Guest Jeff Rimmer Posted October 17, 2000 Share Posted October 17, 2000 I'm sure some of you have done this swap, for a cheve rear end or similar. But I'm very curious as to how you may have set it up, and how it would affect the cornering ability of the car etc... The rear end setup right now is very interesting. I'm fairly new to Zcars, by the way I have a 77 280Z, I havn't seen very many similar setups to that one, but from what I understand from the previous owner, my rear end is on the way out. Since I'm getting ready to start the 350 sway, the last thing I want is to leave the driveay and have my rear end fail on me, so I'm contemplating installing a solid rear end. Any input on this subject? TIA JR Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted October 17, 2000 Share Posted October 17, 2000 Nissan r200 diffs are more than strong enough for anything you can throw at them. The 1/2 shafts are the weakest point, and those can be replaced with CV joints if you have the u-join type(Dunno what a 280z has). *Text edited by Moderator* [This message has been edited by Mikelly (edited October 19, 2000).] Quote Link to comment Share on other sites More sharing options...
Guest Jason Posted October 18, 2000 Share Posted October 18, 2000 I've always felt that independent rear suspension was one of the great parts of a Z, and something worth keeping for a street car. In theory, you get a smoother ride and better roadholding in bumpy conditions due to lower unsprung weight. But if you've got an abundance of extra power, and do your driving on a track, a solid axle makes sense. Quote Link to comment Share on other sites More sharing options...
Guest Jeff Rimmer Posted October 18, 2000 Share Posted October 18, 2000 Well thanks for the input! I guess I should just look at rebuilding it. I was simply pawndering the possibilities. Thanks again Quote Link to comment Share on other sites More sharing options...
Ray Posted October 18, 2000 Share Posted October 18, 2000 Per Herb Adams,- (inovative engineer and racer) " The only real difference on a race car is the ride quality, a properly set up solid axel is easier to tune and alot cheeper" This was in regard to his Cobra replica that Matt was using as an autocross car at the time. I had asked why he didn't use a independent rear, this was his answer. The reason I repeated this was I think the type of rear isn't an issue. It is the way in which it is setup or installed that is the issue. Also consider what you want it to do. Thousands of people have used the stock z suspension for racing with great success. It has short commings are in the area of tire size, adjustabiliy and strength (in a drag race enviroment with slicks and alot of hp). All cars have compromises, if you don't like it change it that is what our hobie is all about. As far as someone's reason for the change, I don't care, as long as it is done correctly. Isn't that what this site is all about, giving people help and support in their project. If you don't like the idea that is ok, but still try and encourage the process. We all modify our cars for different reasons and what works for you may not work for me. THAT'S WHAT I THINK [This message has been edited by Ray (edited October 18, 2000).] Quote Link to comment Share on other sites More sharing options...
Mikelly Posted October 18, 2000 Share Posted October 18, 2000 I have a strong IRS that has been abuse for a long time. I have a well setup rear suspension... is it great? no. It works. If it starts to fail, as Mryon's axle shafts have, then I might swap to something different. Are they strong? yes. Will they last in a 400RWHP car? depends... If you drag race a lot, my guess would be maybe not. Add an automatic trans and again, I say maybe not. I've seen any number of well set up live axle cars rip up a road course, so I would have to agree with a previous poster, they work when done properly... Mike Kelly ------------------ "I will not be a spectator in the sport of life!" mjk [This message has been edited by Mikelly (edited October 19, 2000).] Quote Link to comment Share on other sites More sharing options...
Drax240z Posted October 19, 2000 Share Posted October 19, 2000 Another thought on using an IRS in racing. (I mean road/track, not oval, not drag) To get the highest speed through a corner you are obviously trying to reduce the radius as much as possible by following the "line". This often involves cutting it so that your car is riding on the.. Words failing... The red/white turn in/braking markers at the edge of the road. These are usually raised. (watch british super touring sometime, you'll see what I mean!) Without an IRS in this situation I would expect once you hit the raised portion of the road at speed, control would be a huge issue. Back to the real world... I prefer the IRS personally, but I'm not worried about breaking it. (I'm going to be well under 500hp) If I was building a car that was intended to be a drag racer first off, I'd probably put in a solid axle. For a street driven vehicle that will see high G's in turns and rough terrain (most roads) I'd stick with the IRS. ------------------ "THE STREETS WILL FLOW WITH THE OIL OF THE NON-BELIEVERS" Drax240z 1972 240z - L28TURBO transplant on the way! http://members.xoom.com/r_lewis/datsun.html Quote Link to comment Share on other sites More sharing options...
