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Broken 4340 Stub Axle threads


wozza

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Yes there was a batch that wasn't annealed properly.  Somehow they slipped thru their QC.  Common problem is what you see here too hard the end just snaps off.  If you have a set you would like to have checked please send them back to me.  I will take care of it for you.  Sorry for the inconvenience. 

 

FYI the manufacture just upped their price on each part by $50.00.  So that puts my cost at $750.00 plus shipping almost what they sell them for. Don't forget I need to buy 10 parts at a time. 

 

Thanks  Joe

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Still waiting. I had ordered mine through Mike at WHP. Was told back in December the new batch should be done by the middle/ end of February but have yet to get a confirmed ship date. 

I'm actually wanting to upgrade to the 300M units now after this but apparently those had to be made as well. So I wait. 

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Old thread but current problem. Snapped the left side wheel stub axle on my Viper powered 1972 240Z after approximately 6,000 miles of use. It failed in the threaded portion, not the splines. I have the early Modern Motorsports setup with 280ZX Turbo CV axles and R200 w Quaife which is holding up just fine.

 

What is the current thinking regarding the strongest solution available for the stub axles?

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I think that the answer is the same.  If that's a 240Z axle swap to a 280Z axle.  You'll need a new companion flange.  Looks like zcardepot has a 39 spline option but might not have the companion flange you need.  Chequered Flag (he owns Modern Motorsports now) used to have a long wait time or certain order size before he makes his parts. 

 

There's a variety of possibilities out there.  Not sure that any are simple.  Good luck.

 

https://zcardepot.com/collections/rear-axle-and-differential/products/outer-axle-racing-chromoly-240z-260z-280z-70-78?_pos=1&_sid=6cde3c5c6&_ss=r

 

http://www.chequeredflagracing.net/Datsun.html

 

https://www.silverminemotors.com/datsun/datsun-240z/drivetrain-26/240z-260z-280z-oem-rear-stub-axles-4-lug-with-companion-flanges

 

https://whiteheadperformance.com/performance-parts/datsun-240z-260z-280z-parts/cv-conversion-stub-axles-companion-flanges/

 

 

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The 39 spline option doesn't neck down to the splines, so the splined section is stronger, but it still necks down to the nut, so that part wouldn't be any stronger. The best solution is to get rid of the stub axles and go to a more modern CV where the splined end of the CV plugs through the stub and the axle nut is on the outside of the flange. There are a couple options that are available. 

The unfortunate thing about those is they generally have extremely heavy uprights and require all new brakes, struts, etc. so you might gain strength in the driveline but at the cost of well, cost since you're replacing a lot of parts, and weight. I wouldn't even consider this kind of change without ditching the R200 and going to something with more ratios and LSD options like the F8.8. YMMV.

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Thanks for the input. I’m in no mood to replace the rear suspension to gain a better stub axle solution. I have ordered T3 5 lug stock 280z 27 spline stub axles. May have to replace the wheel studs, not sure what length they come in but i need 2 1/2” studs to clear the thick rotor spacers that my Arizona Z setup uses.

 

We’ll see how well the T3 OEM axles last, if they last as long as the first ones, I’ll be back here in 15 years asking the same question.

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Well, struck out, T3 OEM axles were 25 spline and i need 27 spline. I tried to call Whitehead Performance to see if they actually have their chrome moly stub axles in stock but their voice mailbox is full and couldn’t leave a message. Anyone have another number, maybe a cell, for the manager or owner?

 

Has anyone attempted a weld repair on a broken stub? Maybe a big chamfer at the base of the of the threads where the fracture occurred, may loose several threads, then TIG weld the stub, turn down in a lathe any weld material that sits proud of the shaft diameter? Last resort of course. 

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14 hours ago, Jlhalsey3 said:

Well, struck out, T3 OEM axles were 25 spline and i need 27 spline. I tried to call Whitehead Performance to see if they actually have their chrome moly stub axles in stock but their voice mailbox is full and couldn’t leave a message. Anyone have another number, maybe a cell, for the manager or owner?

 

Has anyone attempted a weld repair on a broken stub? Maybe a big chamfer at the base of the of the threads where the fracture occurred, may loose several threads, then TIG weld the stub, turn down in a lathe any weld material that sits proud of the shaft diameter? Last resort of course. 

Forget trying to call Whitehead's. The only way to contact them is to email, and then cross your fingers. Best to shop elsewhere. They do great work but are absolutely horrible at communication. 

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  • 4 months later...
On 4/23/2021 at 1:34 PM, JMortensen said:

The 39 spline option doesn't neck down to the splines, so the splined section is stronger, but it still necks down to the nut, so that part wouldn't be any stronger. The best solution is to get rid of the stub axles and go to a more modern CV where the splined end of the CV plugs through the stub and the axle nut is on the outside of the flange. There are a couple options that are available. 

The unfortunate thing about those is they generally have extremely heavy uprights and require all new brakes, struts, etc. so you might gain strength in the driveline but at the cost of well, cost since you're replacing a lot of parts, and weight. I wouldn't even consider this kind of change without ditching the R200 and going to something with more ratios and LSD options like the F8.8. YMMV.

 This thread is one the top entries when searching for "280Z rear 5-lug conversion", and that prompted a bump...

 

* As of this writing, the Z-car-depot site looks the most promising.  Checquered Flag is a placeholder website, and the link posted earlier in this thread, is dead.  The Modern Motorsports domain is for sale.  And the Whitehead thread is getting more and more desperate.

* There's also this: https://forums.hybridz.org/topic/128217-ford-super-88-irs-swap-thread-rear-brakes-too/#comments .  But I'm not sure how much of that is applicable if the aim is to retain the R200, and only to replace the half-shafts, stub axles and companion flanges.

* Any updates on the heavy-and-costly option mentioned above?

 

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Joe from Chequered Flag is still on FB, so I just messaged him to find if he's still in business. Just 2 weeks ago people were wishing him luck racing that weekend so it would surprise me if he were out of business.

I don't have the patience to go through that Super 8.8 thread, but that's a very strong differential. I got to the post where the guy was talking about 2000 hp axles and tuned out. Just look out for systems that end up 100 lbs heavier than they started.  Some of the other attempts at 8.8s are just ridiculously heavy. Especially if you have 400 hp, the weight is a bad trade off. 

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