Corner Weighting?

[sykikchimp]

I've heard about this a lot, but have never seen an explanation of how you implement it?  I know you have to have coilovers (or adjustable spring height) but what adjustments do what? and when would it be appropriate??

just curious.

-Charles
(yes.. I am copying you.. lol)

[whoizrob]

I am just starting to learn about corner weighting so I'll tell you what I know, or think I know anyways...

When you throw your car about you want to know that it will handle just as predictable on right turns as well as left turns. You do that by making sure that both right and left are weighted equally (aside from the obvious alignemtns and setting on your suspension). There are small electronic scales which the car sits on (all four sides get their own scale). Now weight jacking, which is changing the height of the coilovers only sort of solves the problem since all you are doing is chaning the percieved weight each tire feels. It's kind of like having a table with a shorter leg than the others, less weight sits on that leg and the other three take the weight more.

The real solution involves moving mass around on the car like the battery and lead weights etc. It's more of a pain but has better results.

HTH,
Rob

[BadMoJo]

I was also wondering about this. I would figure the driver weight would throw it off the most, good thing I am not very heavy. &nbsp;<img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/biggrin.gif" border="0" valign="absmiddle" alt=':D'>

[tnord]

driver weight is incorporated at any performance shot worth it's weight in used penzoil, other things such as location of fuel cells, how much fuel you typically have, if you are setting up for a particular track (vast majority of right turns), etc are taken into consideration. &nbsp;there was an article about this in european car a few years back, i'll see if i can dig it up. &nbsp;basically it involves some pretty fine tuning that most of us wouldn't ever need to consider.

bbp, you got any more on this?

[bbp]

Well,

Corner weighting has been described pretty accurately above. &nbsp;You are basically moving the collars up or down to try and even out the weight on all four corners.

This is how my car weighed out
For example:

807 &nbsp; &nbsp;FR &nbsp; &nbsp; &nbsp;713

592 &nbsp; &nbsp;Rear &nbsp; 569

This is a pretty good set, could be better. &nbsp;What you are trying to get is a cross weight (LF to RR) to be within a low percentage of each other. &nbsp;It is imposible to get the corner all equally weighted without moving batteries etc.

total 2466 w/o driver (roughly, I've added some weight to it since then)

[sykikchimp]

Ok.. &nbsp;so in order to decrease weight on a specific corner you would raise the spring collar right?

What was your weights after you finished corner weighting bbp?

[bbp]

I think you may have it backwards, to reduce weight on a corner you would spin the collar down.

Think of a table with one leg longer than the rest. The longer leg would bear more weight on it. Therefore, by lowering the spring you are shortening that "leg of the table" Dig?

2681 with "a" driver (I don't weight 215). These weightshave changed cause I've changed exhausts, added a big freakin seat back brace, put tranny fluid in it (don't ask!<img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/wink.gif" border="0" valign="absmiddle" alt=';)'>, belts etc. &nbsp;

We will probably throw it on the scales again soon to see where we are. My friends at Kryderacing helped with my car. (http://www.kryderacing.com)

edit: add link

[adey]

How much does i typically cost to bring your car in for corner weighting, and can pretty much any shop do this? I assume specific/special equipment is needed...

[sykikchimp]

what I was thinking in my head is hard to describe..

Seems to me that when you raise one corner that would cause the weigt to shift away from it. &nbsp;Image a 3d rectangle with legs at each corner. &nbsp;You increase the height of the one corners leg and you change the angle at which the rectangle is sitting. &nbsp;Thus removing a portion of the mass over that leg, and increasing it over the adjacent leg. &nbsp;raise Right Rear, increase weight over left front.. &nbsp;understand?

Why would that not apply to what you are saying?

[tnord]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (adey @ May 08 2002,3:19)</td></tr><tr><td id="QUOTE">How much does i typically cost to bring your car in for corner weighting, and can pretty much any shop do this? I assume specific/special equipment is needed...</td></tr></table><span id='postcolor'>
no, not any shop can do this. or if they can, i wouldn't trust them. &nbsp;pretty much any place that's a chain, like midas, forget about it. you'll have to find a local race shop (not the place that sells intakes and wheels).

[bbp]

here is a goodpost (http://forums.improvedtouring.com/it/Forum1/HTML/000254.html)about this.


edit:add post

[matic 240sx]

omg.. this is the first post i read today and didn't get pissed about how gay it was... i learned a little something reading it...

good job chimp

http://www.stink-blossom.net/STFU/ThisThreadRocks.jpg

[sykikchimp]

ok, after reading that, I wonder how is it possible to get 50/50 cross weights??? &nbsp;That would indicat that there is the same amount of weight on LF as RR?? &nbsp;If you've got a gutted race car with the engine in the front, how is that possible? &nbsp;I don't think I understand what they mean by "50/50 Cross weights"

[thich]

here's a good site too:

Grassroots Motorsports' Explanation of Corner Weighting (http://www.grmotorsports.com/cornerweight.html)

[rotaryknight]

No chain shop will have the scales...like an above post stated it would have to be a specialty or race shop. &nbsp;Not only that it takes alot of time.....shops don't like that and they show you that for charging you for that time.

