I have no knowledge to share ... but my understanding, after reading a lot, is that one sets cornerweight to improve handling and balance ... and that is more important than ride height ...
I am lowered on stock bolts, and my ride height is consistent, with proper rake. I intend to corner weigh and weight this winter ... and see what I think of it next spring ...
Questions:
I read somewhere to weight with driver and 1/2 +/- tank fuel ... did you set with 1/8th because that's the way you run autox?
Did you disconnect your sway bars when you weighted?
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Questions:
I read somewhere to weight with driver and 1/2 +/- tank fuel ... did you set with 1/8th because that's the way you run autox?
Did you disconnect your sway bars when you weighted?
I have lately been running pretty low with fuel load to save weight & so 1/8 was about what I figured. I can add about 100 lbs of gas weight to further tune the f/r balance & may try that. That would probably mess with the lf/rf a little bit, but I am not going to go crazy over +/- a couple of pounds. Most (little car) courses I run do not require the extra power/weight boost that I get by dropping the 100 lbs. This is (of course) autox specific, not track or drag.
I did not disconnect the bars, I do not think that there is any significant pre load on them. Last time I messed with them they seemed pretty neutral. The front bar is "floated" with a few washers (to prevent the bushings from Having a "death grip" on the bar.
Yes, corner and cross weights are more important than ride height. However, obtaining the proper rake is only slightly less so. Although corner weighing and adjusting the ride height adjusters in order to get the cross weights as equal as possible can be accomplished without disconnecting or removing the swaybars, there is a chance you will end up with preload on them. By using adjustable swaybar endlinks this can be avoided. You disconnect or remove the swaybars, set the weights and then reconnect the swaybars and adjust out any preload that resulted.
Without adjustable swaybar endlinks, e.g. the stock swaybars, you may have to compromise cross weights somewhat in order to avoid swaybar preload, although it's usually not a significant amount as you discovered.
Yes, corner and cross weights are more important than ride height. However, obtaining the proper rake is only slightly less so. Although corner weighing and adjusting the ride height adjusters in order to get the cross weights as equal as possible can be accomplished without disconnecting or removing the swaybars, there is a chance you will end up with preload on them. By using adjustable swaybar endlinks this can be avoided. You disconnect or remove the swaybars, set the weights and then reconnect the swaybars and adjust out any preload that resulted.
Without adjustable swaybar endlinks, e.g. the stock swaybars, you may have to compromise cross weights somewhat in order to avoid swaybar preload, although it's usually not a significant amount as you discovered.
I should check the bars now that I have jacked the rr a little. What's a good front bar with adj links? Can't change the rear (rules).
You have a few options as far as the front bar. You can use seperately available adjustable endlinks with the stock bar, use the GM T1 front bar which comes with adjustable links or, the Pfadt front bar which also comes with adjustable endlinks as well as holes that allow you to adjust torsion.
Be aware that if you increase only the front swaybars torsional rigidity, i.e. a larger bar, you will increase understeer. To counter this you will need to increase front-end grip. If you haven't already done so, you're better of starting with a front/rear wheel and tire combination that offers more grip.
You have a few options as far as the front bar. You can use seperately available adjustable endlinks with the stock bar, use the GM T1 front bar which comes with adjustable links or, the Pfadt front bar which also comes with adjustable endlinks as well as holes that allow you to adjust torsion.
Be aware that if you increase only the front swaybars torsional rigidity, i.e. a larger bar, you will increase understeer. To counter this you will need to increase front-end grip. If you haven't already done so, you're better of starting with a front/rear wheel and tire combination that offers more grip.
Do you have a source for the seperate adj end links that work with the stock bar?
I don't really want to mess with the rates at this time, but that sounds like it would be a smart thing to do. Do they adjust like a "turnbuckle" type of hardware with lock nuts? Just snug up hand tight & lock them?
Adjustable endlinks (non T1) are available from both Guldstrand Motorsports and Vette Brakes & Products. Pfadt Race Engineering swaybars come with adjustable endlinks.
And yes, they are similar to a turnbuckle. They are Heim jointed and use a rotating, internally threaded sleeve and a locking nut. It's self-explanatory when you see a photo.
Adjustable endlinks (non T1) are available from both Guldstrand Motorsports and Vette Brakes & Products. Pfadt Race Engineering swaybars come with adjustable endlinks.
And yes, they are similar to a turnbuckle. They are Heim jointed and use a rotating, internally threaded sleeve and a locking nut. It's self-explanatory when you see a photo.
