ekremors1
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| posted on 6/9/05 at 11:28 AM |
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Weight Distribution
Hello,
I started to built my own car about 4 months ago. Engine was at the rear part of the car. It is Renault Clio 1.4 engine.
I want to ask what must be the weight distribution that comes to the front and rear tires?
 
Rescued attachment CIMG1114-rev.JPG
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scoobyis2cool
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| posted on 6/9/05 at 11:37 AM |
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Ideally 50/50 split between front and rear with all passengers, fuel etc
Pete
It's not that I'm lazy, it's that I just don't care...
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kb58
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| posted on 6/9/05 at 01:44 PM |
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There is no one answer! Everyone one thinks this stuff is black-and-white... it's isn't
Somewhere between 50/50 and 40f/60r will be fine, but then again, define "fine". It all comes down to you and what plans you have for the
car.
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
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andygtt
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| posted on 6/9/05 at 02:26 PM |
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as a guide an Ultima is 37f/63r and they handle well.
I am aiming for 50/50 wet which will drop to a rearward bias when the 90 litres of fuel is consumed.
however as stated there appears to be no definative answer to this as so many other factors need to be considered... for example I would imagine a
high C of G will need to be much closer than 50/50 split than a low one etc.etc.
I think its more important that you try to keep the weight inside the wheelbase and as low as possible..... but then there are porsche 911's
Andy
please redefine your limits.
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kreb
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| posted on 6/9/05 at 02:37 PM |
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For all-around use 50-50 or thereabouts works great. For racing, a rearward bias is preferable due to better braking and acceleration characteristics,
but also a little more difficult to handle due to a greater tendency to spin.
Your middie looks great! Forget about even weight distribution though. You are pretty well commited to a rearward bias at this point.
btw, the rear engine Porshes handle great despite their engine location, not because of it!
https://www.supercars.net/blog/wp-content/uploads/2016/04/1966_FiatAbarth_1000SP1.jpg
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andygtt
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| posted on 6/9/05 at 04:04 PM |
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quote:
Originally posted by kreb
btw, the rear engine Porshes handle great despite their engine location, not because of it!
thats what I meant, ie even with really high rear bias it can still handle if done right.
Andy
please redefine your limits.
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britishtrident
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| posted on 6/9/05 at 07:09 PM |
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50/50 in theory gives the most cornering power however a rearward bias has a lot of advantages but demands care when driving, likewise having all the
weight clumped together within the wheel base bring nimble changes of direction due to the low polar moment of intertia but it will also cause the car
to spin out very much quicker.
I always take the view that one end of the car needs to be domminant that is spot on 50-50 weight distribution will be harder to catch than 52-48 or
48-52
If going the rear or mid engined route on a road car I wouldn't for too short a wheel base as a longer wheel will give more stability and
predictability and be easier to drive ie a better "sneeze factor".
With a rear or mid engine the tyre contact area should be bigger on the rear than the front and also the front roll-centre needs to be slightly
higher than a in front engined car. With careful design even a 30 front -70 rear weight distribution can give neutral handling but it will always
demand a clean slow in fast out driving style ie gettng off the brakes before the corner.
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Liam
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| posted on 6/9/05 at 08:35 PM |
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Cant add much to the good advice here! You're pretty much stuck with a fairly heavy rear weight bias, but dont worry too much. Try and get
everything else up front - i.e. battery, fuel tank, rad etc etc. Maybe add a nice crash structure up front too and you'll get a more even
distribution. Even with a heavy rear bias you can achieve neutral handling with good tyre size and spring rate choice. With that short wheelbase
too, you're in for some frantic handling if you push over the limit. Should be fun! Lancia Strato's springs to mind (or even the crazy
fiat cinquecento my mate is building with an Alfa 164 V6 entire front subframe in the back!).
Good luck,
Liam
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Volvorsport
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| posted on 6/9/05 at 09:56 PM |
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a certain adrain newey favours 40/60 in favour of weight over the driven wheels , to give better traction .
www.dbsmotorsport.co.uk
getting dirty under a bus
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crbrlfrost
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| posted on 6/9/05 at 11:55 PM |
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Focussing to much on the static, vehicles move dynamically, especially on short tracks or back country roads where we all love to drive. A 50:50 will
give maximum lateral acceleration IF the corner is steady state (constant radius, smooth road, etc) with no longitudinal accelerations. It will also
move dynamically more rearward under acceleration or forward under braking. Rear bias enhances the percentage on the rear under acceleration, and more
closely approximates 50:50 under braking (rear wheels do more braking, nice concept). Being that handling is always a tire based issue, you have to
look at how you load those tires based on the weight distribution. Widening of the track, greater tire width, camber curves, roll gradiants, shock
damping, bump steer, and quite a few more determine ultimate over/understeer characteristics. Old porsches for instance had trailing arm suspensions
that tended to go slightly toe out when unloaded, doing this midcorner has led to a reputation of sorts. Don't let any of this deter anyone,
just design for simplicity and consistency. Toe in is always better then toe out in the rear, roll gradiants can be changed with anti-roll bars to
suite within reason, and camber is adjustable. Happy building!
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kreb
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| posted on 7/9/05 at 01:43 AM |
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If you're just cruising along, the 50/50 works the best, but if you're going at it with any sort of enthusiasm, you're going to be
getting into the throttle well before you stop turning. That will upset your balance, so will various other techniques, so the 50/50 is primarily a
talking point. Little else.
https://www.supercars.net/blog/wp-content/uploads/2016/04/1966_FiatAbarth_1000SP1.jpg
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ekremors1
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| posted on 7/9/05 at 11:24 AM |
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According to your answers,
I think ı am going to adjust it 50:50
Thank all you..
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britishtrident
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| posted on 7/9/05 at 12:36 PM |
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Anything near 50/50 is just not possible with your layout unless you put an engine sized block of concrete in the front ---
Porsche on the early 911 fitted weights in the front bumper to move the cg forward.
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britishtrident
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| posted on 7/9/05 at 12:43 PM |
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quote:
Originally posted by Volvorsport
a certain adrain newey favours 40/60 in favour of weight over the driven wheels , to give better traction .
True Davrians and Porsches truly fantastic traction and nothing (except a full blown F1 car) out brakes them.
The trick is to have more rubber on the rear than the front, and make the front stiffer in roll than the rear.
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