Also if you do it you should be in the car with roughly the amount of gas you would use when autox or competing. &nbsp;And by all means clean all the crap out of your trunk. &nbsp;Basically you want the conditions of the car exactly how you would compete with when you are being weighed.

[whoizrob]

Hey Chimp,

The idea is to get the left to right balance right not so much the front to rear balance (although that'd be nice too). Corner weighting ensures CONSISTANCY between left and right side handling nothing more.

When you start worrying about front to rear balance then you are thinking more about rotation which is WAY more complicated.

rob

[HippoSleek]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (bbp @ May 07 2002,3:08)</td></tr><tr><td id="QUOTE">total 2466 w/o driver (roughly, I've added some weight to it since then)</td></tr></table><span id='postcolor'>
God lord, that's nice! &nbsp;

I didn't think a 240 would get under 2500#. &nbsp;I assume your intererior is all nice, red metal but you have a dash. &nbsp;Cage weighs a bit. &nbsp;How large is the fuel cell? &nbsp;What kind of seat?

I was talking to a buddy who was going to gradually build a 240 into a racecar and was wondering how light he could get it w/ basic gutting, a cage, and a cell. &nbsp;I guessed about 2550# - but it seems I was way off. &nbsp;

What is the min. weight for that car in ITS?

BTW: good discussion of cornerweighting... the "other" use for fancy schmancy coilovers or GCs <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/wink.gif" border="0" valign="absmiddle" alt=';)'>

[bbp]

As you can see in the pics on my website. The interior is gutted except for Dash and lightweight seat. &nbsp;Stock fuel tank is still in there. All sound deadening and rust coating has been removed, inner fender plastic, most of the smog equipment, driver door glass.

The wheels are next, stock wheels are really heavy!

IIRC, Min for ITS is 2680 with driver

[240S15DETE6K]

50/50 cross weights means you want the sum of the diagonally opposite corners to add up the same. &nbsp;A FWD car, for example, will obviously have most of the weight at the front, but it can still have 50/50 cross weight. &nbsp;That's all you're really trying to achieve with coilovers. &nbsp;To change the side-to-side or front-rear distribution, you have to move stuff around which may not be legal for a class (ITS for example, we can't move the battery)

[Ballistic-Mobile.com]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (matic 240sx @ May 07 2002,7:11)</td></tr><tr><td id="QUOTE">omg.. this is the first post i read today and didn't get pissed about how gay it was... i learned a little something reading it...

good job chimp

http://www.stink-blossom.net/STFU/ThisThreadRocks.jpg</td></tr></table><span id='postcolor'>
HAHAHAHAHAHAHAHAHA! I remember this picture from a photshopping thread over at I-Club.com &nbsp;Now that was a badass thread <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/hehe.gif" border="0" valign="absmiddle" alt=':hehe:'>

[sykikchimp]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (240S15DETE6K @ May 08 2002,11:48)</td></tr><tr><td id="QUOTE">50/50 cross weights means you want the sum of the diagonally opposite corners to add up the same. A FWD car, for example, will obviously have most of the weight at the front, but it can still have 50/50 cross weight. That's all you're really trying to achieve with coilovers. To change the side-to-side or front-rear distribution, you have to move stuff around which may not be legal for a class (ITS for example, we can't move the battery)</td></tr></table><span id='postcolor'>
OH.. ok.. &nbsp;I understand now. Thanks. &nbsp;so:

LF+RR=RF+LR &nbsp;ratio should be 50/50. &nbsp;Gotcha. &nbsp;Makes MUCH more sence now.

[sykikchimp]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (thich @ May 08 2002,01:03)</td></tr><tr><td id="QUOTE">here's a good site too:

Grassroots Motorsports' Explanation of Corner Weighting (http://www.grmotorsports.com/cornerweight.html)</td></tr></table><span id='postcolor'>
Thanks.. &nbsp;That link really helped a lot too..

[HippoSleek]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (bbp @ May 08 2002,08:53)</td></tr><tr><td id="QUOTE">As you can see in the pics on my website. The interior is gutted except for Dash and lightweight seat. Stock fuel tank is still in there. All sound deadening and rust coating has been removed, inner fender plastic, most of the smog equipment, driver door glass.

The wheels are next, stock wheels are really heavy!

IIRC, Min for ITS is 2680 with driver</td></tr></table><span id='postcolor'>
Your website is where? &nbsp;<img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/whatsthat.gif" border="0" valign="absmiddle" alt=':whatthe:'>

Hey - bbp (do you have a first name?) and Brad: &nbsp;Are either of you going to the NASA HPDE at Summit Point on 6/22-23/02?