PT Cruiser owner regrets purchase, wants to improve the car he can't afford to dump
June 13, 2008 7:43 AM   Subscribe

I'm an ignorant person when it comes to cars, so this is a pretty dumb question. I own a 2007 PT Cruiser which has no anti-lock brakes. It skids like crazy, and got me into a minor accident. Is there any way I can get add anti-lock breaks to it?

My mom's friends told her that the best way to buy a car was to get an auction proxy, so we went to an auction lot to go car shopping. We were intending to get a compact Japanese car with decent milage. However, the proxy talked us into getting a 2007 PT Cruiser which was $9000 on the lot. I was no fan of the aesthetics of the Cruiser, but I did like the interior space and the fact that the proxy pitched it as being 28 MPG (A good but not great amount. Turns out he was mistaken, it gets 20). We rushed to bid on it, and the next day we got it, only to discover it was a cheap model with no antilock brakes. I don't blame the proxy for this, he was as surprised as we were, and I really don't think this is in the spirit of false advertising. It's just the nature of auctions, it's fast paced and you don't get to test drive the car, and I had no prior knowledge of how a PT Cruiser drives.

I'm no good at threshold braking and recently skidded into a guardrail because a guy behind me in a huge truck was tailgating me at a high speed. It was scary, and it took two weeks to get it repaired, but insurance paid for it, and I was okay. I now know I should have taken that turn slower, or let the guy in the pickup hit me.

The guy at the repair shop says the brakes are pristine, so I can't blame it on old brake pads. The mechanic did remark he got 3 PT Cruisers who got into the exact same type of wreck.

This brings me to my question. I would love to trade in the PT Cruiser for something that I can afford to buy gas for and with good enough brakes to handle the curvy roads in my town. However, it seems to be outside of my means to do so. Would it be possible to augment the car with an antilock braking system? Or if not, is there a good, safe way to learn how to threshold brake?

Thanks for your help, guys.
posted by mccarty.tim to Travel & Transportation (22 answers total) 1 user marked this as a favorite
 
No, it is impossible and/or far outside the realms of financial sense to retrofit ABS. Wiring looms, plumbing, valve blocks and all sorts need to be changed. Forget that idea straight away.

I'm no good at threshold braking and recently skidded into a guardrail because a guy behind me in a huge truck was tailgating me at a high speed.

The problem clearly is you, I'm afraid. If someone is tailgating you "at high speed" then just slow down. Just because you didn't create the dangerous situation doesn't mean that you can't be the one to remove the danger. If you readily admit you struggle with braking at the limit (which clearly needs addressing) then you should not be driving at high speed without enough space in front and behind you to react within your limits. To do anything else is dangerous and irresponsible.

I'm sorry you were steamrollered into buying a PT cruiser - they are awful cars (dynamically and from a fuel economy point of view). But being as you are driving one, you need to drive responsibly and within the limits of the car and yourself and not blame your accident on the guy behind you.
posted by Brockles at 8:07 AM on June 13, 2008 [5 favorites]


As for learning to 'theshhold brake', a bigger part of learning is planning and awareness. If you plan your driving accordingly, you will only need to use your brakes to their fullest effect in extreme circumstances - by which I mean something breaks on your car, or someone has an accident in front of you with no warning. It is not something you should ever need or rely on in 99% of driving. Proper driving is the removal (to the best of your ability) of the need to use the limits of your car.

Like oversteer and sliding/skidding, often the problem is that panic sets in - not that you turn into a gibbering wreck, but that your responses and ability to reason are affected. Familiarity and understanding are the best responses to that (in addition to the removal of the need to use, as above...). Take a skid pan course and ask the instructor to help you understand how and why wheels lock - it's not just as simple as braking too hard.

Also, go to a large gravel/dirt area and drive between two points and brake (from the same starting point) progressively harder and harder until the wheels lock up and you skid (plan for lots of run off and keep the wheels straight initially). Then do it again until you can predict when the wheels will lock. When they do, release a little brake pressure (lift your foot off, but not all the way). Try this repeatedly until you can start the wheels rotating again. Play with this point for a few hours until you are completely comfortable with it.

The traditional and oft mentioned technique of banging on and off the pedal is actually worse than just allowing one wheel to lock and just using enough foot pressure to stop the car with the remaining wheels, in most cases and familiarity (in a safe environment) is really the only way to understand it without proper instruction.

