Mazda 6 Forums banner

1 - 15 of 15 Posts

·
Registered
Joined
·
791 Posts
Discussion Starter #1
Mazda states that the weight distribution for the 6 is 60/40 for both the V6 and the i4.

Nikolas for Duratech Performance posted on another thread that those numbers were for the V6, and the i4 had the better ~55/45 weight distribution. He didn't comment further, unfortunately, and it appears he hasn't had a car to extensively measure himself. I don't know if he measured that himself or if it is word of mouth. Perhaps someone else has some insight? Nikolas?

In Europe, where the V6 is not even available, does it list the weight distribution?

Don't forget though- the listed i4 weight (in the US) does not include the power seat, alarm, alloy wheels, auto climate control, and ABS that the V6 weight measurement does. Those are not standard on the i4, hence were probably not weighed. I bet you'd find the difference in standalone engine weight is more like 150lbs.
 

·
Registered
Joined
·
269 Posts
Reading Topic: weight distribution

You say better ~55/45.... But remember that this is a front drive car! Sporty front drivers do not have a 50/50 balance. Look at the RSX... it's over 60/40. They have to be to maintain traction for one and to be able to rotate the rear end when you lift off the throttle or trail brake into a corner. This does not mean they don't handle well...obviously because both the M6 and the RSX are great FWD cars. If it were a RWD car then 50/50 or 55/45 would be ideal, but don't assume that this applies to FWD as well.
 

·
Registered
Joined
·
791 Posts
Discussion Starter #3
Replying to Topic 'weight distribution'

Actually, something closer to 45/55 would be ideal for a RWD car, not 55/45.

My comment was that if the V6 has a weight distribution of 60/40, the i4 should have a better weight distribution. Since it makes less power, it doesn't need as much weight over the tires to keep the tires planted. I'm curious to what the actual weight distribution is.

The RSX is 64/36, if I remember, which is pretty awful- and it shows. The car is light, which makes it pretty nimble, but its weight distribution makes itself known when the car is pressed. Distribute that weight better and you'd have yourself a perpetual roller coaster.
 

·
Registered
Joined
·
1,806 Posts
Reading Topic: weight distribution

50-50 static weight is nice but cars don't go around corners sitting still. RWD 50-50 is good because it helps keep the car balanced braking/accelerating. Under braking weight is transferred to the front to help steering. Under acceleration it is transferred to the rear to aid traction.

FWD cars turn and accelerate with the front wheels. Whole different can of worms. Hardest thing with FWD is to get the car to rotate and less weight in the rear actually helps. (up to a point)
 

·
Registered
Joined
·
269 Posts
Reading Topic: weight distribution

I meant 45/50... just fat fingered it...
 

·
Registered
Joined
·
34 Posts
Replying to Topic 'weight distribution'

QUOTE
Originally posted by Jonnyspeed6s


            I meant 45/50... just fat fingered it...[/b]
Let's see - 45 + 50 = um, ah, oh, yes 95
Does that mean you are using helium to inflate your tires? :D
 

·
Registered
Joined
·
269 Posts
Reading Topic: weight distribution

Damn... :)

I fat fingered it again :) Gotta stop doing this at work ;)

Once and for all...

45/55
 

·
Registered
Joined
·
541 Posts
Replying to Topic 'weight distribution'

QUOTE
Originally posted by Jonnyspeed6s


            Damn...   :)

I fat fingered it again :)  Gotta stop doing this at work ;)

Once and for all...

45/55[/b]
For a second there, I didn't see the word "fat" in your post. You definitely shouldn't be doing that at work :D
 

·
Registered
Joined
·
8 Posts
Reading Topic: weight distribution

Anything outside a perfect 5050 wt. dist. will hurt lateral performance. FWD, RWD, AWD, doesn't matter. I would be willing to bet the 4 banger will pull a higher g than the six popper, and be less prone to understeer. Physics doesn't care which drivetrain you have, the basic rules of tuning apply across the board and a 5050 car will pull a higher g with all other factors the same. Someone mentioned a light rear-end will rotate easier. What!?!? The relationship between weight and traction is not linear. As weight increases, traction increases at a lesser degree. That is why anti-roll bars(ARB) are God's gift to FWD cars, because a well-tuned FWD car will have a stiff enough rear ARB to transfer most, if not all, the wt. to the outside wheel, thereby setting the rear up with a tractionwt. ratio roughly equal to the overloaded front tires and reducingeliminating understeer. Some tune this wt. transfer with stiffer springs, but don't get me started. From a pure acceleration standpoint, sure, load the driven wheels, and better yet make the rears do some work to take advantage of the wt. transfer. But, it is my understanding that this thread is in reference to lateral acceleration, and polar moment of inertia must be nill to corner the fastest and make the most of all four tires' contact patches. Even coming out of the corner, I guarantee you the SLIGHT increase in traction by having a high polar moment in the front of the vehicle is SEVERELY negated by the loss in speed in the corner due to loss of total traction with all 4 tires being equally weighted.
 

