Guest 2002sentraSER Posted March 25, 2003 Share Posted March 25, 2003 i am wondering because i want to be under the nhra guidlines Quote Link to comment Share on other sites More sharing options...
Mikelly Posted March 25, 2003 Share Posted March 25, 2003 Nope. A Zcar running 10.99 or quicker is outside the rules of IHRA and NHRA IF you run the Stock Zcar configuration. There is only ONE control arm on each rear axle. If you plan to be NHRA legal I'd recommend doing a corvette or solid axle swap. Mike Quote Link to comment Share on other sites More sharing options...
Mike C Posted March 25, 2003 Share Posted March 25, 2003 The Z MIGHT be within the guidlines because it does NOT use the half shaft as a locater as the 'vette and Jag IRS do. There is no doubt that the 'vette IRS is NOT legal for IHRA or NHRA in sub 11 second cars. Quote Link to comment Share on other sites More sharing options...
Tim240z Posted March 25, 2003 Share Posted March 25, 2003 I seem to remember reading something recently that IRS that doesn't use the sideshaft as a structural part of the suspension is not subject to that rule exclusion. I wish the search function worked..... Tim Quote Link to comment Share on other sites More sharing options...
Mikelly Posted March 25, 2003 Share Posted March 25, 2003 I thought the C4 and C5 vette had an exemption, or exception to the rule... Maybe I'm wrong... I always wondered why it was that the Zcar got zinged... You can build hald shaft loops to keep failed axles from taking out the brake lines, and it isn't a structural part of the rear... Mike Quote Link to comment Share on other sites More sharing options...
Mike C Posted March 25, 2003 Share Posted March 25, 2003 I know nothing about the design of the C5 IRS, and as of yet no one has serously broached the conversion topic really since it incorporates a pseudo trans axle assembly and Z space is at a premium. But the C3 and C4 IRS both use the half shaft as a locater. Primary difference is the trailing arm single link on the C3 vs. the two "dog bone" links on the C4. I had a half shaft retaining clip break on my C4 IRS, and the car did some squirrely stuff! Visually there was nothing wrong with the car, but it would try to change lanes for no apparent reason! Talk about a pain in the "rear" to fix... Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted March 25, 2003 Share Posted March 25, 2003 If someone has an NHRA rulebook, please look this up and put this "debate" to rest. Every reference I have seen regarding NHRA rules and Corvette IRS, none makes any specific references to the C4 or C5. MOF, here is the specific NHRA verbage that went along with the modification of this rule: E.T. Brackets A long-standing rule that requires any car with independent rear suspension (IRS), weighing over 2000 pounds, and running 10.99 or quicker to replace the IRS with a conventional rear-end housing has been modified. For 1999, only those IRS designs which utilize a lower control arm only (like a 1963 to 1982 Corvette) will have to comply with the above requirement. If the suspension utilizes both upper and lower control arms, the IRS may be retained regardless of weight or e.t. Of course, NHRA left it wide open for debate. Why spell out 1963 to 1982? If the C4 is illegal, why not spell it out clearer and say "1963 to 1996 Corvette" to include the C4? To make it even more confusing, the IDRC (oldest import racing sanctioning group) states the following: All RWD vehicles equipped with an independent rear suspension (IRS) from the factory must have and keep the upper and lower control arms. Any vehicles quicker than 10.99-seconds equipped with IRS without upper and lower control arms may replace live unit to a conventional straight axle unit. Once again, wide open for debate and note the "may". Does anyone know if SupraTTs and 3rd-gen RX-7 have rear upper control arms? Quote Link to comment Share on other sites More sharing options...
Mike C Posted March 25, 2003 Share Posted March 25, 2003 I agree Scottie that the terminology is screwy. Effectively, the Corvette half shaft is the upper control arm, but that completely leaves strut type IRS uncovered. Hopefully somebody can find more info. I've been curious as to the design of the Supra IRS as well. You'd think this wouldn't be such a difficult concept. Quote Link to comment Share on other sites More sharing options...