Points to remember

- you can brake harder at higher speeds - pedal pressure should be reduced as the car slows, and a lot of people press the pedal progressively harder through the braking zone, which is the exact opposite of the grip ability of the tyre to stop the car.

- Always try and brake in a straight line if possible - it is the steering while braking that causes a skid in most cases. Other considerations are trying to make sure you are not braking across a surface change (ie half the car is on gravel) and other elements that require planning.

- if you always leave enough room to stop relatively quickly + 10%, you are unlikely to need to use emergency braking. ABS is an aid to braking, not something that should be used in anything other than an emergency situation. It should not be a substitute to proper planning to avoid accidents any more than airbags are.

In summary, you will not get enough information from reading about it on an internet forum. You will need to practice it, as the reality of the situation causes most of the issues. You need to be comfortable enough with the sensations that they don't shock you into inadvertent reactions that make the situation worse. I strongly advise a skid pan course.
posted by Brockles at 8:22 AM on June 13, 2008 [4 favorites]


I'd never say never, but I wouldn't be too optimistic about the prospects of adding ABS to a non-ABS car. It would be expensive and tricky.

Anti-lock brakes consist of a complete system. This consists of a control computer, a set of sensors on all wheels, and a specially equipped master cylinder. The computer is constantly watching all four wheels via speed sensors, and not just during braking. If one or more wheels slows abnormally while the brakes are applied, the computer directs the system to pump the brakes in such a manner that it avoids locking the wheels. These sensors are usually also used as a traction control system; if one or more wheels start spinning (such as what would happen on a patch of dirt or ice) the computer directs the brakes to bring the spinning wheel under control to match the speed of the other wheels. These systems in many cases also are set up to read your steering wheel inputs and other things, so that it can figure out what you're trying to do vs. what the car is doing. For what it's worth, ABS is one of my required features for any car I buy now. I am someone who is actually very good at braking without it; however, if ABS saves your bacon just once (as it has for me a few times), you'll be thankful for it. No matter how good you are, you can't work faster than the ABS computer.

But more importantly, you need to learn better driving habits, because no safety technology can save a driver that puts themselves in harms' way. For example, the above mentioned tailgater. What's going to happen if you slow down or maintain the speed you were doing before that tailgater showed up? Is he going to run you over? No. I keep hearing about drivers who say "I've gotta drive fast so I don't get run over." Problem is, I don't know of very many people who get hit from behind at highway speeds. I do however know of many people who get in rear-end accidents because they were driving too fast to stop when the rest of traffic did. Or who were driving too fast for conditions and couldn't handle a dangerous situation when it arose. If you've never taken a defensive driving class, I'd do it - and take the course material to heart.
posted by azpenguin at 8:23 AM on June 13, 2008


Invest in some good quality tires. The stock tires on most new cars are sub-par.
posted by runningdogofcapitalism at 8:33 AM on June 13, 2008


I would invest in better tires. There's a wide range of quality when it comes to wet traction for tires. Spend some time on www.tirerack.com and read the reviews/ratings for tires that fit your vehicle.

As an example -- I had high-performance stock tires on my car when it was new. Car used to fishtail very easily (as in, not on purpose) on corners when it was wet. When it came time to replace them, I visited Tire Rack and found some other tires that were very well reviewed, and I put one particular set on, and now I can't make the car fishtail even when I try.

Bottom line: there are definitely tires that perform better than others, and don't take the tire salesman's word for it -- do some research and choose the tires you want.
posted by eas98 at 8:37 AM on June 13, 2008


No, it is not cost-effective to add ABS to a car.

I'll add my vote for "buy new tires" (and keep them properly inflated -- there is a sticker in the driver's side door area that will tell you the correct pressures. Don't assume that the mechanics at the oil change place have properly inflated your tires.) and to consider taking a driving class. Even a so-so car like the PT Cruiser should not be sliding around on the road when there is no ice and snow around.

Get some decent, name-brand tires -- not high performance tires, just regular "all weather" tires with a good warranty and that have good reviews. Costco usually has good prices, as do some of the chains. Get a good tire gauge, keep it in the glove box, and get used to checking the pressures on a weekly basis. It'll cost you a few hundred dollars, but that is a lot cheaper than having another accident.

