toki Posted May 31, 2007 Share Posted May 31, 2007 I keep reading old threads with people talking about stub axle failure being fairly common under road racing scenarios. My question is, is the problem really that serious, something you should count on happening eventually if you run a big tire with a solid suspension setup? I couldn't see the car ever being raced with anything LESS than a sticky 275 street tire (rt615 or something of the sort) out back and will see time with slicks on it. Just trying to figure out if a safety issue is really at hand, and I should just suck it up and get the billet ones from MM. Quote Link to comment Share on other sites More sharing options...
1 tuff z Posted June 1, 2007 Share Posted June 1, 2007 a few years back, when i converted to coilovers-we removed the left rear strut and heard a 'rattling noise'. turned out to be the stub axle nut [with the remains of the stub axle end still attached] rolling around... the stub axle had twisted apart! i replaced it with another 240z stub but have since upgraded to 280z stubs-at ross' recommendation [as well as others]. back then i was running a 280zx turbo engine with a jim cook supercharger setup, probably around 200 hp...very few track days, no slicks. yes, it is an issue if you're running greater than stock hp and not granny driving. Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted June 1, 2007 Share Posted June 1, 2007 Well I was hoping more people with first hand experience would chime in. My biggest worry is the degree of damage that could result should one fail while driving. When the stub breaks the whole wheel comes off the car. Rear disk brakes will at least keep the wheel in the vicinity of the car. I don't know what the risk of breakage is but I do know the potential damage when they go is totally unacceptable to me. Quote Link to comment Share on other sites More sharing options...
1 tuff z Posted June 1, 2007 Share Posted June 1, 2007 i was running the factory drums at the time and am thankful the wheel decided to stay with my z and not depart and leave me stranded! Quote Link to comment Share on other sites More sharing options...
fastzcars Posted June 1, 2007 Share Posted June 1, 2007 I persoanly broke 1 and upon inspection of the other side found the stub splines rotated one full spline! And a friend snapped one at the drags. So That's 2 cars That I have first hand knowledge of! I'm now running MML stubs. Quote Link to comment Share on other sites More sharing options...
jt1 Posted June 1, 2007 Share Posted June 1, 2007 I broke one at VIR last fall. Luckily it broke on the inside and at a slow speed, so the wheel didn't come off and there was only minimal damage from the halfshaft flopping around. It's a combo of sticky tires, more torque, and abuse. For instance, curb hopping under power is very hard on the axles because of the shock loads. I think if you're over 300 hp, and running R's or slicks you need the MM axles. John Quote Link to comment Share on other sites More sharing options...
johnc Posted June 1, 2007 Share Posted June 1, 2007 I keep reading old threads with people talking about stub axle failure being fairly common under road racing scenarios. My question is, is the problem really that serious, something you should count on happening eventually if you run a big tire with a solid suspension setup? I couldn't see the car ever being raced with anything LESS than a sticky 275 street tire (rt615 or something of the sort) out back and will see time with slicks on it. Just trying to figure out if a safety issue is really at hand, and I should just suck it up and get the billet ones from MM. Its not something to worry yourself about if you treat your car like a real race car (meaning regular monthly inspection of the chassis, driveline, and suspension). The typical road race stub axle failure is the wheel stud flange separating from the stub axle itself at the fusion weld. Its caused by the flange and the stub axle flexing at the fusion weld. Any imperfection (rust spot, small crack, scratch) will create a stress riser and, over time, a crack will propogate from that point. In 10 years of racing 240Zs (probably 60,000 track miles) I've had two fail. And that was with 225 width tires and 200 horsepower. Once I polished the fusion weld area, kept my stubbies clean, and inspected them every month (along with the rest of the car) I never had another failure - even with 275 width Hoosiers and 320 horsepower. EDIT: And I was (am) a curb hopping fool. The Penske's I ran had special blowoffs that allowed me to pound a curb and not upset the chassis at all. I was running the 280Z 27 spline 4 lug stub axles and a Quaife diff. Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted June 1, 2007 Share Posted June 1, 2007 In 10 years of racing 240Zs (probably 60,000 track miles) I've had two fail. And that was with 225 width tires and 200 horsepower. Once I polished the fusion weld area, kept my stubbies clean, and inspected them every month (along with the rest of the car) I never had another failure - even with 275 width Hoosiers and 320 horsepower. How many have you replaced because they failed a monthly inspection? And would you have bought the MM ones had they been available back when you actively raced? Quote Link to comment Share on other sites More sharing options...
johnc Posted June 1, 2007 Share Posted June 1, 2007 None suprisingly, but I had a set of brand new 280Z 27 spline stub axles that I had shot peened and polished. Never had a problem again. Ross' stub axles are impressive and if I was building a similar car again I would probably go with them if I couldn't find a nice set of the 27 spline stub axles and companion flanges. Shot peening and polishing cost me $150 for the pair and junkyard 280Z stubs and companion flanges are $25. Quote Link to comment Share on other sites More sharing options...
srgunz Posted June 1, 2007 Share Posted June 1, 2007 The typical road race stub axle failure is the wheel stud flange separating from the stub axle itself at the fusion weld. Its caused by the flange and the stub axle flexing at the fusion weld. Any imperfection (rust spot, small crack, scratch) will create a stress riser and, over time, a crack will propogate from that point. I agree w/John, that break location is typical of road racing that I have seen too. In that situation the wheel leaves the car. (with drum brakes) Yikes! Quote Link to comment Share on other sites More sharing options...
