Embiber

Even for those whom have not been fortunate enough to drive a 1st Gen, have reveled at the legendary handling capability of this extrodinarily unique synergistic composition of parts we call Rx-7. For it is truly considered by all prominent, that the Rx-7 is perhaps one of the only pure sportscars ever built.

....I could write much more...

Q: What made the handling of the Rex so close to perfection?

Northern 7

iTrader: (3)

I hate to disagree, but in stock form, the handling in these cars is not close to perfection. On the other hand, in it's day.. pretty damn good. I would say weight distribution was the key.

vipernicus42

iTrader: (4)

Yup... the Rx8 boasts a perfect 50/50 weight distro.

Take a first gen, add tokico adjustible shocks/struts and some RB springs and swaybars, polyeurethane bushings and some good tires and you have Ub3r suspension.

Jon

Embiber

Ok before I rebutt, And believe me my intentions are to bring yo from the Dark Side. What is it that you proclaim is lacking in the stock version.
were talking sports car, not racer.

Embiber

50/50 weight ditrobution is the correct answer, and all models were engineered with this in mind.

purple82

Weight too, 2300 pounds makes for a tossable machine.

1984special

Good tires are so important! I have some crap Dunlop Sport all seasons and wow they suck! =P

peejay

50/50 weight distribution means nothing significant.

Best handling car i ever drove had the engine way out in front of the front wheels and a transmission that weighed twice as much as the engine mounted directly over the front wheels. But the suspension geometry and the spring and shock tuning were spot on for that particular layout*.

Let me ask you this... 50/50 weight distribution is fine if the car is sitting still. What if you are braking? You want more of the weight rearward so the load is evenly distributed on all four contact patches under deceleration. What if you are accelerating? If you have a RWD then you want to be able to transfer as much load as possible over the rear tires for traction while still maintaining enough over the front for steerability.


*It also helps that the car drove all four wheels. 4WD will plow if you drive like a pansy *** road racer, to overcome that you need to throw it at corners so that the car is doing most of its rotation before the corner itself so that you can just plant the throttle when you're pointed almost in the right direction. And since the center of mass was so forward, the chassis pivoted around a point close to the front wheels, so the mass of the car stayed close to being on the line the car was actually taking. If the mass was more rearward, cornering would be like swinging a hammer.

50/50 is perfect in the sense that it is a nice round number for brain-dead marketing droids to latch onto and proclaim is perfect. After all, the numbers are nice and even...

Northern 7

iTrader: (3)

OK - I'll buy that, to a point. The engine has to go some where so you have pointed out that either too far forward or too far back could cause braking or acceleration problems. So where is the best place for the engine? IMO, with the suspension the way it was with this car 20 yrs ago, Mazda probably put the engine in the best location for this particular car. I can't imagine the tail slop this car would have with a forward engine
Comparing to todays suspension, or even 4WD sport cars, is not a fair comp. and may be what you are referring to when gauging the importance of 50/50. Anyway PeeJay, you didn't really answer the question... why do / did these cars handle well in their day? I may have misunderstood your post - if so, straighten me out

peejay

Why did they handle so well? Light-ish weight, half decent suspension geometry and shock damping, light direct steering, stiff chassis. Light enough to not require huge tires for decent cornering grip made the steering feel good. Light enough to only need 100hp to have fun meant that you were unlikely to overpower the chassis, too.

The problem is, they used the same springs throughout the car's life, so while the early SA's weighed only 2400lb or so, the FBs were almost 100lb heavier and the GSL-SEs were 100lb on top of that. Ride height kept getting lower, throwing suspension geometry out of whack (the real reason, I suspect, that they reduced the rear anti-roll bar size... the geometry changes from the ride height loss and all) and it startd falling downhill.