And please, please take a driving class or two. Regular defensive driving, or one of those fancy drive-fast-on-a-track classes, or ideally both. (Bonus: with the right class, you may get a discount on your insurance.) What you are describing is not a normal part of driving and should not have happened -- imagine if there had been a bicyclist on the shoulder when you started skidding? From this and your previous question, I think you could really benefit from some direct, one-on-one assistance from a professional driving instructor.
posted by Forktine at 9:13 AM on June 13, 2008 [1 favorite]


Here's what the part cost estimate would be for a motorcycle, ya know, just for fun. I know it's not a PT cruiser but its what I am familar with. It's just to give you an idea.

To upgrade a K100(a BMW motorcycle) rear break to ABS you need at least:
a new break disk: $424
a sensor for wheel speed: $195
a bracket to hold that sensor: $26
break hoses: $57 + $31 + $33 = $121
hydraulic modulator: $1734 (no joke: part no 34511457466)
A bracket to hold that: $112
abs computer: $1809 (also no joke: part no 34521459699, controls front and rear wheel)
bracket to hold that: $51

total parts: $4472

Now things might be very different for a PT Cruser. They might use the same rotors on the abs and non-abs models, they might use the same break hoses for both, who knows. If you started with a non-abs K100 you would need these parts. It just gives you an idea of what an ABS retro fit looks like in one case. These are for new parts for just the rear wheel. Don't forget the cost of labor.
posted by bdc34 at 9:27 AM on June 13, 2008


Upgrading your existing car to ABS is cost prohibitive.

If someone tailgating you at high speed caused your accident, you were already going at high speed. Please consider pulling over to let the crazy driver pass. I live on a twisty mountain road. Sometimes I'm the slower driver, sometimes I'm the faster driver. When I'm slower than someone else, I'll signal early and pull out of the way as soon as possible.

How well your car brakes should never ever be an issue.
How well you control your car at the limit of adhesion should never ever be an issue (on the road).
ABS brakes should absolutely not be the answer when someone is tailgating you.

I'm sorry for your accident, which sounds pretty scary.

Driving skills instruction may help, and will certainly be fun, but if you re-evaluate your mental answers to driving you'll be able to avoid situations like this in the first place.
posted by lothar at 9:43 AM on June 13, 2008


Please, please, please take an advanced driving course, with a skid control section. And start preparing for turns such that you don't have to get on the brakes mid-turn. Know the places where it's easy to let tailgaters pass you... and use them.

What if there had been a cliff (or a kid) there instead of a guardrail? You hit the rail because you entered the turn too fast for your comfort, and then got on the brakes too late and/or too hard, so you lost steering control and inertia took over. ABS may or may not have helped you here... but you shouldn't have been in a position to need it in the first place. (and no, you can't really add it after the fact)

You need to build up some comfort, which involves experience in a car at the limits of adhesion. When you do enter a corner too fast, if you know that you're able to keep the car on the road (even if there's some squiggling involved), you're going to be a lot less likely to pound on the brakes in a futile attempt to panic-stop. And you're much more likely to stay on the road, too!

Also, if you followed the previous thread's recommendation to overinflate your tires to gain a few MPG, reconsider it. While harder tires do require less energy to operate, they also have less grip (which is why they require less energy to roll). Yes, the autocrossers pump their tires up hard, but that's about keeping the sidewalls vaguely upright in cornering situations that you don't want to see in everyday driving.

PT Cruisers aren't known for their handling, and they do tend to understeer a bit at their limits (understeer is when you hit the rail with your nose, oversteer is when you hit it with your tail). But, I strongly suspect that a better trained driver could've negotiated that turn in your car, with that truck on his butt, (and quite possibly at the speed that you entered it -- but certainly faster than you currently can).

Be that better trained driver.
posted by toxic at 10:12 AM on June 13, 2008


One simple thing to learn, particularly for roads that you drive regularly, is to never apply your brakes in a curve or corner. You accelerate through a curve or corner, having done all your braking, as necessary, before you enter the curve/corner, while still traveling a straight line. This maximizes your braking effect, and works with the laws of physics, instead of against them. You need to apply power to a car in a curve, to supply the energy needed to create momentum in a new direction, so that you are at speed exiting the corner. You'll find that your car, especially one that is slightly top heavy and front wheel drive, like a PT Cruiser, feels much more "balanced" on its suspension, if you do this.

