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Z31 Axle Swap R200 CLSD - M2 Differentials

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Joe's "930 deal" doesn't show on either of his links.  The internet is boon and bane, you have to learn how to use it.

 

Interesting break point for j1jz, right in the middle of the splines.  The stress riser must have been the edge of the CV female spline.  I've wondered before why people don't massage their axles like they do their connecting rods.  Get rid of sharp edges, shot peen. polish, all of that.  It's all about stress distribution.

 

 

Edit - I found the page.  Bu t it doesn't really answer the questions.  Internet ........

 

http://www.modern-motorsports.com/datsun-240z-280z-complete-cv-axle-conversion.html

Edited by NewZed

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Did you snap that on the differential end or the wheel end?

You can see the circlip slot, so it's the differential side.  Looks like a stock 4 hole 300ZX turbo axle.

 

The only difference to Joe's kit then is "chromoly" (whatever that might actually mean) over whatever material and heat treatment Nissan used.  Never seen any actual evidence that the chromoly is actually stronger.  Nissan's part might be "chromoly".

 

Too bad he can't just get the CV axle end in chromoly since that's the broken part.  If chromoly is actually better.

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Chromoly is 4130 alloy steel. It's pretty commonly used for lots of things that require light weight and high strength.

What are the Nisan axles made from?

 

And "chromoly" is a vague term that covers a range of steel formulations.  If it's 4130, just call it 4130. And without the heat history, the final properties can't be known.  A couple of Hybridz members have had heat treatment issues in the past.  

 

Just saying, know what you're actually working with, if you can.

 

https://www.onlinemetals.com/productguides/alloysteelguide.cfm

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I think my axles were 4130 and similar heat treat. What is probably the important factor is the axle diameter and spline count on the Z31 CV vs the Porsche 930 CV. I can't recall specs on those, you'd have to dig a bit for them.

EDIT--Snapped axle looks like one of the batch that I had to have heat treated again because they came out of the machinist not hard enough. They were induction hardened on the ends to a pretty high number. Want to say it was mid 50s on the Rockwell C scale.

Edited by JMortensen

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So it is the CV axle?  Sorry Rebekahz I was wrong there.  I didn't look far enough down the picture.  So, maybe he just needs a new axle.

 

I haven't really added to the potential solution discussion.

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just to be clear. When the kit was bought (chromoly axles, companion flanges and stub axles) from chequered flag/modern Motorsport, there were some issues with one of the shafts so everyone was sent 1 additional axle to replace one that was originally supplied. This replacement axle is the one that broke. As I want to run the car this weekend I have put the originallly supplied axle back on as the cv doesn't appear to be damaged.

 

I feel it may be an issue with the axle but I'm just trying to run something I can trust. I looked at my friends 930 kit and the splines are larger plus the cv in modern and also larger. I also like the diff end stub. I have messaged joe for a price of the 930 kit minus the wheel side stub axles that I already have. Depending on price, this may be the was forward.

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No. I was selling the shorter CV shafts through my company M2 Differentials. I also had Z31T companion flanges made for the 27 spline stub axles. I had an issue with one batch of shafts that I produced. None of that has anything to do with Modern Motorsports or Chequered Flag. 

I gave up on Joe's supplier, because like I said, I got promises and no parts for about a year. I had someone else make the parts that had issues. Those problems aren't in any way related to what Joe is selling.

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Sorry Jon, I'm not really sure who these were bought through as my memory isn't that good. The stub axles have chequered flag written on the outside. I'm not trying to blame anyone or say there is anything wrong with the products Joe is now selling. Just trying to understand why it broke so I can feel comfortable when I launch off the line.

 

On the shaft that broke you can clearly see heat treatment to the end. The original shafts that were sent, maybe from M2, have been painted but as far as I can see there is no sign of heat treatment. The shaft that didn't brake also has no sign of heat treatment. Another friend of mine who bought these at exactly the same time (shipped together) is running a lot of power with an RB30 and not had any problems. He never bothered swapping out the replacement shaft he was sent. Did notice that the shaft I broke is about 1" longer than the one I have just put back in. I changed the shaft with the car lowered on its wheels and I have around an 1" of clearance before I bolt the axle to the companion flange. Interestingly the other side has about half this. Any comments on this? I do have adjustable bottom arms and camber plates.

Edited by John1jz

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I think the CV has about 1 7/16" worth of plunge, so at 1" you should be fine You can double check me on that pretty easily. From full droop to full compression on my car the length change of the shaft was 3/8".

 

I sent that batch of axles out and Jamie twisted one right away with his 600 hp turbo V8 drag racer. I figured out what the problem was (incorrect tempering) and recalled the ones that had been shipped without the correct heat treatment, had them treated, and reshipped them out with a different shorter axle. They way they were the first time (lengthwise) was really OK, that's why your friend didn't have any issues. I don't have a firm hp or torque number that they will fail at without the correct heat treat. 

The earlier shafts that I sent out were from a different machinist and so were correctly tempered the first time, so wouldn't have the obvious burnt looking part at the ends.

If you just want better ones, the stuff that Joe is selling now is stronger 4340 and has the correct heat treat. 

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I had a measure up of the gap between companion flange face and the side of the r200 and both sides measure 408mm.

 

Drove the zed to the drag strip yesterday which is just over 100 miles and it all felt smooth and OK with the shaft swap. Did a slow pass run to check all ok. On the second run I stated the burnout in the water and as I rolled out onto the sticky tarmack, the tyres gripped and this time the prop rear UJ.

 

I'm not having much luck at the moment but will continues to upgrade what brakes and push forward with the car.

post-26912-0-07459900-1494758459_thumb.jpeg

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I think that's better ID'ed as the "yoke" that holds the joint.  The joint itself looks okay.  And it's actually the flange that let go.  Looks like it might have had improperly sized, or loose, bolts, allowing stress risers at the holes.  To my earlier comment about finessing all of the various pieces and areas that a person can, to distribute the loads most effectively.  The parts look crude and hammer-proof, but they are actually precision-machined at the areas that matter.  People tend to just throw them together and torque 'em down and if they break they go bigger.

 

 Is that a custom shaft, the u-joint clips aren't Nissan style.  Another precision piece, Nissan actually has a range of internal clips to precisely center the u-joint caps.  Installing the u-joints by the Nissan method is a highly skilled procedure in itself.

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