Guest Anonymous Posted August 31, 2001 Share Posted August 31, 2001 wow...thats amazing. scottie you are a god. Quote Link to comment Share on other sites More sharing options...
pparaska Posted August 31, 2001 Share Posted August 31, 2001 Quote Link to comment Share on other sites More sharing options...
johnc Posted August 31, 2001 Share Posted August 31, 2001 Scotty, Have you checked with your race sanctioning body about any limitations to IRS rear suspensions? I know with NHRA when you get down into the 10's you are not allowed to run an IRS that has the axles as a stessed member of the suspension. The C4 Corvette IRS is normally not allowed on vehicles going that quick becuase the axles are the upper locating links for the rear suspension. Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted September 1, 2001 Author Share Posted September 1, 2001 John, the following is a discussion on the NHRA website regarding this issue in the NHRA rulebook. quote: 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. Note that it specifically says 63-82, 82 being the last year of the C3. The suspension was redesigned in 84 for the C4. But to be honest, I am really only concerned about the rules the local FL tracks enforce because that is where I will do 99% of my racing. If I ran in a sanctioning body like NHRA, I would not be competitive in the class they would place me and if I intended to, it certainly would not be with my current stock engine, trans and street tires. I would get serious and spend some real money to build a chassis like Ron's, keep it under 2400lbs, then it does not take $much$ to massage 650hp out of a Buick turbo with a girdle. I will be tickled if I can get 10.80 out of the car as it is. Quote Link to comment Share on other sites More sharing options...
Cyind Posted September 1, 2001 Share Posted September 1, 2001 Hey, it is good to know I'm not the only one with a Corvette IRS in a Z... I hate the thought of removing mine someday to powder coat it so I would do it now if you can. Hope some of the pictures I sent you helped make up your mind. Are you planning on cutting down the stubs any? Any information you can pass-on about hooking up the e-brake would be helpful cause I got to fix mine soon. If you have to make any bracker for the back of the stock caliper make me a set while your at it. The way mine was done did not last so let me know what you used or make a set of two up and sell me one... Z U V8ter Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted September 1, 2001 Share Posted September 1, 2001 "massage 650hp out of a Buick turbo with a girdle." Think of the horsepower if used a bra or panties... , Lone Quote Link to comment Share on other sites More sharing options...
johnc Posted September 1, 2001 Share Posted September 1, 2001 Scotty, A lot of tracks comply with NHRA rules as an insurance condition regardless of whether its an NHRA event or not. I don't know if that's the case where you run. I spend a bunch of time working with Viper guys and once they started getting into the 10's they were banned from pretty much any track here in the West coast until they swapped the diff for a solid axle. After a year's worth of work they were able to get an exception, specific to the Viper, to allow them to run at NHRA sacntioned tracks. That is the rule change you cite in your post. It could be (and has been) argued by a track official that the C5 rear suspension doesn't meet the upper/lower control arm requirement ("If the suspension utilizes both upper and lower control arms, the IRS may be retained regardless of weight or e.t.") because the upper arm is the halfshaft. I know of at least 1 C5 Corvette guy that got asked to leave an event at Pomona when he turned a 10.98. That may have been an isolated incident. I'm not trying to be an jerk about this. I would just hate to see you turn a 10.xx and then be asked to leave. Does anyone have a current NHRA rule book? Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted September 1, 2001 Share Posted September 1, 2001 Hrm, it occurs to me that the Z IRS may also fall to this ruling. Am I incorrect? Not that I really thingk I'll run that fast but a healthy V8 with a shot of juice ought to come close to scaring 10s - yes? Quote Link to comment Share on other sites More sharing options...
blueovalz Posted September 1, 2001 Share Posted September 1, 2001 Not the Z IRS. With the Z, the suspension is still intact without the driving halfshafts. With the Corvette, if a halfshaft breaks, the suspension is basically "gone". Quote Link to comment Share on other sites More sharing options...