In contrast, braking into a corner, while changing your front tire's angle of attack to the road, also forces more weight transfer to the front tires just as the change in thrust angle makes your front tires more prone to skid, and simultaneously unloads the back tires, which are then more prone to lock up. Braking in a corner thus does bad things, simultaneously, at both ends of the car. So, to recap: brake going into a curve/corner, while still going straight, and get off your brakes entirely as you enter the curve/corner. Accelerate gently through the corner, for maximum control and confidence.
posted by paulsc at 12:57 PM on June 13, 2008


In my country there are post-driving-test instruction programmes with names like "pass plus" and "Advanced Driving Test". You can get instruction for these tests, just as you can get instruction in preparation for a normal driving test.

You could contact driving instructors in your area and see if they offer any advanced driving courses, specifically mentioning skid control.

As to performing an upgrade, I agree with other posters here that you aren't going to be able to buy a third-party ABS system. However, it wouldn't hurt to phone a dealership and ask if it's possible to get the option added - it might be possible, and costs nothing to ask!
posted by Mike1024 at 2:17 PM on June 13, 2008


One simple thing to learn, particularly for roads that you drive regularly, is to never apply your brakes in a curve or corner.

This is over stated to a fair degree. There is nothing to support this theory unless you also state 'if the car is at its limit of adhesion and grip'. A car below its grip threshold is perfectly capable of braking and changing steering inputs without any ill effects at all. The only problem occurs if you are going too fast.

forces more weight transfer to the front tires just as the change in thrust angle makes your front tires more prone to skid

There is a whole load more to the system than that simplistic model. Loading the suspension through braking can also change geometry and spring/damper forces and make you less inclined to skid. The conclusion you are drawing is way too simplistic to be considered 'blanket good advice'. The system depends on too many variables.

So, in summary, planning is everything. Get the speed off before the corner, and if you have judged your speed accurately, being able to brake and avoid a small child mid-corner should be perfectly easy to do. If not, you were just going too fast, then that is the problem, and grip circles and 'working with physics' (whatever that is supposed to mean) don't come into it.
posted by Brockles at 3:05 PM on June 13, 2008


"... A car below its grip threshold is perfectly capable of braking and changing steering inputs without any ill effects at all. ..."
posted by Brockles at 6:05 PM on June 13

Unless, of course, the sudden application of those additional braking and steering forces are just enough to break the adhesion of tire to road surface, turning the once-under-control rolling vehicle into an out of control, skidding mass. And frankly, loading the suspension of a PT Cruiser, which has a bit of anti-dive geometry in the suspension, assuming that the front end isn't skidding, can set a driver up for a rapid, unplanned unloading of the suspension, just as the vehicle enters a loss of traction event.

The point of braking into a corner, and accelerating out, is simply to keep the vehicle suspension minimally loaded while both braking and cornering, and to get the braking done while the vehicle is in its most stable mode (straight ahead rolling). For a softly sprung, understeering American passenger car, without ABS, traction control or stability control assistance, that's pretty conventional wisdom.

If you should encounter a small child in a corner, especially in a non-ABS equipped vehicle, your best bet is to first try steering out of the way of the child, and lastly, to hit the brakes. That's because, as the New Mexico State Police advise [ link to .pdf file] in their Winter Driving Tips:
"If you have standard (non-ABS) brakes, you should pump them lightly and attempt to steer out of trouble. If you cause the wheels to skid, you cannot steer. At that point release the brakes and steer, then pump the brakes again until you are out of danger. "
But, of course, if you've gotten into a situation where you didn't see a small child in a corner, and also aren't able to steer around the child, then, sure, ignore my previous advice to never brake in a curve, and as a last, unplanned resort, brake as hard as you can. Presumably, this is a once in a decade or, better yet, once in a lifetime occurrence, if you're not driving like a madman. You'll probably still hit the kid, but you may, at least, lay down some skid marks and knock off some kinetic energy before impact.
posted by paulsc at 6:32 PM on June 13, 2008


A car below its grip threshold is perfectly capable of braking and changing steering inputs without any ill effects at all. The only problem occurs if you are going too fast.

...or if you believe that you are going too fast, and can't do anything about it but poke the brake pedal (and have been trained by stability control and ABS to think that this is an OK thing to do on a regular basis). Cars frequently break loose because drivers lock up the breaks when they should be concentrating on steering.

