Unsprung weights, motion ratios, and natural frequencies?
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Unsprung weights, motion ratios, and natural frequencies?
I tried posting this in the suspension section, but nobody seems to have any answers. I've seen some pretty technical discussions going on over here, so hopefully y'all can help me out.
I apologize if this information is available elsewhere, I honestly couldn't find it.
I was wondering if anybody had estimates for any of these numbers for a g35 coupe (or 350z) in stock form.
1) unsprung weights
2) motion ratios (I've heard 0.76 F and 0.39 R, but nobody was sure)
3) natural frequencies
4) Corner weights (don't have access to a set of scales, sorry)
I'm picking out suspension components and trying to get a really good handle on the natural frequencies of the vehicle. Thanks in advance guys, have a good one.
I apologize if this information is available elsewhere, I honestly couldn't find it.
I was wondering if anybody had estimates for any of these numbers for a g35 coupe (or 350z) in stock form.
1) unsprung weights
2) motion ratios (I've heard 0.76 F and 0.39 R, but nobody was sure)
3) natural frequencies
4) Corner weights (don't have access to a set of scales, sorry)
I'm picking out suspension components and trying to get a really good handle on the natural frequencies of the vehicle. Thanks in advance guys, have a good one.
#2
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Corner Weights
2006 350Z Base with 1/2 tank of fuel, not spare, tools, no driver.
LF 889 RF 903
LR 694 RR 730
Left Side 1583 49.2%
Right Side 1634 50.8%
Front 1792 55.7%
Rear 44.3%
Cross (RF/LR) 1598 49.7%
Unsprung Weight
Stock spring, Koni Sport, Enkei RPF1 18 x 10 w/Hankook R214 285/30-10, stock calipers, Hawk DTC70 pads.
Front 135 lbs. (estimated)
Rear 130 lbs. (estimated)
Motion ratios and bump steer curve are already posted in this forum. Just do a search.
2006 350Z Base with 1/2 tank of fuel, not spare, tools, no driver.
LF 889 RF 903
LR 694 RR 730
Left Side 1583 49.2%
Right Side 1634 50.8%
Front 1792 55.7%
Rear 44.3%
Cross (RF/LR) 1598 49.7%
Unsprung Weight
Stock spring, Koni Sport, Enkei RPF1 18 x 10 w/Hankook R214 285/30-10, stock calipers, Hawk DTC70 pads.
Front 135 lbs. (estimated)
Rear 130 lbs. (estimated)
Motion ratios and bump steer curve are already posted in this forum. Just do a search.
Last edited by betamotorsports; 03-26-2010 at 07:46 AM.
#3
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I really have searched, and I've come up with conflicting information. Here's what I've found so far for motion ratios.
1) 0.79 F 0.36 R
2) 0.53 F (with 10 degree AC) 0.36 R
3) 0.688 F 0.649 R
The third option sounds more correct considering the stock spring rates, but I've seen the other two options quoted much more frequently. Which is correct?
Thank you for the information on corner weights and unsprung weights. I'll tack on the difference in wheel weights (I'm rolling on the Infiniti OEM 19's) and call it a day.
1) 0.79 F 0.36 R
2) 0.53 F (with 10 degree AC) 0.36 R
3) 0.688 F 0.649 R
The third option sounds more correct considering the stock spring rates, but I've seen the other two options quoted much more frequently. Which is correct?
Thank you for the information on corner weights and unsprung weights. I'll tack on the difference in wheel weights (I'm rolling on the Infiniti OEM 19's) and call it a day.
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To figure out wheel rates with the stock pickup points.
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Yeah, I'm just running the numbers for different aftermarket suspension kits. Seeing how the roll stiffness and natural frequencies are affected. There's not a whole lot I could do until I get the springs on my car, but I'm a mechanical engineer and I like running the numbers . Makes me feel better and I like to make sure everything makes sense before I buy the stuff.
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+1 as an ME myself too i am forever doomed to run numbers like that. ive been surprised at some of the numbers & conclusions I've come up with from so called performance parts though.
Last edited by diablox1; 03-30-2010 at 06:37 AM.
#12
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Found a calculation chart from third party's site. On SPL's website under the 350z's suspension area (springs to be precise). It has a Excel Calc that shows the ratio around 1.66 (Note SPL listed this as an inverse relationship than what is generally measured, spring to wheel Vs wheel to spring motion).
http://www.splparts.com/main4/parts/...Calculator.xls
Last edited by Zazz93; 01-13-2011 at 08:58 AM.
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From my understanding there are two points to calculate from at the rear.
Rear OEM coil ratio is 0.36. The rear shock loaction ratio is 0.59. Is that used when your calculating for a proper rear mounted coilover?
Good find Sash,
Found a calculation chart from third party's site. On SPL's website under the 350z's suspension area (springs to be precise). It has a Excel Calc that shows the ratio around 1.66 (Note SPL listed this as an inverse relationship than what is generally measured, spring to wheel Vs wheel to spring motion).
http://www.splparts.com/main4/parts/...Calculator.xls
Found a calculation chart from third party's site. On SPL's website under the 350z's suspension area (springs to be precise). It has a Excel Calc that shows the ratio around 1.66 (Note SPL listed this as an inverse relationship than what is generally measured, spring to wheel Vs wheel to spring motion).
http://www.splparts.com/main4/parts/...Calculator.xls
Last edited by BeaverMeat; 08-02-2016 at 08:05 PM.
#14
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.97 is commonly used in the rear when the spring is mounted on the shock. Front I would have to look, but I thought I'd was like .73 or .68
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