How to Make Crappy Cars Handle Well!

Handling is a difficult subject for many people to wrap their heads around.  Many cars, especially lower end sport compacts have a reputation for awful handling that can’t be fixed or for some makes their owners insist that their car handle but none get any noteworthy results on the track even if their internet forum collective always gives themselves high fives for effort. If you want a good place to start to learn about suspension and handling, may I suggest you read our handling guide articles as a starting point. 

Some cars that are popular to modify like the Nissan Sentra, particularly the B14 variant and the EP3 Honda Civic have a reputation for bad handling. Well, the bad news is yes these cars handle poorly in stock form and even with basic bolt on mods.  The good news is you can fix this stuff, it might take a little effort, some fab work and some knowledge but its all doable and not as hard as you might think.

A lot of the trouble with the handling of economic sport compacts is that they usually have McPherson strut suspension.  Not all cars with McPherson struts handles poorly though. Some strut equipped cars handle exceptionally well, cars like the E36 and E46 BMW, Nissan S Chassis and Porsche cars all are examples of strut cars that handle well.  However, most compact FWD econoboxes do not have as good of a front end geometry as these cars do.  We feel that the cheaper sports compacts often suffer from parts bin engineering where the geometry is compromised due to the cost savings of using a mash-up of pre-existing components.  Also, cheaper cars are probably engineered for worse drivers and a lot of understeer is built into the geometry.

The main problem with McPherson struts is as the car gets lowered, the lower control arm gets set to where it is actually pointing upwards towards the spindle. This causes two problems, one the roll center gets really low, this makes the distance between the roll center and the center of gravity longer.  This distance is called the roll couple and it is the lever arm that centrifugal force uses to cause body roll. Longer roll couple more roll. The other problem is once the lower control arm angle to steering axis line gets to be greater than 90 degrees, the suspension will start to gain positive camber.  This is not great as the car rolls, the tire will start tipping toward the outside putting the load on the outside edge of the tire.

The other problem with McPherson strut suspensions is bump steer.  Bumpsteer is when the tie rod and lower control arm are out of plane with each other. When the suspension compresses, the tie rod and lower control arm travel in different arcs. the difference between the arcs is bumps steer as the spindle will steer with no input from the driver. Sometimes this is done on purpose to cause toe in under roll to increase understeer.  Many other times the bump steer is just the byproduct of sloppy engineering and cost-cutting, most likely so existing parts can be used to reduce costs on a new model.

When a car with poor strut geometry is lowered, things get worse, sure the propensity to roll is less due to the lower height of the center of gravity but the roll couple gets longer and the tires will start to lose negative camber with roll until they are rolling up on their outer edges on the cars heavily loaded outer side. As you can see in the above picture, the bump steer will get worse as the ride height gets lower as well.

On good handling strut cars like BMW’s, Porsches, and Nissan S Chassis the location of everything is designed to be in the right place so negative camber loss, bump steer and roll center migration are not as serious issues.  This is not true on most econoboxes, their geometry is not so great to begin with and gets even worse when lowered.

The Nissan B14 Sentra and 200SX compacts have been popular cars to modify, especially the versions powered by the SR20DE engine. However, these cars have some most the most diabolical front-end geometries. When lowered these cars have half the amount of bump steer as wheel travel.  This means when the suspension compresses an inch, the toe changes a half inch! They also gain positive camber as the vehicle rolls.  This adds up to a vicious understeer that in the old days was tuned out by raising the rear spring rates to astronomical levels.  They also have twichy steering due to the bump steer.

18 comments

  1. The Mk4 Jetta/Golf chassis is MacStrut in front, and Torsion Bar in back, and has a lot of potential for great handling. There are a ton of parts you can take from the Audi TT, like the bushings and balljoints. I did find a Boxster front suspension at a junkyard and found out you could easily swap it over to the Mk4 chassis (although I haven’t done it yet.)

    Personally, I kind of hate MacStrut cars, but when you up the spring rates it seems like you can get some really great handling out of them. The front is a little stiffer than stock with Bilsteins, and I put some really stiff springs on the rear with FK shocks, with stock front ARB and no bar on the rear and the car handles great. I’m really surprised how well it handles since I had a EG6 for my last car. Practically no bumpsteer, and the chassis is much stiffer as well. Obviously, we have a lot of engines to choose from on the VW side, I hope to get a 1.8T built up soon. There are so many Bugs and Jetta/Golf cars in the junkyards now so it’s never a problem to source parts. I did some pretty drastic things to cut some weight on the car, and once you do that, they are really competitive.