Most cars can far outperform the driver behind their wheel, and it's very easy to for a driver to go from "in control, tires squealing, knuckles whitening" to "drifting in a straight line towards that stationary object, and pressing harder on the brake isn't slowing me down" -- especially if the driver's brain is going "too fast, too fast, slow down, slow down, brake brake!... Check for broken bones. Clean shorts." instead of "too fast, FWD car isn't fully turning, lift off, correct with steering, add gas, unsharpen as rear end comes back inline, slow down as you straighten out. Clean shorts."

A few days spent in an open, wet, slightly soapy lot exploring the limits of your tires, while someone explains the physics and shows you how it's supposed to be done (and gives you wide open space to slide into when you don't get it right the first time) is invaluable at re-training your brain to go from "too fast, brake" to "losing control, rein it in". And you'll gain a whole new definition of what "in control" means.

I agree, that a blanket statement like "don't ever hit the brakes while turning" is overstated, but it's on the right track. If you regularly are applying the brakes mid-turn, as part of your normal driving, then there's something wrong with your technique and possibly your entry speed (or judgement thereof)... add that to a little rain on the freshly fallen leaves, or a tailgater, a broken-down microbus, or a moose in an ess curve, and you're a big hazard. It's just a matter of time until you run out of adhesion again, it happens to us all... the question is how prepared you'll be to recover from it, and whether you saw it coming.

Is "Plan your turns so you don't normally feel the urge to brake mid-corner" better?
posted by toxic at 6:36 PM on June 13, 2008


And frankly, loading the suspension of a PT Cruiser, which has a bit of anti-dive geometry in the suspension, assuming that the front end isn't skidding, can set a driver up for a rapid, unplanned unloading of the suspension, just as the vehicle enters a loss of traction event.

Good lord. Trying to use buzz words and trite phrases really doesn't cover your lack of understanding of the physics or mechanics involved to anyone other than the uninitiated.

How about you explain precisely how the anti-dive geometry helps or harms the situation you describe? Or perhaps you can explain precisely how this 'rapid unloading occurs' as the total bluff in your answers is really quite incredible. And what, precisely is a "loss of traction event'?

Such utter bluster is not helpful when people need a question answering. From the perspective of someone that works with vehicle dynamics and driver coaching on a daily basis, your answer shows nothing but regurgitated nonsense from manuals that lack depth and proper research.
posted by Brockles at 12:46 AM on June 14, 2008


Unless, of course, the sudden application of those additional braking and steering forces are just enough to break the adhesion of tire to road surface, turning the once-under-control rolling vehicle into an out of control, skidding mass.

What you describe is a vehicle that is AT it's limit of cornering. Hence my assertion that being below that limit will allow braking and steering without incident. If the car is close enough to the limit that any further input or change of dynamics produces an 'out of control skidding mass' then it was clearly going too fast. The issue is that of too much speed - nothing more, nothing less.
posted by Brockles at 12:51 AM on June 14, 2008


the proxy pitched it as being 28 MPG (A good but not great amount. Turns out he was mistaken, it gets 20).

I recently managed 27.95 MPG with my 2002 model, which had lower ratings than your '07, since I started driving to maximize mileage (60 mph max, gentler acceleration, etc.). Check the tire inflation, too.

To your main point ... forget trying to add ABS, it would be absurdly expensive.
posted by pmurray63 at 12:38 PM on June 14, 2008


"... How about you explain precisely how the anti-dive geometry helps or harms the situation you describe? Or perhaps you can explain precisely how this 'rapid unloading occurs' as the total bluff in your answers is really quite incredible. And what, precisely is a "loss of traction event'?

Such utter bluster is not helpful when people need a question answering. From the perspective of someone that works with vehicle dynamics and driver coaching on a daily basis, your answer shows nothing but regurgitated nonsense from manuals that lack depth and proper research."

posted by Brockles at 3:46 AM on June 14

Someone who supposedly "works with vehicle dynamics" should probably understand that anti-dive geometry is commonly engineered into passenger cars to limit the nose dive and weight transfer to the front axle that a car without anti-dive experiences under hard braking. In other words, anti-dive exists to prevent, as much as a passive design feature can, a suspension being "loaded" by a driver. I offered that bit of data, simply to make it clear that your statement "Loading the suspension through braking can also change geometry and spring/damper forces and make you less inclined to skid." runs counter to the very design of a car like a front wheel drive PT Cruiser, where all of the drive forces, and about 70% of the total braking forces are delivered only by the front wheels. In the 1960s, advising SCCA racers in their rear wheel drive G and H production class Austin-Healeys and Sprites to "load up" as means of getting around corners on flat county airport courses a bit quicker might have made some sense. In the current discussion, it's pointless, and I don't know why you'd bring it up, in the first place. But you did. So I refuted it.