Mikelly Posted October 19, 2000 Share Posted October 19, 2000 This thread has been edited by Mike Kelly... Any non-rear axle related discussion should be taken to another category or off line. Thank you The HybridZ Staff ------------------ "I will not be a spectator in the sport of life!" mjk Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted October 21, 2000 Share Posted October 21, 2000 Mike, why do you think an Auto tranny would last longer? I'd say th eloads imposed by a manual would be worse on th eUjints not better. Granted, you can make a really nasty auto trans that snaps your neck but for th emost part I've always observed that automatics are easier on the drivetrain not harder. FWIW - I'll be hunting Neapco solid U's "soon" for mine. My last source fell through and I don't think I wish to use these MSA Spicer joints. Quote Link to comment Share on other sites More sharing options...
Guest Drewz Posted October 22, 2000 Share Posted October 22, 2000 If you intend on staying with the IRS let me know since I have a couple of good ones as well as a rebuilt spare. I am looking at the turbo 200 diff. since I will not be using slicks it may hold up. I am located not real far from ya. Later bud. ------------------ The only stupid question is one you wanted to ask but never did!!! Drewz Quote Link to comment Share on other sites More sharing options...
Michael Posted October 22, 2000 Share Posted October 22, 2000 The solid vs. independent rear comes up form time to time, but I've yet to see a rigorous explanation for the situations in which one is superior to another, except of course the superiority of IRS for rough pavement. Herb Adams' book is interesting reading, but too is vague about the issue. In the solid rear axle setup, the orientation of the rear tires relative to one another does not change, apart from minor motions caused by deflections of the axle under load. In the IRS, the camber of the left and right wheels changes relative to one another, depending on the vertical deflection of the suspension. That part is, of course, obvious. But what's far from obvious is whether this relative camber change necessarily reduces traction on launch (for example). There is little doubt that a Ford 9" solid rear axle is stronger than a Datsun IRS with R200. What I'm wondering about is whether in a hypothetical apples-to-apples comparison, the solid axle setup has better traction. IF the two systems, when "properly set up", have comparable performance - that is, if the difference is only a matter of strength and durability - I would prefer to stick with the IRS. But if I find that I just can't put the power to the pavement, even with huge slicks, then I would persuade myself to spend the >$5000 on a custom solid rear end and 4-link. Quote Link to comment Share on other sites More sharing options...
pparaska Posted October 22, 2000 Share Posted October 22, 2000 One thing I can't believe no one has brought up is the NHRA rules on "swing arm" axles. Unfortunately, they see anything but a solid axle as swing arm, even though the IRS is better than swing arm. In the older vettes, the halfshaft is part of the suspension (it acts as the upper control arm), and if it snaps, you lose control. It seems that as far back as 1998, NHRA said that many classes of car could not use swing arm rear suspension if the car weighed more than 2000 lb. Since then, I've heard they re-wrote that to allow upper/lower control arm rear suspension for weights above that, supposedly to allow the Vipers to run. Anybody have a 2000 NHRA rule book to check this? Anyway, I've heard of people's quick Z's being banned from a track because they moved into one of these classed (went too quick for their old class) and that rule knocked them out. Any info on this? I'd imagine Michael's car will get into some pretty quick times once he gets the Big Block he wants in it (not the truck motor he has now). I'd figure Ron Jones would know about these things as well. ------------------ Pete Paraska - 73 540Z - Marathon Z Project - pparaska@home.com">pparaska@home.com - Quote Link to comment Share on other sites More sharing options...
Guest RON JONES Posted October 23, 2000 Share Posted October 23, 2000 This is a quoted from the 2000 NHRA rule book:Aftermarket axles and axle-retenion device mandatory on any car running 10.99(6.99 1/8 mile)or quicker or any car with locked differential.Cars running 10.99(6.99) or quicker that weigh more than 2,000 pounds with independent rear suspension without upper and lower (both) control arms must replace swing axle differential with conventional differential housing assembly (example: 1963-1982 corvette).Cars with independent rear suspesion using upper and lower (both) control arms may retain swing axle assembly regardless of weight or E.T.Must have 360 degree,minimum 1-inch wide by 1/4-inch thick axle retention loop on each axle. Quote Link to comment Share on other sites More sharing options...
