Pop N Wood Posted August 13, 2003 Share Posted August 13, 2003 From reading this site http://zparts.com/inprogress.html and this post http://www.hybridz.org/phpBB2/viewtopic.php?t=23450&highlight=stub+axle and past comments on this board, I am getting a little worried about the 33 year old stub axles in my 240. My car is a near stock engined garage queen right now, but in the not too distant future I want to go with an LT1 upgrade. I have the parts for Ross C's 240SX rear disk upgrades and I know those will help "retain" the rear wheels should the stub axles let go, but I can't help wondering if I should go ahead and upgrade the stub axles and replace wheel bearings when I put the rear disks on. What options do you guys think I have if I upgrade? Just go with a 280 stub axle? Or are there other alternatives? John C does a good job of describing the differences in 240 vs 280 stub axles in this thread http://www.hybridz.org/phpBB2/viewtopic.php?t=24034&highlight=stub+axle Since the spline count is different, does that mean I will need to upgrade half shafts too? The car already has an R200, but I swear I kept the original half shafts. Quote Link to comment Share on other sites More sharing options...
BRAD D Posted August 13, 2003 Share Posted August 13, 2003 For an LT1 I would upgrade, you only need the stub shaft and flange. The half shafts should just bolt up. Quote Link to comment Share on other sites More sharing options...
pparaska Posted August 13, 2003 Share Posted August 13, 2003 U-joint half shafts are the same. The companion flange between the 280 and 240Z stubs are the same where the stub axle bolts up, only different in the size of the splined hole and the spline count. I think a 240Z with other than slicks or sticky tires, driven hard but not trying to kill it, and the 240Z stubs will last fairly long. Put 500 lbft into it, do clutch drops, with sticky tires and you'll eventually end up breaking the u-joints and/or the stubs. Counter point: A used pair of 280Z stubs with new bearings is probably under $200. Quote Link to comment Share on other sites More sharing options...
blueovalz Posted August 13, 2003 Share Posted August 13, 2003 The only stubs I've ever run were the 240 stubs. Yes, the powerplant is not a high torque monster, but I am running 315 tires (oh yes, I did race with these stubs using 12.5" soft compound Goodyear slicks for years), and have had no reservations with leaving black stripes on the road perodically. The stubs never broke (knock on wood) and I still have the same ones that came in the car from Datsun. Correct me if I am wrong here, but is the splines the only area where the 280 stub axle is bigger? It uses the same bearings, and are necked down around the bearing jourals, so were exactly is the additional material other than the immediate area of the splines? Quote Link to comment Share on other sites More sharing options...
pparaska Posted August 13, 2003 Share Posted August 13, 2003 Surely John Coffey will chime in. I believe the other issue is the difference in the method of welding the flange to the axle. Better in the later 280Z? Maybe the larger one also has less of a stress riser between the end of the splines and the middle of the shaft? Quote Link to comment Share on other sites More sharing options...
johnc Posted August 14, 2003 Share Posted August 14, 2003 The most common failure mode of the stub axles that I have seen (remember, road racing bias) is the separation of the wheel stud flange from the stub axle shaft. This is caused by the flexing of the flange at the fusion weld joining the flange to the stub axle. The flexing is caused by the high lateral G-loads imposed by racing tires on a race track. I have seen pictures of stub axle failures where the axle itself fractured starting at a stress riser in the splines. This was caused by repeated hard drag race launches with racing slicks, but only after the owner had gone through a number of halfshafts that failed in 3 previous years of drag racing. If you are not in the above two categories I wouldn't worry about your stub axles. Do a simple visual inspection of the fusion weld where the flange is attached to the stub axle or take the part to a metal inspection surface and have it checked for cracks. If you are in one of the above two categories then get the 27 spline stub axles and halfshafts. They are beefier in the spline area and (at least the later versions) have a stronger, better radiused, fusion weld. You also have to get the matching 27 spline companion flanges. And, lastly, if you come across the 27 spline, shot peened, and stress relieved Nissan Competion stub axles and companion flanges buy them, clean them, oil them, cherish them, and keep them hidden from racers like me. Quote Link to comment Share on other sites More sharing options...
jt1 Posted August 14, 2003 Share Posted August 14, 2003 John, do you think all 280 stubs are the same? I have *heard* that the 77-78 stubs are more desirable than the 75-76 ones, but have no tech on that. Any truth to it or just BS? Thanks, John Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted August 14, 2003 Author Share Posted August 14, 2003 Sounds like good advice. Would hate to lose a rear wheel at highway speeds. I do think I will pull the shafts, inspect the stubs and replace the bearings when I do the rear disks. If you look at that first site I posted, the guy is soliciting information about broken axles. He is also promising "a full article with documented solutions to the problem, will appear later" Quote Link to comment Share on other sites More sharing options...
stony Posted August 14, 2003 Share Posted August 14, 2003 im using the 300z stubs and broke one first attempt at the track after i finished the mod. im sure the new hks twin plate clutch, 4.88 ratio diff, and new cromoly cv axles had something to do with it but it surprised the hell out of me that they broke so easily. i only launched at 2500 rpm. Quote Link to comment Share on other sites More sharing options...
johnc Posted August 14, 2003 Share Posted August 14, 2003 Would hate to lose a rear wheel at highway speeds. I lost my right rear one in a 80mph left hand turn at Buttonwillow. The only thing that kept me from wrecking was that the brake shoes and the brake drum held the flange, wheel, and tire on the car. I have *heard* that the 77-78 stubs are more desirable than the 75-76 ones, but have no tech on that. I can't answer that, but I did buy the last 4 new OEM ones that Courtesy Nissan could get their hands on and they had the good fusion welds. Quote Link to comment Share on other sites More sharing options...
dmyntti Posted August 15, 2003 Share Posted August 15, 2003 Stony, How (where) did your stub axle break? Was it a twisting fracture? It could be that with your custom axles you are getting more shock to the stub axles. On most rear drive cars the axles twist a little as torque is applied. This helps absorb some of the shock in the system. With your custom axles and clutch you are probably exerting much mor shock load than most and that may be what caused your failure. Jus a thought. Quote Link to comment Share on other sites More sharing options...
stony Posted August 16, 2003 Share Posted August 16, 2003 twisted it off right where the inbd splines end and the bearing surface begins Quote Link to comment Share on other sites More sharing options...
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