To continue, 'rapid unloading' of a suspension can occur, anytime a road condition happens which changes tire contact with the ground, or introduces new forces to the vehicle. Potholes, pavement changes, wind, loss of traction, etc. are all conditions which can cause potential energy stored in a "loaded" suspension's components to be released quickly, and unexpectedly. The general result of rapid unloading is a quick, often uncontrollable change in expected vehicle behavior, frequently leading to a loss of control, such as when a car engineered with significant, predictable understeer, like a PT Cruiser, suddenly oversteers, due to the rear end breaking loose. Thus, as much as humanly possible, a passenger car driver, operating in traffic on public roads, generally wants to avoid intentionally loading his suspension, particularly with the complex and sometimes contradictory inputs commonly applied in racing situations.

A 'loss of traction' event should be self-explanatory. It's simply a loss of control occasioned by a sudden loss of traction, as opposed, say, to a "rollover event" where the loss of control is due to a sudden shift of the center of gravity of the vehicle.
posted by paulsc at 7:03 AM on June 15, 2008


Someone who supposedly "works with vehicle dynamics" should probably understand that anti-dive geometry is commonly engineered into passenger cars to limit the nose dive and weight transfer to the front axle that a car without anti-dive experiences under hard braking.

I do understand it. Perfectly well. What you don't understand is the difference between 'limiting' something and 'preventing' something.

your statement "Loading the suspension through braking can also change geometry and spring/damper forces and make you less inclined to skid." runs counter to the very design of a car like a front wheel drive PT Cruiser,

Utterly wrong. Anti-dive geometry doesn't stop the suspension being loaded at all. It stops overloading of it, reduces the possibility of the opposite end being unloaded and is as mostly to do with allowing more freedom of spring rates. It is not at all intended for 'preventing loading'. Anti-dive geometry (designed into all road cars and race cars and has been for many years) is a means of controlling pitch (front down, rear up) behaviour under braking without relying on purely the spring rates and rebound damping to do so. This allows better behaviour and control of the platform of the car under braking, while still allowing the use of softer springs and damping for ride comfort and tyre control. Again, your understanding of the purpose and the geometry is completely flawed.

But from someone that spent many hours insisting the plane on a conveyor would not take off, I'm not entirely surprised.

Weight transfer to the front axle - particularly in a front wheel drive car that brakes predominately with that axle - is a good thing. More weight on the tyres produces more defelection, more force in the spring/damper package allows greater control over the wheel and upright assembly over surface imperfections. The bad element of that transfer is if the car pitches enough to reduce the weight on the rear of the car (producing unstable braking) or overloading of the front tyres. Limiting this effect to the favourable load conditions and pitch angles and rates through suspension design and geometry is a means to have less demands on control on purely spring and damping.

To continue, 'rapid unloading' of a suspension can occur, anytime a road condition happens which changes tire contact with the ground, or introduces new forces to the vehicle. Potholes, pavement changes, wind, loss of traction, etc. are all conditions which can cause potential energy stored in a "loaded" suspension's components to be released quickly, and unexpectedly.

This is why damping and shock absorbers are used in modern cars. They exist entirely to prevent the conditions you claim are a danger to the stability of the car. Your hypothetical situation would only come to pass if the shock absorbers on the vehicle were malfunctioning, or the car was already previously overloaded - ie already going too fast. Damping essentially slows the reaction of the spring to these 'new forces' and inputs to allow the tyre to better recover from the new input with the minimum of lost traction. If the unloading is 'sudden' then either the dampers are shot, or the car has reached some sort of suspension limit - full droop, full compression - outside the normal dynamic range, basically. In other words the car is overloaded and is going too fast. This should never happen in normal driving conditions.