    1. Why would you up the spring rates on anything other then butter soft suspension? You will F*** up compliance. Geometry is key, then comes damper/shock absorber rates, then a anti-rollbar/saybar, and finally springs. Getting away with the softest springrates without bottoming out is key. Otherwise you’ll just overload the tires. It may feel faster, but thats far from the truth.

      What you are doing is throwing away rear grip to compensate front grip balance. The above way, and the way in the article for that matter, is to not compensate but improve front grip, getting it on par with the rear.

      @Mike Kojima: Great writeup! What I find really confusing is that the geometry on the econoboxes started to go wrong during the early 90’s Although I could be off by a decade. During the 70 and 80’s era cars geometry still wasn’t perfect but way more in line then later models?

      1. Well, you could rephrase that question a but more politely. But, I’ll bite. The main reason I stiffen the rear so much is because, for one torsion bar suspension isn’t exactly compliant in the first place, and it helps the car rotate. The second reason is that I go camping a lot, and I load up the trunk with hundreds of pounds of gear, and I don’t like having the car bottom out., which was happening with the old H&Rs.

        Engineering is all about making the best compromise for the situation. This isn’t a dedicated racecar, just a street car built to handle well.

        Also, if the car didn’t feel better I would’ve went back to the old rates. But, it actually handles really great. The proof is in the pudding. The main theory behind it, is that rear is so stiff that there is no squat on acceleration which really helps it hook up on the front. FF cars don’t actually need a lot of traction on the rear, and the other option was getting a rear ARB, so I choose to put some stiff springs on it.

        1. @ Joe: For your info: I live in Europe. VW’s Golfs make up about 20% of all cars around here, so I know them inside out. They are about as common as grass over here. But the one thing I’m not getting is a torsion bar? They use a spring in the back? And H&R doesn’t make torsion bars for that car. Most likely because there aren’t any. H&R’s headquarters isn’t to far off from here, so I could always ask when I’m in the neighborhood.

          Torsion bars are perfectly compliant . It works as a Spring. Understanding them correctly is a different matter though. They can be measured on a rig with the suspension arm attached on the cheap. Or the right way with a rig that calculates bending forces.

          And lets not forget that most of the weight on a VW Golf is at the front anyway. Close to 60%. It’s the same cast iron engine design the car came with since the very first Golf GTI (1976). Even the diesel engine uses the same block, so the crankshaft is swappable for higher horsepower applications. It also uses the same components as the Audi A3, Audi TT, New Beetle, Jetta/Bora, Seat Leon, Seat Toledo, and the Skoda Octavia. Most of which you probably don’t get in the states.

          And no, a FWD car needs all the grip it can get. The same as every other car. The BIAS needs to be at the front. Thats what you’ve altered. Only it’s by worsening grip in the rear. Thats what feel is all about. Comparing latteral grip, cornering speed, etc is what grip is about. I drive and especialy race with my ass, but it still isn’t a butt-dyno.

          So the only actual point that still stands it needs heavier springs for camping, which is a viable reason. But that has nothing to do with better grip. It’s just a means to an end. Which still leaves the question: Why is it bottoming out? How much stuff do you carry with you when camping? Because on a stock Golf (non GTI), loaded with 4 adults and and bagage, as long as you do not exceed slightly more then 600KG (which the car is max rated for) it does not bottom out if you drive normal. Only towing something would do that, But then again: With a towing hitch it’s still rated at about 1000KG minimum for the 1.4.

          600 KG = 1323 LB
          1000KG = 2205 LB

          Just for reference in the antiquated system.

          So all in all it has probably more to do with overloading the suspension then anything else, or broken parts. Or parts that aren’t supposed to be there, like torsion bars….

          1. Kevski, I imagine he means twist-beam when he says torsion bar.

            Joe, you should look into the improved geometry from running TT front control arms, struts and spindles (on the cheap), or H2Sport spindles (on the not-cheap). TTs also got stiffened front subframes and quicker steering racks. the front anti-roll bar attaches to the arms on the VW products, and on the strut on the TT, so you’d have to swap that over as well.

          2. @stylngle2003:

            Your right, but although the principle is the same, the suspension itself acts differently. A torsion bar has splines, and isn’t always linked to the other side, but can be. Old VW Beetle’s for instance are linked in the front, where as something like a Peugeot 205 has a torsion bars in the rear that aren’t linked. A twist beam is always linked. So in a way a twist beam is semi independant, where as a torsion bar is semi independent or independant.

