Matt21
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| posted on 27/4/17 at 03:51 PM |
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Corner Weighting Help
Hello,
I've just had my car on the scales to try and set the corner weights myself (Cant find any one local at all to do it for me  )
Can anyone tell me if I have got this somewhere near right or if I'm way out?
Front Left
109.7kg
Front Right
127.1kg
Rear Left
171.5kg
Rear Right
185.2kg
This gives me a cross weight of 50.3%
Left-Right of 47.37%
and Front to rear 60.1 to 39.9%
(I Think?!)
I have had it set up previously and the weights were:
Front Left
125.5kg
Front Right
125.5kg
Rear Left
168.5kg
Rear Right
191.0kg
Cross weight: 51.8%
Left to right: 48.1%
Front to rear: 58.8 to 41.2%
The thing that has me concerned is that the previous set up had the same weights on both front wheels. Does this matter?
Do I need to get the left to right % closer to 50% as well as keep the 50% cross weight?
Any help would be much appreciated!
Instagram: @matt211988
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gremlin1234
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| posted on 27/4/17 at 04:31 PM |
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are those weights with you in it? (ie normal driving condition)
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Matt21
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| posted on 27/4/17 at 04:35 PM |
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yer me in it, half a tank of fuel, all fluids etc
Instagram: @matt211988
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My YouTube
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Camber Dave
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| posted on 27/4/17 at 05:06 PM |
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In my opinion, cross weight is a function of the arrangement of the components during the build and virtually irrelevant to set up for handling.
My criteria are
• Front damper perches at the same height
• Front ride heights the same
• Front Corner weights the same
Do most of the adjustments on the rear. You will find the RR perch will finish up 10 to 20mm higher than the l/h side (depending on springs
fitted).
With the correct springs the ride height (with driver) should be just 5 to 10mm higher.
This means that the car will respond the same whether turned left or right, front wheels and steering will react the same over road deflections and
the car will give equal and maximum braking reaction from both wheels.
The trade off is that the Right Rear will be heavy because of the drivers weight.
When turning right the extra weight from the right will transfer to the L/H/R wheel in proportion to the G force of the corner: Turn Left the extra
weight is already there to give grip.
Braking on the rear is less than that of the front so less important.
Your original weights fit with my criteria.
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Matt21
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| posted on 27/4/17 at 05:20 PM |
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BY original weights I guess you mean from the previous set up? A lot has changed since then so they were wayyyy out when I stuck it on the scales
today.
So If I set the front ride height to where I want it, then adjust the rear shocks to get both the front weights equal?
What sort of effect would the extra weight on the RR have when cornering? any weird handling traits?
Instagram: @matt211988
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My YouTube
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Camber Dave
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| posted on 27/4/17 at 05:50 PM |
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When turning in the priority is how the front reacts to the steering input and road grip.
During the corner the weight transfers to the outer wheels.
Exiting the corner weight transfers to the rear
When turning right the extra weight from the right will transfer to the L/H/R wheel in proportion to the G force of the corner:
Turn Left the extra weight is already there to give grip.
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Matt21
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| posted on 27/4/17 at 06:34 PM |
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Everything I have read online tells me that the cross weight is the most important to get right.
I can see why equal front weights would be good, but nothing I've read says this apart from what you said and the previous set up. So now
I'm a little confused as to what I need to be aiming for
Instagram: @matt211988
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My YouTube
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Camber Dave
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| posted on 27/4/17 at 07:14 PM |
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My scales have features called 'Oval' and 'Winston cup' both of which prioritise cross weighting and total R/H or L/H
weights.
I use the 'Road Racing ' function.
I’me not a registered trader on here so don’t advertise my wares or promote my company
I started by prepping and setting up single seaters over 40 years ago. I set up 30 or more Racing cars, track day and touring 7’s, each year.
I consult to a shocker company and will be showing at Stoneleigh next weekend.
I tell everyone who's car I set up how to do it themselves, and still they return annually, track cars 2 or 3 times a year.
I offer my experience and advice here for all to read, ignore or challenge.
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Matt21
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| posted on 27/4/17 at 08:12 PM |
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Sorry I think I may have came across as dismissing your advice base don what I had read online, that wasn't what I intended, just simply trying
to get my head around the two different recommendations, You know a lot more about this than I do so i'll give it a shot and see what
happens.
I'll have another play about tomorrow and hopefully get the front weights equal.
Is there anything else I should be trying to acheive? or simply get the fronts to match and just leave the rest however it happens to be?
While I was playing earlier I did manage to get them equal, I think they were around 120kg, the rears were something like 165kg and 190kg, would
something like that be good?
Cheers
Instagram: @matt211988
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My YouTube
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Camber Dave
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| posted on 28/4/17 at 08:03 AM |
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Thanks
You have the scales, car and domestic commitments permitting, time.
Try the car as it is - then reset it with equal fronts.
We all have favorite local test routes where we get an idea what the car is like.
All set ups are primarily to get the car benign and forgiving - from this the driver gets confidence and the times follow.
Then when when you get on track you can really let it sing.
It is virtually impossible to write an instruction manual for cornerweights.
The final, fine tuning and knowing when to leave it alone is more down to experience and having a 'feel' for it.
Getting all three of my 3 criteria correct is quite difficult and may need to be compromised.
Wind off the dampers before you start and bounce or roll the car every time you make a change. Roll off platforms help - you can also zero the scales
again.