·
Registered
Joined
·
2,972 Posts
Reading Topic: weight distribution

The I4 is oversteered if you let of the gas in corners. :) At least on the snow with me behind the wheel :p

Doesn't .. hmm camber (? the up > down angle) matter? At least on the rear wheels?

Illustration (wheel axle seen from front/rear :D)

|----|
neutral

----/
not good

/----
Better

In corners, the car will "dig" the outer wheel to the tarmac and get better lateral grip...
 

·
Registered
Joined
·
8 Posts
Reading Topic: weigh

To help explain wt. transfer and 5050 more, here's some basic math to put things in perspective. A given tire with 500 lbs vertical load on it will be able to handle 500 lbs. lateral load (traction). So, a high performance unicycle with driver (oh, yeah, this sucker's got recaros and a Kohler motor baby!!) that weighs 500 lbs. all together can pull 1 g in a turn. (lat. lb/ vert. lb). Hypothetically, of course as this is meant to be simple so CG and such are neglected. Now with the same tires, as the vertical load increases the traction decreases. If you were to graph the relationship it would be a decreasing curve. The shape of the curve will vary by tire, but most tires start with greater traction than load, and then the relationship evens out, and then decreases as load continues to increase on the tire. This is known as the tire's loss in cornering efficiency. With our tire in the example, at 200lb load the traction is 275 lbs, at 1000 lbs load the traction is 900 lbs., and at 1500 lbs. load the traction is only 1100 lbs. Now, with a front heavy car, in a turn, more weight is going to go to the front outside tire than is going to the rear outside tire. The wt. of the car obviously doesn't change, but where it is "put down" has. This wouldn't be a big issue except with our tires, the load/traction isn't linear, so overall traction will decline. For example, if a 3000 lb FWD (60/40 split) car has 900 lbs apiece on the front tires and 600 lbs apiece on the rear tires, and then shifts 1000 lbs in wt transfer. The new set-up in mid corner has the front inside tire with 300 lbs while the outside front now has 1500 lbs of load on it. The rear inside has 200 lbs and the rear outside has 1000 lbs of load on it. Our tire characteristics dictate the maximum traction available for the front outside is now 1100 lbs and for the front inside is 350 lbs. The front of the car has a cornering force of 1450/1800, or .81 g. The rear of the car has the outside tire at a maximum 900lb of traction with the new load and the inside at 275 lb of traction with its new vertical load. The rear of the car has a cornering force of 1175/1200, or .98 g. Clearly our car will understeer. If you figure even weight distribution with the same tire characteristics, the car will be neutral and be able to accelerate into and though a turn at higher speeds because overall traction is higher. Take into account that the 6 doesn't even have a LSD and the picture gets even uglier. Hope this helps clear up what is for most people a very dificult concept.
EDIT: my spelling gets worse the more I type...
 

·
Registered
Joined
·
8 Posts
Reading Topic: weight distribution

Blackbird- just saw your post.
Yes- letting off the throttle mid-turn will help cure understeer. This is because of wt. transfer off the rear to help the car rotate. But refer to my above post and I hope you realize why it is meant to correct understeer and not the fastest way to make a car handle. In otherwords, tune the car's wt transfer and you won't need to correct for understeer. Trail and left-foot braking are other means to make "your tail rotate." But will not be the fastest means to take a turn. It is a shame.
Camber is seen front to rear as you said. You have the right idea, but on the 6 it will not be terribly beneficial as on a strut mounted car. The reason being is that a double wishbone gains negative camber in body roll which helps keep the tires level. Struts, as they are the link between the hub and chassis, will not gain camber but "flop" with the body on the outside tire, which is why dialing in negative camber is so important for strut type cars. It is more benificial in the front than the rears, typically.
 

·
Registered
Joined
·
383 Posts
Replying to Topic 'weight distribution'

QUOTE
Originally posted by alexchu


            more people (at least physics studnets) should read some of Jester's posts![/b]
Yeah, they sure cured my insomnia!
 
1 - 15 of 15 Posts
Top