver hits the brakes hard on tarmac, the wheels stop. But, if the car's going too fast it will keep moving and slide on those locked-up tires. The resulting puff of smoke smells like rubber because that's what it is, and it creates a little flat spot on the tire. That's not a huge problem in rallycross, but watch and see how that driver handles that corner on future laps. You may just have discovered his driving kryptonite and you can bet he's going to try a different technique the next time through it.

3. Glowing brakes
When the driver is braking for sustained periods of time, the brakes get so hot the rotors start to glow red. The brighter and closer to white the glow, the hotter they are. If it's happening on the last lap of a heat, it probably doesn't matter. But if there's still half a race to go, the driver could be in trouble. Brakes being used at the limit this way become less effective over time and the driver will increasingly struggle to get the car slowed down. It's also a sign that grip may be compromised because if the brakes are getting used up, so are the tires.

4. Flat tire
Taking a corner and a bump together at just the wrong angle often causes flat tires. The tire doesn't actually get a hole in it, rather the force of the impact pulls the rubber right off the wheel. The drivers will continue to drive on the bare wheel because there's no time to stop and swap it for a new one.

It can be hard to notice a flat tire from the grandstands but one early clue is the car will begin handling strangely on either lefts or rights. If a right-side tire is flat, left turns will be problematic because the weight of the car will be on the flat tire -- which isn't there to grip the course anymore -- and vice versa.

Front-end flats are worse than rears because it's very hard to steer with a flat front tire. Very occasionally, a tire can wrap itself around a strut or even delaminate -- that is, tear itself apart -- and the consequences can be very bad, with pieces of tire even cutting into the engine bay and slicing through wires. In rallycross this almost never happens, although it happens with some regularity in the longer-form version of rally, and it's something many of the drivers have experienced.

5. Dark cockpit smoke
You know the saying, "If there's smoke, there's fire"? It's usually not the case in racing, but this time it's probably true. Often the culprit of smoke in the cockpit is electrical -- the rubber coating on some wires is burning. When there's enough smoke in the cockpit that it's visible from outside the car, the driver is probably about to pull off and rush back to the pits for a fix. That smoke is acrid and it's very hard to see and breathe when it gets thick. Plus, it's probably getting hot and it's only a matter of time before something critical stops working and the car stops on its own.

Liam Doran, Ken Block
Liam Doran won a gold medal at X Games Munich despite running the final laps on a flat tire. Fortunately for him, it was a left rear tire and he was able to hold off Ken Block on a course with mostly left turns.

6. Erratic handling
If all four tires are still round and the car's still behaving strangely, then something's probably broken and the most likely culprit is a broken drive-shaft or maybe the steering linkage.

7. Blue tailpipe smoke
A puff of blue smoke from the tailpipe when the driver lifts off the throttle is a bad sign for the long-term health of the engine. That's oil that's burning, and the engine needs that. It's a problem that usually gets worse until the engine blows up, so if there's another day of racing ahead, blue smoke could mean the team is preparing for an all-night engine swap.

8. Black tailpipe smoke
When the smoke that comes out of the tailpipe is black, with no blue hue to it, that's unburnt gasoline. It signals that something isn't quite right with the engine. Impending engine failure is certainly possible, but that's not usually what this signals -- depending on the particular reason that motor is "running so rich" (as any mechanic will say to describe the problem of having more fuel in the engine than it is burning). Another clue: It smells like a gas station.

9. Steering wheel shake
This has probably happened to you: You're driving along the highway and your steering wheel starts vibrating wildly in your hands when you reach a certain speed. When you feel it, it probably means you've lost a weight from one of your wheels (and you should go to a shop and ask them to balance them for you; it's a simple and inexpensive job).

When that happens in a rallycross car, the likely culprit is added weight in the form of a whole bunch of mud or dirt that's clinging to one or more wheels. The mechanics will fix it by cleaning the car.

10. White smoke
Dense, white smoke often signals the end of the line for a turbo and it won't be long after the first puffs that the car slows down. The engine might start sounding funny -- in the parlance, it's described as "soft," because it can't make the power to be as sharp and responsive as it should. When the turbo does fail, white smoke can emerge from under the hood as well as the tailpipe, and suddenly introducing a whole lot of oxygen -- like, say, by opening the hood to see what's up -- sometimes sparks a fire.

11. Sweet, white steam
It can be hard to tell white smoke from white steam but, if you're close enough, the particular kind of steam that cars in trouble are going to be making smells sweet, with a hint of lemon-lime jellybean (I'm not kidding).

Although it smells kind of nice, steam signals big trouble for a car's engine. If it looks like it's coming from inside the rear of the car, it's venting out of the rear-mounted radiator and signals that the engine is overheating and the car has to stop soon or it'll be game over. Also, though this is rare, there could be scalding liquid escaping into the car in that general vicinity.

If the white clouds are coming from the tailpipe, you could also be looking at a car that's just blown a head gasket -- also bad news for the engine. In that case, what's coming out of the car is mostly coolant that's turning to steam inside the hot engine and shooting out the tailpipe. The thing is, coolant isn't supposed to be able to get inside the engine at all, and that car is about to pack it in for the day.

12. Rotten eggs and fish smell
The smell is characteristic of the very slippery and very expensive oil used to lubricate the transmission. It is a noxious smell and it lingers in the air. If you smell it, but none of the cars have stopped, watch and see if one driver seems to be struggling to keep pace with the field in a certain range of speed. He may have lost the use of one or more gears and now will be trying to drive around the issue by using the other ones. That might work for a couple of minutes, but it's a problem that often gets worse fast because broken pieces can wreak all kinds of havoc inside the transmission.

Meanwhile, back in the pits, if the team has a huge, cone-shaped metal thing on standby, they are planning to race the clock on a transmission swap. It's a big job and it could take more time than the mechanics have between heats, but it's impressive and absolutely worth sticking around to watch. There will be lots of high-fiving if they get it done.

13. Cracked paint
While a few love taps and dents to the body panels don't mean much, a hit that's hard enough to send shocks through the frame of the car and crack the paint probably ended that car's race early. If there are paint cracks on the chassis (under the hood, for example) more than a couple of inches away from the point of impact, it's a sign that the frame of that car has taken a very hard hit and the damage is more than skin deep. After the mechanics have replaced the other parts that are broken (because there are certainly other broken parts) and the car returns to the course, undiagnosed issues could start to emerge under the stress of racing.

If the paint on the roll cage is cracked, that's even worse, and officials usually won't let the car race again without a major rebuild.