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M2 Z31 Short shaft issue


SUNNY Z

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I'm thinking that the "shiny" axles didn't get heat treated, unless there is/was a polishing step after the heat treat.

 

THATS WHAT I THOUGHT

 

But when I asked, I was told they were :mellow:

 

I dont build these things, so what do I know.

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Still no issues with mine but then I haven't tried it at santa pod yet either

For what odds it makes when new mine came blackened like this

 

th_860498c3.jpg

 

Oh snap! mine did NOT look like these at all. these look nice and burnt so im sure THESE black ones were heat treated and hardened as supposed to be... mine came in super shiny i was like damn! got polished parts for free! ? i guess the machinist "forgot" to heat treat the first batch?..... if so, Fkn great! now we have to send these back as well and wait for the arrival for the new "actual" heat treated ones. lol Standing by for update

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Yeah, I didn't get the first batch run.

 

haha nice! :) hopefully you guys don't encounter either the "too long" or "bending" issues and have long lasting shafts :) can't wait to roll around on my z soon. lol my dad keeps asking me when im going to get my car started alrady. i get super pissed every time, im like" DAD! the car starts..... it just won't MOVE :'( " hahahaha ahhh the irony....

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OK guys. Got one more thing to check on, and then I'll let you know the whole story tomorrow. Axles should be on the way to me tomorrow or the next day, I'm going to have to have them tempered when I get them, and then we'll forward them on to customers.

Edited by JMortensen
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We used two shops to make these axles. The first shop heat treats the shafts in an oven to the mid 30s Rockwell C, roughs out the shaft then induction treats the shaft to mid 50s bends them back to straight, then does the finish machining of the splines. The shop that did the axles for the second group buy did the machining of the splines, then heat treated the axles in an oven to around 40, then turned them to straighten, then sent them to us. The black on some of the axles is just mill scale and oil that was cooked on and turned black during the heat treat process. It plays no part in the heat treating and is not important in determining whether an axle was treated or not. If you got your axles in the second group buy or later, you got the axles that have a problem. The problem is not the material and it is not that they weren't heat treated, it is the heat treat that the second shop used was not sufficient. We now have a pallet of replacement axles which are heat treated to 40 ready to ship to me. They should be here Tuesday or Wednesday.

 

We talked to heat treat shops this week and the solution here is to induction harden the splines. Yesterday afternoon I picked up a shaft which had been treated to mid 50s on the ends as a test. The gears still fit perfectly on the ends, and the shaft is not bent. This induction method is a common way of heat treating axle shafts because it avoids the axle bending after the finish machining is done. The stock CV shafts are induction hardened on the ends and one of the shops that I talked to does the exact same thing for the desert race truck axles that they manufacture. The problem for us is that we have customers who have the second group buy 14 13/16" length shafts that need this second stage of heat treating to be brought up to par. We are going to send out emails with shipping labels today and we would like your long axles back.

 

The good news, if there is any out of all of this, is that the heat treating process isn't a time consuming one. The shop that did my test axle said they could get the axles done in about a week if they were busy, less if they weren't when I brought them in. Also they are local so I don't have to wait for shipping when they are done, I can just go pick them up. What we really need from you guys is to get the long axles back ASAP. The quicker we get them back, the quicker we can send the replacements out.

 

For what it's worth, the first shop using the mid 50's heat treat said that it's very common for their drag racing customers to have axles twist more than a spline and then "take a set" and stay like that for years and years. They actually suggested that Josey continue using his shaft, but because of his description of "no drag launches" I had a feeling something else was going on and told him not to use it. The shop told me that a hardened axle will not snap before it twists the splines, unless it is manufactured with what they refer to as a "torque fuse". The first shop said that the stock axle, where it necks down after the spline, has a torque fuse and that it will likely break there first if pushed hard enough. They also said that they try to never machine axles with a torque fuse unless they are being installed on a car that has a very rare differential and the customer would prefer the axle to break rather than damaging the diff.

post-553-017689900 1345836949_thumb.jpg

Edited by JMortensen
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Awesome! :) great news mortensen happy to hear you got good feedback from the manufacturers. So question. we will be shipping you all back the longer shaft and we will be getting the set with both correct heat tempered shafts (for those who payed for the set of two) ?

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Awesome! :) great news mortensen happy to hear you got good feedback from the manufacturers. So question. we will be shipping you all back the longer shaft and we will be getting the set with both correct heat tempered shafts (for those who payed for the set of two) ?

 

Yes.

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Jon - Thank you very much for the thorough explanation. I appreciate you following up and it sounds like you are doing the right thing.

 

"take a set"

 

I believe they are referring to work hardening. The material actually gets stronger as it yields. I wouldn't trust SUNNY Z's shafts because of the little sharp notches where the CV carriage dug into the splines. These little notches are stress risers and may initiate fatigue cracks.

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  • 2 weeks later...

Got the new length shafts in. Have talked to several people who have just sent their axles in. Need to get a few more back before I can go to the heat treaters. Two guys who just sent them back are east coasters, and I've checked and several people who haven't sent them yet are east coast as well, so I'm going to do a little prodding so we can get this thing going. Figure if I'm lucky I might get the shafts by the end of next week.

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I believe they are referring to work hardening. The material actually gets stronger as it yields. I wouldn't trust SUNNY Z's shafts because of the little sharp notches where the CV carriage dug into the splines. These little notches are stress risers and may initiate fatigue cracks.

 

Somebody get this guy a beer. I broke that shaft yesterday.

 

2012-09-07_17-53-17_319.jpg

 

Outboard

 

2012-09-07_18-15-15_119.jpg

 

Inboard

 

2012-09-07_18-15-41_204.jpg

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