          3. I know everything you’re talking about. I have raced many cars before at high levels of motorsport. I would totally agree with you under normal conditions. I don’t think you want to over do it on spring rate, along with ARB stiffness, and should run the softest rates you can get away with considering that street tires/race tire lateral load levels are quite different. Obviously, you’re going to target your maximum G levels and work backwards from there.

            With all that considered, I have always benefited from a higher spring rate in the rear for FF cars. It has more to do with having a higher rear ride frequence than the front, so when you hit a bump, the rear vibrates at a higher frequency and cancels out the front instead of resonating with it. These principles have been thoroughly explained in John Dickson’s books.

            https://www.sae.org/publications/books/content/r-168
            https://onlinelibrary.wiley.com/doi/book/10.1002/9780470682906

            Here’s a good explanation that goes into more detail, this is a copy/paste from Google.

            Comrade Guevara
            03-13-2013, 10:42 AM
            Boys it just very easy thing that we have
            The out of phase motion between front and rear vertical motion, caused by the time delay
            between when the front wheel and rear wheel hit the bump, is accentuated by the frequency
            difference. A result of the phase difference is pitching of the body. To reduce the pitch
            induced by hitting a bump, the rear needs to have a higher natural frequency to “catch up”
            with the front. This notion is called producing a “flat ride”, meaning that the induced body pitch from road bumps is minimized…..

            For a given wheelbase and speed, a frequency split front to rear can be calculated to minimize
            pitching of the body due to road bumps. A common split is 10 – 20% front to rear.
            The above theory was originally developed for passenger cars, where comfort takes priority
            over performance, which leads to low damping ratios, and minimum pitching over bumps.
            Race cars in general run higher damping ratios, and have a much smaller concern for comfort,
            leading to some race cars using higher front ride frequencies. The higher damping ratios will
            reduce the amount of oscillation resultant from road bumps, in return reducing the need for a
            flat ride. Damping ratios will be explained in the next tech tip in detail. A higher front ride
            frequency in a race car allows faster transient response at corner entry, less ride height
            variation on the front (the aerodynamics are usually more pitch sensitive on the front of the
            car) and allows for better rear wheel traction (for rear wheel drive cars) on corner exit. The
            ride frequency split should be chosen based on which is more important on the car you are
            racing, the track surface, the speed, pitch sensitivity, etc…….

            About our discussion on CC IC engine components:
            Langley Research Center, Hampton, Virginia

            Internal-combustion engines would be constructed with cylinders and ringless pistons made of lightweight carbon/carbon composite materials, according to a proposal. This proposal is a logical extension of previous research that showed that engines that contain carbon/carbon pistons with conventional metal piston rings running in conventional metal cylinders perform better than do engines with conventional aluminum-alloy pistons. The observed performance improvement (measured as increased piston life during high-performance operation) can be attributed mainly to the low thermal expansion of the carbon-carbon composite. Carbon-carbon pistons can continue to operate under thermal loads that cause aluminum pistons to seize or sustain scuffing damage due to excessive thermal growth and thermal distortion.

            In addition to having an extremely low coefficient of thermal expansion, carbon-carbon is about 30 percent lighter than aluminum which provides the benefit of reduced reciprocating mass (lower reciprocating mass can potentially reduce vibration forces and increase r/min. capability). Carbon-carbon composite also has the advantage over aluminum that it fully retains room-temperature strength and stiffness at high temperatures. Further more, the strength, thermal expansion, and thermal conductivity of carbon-carbon composites can be tailored by orientation of the carbon fibers and selection of fiber type, matrix type, and processing methods.

            https://www.techbriefs.com/component/content/article/tb/techbriefs/materials/2258
            https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19940031440.pdf

          4. I apologize, I think you are just blocking links from posting, sorry about that. You’re not a web monkey a**hole, I thought your filtering my IP, but I figured it out finally. My apologies.

            Reply To Kevski:
            I know everything you’re talking about. I have raced many cars before at high levels of motorsport. I would totally agree with you under normal conditions. I don’t think you want to over do it on spring rate, along with ARB stiffness, and should run the softest rates you can get away with considering that street tires/race tire lateral load levels are quite different. Obviously, you’re going to target your maximum G levels and work backwards from there.

            With all that considered, I have always benefited from a higher spring rate in the rear for FF cars. It has more to do with having a higher rear ride frequence than the front, so when you hit a bump, the rear vibrates at a higher frequency and cancels out the front instead of resonating with it. These principles have been thoroughly explained in John Dickson’s books.

            Here’s a good explanation that goes into more detail, this is a copy/paste from Google.

