REVscene - Vancouver Automotive Forum

heleu · 02-28-2009, 10:09 AM

^ Interesting analogy, never heard that before! I guess MR2 NAs have the Camry engine, so that helps the analogy.

The OP asked about people's concerns, so a few people listed them.

HOWEVER, the bottom line is, most people EVEN on a rainy day driving a MR2 will be fine.

cosworth · 02-28-2009, 10:12 AM

MR2s are not the hardest car to drive. Not even by a long shot. A challenge for some.

Maybe the hardest to drive japanese import from the 90s available for under 10k that is mid engined and from a manufacturer called Toyota.

Blinky · 02-28-2009, 10:42 AM

cosworth has some of the right ideas (the traction circle) but what is missing is the role of weight transfer, which is universally applicable, and polar moment of inertia, which is more significant in mid-engined vehicles, especially ones with a short wheelbase.

Let's assume that a car is cornering near the limit, at constant throttle. Additional throttle can cause on-power oversteer. Weight is transferred to the rear which increases rear traction, but the additional power can break the rear wheels free. If the amount of throttle that is applied is *just right* the car will drift on four wheels -- the absolute limit. Check out http://www.youtube.com/watch?v=4kCvGLxmMgk at 0:27 for an example.

If the driver lifts mid-corner, rear traction is reduced as weight shifts to the front of the car. The car rotates. It seems so counterintuitive so it is more likely to catch an inexperienced driver. To complicate things, the same thing that makes a mid-engine car handle well (turn in well), makes it spin quickly too.

Simply put it's easier to spin a 10 kg weight, if the 10kg is in the middle of a 10 cm long bar shaped like: --0-- , than it is to spin a 10 kg weight that consists of two 5kg weights connected by a 10cm long bar: 0----0.

cosworth · 02-28-2009, 10:50 AM

Blinky, car handling takes that into account. But weight transfer etc does not affect a tire's ability to hold %100 traction. How you plant that tire to the ground affects how much lateral G you can extract, but it still only has %100 traction.

You have to think of these are two completely separate things. Failure to do so results in not "getting it". The weight transfer is what moves the percentage around.

Blinky is right, but understand that a tire always has %100 traction. Even in the wet. It has reduced traction, but still %100.

Weight transfer moves the X and Y axis of a certain %. Lateral is X and forward rearward (power, braking) are Y. Weight transfer affects BOTH.

Rich Sandor · 02-28-2009, 11:02 AM

I don't think a confusing 20 page thread on tire physics is going to help our friend here looking at MR2's.

The Porsche 911 turbo came under harsh criticism in the late 70's when it came out; after several wrecks, people complained it was dangerous and unsafe. It wasn't anymore dangerous than an airplane - you just have to know how to operate it properly.

RabidRat · 02-28-2009, 11:38 AM

had an MR2. will definitely say that it's not a friendly car for the inexperienced. but you seem to have the right attitude and a healthy amount of respect for what can happen, so I think you'll be fine. i like that you're being proactive about this, asking for others' experience and budgeting for good tires! very commendable.

the snap oversteer issue honestly is blown out of proportion. all this bitching and moaning about it, all it really means is that there's a lot of bad drivers out there. the margin for error with weight transfer is just smaller than usual and you have to be more careful about it. that's all.

if I had to give you one specific piece of advice, it'd be to get good tires for the rain. Z1 *Spec over the Azenis RT-615, for instance. the car can be a nightmare in the rain. it caught me off guard a couple times and got me into a lot of trouble.

I also wanted to add that FF can snap oversteer. in fact, FF cars can *only* snap oversteer. when I needed slip angle on the Mazda3, i would lift off the throttle and the rear would come out, like clockwork. just a question of weight transfer. and a big enough rear swaybar. =)

Lomac · 02-28-2009, 11:48 AM

Quote:

Originally Posted by RabidRat

I also wanted to add that FF can snap oversteer. in fact, FF cars can *only* snap oversteer. when I needed slip angle on the Mazda3, i would lift off the throttle and the rear would come out, like clockwork. just a question of weight transfer. and a big enough rear swaybar. =)

Yup. Happened on one of my track VW's a few years back. Too thick of a rear swaybar = rear end constantly breaking free.

I've never driven an MR2 but I have driven a few Pontiac Fiero's (another MR car). Snap oversteer is also an issue with those vehicles but only if you lift off the throttle in mid-turn and experience a fair amount of weight transfer. It's just something you need to watch out for when driving. In the dry, it's barely even an issue unless you're pushing it hard.

TommyT · 02-28-2009, 03:30 PM

If you're just gonna cruise in the sun than it shouldn't be an issue at all. Just stay on speed limit and have some healthy tires and its just like any other car. If you're tracking it than that's another story.

The snap oversteer thing is just overly hyped and shouldn't scare anyone who has good common driving sense who just like to enjoy a spirited ride.

68style · 02-28-2009, 06:12 PM

I've got 3 MR2 Turbo's... 93, 94 and 95... never had problems with any of them, it's totally blown out of proportion.

The only things that can get you into trouble are things that get you in trouble in ANY car... ie: flooring it around corners in the rain, trying to go into a corner carrying too much speed and then trying to get the car to carry you around -> can't power out in a controlled manner like you could with a Miata or a Mustang or something more "conventional" it will spin.

The only thing I see being unpredictable in my experience 5 years daily driving the MR2 are with the Turbo model in the rain if you are driving in a spirited fashion, sometimes the surge of power from the turbo rushing on rather suddenly can make you break treaction at weird or unexpected times especially if you happen to go over painted lines like a crosswalk or something hahaha... oh and in the snow, MR2 has awesome grip with the engine being over the drive wheels... except for stopping... rearend likes to try to pass the front

By the way I have a totally restored '93 Turbo for sale if you are interested... check the Members Projects section to see the build

saiko · 03-01-2009, 01:08 AM

Kingshit syndrome, it gets the best of most people.

As most have already said, MR2's are designed by God. And if you obey God, he will not punish you up the ass. They're fun cars, but not one that can easily forgive some drivers.

I believe for anything, if you repect it, it will respect you. In the sense that you don't drive like you own the road, you'll be just fine.

68style's 93 was painted by one of the best. He's done numerous MR2's and they're high above the Kingshit Totem Pole.

hk20000 · 03-01-2009, 01:25 AM

The idea of "snap oversteer" on the MR2 is none of those romantic theories you guys posted about the guy driving it over the limit or what not.

It was a suspension geometry flaw that caused the rear suspension to stop working at near limit cornering situation. A rigid suspension = instant reduction of grip causing immediate traction loss. Hence the word SNAP. It's nothing like the 911 ailment which is purely caused by snobs driving them.

Look it up. It's something that can be fixed and toyota fixed it with a 1992+ geometry. But old ones will still do the snap like it's a casual fun thing to do. Either get suspension that doesn't travel with as much stroke at the limit or stiffen up the rear for the engine weight load will drastically reduce the effect.