pparaska Posted October 23, 2000 Share Posted October 23, 2000 The way I read that is like I had interpretted it from what I heard: Since the Z has no upper control arm (although I think a Chapman/MacPherson strut has an infinitesimally small one up top) then it couldn't weigh more than 2000 and use it's IRS, according to NHRA. Again, the NHRA is pretty slow at coming around to changing it's rules for anything but a standard solid axle car. The rewrite from the late 90s to what Ron posted was to allow Vipers to run, or so I've heard. I think you might be able to protest that functionally, for safety purposes, the Chapman strut set up of the Z is just as safe as the upper and lower control arm setup, in the event of halfshaft (axle) failure. I believe it was the Corvettes with the older style IRS (where the halfshaft served the function of the upper control arm as well) was the point of the original "swing axle" rule. BTW, I was the turkey that moved this to the drivetrain forum . ------------------ Pete Paraska - 73 540Z - Marathon Z Project - pparaska@home.com">pparaska@home.com - Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted October 23, 2000 Share Posted October 23, 2000 FWIW - differences in solid vs independant... I've ALWAYS driven cars with solid rears in the past. One thing I noticed with them is that in hard turns the rear would seem to step out - no panhard rod installed. I've had them move a pretty decent amount let me tell you! Off camber type turns always made me nervous as the rear could do whacky things. Nowadays I drive a Miata - rear is solid as a rock in most turns and when it gets loose it's real predictible. Same with th eZ - when that puppy gets loose I can feel it. I can also feel the rear in both cars moving with the road and that one side isn't upsetting the other. I'm no pro racer by a long shot but I do feel the solid rear isn't as stable when the racing isn't just in a straight line. There's no question in my mind that the solid is stronger too, just make sure you've got NO C-clips retaining your axles! Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted October 24, 2000 Share Posted October 24, 2000 Something that hasn't been discussed about IRS when used for drag racing. I could be off base here, but the movement of the rear on a IRS and a solid axle during a launch are different. Despite stiffer springs the IRS (Z cars in our case) really dips the back end compared to a four link setup. This motion is extra movement that is not being used to propell the car forward. Four link cars do it somewhat but they use the links as leverage further up the chassis to actually jack the rear end into the ground(like ladder bars) where as the IRS can't really do this, the difference in leverage would seem to be a advantage. It comes down to your uses, if you drag race ALOT then you either modify the Datsun rear end system to within a inch of its life to survive it(unless it breaks 10.99 and gets banned) or you put in a proven 9" and worry about other things. For roadracing theres no question the IRS has a superior feel in the way the rear end reacts. I would think roadracing would be a little more gentle on the U-joints despite them maybe getting a bit more load from upshifting/downshifting. The reason I say this is to go quickly you must be smooth (or at least thats what I've heard said a million times) and you roll into the gas not just mash it out of every corner. I could be wrong, but then again, Datsun Z's did rather well on the road courses didn't/doesn't it? Oh well, thats my .08 cents worth (gave ya extra you might not wanted to hear, but theres always that scroll button isn't there?) Lone Quote Link to comment Share on other sites More sharing options...
