Nose dive
08-20-2003, 07:25 PM
#1
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Nose dive 2002 WS6 Hate the way my car nose dives when I'm on the brakes. What can I do about it? Don't like the way the body leans back under hard acceleration. Will one mod fix both? Thanks in advance for any help.
08-25-2003, 11:35 AM
#4
Re: Nose dive
I don't think thats the answer.
Springs support the weight of the vehicle. When you are accelerating or braking, you are moving weight from one end of the car to the other (think of a drag car with the front wheels in the air, all the weight is on the back tires). The more weight you add to one end (or the other) of a vehicle, the more you compress the springs. If you have a wheel rate (spring rate, adjusted for suspension geometry is your wheel rate....it is a very long discussion on it's own) of 400 inch lbs per front wheel, then 800 lbs of weight will compress the front of the car 1 inch (400 in lbs times 2 wheels, equals 800 in lbs). Now, if you have a 3600 lb car and it is 50/50 (ours are not) weight distribution (1800 lbs on each axle) and you dive on the brakes and transfer 50% of the rear weight forward, you have added 900 lbs to the front end and it will drop slightly over one inch.
The problem with this example is that our stock springs generate a wheel rate that is considerably less than 400 in lbs (maybe as low as 200 in lbs). Now, if we transfer 900 lbs onto the front with only a wheel rate of 200 in lbs (400 in lbs total, 2 wheels remember). We will dive over 2 inches!!!
This applies to acceleration as well, just in reverse.
Also, you may in fact transfer more than 900 lbs forward, it could be up to 1600 lbs (depending on brakes, and tire grip among other things). The more weight, the worse it is....
As a side note, the rear springs are only about 130-180 in lbs to start with. If we use 150 in lbs (and forget wheel rate) and transfer 1200 lbs to the rear, we now drop nearly 4 inches (or so).
Many people try to use shocks to control dive. A shock can control the rate of the dive (slow it down so it is not as dramatic) but it can't control the amount of dive, that is left to the springs.
In most every case, it actually is the answer.....
Just my thoughts....
08-25-2003, 11:43 AM
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Re: Nose dive my car used to dive hardcore when I braked, but it barely does now! I don't pretend to know why but it felt like the G2 torque arm affected nose dive the most. I still have stock springs
08-25-2003, 02:20 PM
#7
Re: Nose dive
I don't think thats the answer.
What causes nose dive? weight transfer.
What supports the weight of the car? springs
Why do the springs compress under braking? Weight transfer forward causes the springs to compress (the nose to dive).
Why would springs compress so much? spring rate
How would you keep the springs from compressing so much? stiffer rate
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08-26-2003, 01:16 PM
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Re: Nose dive You guys think you have it bad....try slowing down from anything with 3.5" skinnies in the front and an iron block with hal shocks w/coil overs.... 
08-26-2003, 02:45 PM
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Re: Nose dive no trackbird,I still have stock shocks and springs. It still dives, but it feels like inches instead of feet like it did stock. I'm sure springs/shocks would help more at almost eliminating dive though! :p
08-27-2003, 03:00 PM
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Re: Nose dive
I don't think thats the answer.
Springs support the weight of the vehicle.
In most every case, it actually is the answer.....
Just my thoughts....
For completeness sake, CG height also affects weight transfer and therefor dive. In fact, a torque arm will affect transfer too, as it can effectively add unsprung weight to the rear of the car, which can reduce CG rise, etc. The magnitude of the effect depends on length instant centers and etc, but I've seen setups that squat rather than dive.
Just MHO
08-27-2003, 03:32 PM
#13
Re: Nose dive
I don't think thats the answer.
Springs support the weight of the vehicle.
In most every case, it actually is the answer.....
Just my thoughts....
For completeness sake, CG height also affects weight transfer and therefor dive. In fact, a torque arm will affect transfer too, as it can effectively add unsprung weight to the rear of the car, which can reduce CG rise, etc. The magnitude of the effect depends on length instant centers and etc, but I've seen setups that squat rather than dive.
Just MHO
Kevin
08-28-2003, 08:49 PM
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Re: Nose dive
I don't think thats the answer.
Springs support the weight of the vehicle.
In most every case, it actually is the answer.....
Just my thoughts....
For completeness sake, CG height also affects weight transfer and therefor dive. In fact, a torque arm will affect transfer too, as it can effectively add unsprung weight to the rear of the car, which can reduce CG rise, etc. The magnitude of the effect depends on length instant centers and etc, but I've seen setups that squat rather than dive.
Just MHO
Kevin
