interestedparty
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| posted on 6/8/02 at 04:06 PM |
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Weight distribution, why worry?
People are naturally concerned that the weight distribution of their cars should be correct, but, as Alan B asked recently, who says 50/50 is
perfect?
One thing that people can sometimes forget is that the grip of a tyre is almost directly proprtional to the weight on it. If a front-heavy car is
negotiating a corner then the front tyres have the extra grip they need because they have extra weight on them. The same principal applies to
rear-heavy cars.
In acceleration, as soon as the car starts to move the weight transfers to the rear which is where it is needed (in our cars anyway, anyone running a
FWD Locost?). When braking the opposite applies, which is why our cars don't really need rear discs, the fronts do nearly all the work.
Moral of the story- if you're a but front heavy, don't worry about it
John
As some day it may happen that a victim must be found,
I've got a little list-- I've got a little list
Of society offenders who might well be underground,
And who never would be missed-- who never would be missed!
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Metal Hippy™
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 posted on 6/8/02 at 04:34 PM |
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Considering I'm using the 3.5 BMW, that's a 'weight off my mind'
BOOM BOOM
President of the Non-conformist Locost Builders Club. E-mail for details...
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Jon Ison
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| posted on 6/8/02 at 04:36 PM |
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so the "airbag" sticker they stuck on my belly up at nissan is ok too then ? thought so.....do i care....no..... 
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johnston
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| posted on 6/8/02 at 05:12 PM |
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dont forget the more weight up front the more ur goin to understeer safe but boring
the more too the rear more oversteer u get which is all good of course
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interestedparty
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| posted on 6/8/02 at 09:15 PM |
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quote:
the more too the rear more oversteer u get which is all good of course
Not sure I agree with that
John
As some day it may happen that a victim must be found,
I've got a little list-- I've got a little list
Of society offenders who might well be underground,
And who never would be missed-- who never would be missed!
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Alan B
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| posted on 7/8/02 at 01:51 AM |
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quote:
People are naturally concerned that the weight distribution of their cars should be correct, but, as Alan B asked recently, who says 50/50 is
perfect?
One thing that people can sometimes forget is that the grip of a tyre is almost directly proprtional to the weight on it. If a front-heavy car is
negotiating a corner then the front tyres have the extra grip they need because they have extra weight on them. The same principal applies to
rear-heavy cars.
In acceleration, as soon as the car starts to move the weight transfers to the rear which is where it is needed (in our cars anyway, anyone running a
FWD Locost?). When braking the opposite applies, which is why our cars don't really need rear discs, the fronts do nearly all the work.
Moral of the story- if you're a but front heavy, don't worry about it
John
Another point, expanding on that, is that ONLY time you will actually have the same w/d as the static weight distribution is at a constant speed in a
straight line.
This is the least interesting time from a performance viewpoint. Acceleration, braking and cornering are all of significantly more
interest/importance, and as John says at these times your w/d is all over the place!
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philgregson
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| posted on 11/8/02 at 11:38 PM |
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Yes - under those circumstances the wd is all over the place but it is still surely better if it is starting from the right place in the first
place.
A car with a predomanantly front bias and a car with a predominantly rear bias will both have their wd's all over the place but they will be all over
diferent places!!
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philgregson
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| posted on 11/8/02 at 11:43 PM |
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That was pretty garbled too - off to bed I think!
I guess my point is that weight distribution is important although we may disagree on why and where it should be.
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Alan B
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| posted on 12/8/02 at 01:11 AM |
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quote:
I guess my point is that weight distribution is important although we may disagree on why and where it should be.
I don't think I'd disagree with that
My point is really why is 50/50 the magic number? Personally I'd say anything from 40/60 to 60/40 was pretty good really.
But, it's not just the balance it's the polar monent of inertia too that's important.
Two cars can both have 50/50 wd but say one has the weight concentrated in the middle, and the other has it split at each end. The first car will be
easier to turn and easier to get straight again than the second.
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philgregson
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| posted on 12/8/02 at 07:39 AM |
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Yep - true!
However I think getting all the weight in between the axles is a good start, and still one better than most (if not all) production front engined
cars.
This also (and I hate to admit it) is a certainly an advantage that, mid-engined and some rear engined, production cars have over the traditional
front end layout.
IMHO though, cars are meant to have the engine at the front and the driving wheels at the back, but perhaps I'm just an old stick in the mud!
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interestedparty
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| posted on 12/8/02 at 08:05 AM |
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If comparing the products of manufacturers especially front and mid engine cars it is interesting to consider their reasons for coming up with the
solutions that they do.
As soon as anybody pickups a pencil and tries to design a car they find that the process is dominated by one thing, the height of the engine. As soon
as the engine is moved behind the occupants then this problem more or less goes away. The manufacturers know they can use chassis and tyre type/design
to get rid of any handling problems that may arise from their layout choice.
If we could put the thumbscrews on mainstream sportscar designers and force them to tell us why they make the choices they do, I bet they would have
to admit that their chassis designs have little to do with roadholding and handling, and everything to do with appearance and marketing.
John
As some day it may happen that a victim must be found,
I've got a little list-- I've got a little list
Of society offenders who might well be underground,
And who never would be missed-- who never would be missed!
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philgregson
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| posted on 12/8/02 at 04:01 PM |
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I think you are right - I suspect so many sports prototypes (and road going sports cars) etc are rear/mid engined is more to do with engine height and
aerodynamic considerations than it is to do with handling.
If you think about it you couldn't have fitted an engine in the front of an elise if you'd have wanted too - all car design is about compromise.
Another example: why was the 6R4 mid engined? not beacuse of balance I wouldn't have thought - beacuse a bloody great turbochjarged V6 wouldn't fit
in the same space that used to be occupied by a humble A series engine is my probable explaination.
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Rick
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 posted on 12/8/02 at 07:26 PM |
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I wonder what the wd of a formula 1 car is, since the engine and gearbox are behind the driver.
Surely they cant have 50/50 wd.
Unless the overall length begins to counter balance the rear end weight.
Rick
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johnston
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| posted on 12/8/02 at 08:17 PM |
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sorry to picky but im in a fussy mood the 6r4 aint turbo'd nott the proper original ones anyway it was built that way just to get all the gear in.
the prototype was front engined but it was thought u sat too far bac.
did you no the williams f1 team designed and developed it
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Macca
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| posted on 12/8/02 at 09:12 PM |
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I've never seen an unturbo'd 6r4.
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Jim
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| posted on 12/8/02 at 10:29 PM |
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The original group B 1985/86 6R4 was definitely not turbo charged. They thought the 3 litre V6 would generate roughly the same tourque as the turbo
and not suffer from lag and would keep the cost down. If they ever had the money and the time before group B was band they would have probaly gone for
a two litre turbo unit.
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bob
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| posted on 13/8/02 at 06:16 PM |
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Yeah,williams got the job because they were playing with the Honda V6 at the time in their own toys.
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theconrodkid
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| posted on 13/8/02 at 09:03 PM |
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The original engine was a rover V8 with 2 cylinders cut off,then the v64v was designed in typical british leyland fashion the bean counters arrived
and the engine and trans were never devoleped properly,ive sat in one so there!
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johnston
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| posted on 13/8/02 at 09:40 PM |
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the only turbo'd 6r4 are the rally cross boys the may be quick but there too scared to go on to the stages
real good one over here belongs to dennis biggerstaff good to watch when on song got a vid on comp of him poppin the lights out when landin after a
yump
they maybe 20yo old but in the right hands they can show a cossie, scooby or evo how to do it
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