            Comrade Guevara
            03-13-2013, 10:42 AM
            Boys it just very easy thing that we have
            The out of phase motion between front and rear vertical motion, caused by the time delay
            between when the front wheel and rear wheel hit the bump, is accentuated by the frequency
            difference. A result of the phase difference is pitching of the body. To reduce the pitch
            induced by hitting a bump, the rear needs to have a higher natural frequency to “catch up”
            with the front. This notion is called producing a “flat ride”, meaning that the induced body pitch from road bumps is minimized…..

            For a given wheelbase and speed, a frequency split front to rear can be calculated to minimize
            pitching of the body due to road bumps. A common split is 10 – 20% front to rear.
            The above theory was originally developed for passenger cars, where comfort takes priority
            over performance, which leads to low damping ratios, and minimum pitching over bumps.
            Race cars in general run higher damping ratios, and have a much smaller concern for comfort,
            leading to some race cars using higher front ride frequencies. The higher damping ratios will
            reduce the amount of oscillation resultant from road bumps, in return reducing the need for a
            flat ride. Damping ratios will be explained in the next tech tip in detail. A higher front ride
            frequency in a race car allows faster transient response at corner entry, less ride height
            variation on the front (the aerodynamics are usually more pitch sensitive on the front of the
            car) and allows for better rear wheel traction (for rear wheel drive cars) on corner exit. The
            ride frequency split should be chosen based on which is more important on the car you are
            racing, the track surface, the speed, pitch sensitivity, etc…….

            About our discussion on CC IC engine components:
            Langley Research Center, Hampton, Virginia

            Internal-combustion engines would be constructed with cylinders and ringless pistons made of lightweight carbon/carbon composite materials, according to a proposal. This proposal is a logical extension of previous research that showed that engines that contain carbon/carbon pistons with conventional metal piston rings running in conventional metal cylinders perform better than do engines with conventional aluminum-alloy pistons. The observed performance improvement (measured as increased piston life during high-performance operation) can be attributed mainly to the low thermal expansion of the carbon-carbon composite. Carbon-carbon pistons can continue to operate under thermal loads that cause aluminum pistons to seize or sustain scuffing damage due to excessive thermal growth and thermal distortion.

            In addition to having an extremely low coefficient of thermal expansion, carbon-carbon is about 30 percent lighter than aluminum which provides the benefit of reduced reciprocating mass (lower reciprocating mass can potentially reduce vibration forces and increase r/min. capability). Carbon-carbon composite also has the advantage over aluminum that it fully retains room-temperature strength and stiffness at high temperatures. Further more, the strength, thermal expansion, and thermal conductivity of carbon-carbon composites can be tailored by orientation of the carbon fibers and selection of fiber type, matrix type, and processing methods.

          5. @Joe:

            All true about the suspension what you wrote, although it is a oversimplification. Frequency isn’t only altered bij suspension stifness, but in the first place by weight and by where that weight is located in the chassis.
            But lets not forget that the quoted section is al about rode quality, not about performance. If emcountering bumps on a track, that usually means your of the track…

            And as for the other comment: Leave that in the corresponding topics on another site (again). This isn’t a pissing contest. But try reading the next Time: Carbon carbon composite. Thats something else as carbon carbon. Big difference allthough it almost looks the same….

      2. Continuing our debate from Speedhunters, Carbon-Carbon has been developed for ICs. Maybe it’s a bit cost-prohibitive ($2000 per piston), but otherwise it’s a good compromise for a high-output IC engine.

        “According to NASA: CC pistons can potentially enable high performance engines to be more efficient, be more reliable, and have a greater power output. An engine equiped with CC pistons can operate using leaner AF mixxtures because these pistons can function in higher combustion temperature environments without failure. In addition, because CC material retains its strength and stiffness at high temperatures, CC pistions have greater resistance to structural damage caused by overheating, lean AF mistures and high cylinder pressures that result from detonation. ”

        https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19940031440.pdf

        “Langley Research Center, Hampton, Virginia

        Internal-combustion engines would be constructed with cylinders and ringless pistons made of lightweight carbon/carbon composite materials, according to a proposal. This proposal is a logical extension of previous research that showed that engines that contain carbon/carbon pistons with conventional metal piston rings running in conventional metal cylinders perform better than do engines with conventional aluminum-alloy pistons. The observed performance improvement (measured as increased piston life during high-performance operation) can be attributed mainly to the low thermal expansion of the carbon-carbon composite. Carbon-carbon pistons can continue to operate under thermal loads that cause aluminum pistons to seize or sustain scuffing damage due to excessive thermal growth and thermal distortion.