One more gem - think of the vehicle as a table. if you were cut one leg short, weight will also come off the opposite leg and will transfer to the
adjacent diagonal ones. Conversely if you pack a leg with a spacer the opposite one will also carry half the weight of the table. The springs on our
cars modify this concept obviously.
You can use the latter theory to raise a light wheel or its opposite with a 6mm plywood packer to see which one most effects a correction to the
cornerweight.
As before, carry out Course adjustments at the Front
Then fine tuning at the rear - the change will be more 'gentle' and less likely to cock up the front ride height.
re the actual weights - use your own judgement - setting a numerical target is too frustrating.
Actually I aim to get the front + or - 1% empty and with the driver in for general touring.
Or + /- 0.5 % driver only for a track day car.
A bit like welding - 10% theory and 90% practice, experience and testing
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redturner
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| posted on 28/4/17 at 11:28 AM |
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Camber dave has got it right. One thing that I didn't see mentioned is that the scales must be absolutely level in all directions, to the mm. We
check / set up my single seater every couple of years to the hand book and it handles like a dream. The analogy of the chair legs is perfect.
Obviously a single seater is easier to set up because of the central seating position and not having any weight to one side.....
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adithorp
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| posted on 28/4/17 at 01:13 PM |
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quote:
Originally posted by Camber Dave
Try the car as it is - then reset it with equal fronts.
We all have favorite local test routes where we get an idea what the car is like.
All set ups are primarily to get the car benign and forgiving - from this the driver gets confidence and the times follow.
It is virtually impossible to write an instruction manual for cornerweights.
The final, fine tuning and knowing when to leave it alone is more down to experience and having a 'feel' for it.
A bit like welding - 10% theory and 90% practice, experience and testing
That about sums it up for me and which set-up you prefer will be down to personal preference. I've tried mine in both configurations several
times and prefer equal corners to equal fronts.
I find it more consistent turning l/r and more benign when starting to apply power (or have to lift) mid-corner. Whats more with the unequal corners
the change is different going left or right. Also I find that although initial/mild braking is good with equal fronts it changes fairly dramatically
when the largely uneven rear weight starts to transfer forward under heavy braking (and opposit when coming off the brakes).
But it does come down to preference and individual car so try both... At least by the time you've done that you'll have had plenty of
practice settingit up.
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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Matt21
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| posted on 30/4/17 at 06:25 PM |
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I have got it set with equal fronts now,
something like:
122.3kg 122.8kg
161kg 189kg
Had it out the last few days and I had to pull over at one point thinking I had a flat tyre on the rear right!
The rear end feels quite off, kind of like the rear tyre is rolling over (but it isn't)
I'm finding that its pushing out the front end going into roundabouts quick too, and turning left is when I get the back end roll.
I didn't give it much of a test with equal diagonal weights so i'll see it back with that and give it a good test.
Instagram: @matt211988
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My YouTube
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Camber Dave
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| posted on 30/4/17 at 07:00 PM |
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Hi Matt
Ride height, Camber and Toe at F & R as tested, all OK ?
Can be easy for these settings to migrate as we concentrate on cornerweight.
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Matt21
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| posted on 1/5/17 at 11:01 AM |
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I'll have to check it all again, I'm trying to find someone with a flatter garage than mine as it's taking me ages just to get the
scales set right.
Another question.
If I go for the 50/50 diagonal set up, I have more weight on the rear right wheel, so dropping the spring perch on that shock reduces the weight and
transfers it to the left side, which is all good.
But then because I've lowered that perch, the ride height is lowered on that corner, which means the cars sat low on one side and normal on the
other.
Instagram: @matt211988
Photobucket
My YouTube
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Camber Dave
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| posted on 2/5/17 at 07:48 AM |
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I have been busy at Stoneleigh over the weekend but noted Adithorp's comment with interest.
A conversation at there with a very experienced driver/sportscar dealer started by comparing Caterhams to 'Westfields' handling and moved
to his general perception that Becs generally have "wrong spring rates that dampers don't control well"
OP's and Adithrp's cars (both BEC's?) appear to respond similarly so I am wondering if the much lighter /off set engine in a bec
cause the effect as reported..
I have trawled through about all my 7 setups (all car engines) in the last two years (all +/- 0.1% fronts) and the results on diagonal cross weights
vary from 0.5 to 2% variance.
I have appealed on my local forum for a BEC 7 to try both settings on and get some feed back for future use.
So if there is anyone on here prepared to travel to Castle Combe area I will also do your car for research.
Cost to you £120 to Go /Inspire (we are building a Haynes with hand controls for disabled drivers to do track days)
See https://www.facebook.com/goinspirenow2015/
Results to follow when available.
My 27 April post was going to have an edit to clarify that the criteria quoted work with most cars BUT may not be effective on Bec's.
[Edited on 2/5/17 by Camber Dave]
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adithorp
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| posted on 2/5/17 at 10:07 AM |
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Sorry Dave, I've only just put 2+2 together or I would have come for a chat at Stoneleigh.
I think you're right that BEC's design and weight make differences a more more pronounced. I think the lighter the car the more noticable
the setupis (who worries about cornerweights on a RangeRover?). Other cars of similar weight tend to be single seaters with more even left/right
balance where BECs have the offset along the LF/RR diagonal which is almost unique to them.
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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