How I corner weighed my 04 ZO6 was first thing i did was to build drive on ramps from 2X12's for my scales so I would not have to jack up the car because everytime i do and let the car down it won"t settle all the way down no matter how many times i bounce on it until i go for about a 15 mi drive with it.
Next i lowered the frt all the way and lowered the rear until I had an 1/4 rake. I then drove it in the scales and weighed it putting the respective weights in DG's A/x Setup Secrets corner weight calculator. (see attachmenmts). from the info in the calculator I raised the lf 2 turns and the rr 4 turns and drove the car for at least 15mi and reweighed the veh and got within 3.24 lbs on the first try.
I never disconnected the sway bars because they are not adjustable and if i did and reconnected them and there was some significant preload i would just have to reajust the car again anyway. The rest of the car set up, w/driver, 1/2 tank fuel just as it is raced.
After making the ramps i can do everything in less than 2 hrs.
Last edited by dgoetz : 11-04-2007 at 07:30 AM.
Reason: backwards
... Next i lowered the frt all the way and lowered the rear until I had an 1/4 rake. I then drove it in the scales and weighed it putting the respective weights in DG's A/x Setup Secrets corner weight calculator. (see attachmenmts).
Question: Did you drive the car 15 miles or so after you lowered it before you drove onto the scales?
Quote:
Originally Posted by dgoetz
from the info in the calculator I raised the rf 2 turns and the lr 4 turns and drove the car for at least 15mi and reweighed the veh and got within 3.24 lbs on the first try. ...
Questions:
Does the "calculator" tell you how much to raise based on weights?
Did you raise the front while on the scales? (would seem to be a PITA to get to ... and to unweight the spring to take pressure off the bolt ...
Question: Did you drive the car 15 miles or so after you lowered it before you drove onto the scales?
Questions:
Does the "calculator" tell you how much to raise based on weights?
Did you raise the front while on the scales? (would seem to be a PITA to get to ... and to unweight the spring to take pressure off the bolt ...
Yes, everytime I changed something i drove the car. I did all the adjusting when I drove it off the ramps. Cause if I lifted the car while on the scales then I wouldn't get the car to settle buy boucing it so i would have to drive it any way.
The calculator only tells me which corners need weight and how much weight it is off the rest is guessing and luck.
You can see that I changed it from 45lbs off to 3lbs by the the adjustments I made, I don't know if it would be Proportionately to other veh.
Yes, everytime I changed something i drove the car. I did all the adjusting when I drove it off the ramps. Cause if I lifted the car while on the scales then I wouldn't get the car to settle buy boucing it so i would have to drive it any way.
The calculator only tells me which corners need weight and how much weight it is off the rest is guessing and luck.
You can see that I changed it from 45lbs off to 3lbs by the the adjustments I made, I don't know if it would be Proportionately to other veh.
Thanks ... that all makes sense ...
If I can borrow my alignment shop's scales for a weekend ... I see a winter project ahead ...
I went to an autox yesterday. Car seemed fine, but, My friend (3x nat autox champ) told me that you are supposed to get the CROSS WGT PERCENTS as equal as possible, not the LF & RF. So I guess I did it wrong, but I also think the adjustments might have been in the right direction nevertheless.
Can someone calc the cross wgt %'s on my final wgts or explain how you do that?
Thanks.
Also he said you really need to disconnect the bars & have adj links in the front, so that when you reattach the bar you don't shift the balance. Adj rear links also (if rules allow).
which do you think is more important, equal ride height, or equal (as close as you can get) corner weight>
To which I replied....
Quote:
Yes, corner and cross weights are more important than ride height.
Thus your friend is right (or we're both wrong ). I should add that corner weights and cross weights are interrelated because the ideal crossweight is RF+LR = LF+RR, or as close as possible. Simply add up the corner weights to obtain cross weights. These can vary, however, depending on other factors. Setting cross weights, corner weights, alignment and ride height is a very iterative process and you will of course need scales and the ability to align accurately, preferably while on the scales with your weight in the drivers position.
Disconnecting the swaybars is almost irrelevant unless they have adjustable endlinks. Once everyting is where you want, the endlinks either slip on or they don't. If not then you have to change what you did so that they do. Therein lies the compromise between nominal cross weights, corner weights and getting non-adjustable bars to fit without significant preload.
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). I should add that corner weights and cross weights are interrelated because the ideal crossweight is RF+LR = LF+RR, or as close as possible. Simply add up the corner weights to obtain cross weights. These can vary, however, depending on other factors. Setting cross weights, corner weights, alignment and ride height is a very iterative process and you will of course need scales and the ability to align accurately, preferably while on the scales with your weight in the drivers position. 
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