JoelP
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| posted on 10/4/07 at 09:18 PM |
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quote:
Originally posted by higgsti
maybee the maths is right but were talking about the correct way to corner weight a car
that link doesnt show how to set corner weights, it shows how to do corner weights and ride height together.
Bottom line is geoff was wrong originally because the absence of a driver would ruin you ride height settings, however his maths is sound that
changing weight position affects both diagonals equally.
[Edited on 10/4/07 by JoelP]
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Bob C
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| posted on 10/4/07 at 09:23 PM |
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I did mine recently with bathroom scales & a big propane tank pretending to be me.
I agree with the diagonals concept. However you cannot argue with the fact that if the 2 rear wheels have different weights on 'em, the
differential will make sure that there's always one wheel that breaks traction first & acceleration will be lower because of it. So initial
weight distribution IS an important factor that adjustable spring seats can't completely compensate for. Aside from that, make the diagonals
share the load and get the ride height right. I was surprised how easy and quick the job was. The bathroom scales were 20kg or so above full scale
(when doing the back axle) but seemed to cope alright (went back to zero, results plausible and repeatable)
Bob
PS pre adjustment I had nearly 40kg difference L/R on the back, afterwards 12. And I now get better traction in spite of the quaife ATB diff!
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GeoffT
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| posted on 10/4/07 at 09:26 PM |
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My argument has always been the mathematical one, the diagonal sum weights will still be the same, driver in or not. As JoelP alludes, the car will
"squat down" on the rear offside corner with this setup. Ok with the driver in the car the squat would be adjusted out, but it would sit
high on this corner when unloaded. Not really a problem, but what happens when you drive it with a passenger? Would you want to readjust the setup
every time? Ok if you only drive it without a passenger, then agreed, setting up crossweights with the driver in the car will set the car level, BUT
if you regularly drive with a passenger, then setting crossweights with the car unloaded (or with both people in the car, same result) would give the
best setup to cover all eventualities.
All these things only affect ride height though, the original statement of the need for diagonal (crossweight) equality still stands.
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alister667
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| posted on 10/4/07 at 09:34 PM |
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OK I'm gonna add to this debate!
I have the opinion that the corners weighting benefits most:-
1) Straight Line Braking.
I want the same weight on my two front wheels (with me in the car and petrol etc) when braking in a straight line. This is to allow me to get the
most out of my brakes before locking up one wheel. Ideally both should lock at about the same time.
2) Rear traction.
With an open diff I'd like the weight on the two back wheels to be the same to they break traction as late as possible allowing me to get off
the line ASAP. If this is one properly it will also help minimise the inside wheel spinning up exiting a corner (I've normally only had this
problem in the wet).
Now if both these are met then the diagonals being equal are met OK.
I was told by a world champion hot rod builder that corner weights are not as important to cornering as some folks would have you believe since as
soon as you touch the steering wheel, brake or accelerator you are radically altering the weight pressing down on the four wheels of the car
anyhow.
Can anyone answer me this, since most tracks in the UK are clockwise why don't we set our cars up with more weight on the inside? (Maybe they
do and no-one's told me!!) 
Cheers
Ali
http://members.lycos.co.uk/alister667/
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GeoffT
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| posted on 10/4/07 at 10:05 PM |
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I find with my car that if the diagonals are equal the car is something like 15kg heavier on the nearside, due mainly I suppose to the battery and
exhaust being on that side, plus the engine is canted that way. Problem I found was that if you maladjust the diagonals to say, equalise the weight
across the rear wheels, you end up by pushing the front end even further out of balance, probably compromising front brake balance. I suppose the only
real answer if you need this degree of accuracy is to physically move stuff around in the car, not sure this is really necessary on a road car
though
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alister667
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| posted on 10/4/07 at 10:17 PM |
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I would get the front wheels equal first, I've only ever seen the traction problem come in to play on a stinking wet day at Aghadowy with the
poorest road tyres on you can imagine!!
http://members.lycos.co.uk/alister667/
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higgsti
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| posted on 10/4/07 at 10:56 PM |
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joel the link on blatchat does tell you how to cornerweight your car the adjustment of the corner weights does alter ride heights they are both linked
.but you should start with your front bottom wishbones paralell with the ground for best results.
geoff i drive mainly on my own and my prevous car was a megabusa which has the engine placed to they passenger side which affects the corner weights
far more than a cec so the weight in the car is on the same diagonal
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britishtrident
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| posted on 11/4/07 at 06:45 AM |
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Dosen't matter if one front wheel locks up very slightly before the other under extreme braking -- what matters is the car stays straight under
heavy braking.
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procomp
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| posted on 11/4/07 at 07:14 AM |
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Hi One question. How many people in this topic have acctually played with corner weights on a real car on a track and experimented.
And how many have only worked it out mathamaticly.
cheers matt
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higgsti
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| posted on 11/4/07 at 07:55 AM |
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never felt the need to alter at the track only played with tyre pressures and damper settings.i have a corner weight guage also and finding flat floor
at a track is nigh on impossible.if i had scales those are easier to use and get more accurate reading
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alister667
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| posted on 11/4/07 at 09:52 AM |
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quote:
Originally posted by britishtrident
Dosen't matter if one front wheel locks up very slightly before the other under extreme braking -- what matters is the car stays straight under
heavy braking.