buZy Posted June 2, 2007 Share Posted June 2, 2007 Would not facing or turning the wheel/rotor/drum mounting surface in a lathe also increase strength? Properly turning the surface and blending that cut to the inside fillet radius which keeps the rotor hat on center concentric. This would reduce stub axel runout vibrations at higher speeds and extreme braking in corners. Every little bit counts right? I only mention it because ironicly I just had mine done like that last week. Not a race car, but having a V8 that screams to 7000 rpms does make me wonder. Wish I had the MM parts instead but oh well. Quote Link to comment Share on other sites More sharing options...
katman Posted June 3, 2007 Share Posted June 3, 2007 "Would not facing or turning the wheel/rotor/drum mounting surface in a lathe also increase strength? Properly turning the surface and blending that cut to the inside fillet radius which keeps the rotor hat on center concentric." Nyet, not a strength problem but a fatigue problem usually started by a rust pit or similar stress concentration. Turning on a lathe leaves tool marks in the direction cracks want to start. If you want to polish the radius use a dremel and polish the material 90 degrees to the direction that turning does. I've had 2 stub axle failures on an ITS 240Z. Two different crack locations. First one on wheel centering boss fillet, second one at the root of the splines on a 240Z stub (280Z stub has bigger spline section). Neither was catastrophic because the driver caught it before the wheel came off. However, several races after we sold the car it had another stub axle failure that put it into a wall and totalled it (new owner was told it was due for an inspection, which they didn't do). I attribute all those failures to running a welded diff, and using junk yard stub axles with no prep. Next car I built we polished and shot peened 280Z stubs and ran a limited slip diff and never had a problem. I have also had fellow ITS racers break them. It happens. But JohnC has it right. YMMV. Quote Link to comment Share on other sites More sharing options...
COmputoman Posted June 6, 2007 Share Posted June 6, 2007 Here was my scenario: Driving down the highway at about 60-80, listening to music, thinking about how safe my Z is in the rain, when all of the sudden *BAM* *CRASH* *BOOM*, the rear end of my car dropps to the ground. I slam on my brakes and drift in a zig zag patern trying to stay in my own lane. I slow down to a hault and get out of my car..... The right/rear side is sitting maybe a few inches from the ground. Luckly some police and road workers stop to help. I have my vehicle towed, and inspect the dammage. Apparently the bolt that goes through the bottom of the rear strut that holds it to the controll arm had shaken loose and fell out. My car had dropped to the ground and had been resting on the stub axles CV joint. The boot was shreaded. After trying to dissasemble the CV joint to replace the boot I noticed that the end joint seemed to be machined on in some way. Contacted a local axle repair man, brought him the stub axle and had him replace the boot. upon reinstallation I noticed the other bolt holding on the left side was nearly falling out too.. Kind of a crazy scenario. I will post pics later if anyone cares. Quote Link to comment Share on other sites More sharing options...
toki Posted June 6, 2007 Author Share Posted June 6, 2007 Thanks for all the input and stories guys. Rather than go through having the old stub axles prepped and redrilled, I'm just going to go with the MM axles. Quote Link to comment Share on other sites More sharing options...
260DET Posted June 8, 2007 Share Posted June 8, 2007 Its funny but I have never heard of a single failure in AU, even with the early 240Z type. Maybe we got the better quality JDM stubs Quote Link to comment Share on other sites More sharing options...
johnc Posted June 8, 2007 Share Posted June 8, 2007 Drive a little faster... Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted June 8, 2007 Share Posted June 8, 2007 Maybe those long right hand turns put less stress on them than the long left hand turns. Quote Link to comment Share on other sites More sharing options...
260DET Posted June 10, 2007 Share Posted June 10, 2007 So, you blokes don't believe in the 'JDM is Better' theory, well Quote Link to comment Share on other sites More sharing options...
johnc Posted June 10, 2007 Share Posted June 10, 2007 JDM? Japanese Deceptive Marketing? Quote Link to comment Share on other sites More sharing options...
Phantom Posted June 11, 2007 Share Posted June 11, 2007 Friday night, June 8th, I went out to Renegade Raceway in Wapato, WA with the 280Z. First run started with a .2 second reaction time which was pretty good since I hadn't been on the track in nearly 3 years. My 60' was a 2.1 which again was not too bad because I was trying to take it easy on the car. Grabbed a good shift to second and the car really hooked - and then it broke an axle. Not the half shaft but the stub shaft that runs through the strut. Thus ended my first foray into racing in the fine state of Washington. Flopping half shaft took out the brake line too but fortunately I was able to coast off the track (20 second run) onto a side road and call a wrecker. He was there in less than an hour and I was home by 8:30 PM. Called MSA Saturday morning and have a new shaft, bushings, bolts and seal on the way today for $61 plus shipping. Obviously drag racing will do a stub axle in. When I inspected the carnage I noticed that the stub showed signs of an existing crack that was slowly propagating. The 1-2 shift finished the job abruptly. I'm sooo glad it happened on the 1-2 shift and not the 2-3 or 3-4 shift and that it happened at the track and not on the street. Quote Link to comment Share on other sites More sharing options...
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