Choosing Front Coilover Spring Rate?
01-23-2010, 02:51 PM
#1
Choosing Front Coilover Spring Rate? How do you know if you're using the optimum spring rate in the front of a drag car? What do you look for in choosing or changing the spring rate?
Last year I had moderate weight reduction off the nose of the car, had BMR Kmember, aluminum block, !bumper support, !ABS. I was using 275lb spring in the front with Strange coilovers. But,,,,, I have no idea if that was the spring rate I needed or a heavier spring was needed? This year I'm moving the battery to the back, but I'm also using a heavy 6.0 iron block. I'm debating stepping up to 300lb springs in the front.
Mike
Last year I had moderate weight reduction off the nose of the car, had BMR Kmember, aluminum block, !bumper support, !ABS. I was using 275lb spring in the front with Strange coilovers. But,,,,, I have no idea if that was the spring rate I needed or a heavier spring was needed? This year I'm moving the battery to the back, but I'm also using a heavy 6.0 iron block. I'm debating stepping up to 300lb springs in the front.
Mike
01-23-2010, 07:02 PM
#3
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From what I understand...you have to have your car weighed...know what each corner weighs and figure out compression height of the spring. So figure a 275 x 3" of compression would be 825# for that corner....I believe...if I'm wrong someone correct me....
01-25-2010, 01:57 PM
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From what i understand, if you have a stock weight daily driver, the 325s are fine. If you have a street driven stockish weight bracket car (like mine) the 300s are fine and if you have taken weight off the nose and you race it, the 275s are fine.
01-25-2010, 02:18 PM
#5
Here's the rule of thumb (and there's always an exception) that I was always told:
n/a, nitrous cars, if it's over 3600 lbs, leave the stock springs, if it's over 3200 lbs, 300 lb springs, under 3200 then you can run the 275 springs.
S/C and turbo cars, as they generally have more nose weight, usually need about 25 lbs more spring with the same weights. This, is because of the nose weight, to help support the car up and help distribute the weight some.
That's a very general rule, and is far from 100%, but it gives ya an idea.
Example, a 3800 lb car with an iron block and a supercharger might work with a 275 spring, but there's a really good chance the spring will be almost coil bound to hold the weight up.. whereas a 300 lb spring would be a little better, but still may struggle to hold up the weight, a stock spring, would have no problem.
Again, just an example.
n/a, nitrous cars, if it's over 3600 lbs, leave the stock springs, if it's over 3200 lbs, 300 lb springs, under 3200 then you can run the 275 springs.
S/C and turbo cars, as they generally have more nose weight, usually need about 25 lbs more spring with the same weights. This, is because of the nose weight, to help support the car up and help distribute the weight some.
That's a very general rule, and is far from 100%, but it gives ya an idea.
Example, a 3800 lb car with an iron block and a supercharger might work with a 275 spring, but there's a really good chance the spring will be almost coil bound to hold the weight up.. whereas a 300 lb spring would be a little better, but still may struggle to hold up the weight, a stock spring, would have no problem.
Again, just an example.
01-25-2010, 02:53 PM
#6
So I guess as long as the car sits ok, doesn't bottom out easily etc., then there really is no "track" advantage to running a different spring rate? I thought maybe the front spring rates had more to do with good weight transfer at launch etc... ?
Mike
Mike
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01-26-2010, 11:29 AM
#13
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Here's the rule of thumb (and there's always an exception) that I was always told:
n/a, nitrous cars, if it's over 3600 lbs, leave the stock springs, if it's over 3200 lbs, 300 lb springs, under 3200 then you can run the 275 springs.
S/C and turbo cars, as they generally have more nose weight, usually need about 25 lbs more spring with the same weights. This, is because of the nose weight, to help support the car up and help distribute the weight some.
That's a very general rule, and is far from 100%, but it gives ya an idea.
Example, a 3800 lb car with an iron block and a supercharger might work with a 275 spring, but there's a really good chance the spring will be almost coil bound to hold the weight up.. whereas a 300 lb spring would be a little better, but still may struggle to hold up the weight, a stock spring, would have no problem.
Again, just an example.
n/a, nitrous cars, if it's over 3600 lbs, leave the stock springs, if it's over 3200 lbs, 300 lb springs, under 3200 then you can run the 275 springs.
S/C and turbo cars, as they generally have more nose weight, usually need about 25 lbs more spring with the same weights. This, is because of the nose weight, to help support the car up and help distribute the weight some.
That's a very general rule, and is far from 100%, but it gives ya an idea.
Example, a 3800 lb car with an iron block and a supercharger might work with a 275 spring, but there's a really good chance the spring will be almost coil bound to hold the weight up.. whereas a 300 lb spring would be a little better, but still may struggle to hold up the weight, a stock spring, would have no problem.
Again, just an example.
01-27-2010, 07:28 AM
#17
It will change how the car settles, and the amount of stored energy in the stiffer springs changes how much the car it thrown up at the launch.
Softer spring, with the right dampening would probably help the car settle a little easier when it comes back down, and the lower level of stored energy will help stop the nose from getting thrown up as fast.
You'd have to try it to be 100% sure it works, as every car's different, but I think it would help keep the car a little lower and should waste less time up in the air, like it's likly going to start doing in the near future with the way you're going.
Softer spring, with the right dampening would probably help the car settle a little easier when it comes back down, and the lower level of stored energy will help stop the nose from getting thrown up as fast.
You'd have to try it to be 100% sure it works, as every car's different, but I think it would help keep the car a little lower and should waste less time up in the air, like it's likly going to start doing in the near future with the way you're going.
01-27-2010, 08:33 AM
#18
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if your paco then you might not have to... that is one sweet *** ride....
ok... i guess if its a billet/aluminum BBC, lexan, spindle, nitrous or NA car than your probably right..... those seem hard to come buy for a stock front suspension car.... sounds sexy though
ok... i guess if its a billet/aluminum BBC, lexan, spindle, nitrous or NA car than your probably right..... those seem hard to come buy for a stock front suspension car.... sounds sexy though