In the 1960s, advising SCCA racers in their rear wheel drive G and H production class Austin-Healeys and Sprites to "load up" as means of getting around corners on flat county airport courses a bit quicker might have made some sense. In the current discussion, it's pointless, and I don't know why you'd bring it up

I bring it up because the loading up of suspension is the only thinking that makes it work. You don't know why I bring it up because you are completely out of your depth in this field, it is clear to me. Loading up suspension allows larger forces (through cornering) and deflection of the tyre to produce better traction and grip - tyres deform in order to grip. The more grip you need, the more force the deformation requires (force from loading through spring forces - provided by vehicle dynamic pitch or roll and weight transfer). Loading up the suspension in a correct manner, and providing inputs to the car to utilise pitch and roll angles to transfer weight and loading to the right areas of the car is one of the skills a successful racing driver needs. Without load and weight transfer, there is no reason for the tyre to work properly.

A 'loss of traction' event should be self-explanatory.

Oh, it entirely was. It explained perfectly that you are way out of your depth. It was just a made up little twee phrase from you that amply demonstrated that you are making most of your argument up from incomplete knowledge or lack of understanding.
posted by Brockles at 10:41 AM on June 15, 2008


"... Loading up the suspension in a correct manner, and providing inputs to the car to utilise pitch and roll angles to transfer weight and loading to the right areas of the car is one of the skills a successful racing driver [emphasis added] needs. ..."
posted by Brockles at 1:41 PM on June 15

You do love to rattle on, don't you, Brockles, even when you're not making sense?

The original poster is a college student, who has already had an accident in a base level PT Cruiser; he's not a "successful racing driver," and didn't post his question looking for advice on racing techniques. After inquiing about retrofitting ABS to his car, he asks "Or if not, is there a good, safe way to learn how to threshold brake?" Whether you agree or not, my suggestion that he learn to brake before entering corners, and accelerate smoothly through them, is the safest way for him to learn to do that, in a vehicle of the type he's driving.

He surely doesn't need to be "loadiing up the suspension" on public roads, for heaven's sake. Continuing to suggest that he should is just terrible advice for a young, inexperienced driver, especially considering the settings and vehicle in which he's driving.

"... Your hypothetical situation would only come to pass if the shock absorbers on the vehicle were malfunctioning, or the car was already previously overloaded - ie already going too fast. ..."

What an incredible, self-serving crock! Public roads aren't steady state skid pads, and a bit of sand or oil in a curve, affecting only one or two wheels, among other things, can immediately unbalance a conservatively driven vehicle.

"...tyres deform in order to grip. ..."

Maybe on British racetracks. On U.S. public roads, if you're driving street tires to the point of deformation, you're likely losing traction, as the tire's sidewalls lose flexibility, and the tread contact patch begins losing adhesion with the road. Street tire construction and the rubber compounds are also heavily biased towards wear resistance, and never generate the phenomenal improvements in traction with increased carcass heat that racing tires offer.

Brockles, if you're just posting for the fun of making ad hominem attacks on me personally, fine with me, even if it's a lame rhetorical technique. But, for the sake of the OP, let me close by suggesting that he at least try, for himself, the simple cornering method I've suggested, and see if my advice is sound.
posted by paulsc at 2:18 AM on June 17, 2008


Maybe on British racetracks. On U.S. public roads, if you're driving street tires to the point of deformation, you're likely losing traction, as the tire's sidewalls lose flexibility, and the tread contact patch begins losing adhesion with the road.

Utterly false. Deformation creates a larger contact patch and works the rubber harder - from mild driving to race driving, this is fact. Try pumping your tyres up to 50 psi and seeing how well they grip. The tyres ability to conform to the irregularities of the surface is the very fundamental aspect of how they work. In the nicest possible way, you are talking out of your arse. How, exactly, does a rubber sidewall 'lose flexibility' when compressed? That makes no sense at all. You are clearly unaware that tyres deform all the time - look at a nice round tyre when the car is jacked up - then put it on the floor. Is it still round? The sliding scale of loading and deforming a tyre seems to be missing you entirely.

never generate the phenomenal improvements in traction with increased carcass heat that racing tires offer.

At no point did I suggest that it did. This does not, in any way, affect how tyres work. They just work to a higher level in racing, not in a completely different way.

