NickHolt Posted November 2, 2012 Report Share Posted November 2, 2012 {NOTE: This thread has been moved over here from another thread. In making the move, some of the posts were in the wrong order so a few of the posts made by others are now posted under my name to get them in the correct order. Sorry about that. Nick} Race teams employing "tie down shock" technology stand the risk of being DQd if the springs being used are not strong enough to overcome the rebound in the shock by the time the car hits the Tech Pad. HMP, in good faith gesture to HMP racers, has done away with the ride height rule for their NASCAR divisions. I applaud this change and hope that it fixes a problem that teams that use the current shock technology have faced for the past couple of year as the rebound rates increase, spring rates decrease and bump stops become more and more important. I am certain that I am not the only one who sees the rule change as positive fix for a problem. But I also envision that the change may invite some innovation in set ups since a limiting factor (ride height) is no longer a factor. I would like to see some discussion about how this new rule might change the way cars are set up in the future. Nick Link to comment Share on other sites More sharing options...
NickHolt Posted November 2, 2012 Author Report Share Posted November 2, 2012 I'll start the ball rolling. Do the cars have to run springs? The only real reason springs were being used under the BB/ss, bump-stop setups was to pass the height rule in tech after the race. Several teams failed tech in 2012 due to the soft springs being able to overcome the high rebound values built into the shocks. Under the new rule, if no springs (or very, very soft springs) are utilized, why not just run on bumps and tie down shocks to keep the chassis over the drive train and eliminate all possible body roll? With no suspension travel one can maximize and precisely stabilize the toe, camber, caster for whatever point on the track the team feels is the most critical. With cars running very close to the track surface, aero will be a major consideration from here on out. Whoever can use the air to provide the most downforce will have a distinct advantage. But here's something I envision might happen under the new rule. The moment arm formed between CG height and the roll axis (one of the most important suspension engineering considerations in race cars running on conventional springs) will become nearly meaningless if there is no suspension travel during cornering. A number of years ago I worked with some of the top Karting teams to identify a virtual roll center in unsprung Karts. All we could come up with was the jacking effect produced by the CG height acting on outside tire contact patches during lateral acceleration. Under the new ride height rules, the teams that choose to run with extremely soft springs, or no springs at all, will end up as very large Go Karts. To gain a competitive advantage, teams will have to lower the Center of Gravity height to the lowest possible since the weight transfer formulas will be missing all but the arbitrary G-force constant and the CG height, total car weight and the track width variables. Of course, there are an infinite number of other variables that go into the production of the G-force any car can develop in a turn, but I am strictly looking at the traditional variables suspension engineers use to calculate weight transfer at a given lateral G-force. Gone is the distinction between sprung weight and total weight as well as the existence of weight transfer moment arm (the "Magic Moment Arm" taught in my suspension engineering seminars) and any usable application of roll couple distribution theory. To take advantage of these new rules, teams will have to pay much closer attention to keeping air from under the car which may mean re-thinking and re-skinning their cars, and work to lower the CG height to minimize weight transfer at a given G-force. I'm sure there are other considerations - such as tire sidewall spring rates - that will become more important as teams get the hang of the new rules. I can imagine a whole new business springing up as someone finds a good way to rate tires for spring rates. Bottom line, we could well end up with fields of large GoKarts where traditional suspension engineering becomes a thing of the past. The new height rule may be a good thing, but gone are the days when a low-budget team using suspension engineering principles could compete with the big-budget teams. Nick Link to comment Share on other sites More sharing options...
NickHolt Posted November 2, 2012 Author Report Share Posted November 2, 2012 {NOTE: This is a post from hray in response to my post immediately above.} Nick, there's another variable you left out. The roughness of the track. We tried running on bumps some time back and had to go to very soft bumps because the track surface was just too rough and upset the car in the turns. We finally wound up going back to BBSS. I doubt that a car on Goodyears (very stiff sidewall) with no springs could run competitively at HMP because of the asphalt to concrete transition in the turns. I may be wrong, and I'm sure someone else will try, but "been there, done that" and don't plan to try again. However, I will say that some degree of BBSS, combined with a very low CG, suspension attach point modifications and some other ideas I'd like to experiment with on the left rear might make a difference. Link to comment Share on other sites More sharing options...
NickHolt Posted November 2, 2012 Author Report Share Posted November 2, 2012 {Note: This is a post by Pacecar which is now in the correct order} Nick, Don't speak of doom and gloom, that the race cars will become go-karts. Who knows, the faster setups might be "conventional" using front spring rates ranging from 1500 to 3000 pounds per inch. Link to comment Share on other sites More sharing options...
NickHolt Posted November 2, 2012 Author Report Share Posted November 2, 2012 Ah yes, Larry (Pacecar). We used to buy Richard Petty's rear springs for the front of our LM way, way back in the 1970s! Is the circle is coming around to meet itself? Nick Link to comment Share on other sites More sharing options...