Remember, old Cobras and C3 Corvettes have their entire engine behind the front axle centerline. However, C3 Vettes are downright scary to drive, they have really noodley chassis, and super stiff suspension to try to compensate, and the steering arrangement (hydraulic ram power steering just like the old Ford setup with the loosey-goosey valve in the linkage) was both light and numb. And nobody would ever accuse a Cobra of handling well, they were only fast on road courses because when you put huge NASCAR-sized slicks on a lightweight car, it doesn't NEED to handle well, just don't drive it near its limits and it will still be fast.

edit: Please note!! Don't confuse "handling" with grip! Handling is what the car wants to do and how it reacts to controls when you get near the car's limits. This has nothing to do with how high those limits actually *are*, that's all due to the tires.

oni-dori

i think mazda engineers got lucky! the right combination of all the factors that make a great handling car just came together. honestly though, i think 50/50 weight distribution is the near perfect compromise for a well-balanced car. load transfer would be easier to manage than a forward/rear biased vehicle. ive compared my 1st gen to a 2nd gen mr2 and wrx. granted the newer cars would kill my car anyday but it was the ease of driving the 7 that makes the drive enjoyable and allowing me to push the car to its limits. it takes more work to keep the mr2 to go straight and the wrx was just too much on the work side. they both work and they are fun to drive but i still love my 7. note all cars are stock.

peejay

WRX is work to drive? My interest is piqued. I hope Subaru's handling hasn't gone downhill.

Here's how mine was like to drive: Never ever needed more than 1/8, maybe 1/4 lock to the steering wheel. Brake, flick wheel in, control car's attitude (and therefore turning radius) with the throttle position, sometimes 3 or 4 times in the same corner (Understeer... Oversteer... Understeer... Oversteer...) then when the road looks like it's going to be straight soon, bolt the throttle down to the floor and go to the next corner.

oni-dori

hmm.... maybe im just not used to the awd system then

peejay

Mine were definitely not a WRX, though. Lighter, less power, you know the drill. That's why I worry... because I'd *like* to have a WRX someday, maybe when they get cheap enough and when people have figured out how to make the transmissions live. (All 4WD/AWD Subarus from the originals back in '74ish all the way up to the present have used the same transmission. Originally deisgned for 50 or so easygoing HP, trying to live behind "271"hp in early WRXs and even in Legacy twin turbos. The 6-speed STi box is all new and supposedly much beefier)

purple82

I wouldn't say NOTHING. In steady state cornering, 50/50 weight distribution means naturally neutral attitude.

In the Rx-7's case it's the combination of near 50/50 distribution and the fact that it's nearly all between the wheels of the car that makes it's turn-in naturally sharp.

Yes, yes it can all be dramatically altered with suspension tuning but when the basics are there, you're starting from a better place. I've driven cars with the engine everywhere from way out front (ever seen the engine bay of an Audi 4000?) to way out back (love the 911), and weight distribution ABSOLUTELY makes a difference.

Rutnick

"For it is truly considered by all prominent, that the Rx-7 is perhaps one of the only pure sportscars ever built. "

Dude, WTF are you smoking?

peejay

Well...

- When are you steady-state cornering. If you're driving hard, you're decelerating into the corner or accelerating out of the corner. No steady-state.

- Suspension tuning has a lot to do with the car's "attitude" when cornering. Moreso than weight distribution.

fatboy7

I think the low center of gravity of the rotary helps alot. Less yaw weight transfer, so more weight in the back for braking less for acceleration (but more than many forward biased rear-wheel drive cars). The real bonus of the 50/50 weight is the low rotational moment. Having more weight focused in the center of the car means that it seems to react quickly to steering inputs.

nickj

No, 50/50 isn't ideal, but it's better than havng all the weight up front. What makes the car handle well is the feedback it provides to the driver. It's not about ultimate cornering ability, it's about being seat-of-the-pants fun to drive. RWD, neutral steering, and a live rear axle all help.

peejay

'Zactly.

Besides, show me a factory stock RX-7 that had 50/50 weight distribution. Most were in the range of 53/47. And of course it all changes, since roughly 3% or so of the car's total weight is in the fuel tank, which is either empty, full, or somewhere in between. And of course it's hung way out there at the far back of the car...

Cody

I think it has something to do with the fact that most of us are broke, and when we find an inexpensive sports car to buy....we say its the best, and we feel good about our decision.