Mike C Posted September 1, 2001 Share Posted September 1, 2001 NHRA does require Corvettes that run faster than 11.0 to ditch the IRS. I broke a stub axle retaining clip in my '84 Corvette. Sometimes it was fine and then every once in awhile it would try and drive off the road You'd correct and it would be fine again. Took awhile to figure that out since you couldn't see a problem. I'm not sure if they would let the Z suspension stay or not, but seems more likely than the 'vette setup. Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted September 1, 2001 Author Share Posted September 1, 2001 Guys, I hear you loud and clear and if I appear to be unconcerned about it, it is because I am. If the car decides to get freaky on me and gain say, .5 or more and my local track says I cannot run, then I have 2 choices. I either detune the car to run 11.0s and leave it at that or get serious. I have no idea how much I was losing with the "problems" I was having, but I can tell you I am no where close to maxing out the stock engine because I just do not want to run on the ragged edge. One guy I know in Miami, named Orlando , is running 10.0s @ 130+ in a 3400lb Buick with the stock bottom-end, mild home porting, a healthy cam, a huge turbo and 40# boost with a 20# launch . By my calculation, that is about 625hp. I am running 23-24# with unported heads and a much smaller turbo. I said all of that because if I decide to get serious, that is the HP range I am targeting and it would NOT be in this existing car. By now everyone should know my MO is to fund my next project by selling what I currently have. This means one of you LUCKY folks would get to buy the GNZ chassis with the Vette IRS and that would help fund a back-half, track-only, lightweight GNZ. That should put me in the 9.0 range and be a little more competitive. I might even be able to talk Ron into selling his chassis . Ironically, not all local tracks enforce the rules. There are 2 other GNZs (in ID and PA)running the stock Z suspension with NISMO 3.36 R&P and LSD. One is in the 10.80s and the other has a best of 10.59 but breaks axles as I hear it. Both run around 130mph because they have heads, cam and bigger turbos. Like I said, I might have to make a decision here soon and I do not like the idea of going slower Regardless, this sure is a fun engineering exercise and I just love the testing part [ September 01, 2001: Message edited by: Scottie-GNZ ] Quote Link to comment Share on other sites More sharing options...
Guest needwaymorespeed Posted September 5, 2001 Share Posted September 5, 2001 Scottie looks awesome and relaively cheap in comparison to other alternatives. Why arent you going the dana 44 though?? most corvette guys with power, end up putting the dana 44 or solid axle in if they have the 36. 80 pounds less thats awesome!! Im currently sitting a r230 up in my car but instead of loosing weight ill be gaining,youre pics have me thinking,Boy the wife would shoot me if I changed my mind now. Do you know what year the track width on the corvettes changed seem like 63 hub to hu till 90 then it grew? Keep up the good work,its inspirational to all of us Curtis Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted September 5, 2001 Author Share Posted September 5, 2001 Curtis, thanks. I am not doing a DANA44 because I could not find one for a reasonable price and this DANA36 sort of fell in my lap. Guys are demanding around $1500 for the DANA44 and there is currently one on eBay with a "Buy It Now" of $2,000. With another $200 or so to ship, the price would have gotten out of hand. Progress Report I have decided to slow down, else I drive myself nuts waiting for parts and mods to be done. I ordered the lower strut bar and since it is custom-made, it "will be a couple of days" to make it, then a couple of days after to powdercoat it. Yep, at least 2 weeks. After that is done and I have the exact measurements for the spring, then it will be a couple more days to make that, etc. No hope of having it running before going on vacation at the beginning of Oct. In the meantime, the halfshafts and the toe adjustment rods have been narrowed and the diff is in the car on the rear hangers. I need to fab up a front x-member, pretty up the hangers, install the Spider U-joints, mod the driveshaft... Damn, then what am I going to do tomorrow? Here are the shortened axles and toe adjustment rods after 20 mins with a Scotch-Brite pad. Hangers welded in place and diff hanging from them. As much as possible, every mount point will be attached to a frame rail. A little trimming, sanding and paint needed. View from the back. Stay tuned. Quote Link to comment Share on other sites More sharing options...
pparaska Posted September 5, 2001 Share Posted September 5, 2001 Scotty those halfshafts look beautiful. Now maybe have the clear powder coated ? The install of the diff rear hanger looks so incredibly simple - you have a way of doing that! I'm all for slowing down and taking your time to do it the way you want. But, oh, I forgot, you like to drive your car, not just look at it in the garage Sweet install! Quote Link to comment Share on other sites More sharing options...
alsil Posted September 5, 2001 Share Posted September 5, 2001 Man, that looks like it's going to be a beautiful install. Didn't realize the rear ceterline was that far offset from the struts. When you're done, will you do a breakdown of the whole swap for us? Some of us (ME) might be interested in doing it themselves if it's not too expensive. How much can the Dana36 handle? probably more than I'll ever put through it with my 302. Looks like it's going to be a great swap, keep us posted! AL Quote Link to comment Share on other sites More sharing options...
scottyMIz Posted September 6, 2001 Share Posted September 6, 2001 scottie, are you superman? you have to be with all that knowledge and skill.It looks like it should be under that z.I can't wait til you get it done. Quote Link to comment Share on other sites More sharing options...
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