660Z Posted December 5, 2005 Share Posted December 5, 2005 I`m in the prosses of a full cage and frame rail reconstruction project for my 240z and am considering a solid rear conversion while it`s in the air. I`m soon going to get a 2006 rule book but until then my daydreams are getting the better of me!! I`ve read old posts about what the rules are for back in 2002, about what times you can run before your required to change over. And the rules aren`t clear about what to do whit the datsun setup. Since then factory cars are much faster now in 2005 then in 2002 and NHRA changed the rollbar/cage rule to adjust for that. Also Sport compact cars have come into play as the times on them are also up!!! I know the strength of the R200 setup from seeing quite a few members here running unbelevable times on the it. My question is what times were you forced by NHRA rules to change over to the soild rear? 10.99? never? 2004,05, now 2006? I should state that my car is becoming a race car only and I`d like to play in the early 10`s and dabble in the 9`s if the rules allow. Mark Quote Link to comment Share on other sites More sharing options...
spork Posted December 5, 2005 Share Posted December 5, 2005 The best thing to do is either call or e-mail them to ask. Last time I read the rules it was 9.99, but thats been a couple of years. Not that it really helps, but for nopi it doesn't matter how fast you go...hopefully NHRA is the same way. Quote Link to comment Share on other sites More sharing options...
Michael Posted December 7, 2005 Share Posted December 7, 2005 Good question! The last time that I checked, which was around 1999, the NHRA rules stated something like 10.99 as the no-IRS cutoff point. However, there was (or is now, if there wasn't back then) a loophole that somehow accommodated Vipers and Corvettes. Also I vaguely recall that NHRA distinguishes between IRS where the halfshafts are used as suspension links (such as the Jaguar and most aftermarket hot-rod IRS retrofits), and Chapman struts (such as the Z) where the halfshafts are telescoping and not used for the suspension proper. The difference is that in the former, if a halfshaft breaks, the corresponding wheel comes off. Quote Link to comment Share on other sites More sharing options...
660Z Posted December 7, 2005 Author Share Posted December 7, 2005 Thanks for the replys, I sent an email to NHRA afew days ago, I`m still waiting for a reply I`ll probably end up calling them when the time comes. "Also I vaguely recall that NHRA distinguishes between IRS where the halfshafts are used as suspension links (such as the Jaguar and most aftermarket hot-rod IRS retrofits), and Chapman struts (such as the Z) where the halfshafts are telescoping and not used for the suspension proper. The difference is that in the former, if a halfshaft breaks, the corresponding wheel comes off."[qoute] So if i`m reading this right, our z falls into the jag and aftermarket catagory? I always thought if the half shaft(stub axle) broke the wheel would come off, but I thought that would be for any axle IRS or solid. I know that 10.99 aftermarket axles are required. How are the vette and viper rears setup that the basics would be different then ours? I`m thinking the loop holes are from factory lobbying and not a better setup.. But I`m starting to get off point, has anyone acually had to change over from this rule recently? Mark Quote Link to comment Share on other sites More sharing options...
jnjdragracing Posted December 7, 2005 Share Posted December 7, 2005 Hello Mark, I have wondered the same thing. My brother and I run our car and I would like to change to a solid rear for safety reasons. The IRS does hook when others don't. We have had no problems with our tracks but we are a grudge no time car. We do not run in any events where rules have to be followed. What worries me is if a half shaft broke on the other end of a 1/4 mile and we are pushing 150 - 160 mph is when it lets go and the change from left to right, we would loose control of the car. I welded flat steel under our a-arms so if we broke a half shaft on the other end it would not get caught. I have a friend who changed from IRS to Solid and he lost some et, because the car was not hooking as well. We are planning to run our car again this Saturday 12/10 at Carolina Dragway in Aiken S.C. and since he changed the ring and pinon from a 3.90 to a 3.55 it should be something to see, yes this is a 1/4 mile track. I will be posting video footage and times as always. Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted December 7, 2005 Share Posted December 7, 2005 So if i`m reading this right, our z falls into the jag and aftermarket catagory? No... I think you are reading that wrong. Zcars halfshafts are NOT used as suspension links. If the halfshaft fails, the wheel will not come off. Carefully reread Michael's post. I am not familiar with current NHRA rules. Quote Link to comment Share on other sites More sharing options...
stony Posted December 7, 2005 Share Posted December 7, 2005 Remember though if the stubshaft breaks the wheel will come off. Trust me in know from expeirience. the only thing that kept the tire under the car was the brake caliper. If your gonna do a hi HP track for safety's sake upgrade to a solid rearend now it will save you a couple headaches also . Quote Link to comment Share on other sites More sharing options...
Clifton Posted December 7, 2005 Share Posted December 7, 2005 There are 8 second Supras and Vipers using IRS. Quote Link to comment Share on other sites More sharing options...
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