It's even better for me, since I made my gf buy me my car. :X

rotarygod

iTrader: (1)

50/50 weight distribution is important in handling but its location in relation to the wheelbase is a big factor. Yes the weight transfers around with body roll. This effect is called roll center. Keeping weight low and fairly well centered keeps the roll center more predictable. The car is also much easier to induce understeer or oversteer. The car is not truly 50/50 as it all depends on the weight of the driver, is there a passenger, and how much gas is in the car. The 1st gens all typically weigh more on one side of the car than the other. Each corner of the car exerts a different weight on the ground below it than another corner does and this is without anyone in it. You would think that the car weighs more on the passenger side to account for a driver but this isn't so. The drivers side of the car, specifically the left front corner, is the heaviest side of the car. Now get in and see what happens. 50/50 weight distribution can have a big or little effect depending on where in relation to the wheelbase the weight is located. As central as possible within the wheelbase is optimal for the lowest polar inertial effect when cornering, accelerating, or decelerating. The 1st gens have the gas tank out in the rear, outside the wheelbase. The front end is also fairly long in front of the front wheels. The engine, while being aft of the front wheel centerline, is only just aft. Now lets compare this to the new RX-8. The nose and tails of the car are fairly short. This locates most of the weight within the wheelbase. The gas tank is under the rear seat well within the wheelbase. The engine is mounted well aft of the front wheel centerline and much lower in the car. The weight transfer of the RX-8 is far superior to that of the 1st gen although they both have similar weight distributions. Its all in how you do it. To fully understand why moving the weight inwards is important remember that the less the weight moves around, the more predictable and controllable the handling. Remeber as a kid riding the schoolbus in the back seat how you would fly out of the seat over a big bump while the kids up front wouldn't? You were way outside the wheelbase and they weren't. Who's seat was more predictable and in control? It wasn't that poor kid in back! The same thing affects your car.

Time to teach you all an operational lesson of what goes on in the 1st gen suspension system. Whoever said that the 1st gen suspension is fairly good is smoking something mighty strong! It pure and simple sucks. The rear suspension binds severely. When the car rolls, the small top suspension arms move it side to side due to their orientation of being pointed slightly outward, upward, and rearward. They swing about in two different planes. The Watt's links restrict axle movement vertically. The difference between the motions of these pieces leads to binding. This is felt as an increase in roll rate stiffness as the car corners harder. to make matters worse the top arms are much shorter that the bottom arms and not even mounted in the same plane. When the suspension moves down the differential is forced to turn downward, possibly sharply depending on how depressed the rear end gets, and this leads to premature driveshaft u-joint wear as well as a drivetrain power loss due to this input angle. When the differential points downwards, the inner and outer watt's link bushings are no longer in the same plane and this causes another severe bind. Now because of all the weird geometry changes, when one wheel goes up and the other goes down, the 2 sets of control arms try to rotate the suspension in the opposite direction. The only thing that deflects at this point is the axle bushings! We now have 3 sources of binding in the rear suspension alone. Still think it is a fairly good design? Adding a bigger swaybar only accentuates the already bad problems by causing the rear axle to resist leaning forces. Why transfer the load there? That is what the suspension is for. Basically all this adds up to a car that effectively has a thicker and thicker useful swaybar as the car corners harder. A bigger rear bar equals oversteer. This is why the car gets tail happy really easily. Some people take off the rear bar entirely to help with the oversteer. This helps one problem but creates others. Some people try to cure these binding problems by using spherical bearings but this only adds to the problems. Some replace every bushing with spherical bearings but since they are no longer compliant the only thing that can flex is the cars chassis! I haven't even gotten into the roll steer effect or anti squat. Hopefully this helped shed some light on the big problems with this "true sports car". The rear suspension design is borrowed from the early '70s RX-3 so it isn't a new technological breakthrough for the RX-7. It is old transplanted technology. The front suspension has a few small problems of its own but nothing like the rear. The only way to correct all the flaws of the rear suspension are to completely redesign or transplant a better one.

Lets not even get into the sloppiness of the stock steering system, even when working perfect.

The fact is that the car is small, light, and fun but it has some serious flaws that if fixed could make it handle like a supercar.

Forgie

did anyone actually read that? ^

Bayce

For those that NEED to know - The above post (above this one ^
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purple82

I read it, and I've got a couple of issues:

There is no effect called roll center, the roll center is an imaginary point dictated by suspension geometry. It moves with suspension travel, not weight transfer. The location of the front or rear center of gravity in relation to the front or rear roll center dictates the amount of body lean. Lower is not always better.

I'm not sure I totally agree with this. The more the weight is concentrated at the center of the wheelbase, the less resistance it has to turning is really all that should be said.

The issues mentioned are moslty prominant only when the rear suspension is lowered.