kwadell

iTrader: (6)

I did several searches and I don't think I've ever seen this failure mode show up. This broke right at the transition of the threads to the spline this weekend when I was at a track event. Wild ride to keep it on the track not to mention the damage to my rotor and caliper. Stock 2003 car with a StopTech BBK kit with stock tire sizes, Bridgestone RE-71's.

Anyone else seen this problem before?

dkmura

iTrader: (64)

What kind (if any) LSD were you running?

kwadell

iTrader: (6)

Everything is stock. Stock LSD. The car only has an adjustable sway bar on the back, front adjustable sway bar, front adjustable camber arms, and a 4 wheel StopTech BBK. I have been running this combination since about 2004. The fracture surface shows a classic fatigue failure. I'm thinking there was some sort of a defect in the induction hardening of the splines and how the heat treatment transitioned to the threaded portion. I unfortunately was the unlucky receiver of the parts. Half-shafts are the originals from the factory. Oh...and I only have about 32,000 miles on the car.

dkmura

iTrader: (64)

It appears you have a Touring model with the VLSD. It's very rare to see that kind of fatigue on a viscous unit. I'd agree on your theory of a production defect in the spline section. Unfortunate, but at least it's a relatively easy fix and didn't happen at high speed on a dark road far from civilization.

dboyzalter

iTrader: (3)

Thats interesting that it broke in that spot, wouldn't put that as the weakest link on the axle.

Did it cause any damage? I wouldn't think that they would have enough play to even come out of the spline when it's still bolted to the diff.

kwadell

iTrader: (6)

It caused plenty of damage. When it breaks at that point the only thing holding the tire and rim on the car is literally the brake caliper and rotor. It doesn't help that the failure happened on the track taking corners at 70-80 mph. The hub and brake rotor start walking away from the car and the caliper tries to hold it in place. I have StopTech rotors on all four corners and I had just put brand new track pads on. So, it ruined the drivers side brake pads, damaged the friction disc beyond repair, damaged the caliper beyond repair, and took out the hub and bearing. It won't be cheap to fix but at least I didn't roll the car!

dboyzalter

iTrader: (3)

Well the axle doesn't hold any of that in place, your rear wheel bearing should have kept everything together, unless the wheel bearing also failed. I removed the axles and the brakes from my parts car and everything stayed as it should and rolled fine...

Im sure the high speeds and turn was the main destructive force with the broken axle.

Could you post more pictures of the carnage I would be interested in seeing how that wheel bearing looks

Blurvision

iTrader: (4)

Check the torque on the axle nuts. Over or under could cause this. Also wheel bearings could put stress on the axle and are notorious for failure.

Glad you were able to keep it under control.

dkmura

iTrader: (64)

A bit late to post this, but I suffered a similar failure this year on my Touring 3-spec Z. When the 32 mm nut breaks loose, there's only a cotter pin and the caliper to hold the rotor/wheel onto the car. Repeated side loads against that loosened nut put stress on the threaded splines of the axle, until a spiral fracture begins to form in the weakest part of the axle itself. In my case, I suspect it was the wheel bearing which failed first, allowing the nut to loosen and cause the cascade failure which followed..

03threefiftyz

iTrader: (25)

^This. That is a prototype case of the axle nut coming loose like dkmura said....seen it happen a few times.

guitman32

iTrader: (15)

I check torque on the axle nut before each weekend for this reason. Look out for the cotter pin combo pack on sale at harbor freight

kwadell

iTrader: (6)

Interesting to see some others have seen a similar failure. There is a little more to my story. In order to help others catch this early here is some information. My first symptom was a very light periodic scratching sound from the rear. It sounded like brake pad scratching. It was always somewhat subtle and I kept looking for an issue and couldn't find it. Then when I did a pre-track inspection I found a lot of play in one of my rear tires. When I started to take things apart it looked like a rear wheel bearing failure but when I went to take the axle nut off it was only finger tight. The bearing felt pretty good with no resistance or indication the internals had failed however just to be safe I put a brand new OEM wheel bearing back in. I torqued everything up to spec and headed to the track. The axle broke literally after 2 warm up laps. My prediction is that when that nut was loose the axle had actually cracked part way through the cross section. So, even though I put a new bearing in, new nut, and torqued to specification the fact that the shaft was already cracked came back to bite me. I think there was enough section left on the axle shaft that had not cracked that I could still draw full torque to specifications. However, once you add the dynamic loads from the track it quickly failed. That's the theory. So, my advice is that if you find the axle nut loose get the axle shaft inspected for cracks behind the nut. Depending upon how long it ran with the loose nut it might partially crack the shaft. I ended up putting on a new half shaft, new bearings, new rotors, and new calipers back on. I used all OEM parts since I wanted the top quality so that was $$$$. All was fine after that. It's possible the shaft cracked first and caused the nut to loosen too? I'll never know.