Mikelly Posted October 24, 2000 Share Posted October 24, 2000 Jim, I draw my conclusions about the LSD Vs. Live axle from what I saw back in 1996-98 in dealing with someone who had a 327 in a 280z with a lot of Nitros and a Turbo 350. That car was running 6s in the 1/8th and he was always having trouble, and with comments posted on this board. It just seems to me, and I could be wrong, but it "SEEMS" to me that the auto trans guys are dealing with more failures to U-joints and axles on a more regular basis. I don't mean to put anyone off or offend anyone. I'm only saying this based on what I noticed at the track and what has been posted here. Why they seem to be breaking more with Autos? Maybe it is just the fact that more guys are drag racing with auto trans than manuals. That could very well be the case. My car has been driven hard, but the u-joints have held up fine so far. Will I have problems? Sure, I broke a few when I was pushing a 250HP 6 cylinder... I damn sure plan a few failures with the current configuration. I'm gonna look into getting some CV axles or custom axle shafts made when I re-address this in the spring. Mike ------------------ "I will not be a spectator in the sport of life!" mjk Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted October 24, 2000 Share Posted October 24, 2000 Excellent topic and posts. It is mind-boggling how someone can break a u-joint with the 6-cyl and others can race unbroken with mega-HP & torque. Like Mike, I snapped 2 when I had my L28T running less than 10# boost. I conceded a long time ago that the OEM setup will eventually break and at that point I will consider a solid rear. Those of us running tweaked GN engines are thumping out close to 500 lbs/ft torque because this engine puts out way more torque than HP (not a joke). I would, however, like to refute a couple of statements in earlier posts. Firstly, it does not take mega-bucks to setup and successfully run the IRS in drag racing or any hard racing for that matter. What I did was target the optimal combination and installed those pieces. For me that was an R-200, CVs with an adapter, and 280 stub axles. One of the problems I think people run into is trying to drag race with a road race setup that is too firm. The big swaybars, stiff springs and shocks are not what you want and in fact causes wheel hop. The resulting wheel hop can be subtle but damaging none the less especially on less than smooth roads. I went from 2.20s 60' to consistent low 1.60s with a launch that is very fluid. The combo that I eventually got to work was removing the swaybars, running a spring that was not too stiff (like 200# +) and setting the Illuminas on the softest setting. That brings me to the 2nd point about the infamous Z-car rear end squat being a disadvantage. If it is, then Derek, Kyle and I sure do not realize this because our cars run 1.40, 1.50s and 1.60s respectively. I am also certain there are some V-8s with IRS in that class on this very forum. The only thing that counts is the 60' and it does not matter you do it. I can see a mad scramble tomorrow with you guys ripping out your swaybars and digging in the garage for those soggy springs you did not put in the trash My point is, do not give up on the IRS until you have the optimal IRS setup or some regs dictate that you do. The improved fluidity on my launches was noticeable when I switched to the CVs. Remember that the stiffer the suspension the more you are prone to wheel hopping. Violent wheelspin might look cool but not only is the car not going anywhere but you are on your way to breaking something. I try not to get more than 10' of wheelspin off the line with 8# boost on a transbrake. It does not look spectacular, it is just quick. ------------------ Scottie 71 240GN-Z http://www.mindspring.com/~vscott911/gnz.html Quote Link to comment Share on other sites More sharing options...
MYRON Posted October 24, 2000 Share Posted October 24, 2000 This is a great topic! I think i will jump in and voice my .02 worth... I am with the majority here on the choice of setup to use. I love to carve up the corners so a IRS would be better, I ALSO love blasting down a straight stretch and dragggg a happles mustang/TA/corvette down that stretch. My solution get 2 Z cars! one for each application!.. I made the decision to go with a solid axle on my 77 because I have already gone through 1 diff. and 2 ujoints. I am also going this route with my 77 because I am building alot of hp/tq and the engine sits up too high for the car to ever handle well. Yes I could buy new heads or have custom headers made and lower the motor and beef up the rear end. or just put a solid axle in it. I have a 78 that will be a nice IRS setup. That car will be more of a pro-touring type ride... One thing that we have failed to mention. Where is your fuel pump mounted on your hi-po Z car??? what happens when a ujoint goes and your axle starts pounding on your electric pump??? DOH!!! Myron Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted October 24, 2000 Share Posted October 24, 2000 Pump mount is a good point Myron. My Mustang hs it right behind the rear bumper - with 13inch brakes you'd better believe I'm nervous about that! Not sure where it will go in the Z when it's done but I'll be watching out for theaxle whip when I mount it. Has anyone considered some sort of safety loop? Is it even possible with all of the suspension travel? Nothing wrong with a solid axle, don't get me wrong, and if this car were a drag car I'd be seriously considering it. For that matter - I'm considering a 'vette rear if this sucker blows too easily. It'll come down to price between the 'vette rear and a solid rear. I guess I just go more for the "touring" than I do the straight line and in touring mode the live axle just isn't as much pleasure to drive. Scottie - the 60ft times you've got are great! I DO think the extra squat is wasted power but if you react properly that's all done with before you leave the box so no biggie! Wheelhop is a good point - the Cobras are DYING from this - axles going left and right with slicks at the starting line. Ford has a big problem there! Interesting note about the CVs over the Ujoints being smoother. Wish we could come to a consensu on the best way to convert to them! As a side note - looked at a friend's 280ZX turbo on a lift today. Niiice CVs It won't all just swap over lock stock and barrel huh? Bummer! Quote Link to comment Share on other sites More sharing options...
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