Importance of lower unsprung weight?
03-27-2003, 06:26 PM
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Importance of lower unsprung weight? I recently ordered a set of 275 40 17 BFG KDs for my SS and now need wheels. This will be a road course, and perhaps occasional autocross tire/wheel setup. I'm looking hard at a 9.5" width since, as far as I know, there are no 17x10s out there, and 11s are too wide for this tire (disagree, if you wish).
There are budget friendly wheels (ZR1 Replicas, for example) out there that weigh 26.5 lbs each. SLPs 9.5s weigh about 22 each, but run quite a bit more. After that, I'm sure there are some exorbitant wheels out there that might weigh less than 20 lbs each, but I need both arms and legs to drive.
First, is the tire performance gain in going from 9" stock to 9.5" worth the extra dollars? I can get used, painted, 10-spokes for $400. Remember, this is for road course.
Second, if I drop $500 to drop my unsprung weight by 18 lbs by going with a 22 lb vs 26.5 lb wheel, do I get a noticeable improvement in handling on the road course and what will I notice? Will a skilled driver notice the difference?
Assume I will be lowering my center of gravity and upgrading LCAs and torque arm at some point. Currently have a 2-pt STB and SFCs, and I may upgrade to 3-pts on each of those.
Bit of a long one here, but I'd love to hear your experience and wisdom <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" /> .
BobP
There are budget friendly wheels (ZR1 Replicas, for example) out there that weigh 26.5 lbs each. SLPs 9.5s weigh about 22 each, but run quite a bit more. After that, I'm sure there are some exorbitant wheels out there that might weigh less than 20 lbs each, but I need both arms and legs to drive.
First, is the tire performance gain in going from 9" stock to 9.5" worth the extra dollars? I can get used, painted, 10-spokes for $400. Remember, this is for road course.
Second, if I drop $500 to drop my unsprung weight by 18 lbs by going with a 22 lb vs 26.5 lb wheel, do I get a noticeable improvement in handling on the road course and what will I notice? Will a skilled driver notice the difference?
Assume I will be lowering my center of gravity and upgrading LCAs and torque arm at some point. Currently have a 2-pt STB and SFCs, and I may upgrade to 3-pts on each of those.
Bit of a long one here, but I'd love to hear your experience and wisdom <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" /> .
BobP
03-27-2003, 10:43 PM
#2
Re: Importance of lower unsprung weight? One of the largest benefits of reduced unsprung weight that is removed from the tires and wheels is faster acceleration and better braking. It takes horsepower to accelerate the weight of the tire (and brakes to stop it) and not only do you have to move it in a forward direction, it also has to rotate and that takes even more HP than just "stationary" weight. It will also reduce the loads on the shocks (slightly reducing shock temps and oil foaming...or the potential for it). Honestly, I'd probably look at the ZR1 style wheels (or 10 spoke SS rims) and run them for now. I don't suspect that the difference is enough to be worth spending more than an extra $100 or so (at the "weekend track event" level). One of my books on chassis tuning mentioned weight reduction and said "the best place to remove weight is the flywheel, followed by rims and tires and after that, just from the actual car body, etc). Just my random thoughts.....and good luck fishing!
03-27-2003, 11:40 PM
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Re: Importance of lower unsprung weight? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by trackbird:
<strong> One of the largest benefits of reduced unsprung weight that is removed from the tires and wheels is faster acceleration and better braking. It takes horsepower to accelerate the weight of the tire (and brakes to stop it) and not only do you have to move it in a forward direction, it also has to rotate and that takes even more HP than just "stationary" weight. It will also reduce the loads on the shocks (slightly reducing shock temps and oil foaming...or the potential for it). Honestly, I'd probably look at the ZR1 style wheels (or 10 spoke SS rims) and run them for now. I don't suspect that the difference is enough to be worth spending more than an extra $100 or so (at the "weekend track event" level). One of my books on chassis tuning mentioned weight reduction and said "the best place to remove weight is the flywheel, followed by rims and tires and after that, just from the actual car body, etc). Just my random thoughts.....and good luck fishing! </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">My big front C5 brakes I just installed stop faster, but I do feel the xtra unsprung weight on acceleration.
Leo
<strong> One of the largest benefits of reduced unsprung weight that is removed from the tires and wheels is faster acceleration and better braking. It takes horsepower to accelerate the weight of the tire (and brakes to stop it) and not only do you have to move it in a forward direction, it also has to rotate and that takes even more HP than just "stationary" weight. It will also reduce the loads on the shocks (slightly reducing shock temps and oil foaming...or the potential for it). Honestly, I'd probably look at the ZR1 style wheels (or 10 spoke SS rims) and run them for now. I don't suspect that the difference is enough to be worth spending more than an extra $100 or so (at the "weekend track event" level). One of my books on chassis tuning mentioned weight reduction and said "the best place to remove weight is the flywheel, followed by rims and tires and after that, just from the actual car body, etc). Just my random thoughts.....and good luck fishing! </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">My big front C5 brakes I just installed stop faster, but I do feel the xtra unsprung weight on acceleration.
Leo