It depends what you meant by "very slighty" you'll do well to get them to lock up at exactly the same point, but by getting them to
lock very closely you will get much more out of your brakes. Once they lock you loose about 30% of the grip on that wheel, and , of course,
you'll have trouble turning in until you release.
I've never had a problem with incorrect set-up leading to brakes pulling one way - the problem I've had (on track) i one wheel locking up
early, and corner weights is the way to solve this.
I *would* have thought that with similar calipers/pads etc a similar amount of braking force would be applied by the wheel to the ground until one
wheel locks.... But I could be wrong!
I have played with corner weights on track and I'm very interested in knowing more. I don't know everything and I'm keen to learn.
If I'm wrong in what I say please let me know!
Thanks
Ali
[Edited on 11/4/07 by alister667]
http://members.lycos.co.uk/alister667/
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britishtrident
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| posted on 11/4/07 at 10:01 AM |
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I used to race Imps the worst case scenario for corner weight distribution, the weight bias towards the right side of the car was huge. The left front
corner carried sweet f-a weight on the standard car.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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britishtrident
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| posted on 12/4/07 at 07:23 AM |
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quote:
Originally posted by alister667
snip snip snip
Once they lock you loose about 30% of the grip on that wheel, and , of course, you'll have trouble turning in until you release.
snip snip
Thanks
Ali
[Edited on 11/4/07 by alister667]
Trailling the brakes into a corner is not a good idea, particularly on a RWD car. Brake neat and tidily in straight line, compeltely off the brakes
just at the very start of the curve, as the nose rises start to turn in and gently start feeding the power in as early as it will take it.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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alister667
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| posted on 12/4/07 at 07:20 PM |
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Yes of course you're right, neat and tidy is quickest, the point I was making was that if you lock up the fronts you have no steering, at least
turning in under controlled braking (usually done only when I've made a mess of the braking) you can turn in, even if the back becomes very
light.
There are a couple of corners I know where you have no choice but to brake while cornering so it can be done, but with some care to avoid swapping
ends.
I was hoping for more input from procomp who sets up cars professionally and would know a lot about this - I'd be interested to hear his
thoughts on corner weights.
http://members.lycos.co.uk/alister667/
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procomp
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| posted on 13/4/07 at 08:15 AM |
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Hi this topic could run as long as the old bec v cec.
But the answer will be simallar in that there is no real difinitive answer each has it's merits in certain applications and differing types of
car. Even with our verry simalar cars there is a difference between live axle and irs setups .
But at the end of the day if you have a driver who truley belives that it should be done this or that way then if that is what he wants as he belives
that will make him quicker round a circuit then so be it . If he has the confidence to drive with the setting he has and knows what to expect in a
given situation and can drive the car accordingley it might not be the text book setup but it could well be that for that driver it works out
quicker.
The point of my post above was to see if anyone had acctually driven a car set one way and then readjusted to be the set the other way as a back to
back test situation and conclucivly proved to himself that one way was better than the other.
It is somthing that if driving/sprinting /racing on a regular basis could be off intrest to see what suits you your setup and the most important part
your driving style as it is relativly easy to alter a cars setup but it is a hard thing to try and change a drivers complete driving style .
I also think that if you as a driver are getting down to the technicalities of differing corner weight setup on cars as light as our type there are
many other things that should also be taken into account before comming to any given conclusion such as dampers and the general geo setup on the car
.
cheers matt
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TangoMan
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| posted on 13/4/07 at 07:10 PM |
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So Matt,
When you set my corner weights and ride height, will I be sitting in the car
I will be down soon for the setting up but want to make sure it will be plain sailing. I have freed the rears ready for adjustment but the front
platforms are seized and I broke a torx bit in while trying to remove the seized grub screw. I will have another go this weekend unless the sun
stays out.
Summer's here!!!!
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alister667
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| posted on 13/4/07 at 09:41 PM |
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I wouldn't disagree with you. Very interesting, thanks for the response.
Ali
http://members.lycos.co.uk/alister667/
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higgsti
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| posted on 15/4/07 at 08:29 AM |
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geoff ive tried to corner weight your way but my pace guage doesnt work on the rims that are on .have you tried it with driver in the car?
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GeoffT
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| posted on 15/4/07 at 02:32 PM |
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quote:
geoff ive tried to corner weight your way but my pace guage doesnt work on the rims that are on .have you tried it with driver in the car?
My weighing setup is nothing more elaborate than a bathroom scale on which I've 'stretched' the readable scale from 150 to 165
kilos, and 3 blocks of wood which bring the other wheels up to the same height. Sounds crude, but gives repeatable results to within a couple of
kilos, good enough for what I need.
This method does, though, throw up a couple of more reasons why I don't bother with a driver in the car :-
a) the scales won't read that high....
b) I can't read the bloody scales when I'm sat in the car..
.....so the answer to your enquiry I'm afraid, is no.
What's the Pace gauge like, is it just a scale, or something more elaborate?
[Edited on 15/4/07 by GeoffT]
[Edited on 15/4/07 by GeoffT]
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higgsti
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| posted on 15/4/07 at 03:05 PM |
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its actually an adr guage it lifts one wheel off the ground on a lever principal the car has to be on a level surface and has to be lifted the same
height for each wheel.you are weighing on a level surface arnt you?
[Edited on 15/4/07 by higgsti]
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