NickHolt Posted November 2, 2012 Author Report Share Posted November 2, 2012 Nick, there's another variable you left out. The roughness of the track. We tried running on bumps some time back and had to go to very soft bumps because the track surface was just too rough and upset the car in the turns. We finally wound up going back to BBSS. I doubt that a car on Goodyears (very stiff sidewall) with no springs could run competitively at HMP because of the asphalt to concrete transition in the turns. I may be wrong, and I'm sure someone else will try, but "been there, done that" and don't plan to try again. However, I will say that some degree of BBSS, combined with a very low CG, suspension attach point modifications and some other ideas I'd like to experiment with on the left rear might make a difference. Yes, you are correct to bring up the issue of tire compliance on rough tracks. For that very reason (among several other very important reasons), I have been teaching the conventional version of the BB/ss setup for over 30 years. And it works because we are able to use the moment arm(s) to play role-couple distribution and spring-frequency games. When you run soft springs and allow the weight transfer to load the outside tires down through the suspension in addition to lateral weight transfer, you can use swap out springs and and change geometry settings (bump steer, caster changes, camber curves, etc) to tune the car for the entire track, not just the "one sweet spot" you can obtain on bump stops. The biggest handling change is going to be with the cars that are able to keep all the air out from under the car. This would include the Pro Mods more than the Modifieds since the Modifieds have no way to keep all the air out from under the car. On the positive side, the Modified teams won't have to struggle to pull the chassis back up to legal ride height before hitting the tech pad any longer. I'm not taking a stand one way or another on the rule change. Mostly I just want to stimulate the discussion about how folks anticipate things will change under the new rule. Nick Link to comment Share on other sites More sharing options...
Pacecar Posted November 2, 2012 Report Share Posted November 2, 2012 {NOTE: This thread has been moved over here from another thread. In making the move, some of the posts were in the wrong order so a few of the posts made by others are now posted under my name to get them in the correct order. Sorry about that. Nick} It happens when you have to "edit" yourself......... Link to comment Share on other sites More sharing options...
MikeReininger Posted November 2, 2012 Report Share Posted November 2, 2012 Pandoras box was opened when bump stops were allowed. That's when the ride height rule should have gone away. It was frustrating to go through tech at THR with a conventional set up and sweat the wheel, then watch the bump stop cars easily clear because they were able to ride higher in the pits. The shocks would hold the front down on the bumps when on the track. Don't know how they can get much lower than they already were in the corners. But I'm sure there are differing opinions on that. Anyway, post race ride height was more stressful than the race. So I applaud HMP for making the effort to not DQ cars after the race. Unfortunately it's us racers that will make a mess of the good intention. Link to comment Share on other sites More sharing options...
hray Posted November 2, 2012 Report Share Posted November 2, 2012 I think it's good that HMP did this and I applaud them for it. Also, I say let those that want to experiment with new configurations (within the rules) have at it. After all, that's the way technology is advanced. Also, the way I read the rules, you can't plate the bottom of the car, so it will be very difficult to keep air from under cars like modifieds/promods. Link to comment Share on other sites More sharing options...
NickHolt Posted November 2, 2012 Author Report Share Posted November 2, 2012 I think it's good that HMP did this and I applaud them for it. Also, I say let those that want to experiment with new configurations (within the rules) have at it. After all, that's the way technology is advanced. Also, the way I read the rules, you can't plate the bottom of the car, so it will be very difficult to keep air from under cars like modifieds/promods. I agree. I think the NASCAR Fiesta Modifieds will have a tough time keeping the air out, although we have already seen some noble attempts to do so. I honestly believe they will play a bit more with soft bump technology, more severe rebound numbers and work harder at lowering the CG height of their frame, cage and drive train. But I think the NASCAR BWFS 360 Trucks will be able to keep the air out since many of them already have done so. Tie down shock technology will really play a part in the trucks especially if they find they are able to keep the rear suspension from moving through much travel. If a truck team takes fulll advantage of the new ride height rule, they should be able to nearly eliminate the rear trailing-arm binding problem so prevalent with the 4-link chassis. I'm not too sure what direction the NASCAR Stock Cars will take. Since the suspension components have to remain basically stock, lowering the car may result in unexpected handling characteristics that I won't get into here since it involves moment arms and roll steer. Fun stuff for sure. Nick Link to comment Share on other sites More sharing options...
SASPEEDRACER24 Posted November 3, 2012 Report Share Posted November 3, 2012 ... I'm not too sure what direction the NASCAR Stock Cars will take. Since the suspension components have to remain basically stock, lowering the car may result in unexpected handling characteristics that I won't get into here since it involves moment arms and roll steer. Fun stuff for sure. Nick I imagine there are a few guys with Nova's that are happy to see the ride height rules go away in the Stock Cars... Link to comment Share on other sites More sharing options...
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