what pound springs are you track people running up front
05-16-2012, 10:07 PM
#76
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Lol sort of. The length of the spring you choose is dependent upon the coil density and the amount of total displacement of the spring itself that you desire.
You've been rather brusque lately, seems uncharacteristic. Everything alright?
You've been rather brusque lately, seems uncharacteristic. Everything alright?
05-17-2012, 12:33 AM
#78
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A straight rate 1000 pounds per inch spring (for example) takes 1000 pounds to compress the first inch, an additional 1000 pounds to compress an additional inch, etc. The length and number of coils doesn't affect the spring constant.
A shorter spring (the deflection divided up among less coils) will experience more material stress than a longer one with more coils, and will fatigue faster assuming equal steel characteristics. However, this fatigue occurs on an almost geologic time scale in most designs so it's not something I'd waste sleep worrying about.
A shorter spring (the deflection divided up among less coils) will experience more material stress than a longer one with more coils, and will fatigue faster assuming equal steel characteristics. However, this fatigue occurs on an almost geologic time scale in most designs so it's not something I'd waste sleep worrying about.
05-17-2012, 12:38 AM
#79
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The range between front and rear seems excessive to most of us. Why is it specific to the B.E.Cups? Wouldn't having more than double the rate on the rears induce oversteer.
05-17-2012, 12:43 AM
#80
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BTW I run 725/864 with 275's on 9" square.
05-18-2012, 07:22 PM
#81
For a rookie: So should the effective spring rate be the same for best results?
And some people running the same front/rear still have a balanced car...?
Is there an answer on this?
I run Ledas 24-way adj with 400/650 and springs are 8" long. I don't have helper springs but need to be able to lower it without springs getting loose on full droop.
You Leda guys what do you have in rates and how long springs?
Looking more an more to build a track-car out of mine.
Ran 225/285 Kumho V70 and this felt understeer... Will 255 it on 8,5"?
/Peter
And some people running the same front/rear still have a balanced car...?
Is there an answer on this?
I run Ledas 24-way adj with 400/650 and springs are 8" long. I don't have helper springs but need to be able to lower it without springs getting loose on full droop.
You Leda guys what do you have in rates and how long springs?
Looking more an more to build a track-car out of mine.
Ran 225/285 Kumho V70 and this felt understeer... Will 255 it on 8,5"?
/Peter
05-18-2012, 08:26 PM
#82
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I only mentioned that due to the valving on the Bilstein Escort Cups. If you run say 300lb springs (not including torsion bars) on them, the car will be way undersprung and the springs will be fighting against the damper and losing. Once again, spring rate should be matched to valving. As for the spring range difference, you need to take into account the motion ratios and the end resulting wheel rates.
Lets use the 400F/800R example.
400 * .8836 = 353.44 wheel rate
800 * .4225 = 338 wheel rate
So, there is still less effective spring in the rear.
Lets use the 400F/800R example.
400 * .8836 = 353.44 wheel rate
800 * .4225 = 338 wheel rate
So, there is still less effective spring in the rear.
400 * .8836 = 353.44 wheel rate
25.5 TB ~ 150 + 225 * .4225 = 95 for a total wheel rate of 245 rear?????
245/275 x18's BTW....seems like I need to bump the rears up to 500's....
05-18-2012, 09:52 PM
#83
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OE setups use stiffer front ratios because of legal liability. They intentionally design cars with push. That's why.
And you have to consider the sway bars (if used) when determining spring ratios. Not all sway bars are equally stiff. And all (aftermarket) are adjustable as well, each with various linkage ratios.
So the best you can do is to start with a known setup that works fairly well, on a car that is setup similarly well to yours, with similar weights, and a similar design purpose (street car vs light weight dedicated track car for example).
As for tire size... if you can heat them up properly, you can't go too big.
TonyG
And you have to consider the sway bars (if used) when determining spring ratios. Not all sway bars are equally stiff. And all (aftermarket) are adjustable as well, each with various linkage ratios.
So the best you can do is to start with a known setup that works fairly well, on a car that is setup similarly well to yours, with similar weights, and a similar design purpose (street car vs light weight dedicated track car for example).
As for tire size... if you can heat them up properly, you can't go too big.
TonyG
05-18-2012, 09:55 PM
#84
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TonyG
05-19-2012, 04:28 AM
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05-19-2012, 09:59 AM
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Thanks for the responses...
This car has been my project for the last 6 months, and in my first test and tune a few weeks ago the rear springs were coming out of their perch's under hard cornering....
This car has been my project for the last 6 months, and in my first test and tune a few weeks ago the rear springs were coming out of their perch's under hard cornering....
05-19-2012, 01:02 PM
#89
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Every stock car I've ever driven pushes except for maybe for a few of the new high end sports cars... including a stock 951 & 968. Do you not think that Porsche intended for the 951 to handle like it does in stock form... or was it a poor setup on their part?
As far as "most known setups being wrong". That might be. But what I said was to use a known setup that works. In other words... someone that is doing well on the race track with their setup and start there.
TonyG
As far as "most known setups being wrong". That might be. But what I said was to use a known setup that works. In other words... someone that is doing well on the race track with their setup and start there.
TonyG
I told you the reason why and it's not as simple as "because it will push". I have been in a ton of cars that did not "push" that had 100% factory suspension on them. There are too many variables to account for.
Swaybars should be utilized as little as possible. The rear shouldn't have one at all. Lifting wheels makes you slower.
Most "known" setups on here have been wrong to pretty big degrees and doing the math will give you a much better starting point than randomly picking a guys suspension setup on a forum.
Heat ranges, tire compound, tire structure, and contact patch are all important.
Swaybars should be utilized as little as possible. The rear shouldn't have one at all. Lifting wheels makes you slower.
Most "known" setups on here have been wrong to pretty big degrees and doing the math will give you a much better starting point than randomly picking a guys suspension setup on a forum.
Heat ranges, tire compound, tire structure, and contact patch are all important.