        In addition to having an extremely low coefficient of thermal expansion, carbon-carbon is about 30 percent lighter than aluminum which provides the benefit of reduced reciprocating mass (lower reciprocating mass can potentially reduce vibration forces and increase r/min. capability). Carbon-carbon composite also has the advantage over aluminum that it fully retains room-temperature strength and stiffness at high temperatures. Further more, the strength, thermal expansion, and thermal conductivity of carbon-carbon composites can be tailored by orientation of the carbon fibers and selection of fiber type, matrix type, and processing methods.”

        https://www.techbriefs.com/component/content/article/tb/techbriefs/materials/2258

      3. Continuing our discussion on CC IC engine parts. It seems that CC pistons work just fine:

        Langley Research Center, Hampton, Virginia

        “Internal-combustion engines would be constructed with cylinders and ringless pistons made of lightweight carbon/carbon composite materials, according to a proposal. This proposal is a logical extension of previous research that showed that engines that contain carbon/carbon pistons with conventional metal piston rings running in conventional metal cylinders perform better than do engines with conventional aluminum-alloy pistons. The observed performance improvement (measured as increased piston life during high-performance operation) can be attributed mainly to the low thermal expansion of the carbon-carbon composite. Carbon-carbon pistons can continue to operate under thermal loads that cause aluminum pistons to seize or sustain scuffing damage due to excessive thermal growth and thermal distortion.

        In addition to having an extremely low coefficient of thermal expansion, carbon-carbon is about 30 percent lighter than aluminum which provides the benefit of reduced reciprocating mass (lower reciprocating mass can potentially reduce vibration forces and increase r/min. capability). Carbon-carbon composite also has the advantage over aluminum that it fully retains room-temperature strength and stiffness at high temperatures. Further more, the strength, thermal expansion, and thermal conductivity of carbon-carbon composites can be tailored by orientation of the carbon fibers and selection of fiber type, matrix type, and processing methods.”

        “According to NASA: CC pistons can potentially enable high performance engines to be more efficient, be more reliable, and have a greater power output. An engine equiped with CC pistons can operate using leaner AF mixxtures because these pistons can function in higher combustion temperature environments without failure. In addition, because CC material retains its strength and stiffness at high temperatures, CC pistions have greater resistance to structural damage caused by overheating, lean AF mistures and high cylinder pressures that result from detonation. ”

        https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19940031440.pdf

  2. Any chance your guys (and gals) could do a series on setting up rally suspension. Preferably gravel. I know rally suspension is kinda a Broad Ax to road racings scalpel.
    But still, it would be cool.

  3. To the web monkey asshole who is blocking me from posting a reply. That’s seriously disturbing behavior. Luckily, I don’t see the same activity on Speedhunters, so I’ll just post my reply to Kevski there.

    1. Please disregard, or delete this comment. I had some web links in a reply and it kept blocking the message, but generating no ERROR message. So, I assumed my IP was being filtered for some reason. I apologize for the crude language.

  4. If only I could have Mike come spend a few hours with the Benzes I race to help get them sorted. It’s some wacky geometry with really long springs. Car is an 82 W123.

    On the one car we have a bad weight distribution, that’s not changing any time soon. We just stepped up to a decent size tire, 225/45R17 RT615k. Coming from smaller 195/60R14 tires the car now shows some new issues. The front end grip is great and allows much faster cornering speeds, which leads to hitting a new understeer wall. The rear end used to stay planted and not rotate but now it’s picking up the inside tire on corners and we’re getting bad wheel spin. So we’re getting better corner entry speeds leading to mid corner understeer and mid-late corner wheel spin so it actually feels like it’s coming out of the corners slower than before, even though we’re going in faster.

    The front suspension will only take -1.5* of camber, so that’s what it has. It’s a weird geometry so I don’t think there’s an easy fix to that. An LSD would be nice, but I can’t find one available for this chassis in the US. On top of that, from everything I’ve read an LSD would likely give us more understeer. I’ve been told to remove the rear sway bar. It sounds like it won’t help the car rotate but will give us some more grip, which would then lead to more understeer.

  5. Hey Mike, how do you determine the roll center of a basic twist beam rear suspension(no panhard rod or Watts link) ?

    Also how does one become a chassis engineer?

  6. I would be interested what you would do to help a Hyundai Genesis Coupe suspension. Front control arm mounts to knuckle from the bottom, front tension rod mounts to the knuckle from the top. Not sure what could be done to correct roll center other than convert to a single control arm and space it down from the knuckle.

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