As I have said up there, the advice was basically sound, in as much as lower speed is always safer than higher, its just the reasoning and justification for it is utterly false - your understanding of the dynamics are completely out of whack. Slowing down for the corner ('going too fast is bad' is in almost every answer here) is always good advice, as excessive speed is the basis of almost any accident. But 'slowing down until you stop' is overstating the case, as is your version. It doesn't make it bad advice, it just makes it overstated. As I said. There is no need to 'accelerate through the corner' as you state, and this may make the car unstable, too. Going through a corner in a front wheel drive car with trailing throttle (at a safe speed for the corner) is as good and usually more suited to most front wheel drive cars - application of a steady throttle input is the next stage of good balance in those cars. Accelerating through is a technique more suited to old style rwd cars.

What an incredible, self-serving crock! Public roads aren't steady state skid pads, and a bit of sand or oil in a curve, affecting only one or two wheels, among other things, can immediately unbalance a conservatively driven vehicle.

I'm sorry, but what? Self serving? How on earth is that self serving? Did you mean to use a different patronising phrase that actually makes sense in order to try and hide your ignorance of the matter? If you think that damping forces only function on smooth roads, then you are nuts. Any car that, especially when conservatively driven, is 'unbalanced' over surface changes is defective in some way. Suspension systems are designed to cope with surface changes - that is precisely what they are for, and correctly functioning systems will minimise or remove the affects of these irregularities.

'Brockles, if you're just posting for the fun of making ad hominem attacks on me personally

No, I'm posting because I am tired of the massive amount of poor advice on the car related askme questions - even some of the basically sound posts are wrapped up in urban myth, falehoods and misleading perceptions of how vehicles work. It is possibly the subject with the most amount of posters claiming some level of knowledge with bluff and regurgitated 'facts' and it is often a long way off the mark. I'm beginning to see why Languagehat gets so pissed off in the language discussions. Comments such as this:

One simple thing to learn, particularly for roads that you drive regularly, is to never apply your brakes in a curve or corner. You accelerate through a curve or corner, having done all your braking, as necessary, before you enter the curve/corner, while still traveling a straight line. This maximizes your braking effect, and works with the laws of physics, instead of against them.

Have no basis in fact in current vehicle dynamics. You make a wild and confident sounding assertion as to suitable driving technique and, when challenged, produce streams of faulty reasoning and flawed 'physics' that suggests authority (and bizarre random wikipedia links to 40 year old cars, for some unknown reason). That sort of answer (and you are by no means the only one) make automotive questions on Askme a confusing minefield as the genuinely knowledgeable answers are fogged out by the noise much more so than in other topics (or, at least, the ones I understand enough to be able to judge).

He surely doesn't need to be "loadiing up the suspension" on public roads, for heaven's sake.

Again, you seem unable to understand that vehicle dynamics are a sliding scale of the same elements - braking and cornering forces load suspension. Loading the suspension makes it more stable. This is fact. I am not in any way suggesting that the OP slams both feet on the brakes until he has achieved full front suspension compression and throws the car in at mach5 like a racing driver. However, the basis of understanding vehicle dynamics is entirely the same as I teach drivers every day - it's just you do everything a lot less in road cars. Suspension systems have a way of working that is just taken to the extreme in racing - the fundamentals remain the same as in a road car (geometry and weight distribution dependent). Attempting to dismiss a description of how vehicle dynamics work (and I only mentioned it to refute your faulty advice) is hardly me trying to train the guy to be a racing driver, just trying to demonstrate why the faulty advice was wrong. Bringing in better understanding and facts seemed to me the best way to do it.
posted by Brockles at 6:34 AM on June 17, 2008


Not an answer to the ABS retro-fit, which is an unwieldly and unlikely modification, but just a suggestion about maintaining control whilst madly braking. When you pump the brakes, try to do it from the hip. This is to say that you should get your whole leg involved in the activity and not try to do it just by changing the angle of your foot from the ankle. I took a high performance driving class at Sears Point many years ago and this is one of the lessons that really stuck with me. It really works and yields so much more control. Try it.

Oh, and if you do get a vehicle with ABS. Don't brake from the hip. Let it brake from its, er, hip or you might break your hip. Hip?
posted by bz at 8:42 PM on November 5, 2008


« Older Vroom Vroom - Gas is too expensive!   |   Help me look my best at my wedding Newer »
This thread is closed to new comments.