Guest 2002sentraSER Posted March 26, 2003 Share Posted March 26, 2003 is there a way to make to datsun rear end legal for race by adding an upper control arm? Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted March 26, 2003 Share Posted March 26, 2003 Reason why I am so interested in the SupraTT and 3rd-gen RX-7 is that those cars were competing in the NHRA Sprots Compact Street-Tire class last year with the quickest Supra going 9.0! This year they are allowed to run "DOT-legal" tires, meaning ET Streets and QTP and I fully expect them to get down in the 8.70 range. It would be ironic if their suspensions contradicted the current rule, considering the Supras must have a minimum weight of 2,900#. Quote Link to comment Share on other sites More sharing options...
Tim240z Posted March 26, 2003 Share Posted March 26, 2003 Don't know what version of the rules are, but found this on the net: 2.11 REAREND Welded spider gear rearends prohibited in all classes. Four-wheel-drive permitted in all ET cars running 12.00 seconds (*7.50) or slower. Aftermarket axles and axle-retention device mandatory on TF, FC, TAD, TAFC and 10.99 (*6.99) or quicker ET cars; also mandatory on any car (regardless of class or ET) with a spool. After market axles and axle-retention device mandatory on any car running 10.99 (*6.99) or quicker and any car with locked differential. Cars running 10.99 (*6.99) or quicker that weigh more than 2,000 pounds (907 kg) with independent rear suspension must have swing axle differential replaced with conventional differential housing assembly. Found it here: http://members.tripod.com/~MY5LTRLXCPE/NHRArules.html Or this from 1999: E.T. BracketsA long-standing rule that requires any car with independent rear suspension (IRS), weighing over 2000 pounds, and running 10.99 or quicker to replace the IRS with a conventional rear-end housing has been modified. For 1999, only those IRS designs which utilize a lower control arm only (like a 1963 to 1982 Corvette) will have to comply with the above requirement. If the suspension utilizes both upper and lower control arms, the IRS may be retained regardless of weight or e.t. Tim Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted March 26, 2003 Share Posted March 26, 2003 Well, talk about contradictory and vague....but it sounds like the main culprit to dangerous rear ends is the early Vette. IMHO, and because I'm optimistic, I think the rear strut can be called an "upper control arm" Quote Link to comment Share on other sites More sharing options...
Dan Juday Posted March 27, 2003 Share Posted March 27, 2003 I'm thinking like you Nathan. What does an upper control arm do? It combines with the lower arm to locate the hub. That is the same thing the strut does. And, as allready stated, the half shaft is not called upon to do anything but transmit power to the wheel. Sounds like an effective argument can be made in favor of the Z IRS. Now if you can just keep the u-joints together below 10.99. Quote Link to comment Share on other sites More sharing options...
Guest 2002sentraSER Posted March 28, 2003 Share Posted March 28, 2003 i wil call the tack and find out Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted March 28, 2003 Share Posted March 28, 2003 Some one once mentioned that losing a stub axle will cause you to lose the rear wheel unless you have something like a rear disk brake upgrage. Might still need to address the positive rear axle retention issue. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted March 28, 2003 Share Posted March 28, 2003 hey scottie, i like the new look looks like new fenders and a hood. how much was the hood and where did you get it? Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted March 28, 2003 Share Posted March 28, 2003 Thanks. The fenders are used stockers that replaced my originals with the broken flare. The hood is also used that I got in a trade from a buddy. It needed work but turned out OK. Quote Link to comment Share on other sites More sharing options...
johnc Posted March 28, 2003 Share Posted March 28, 2003 A broken stub axle will almost always result in a "lost" rear wheel. Sometimes you get lucky and the brake drum or disk brake caliper will retain the tire/wheel/stub axle assembly for a very short time. Most of the time you're not so lucky. Quote Link to comment Share on other sites More sharing options...
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