Rear 5-lug conversion options: what's new in 2015?

[Michael]

Perusal of the "Brakes Wheels Chassis" subforum reveals that the 5-lug conversion option, that is to 5x114.3mm, has been entertained literally since the day that this site was started.  Back then, options for wide wheels in our backspacing and bolt-pattern were limited.  Time and changing fashions have only exacerbated the problem.  Look for example at the various wheel choices in the "Show your wheels" thread that are now no longer available.

 

Meanwhile, businesses offering redrilling of the S30 stub axles, or completely new parts, have come and gone.  One such business, "fonebooth", at one time had a splendid selection of brake and suspension parts.  It is evidently now defunct.  Likewise with a very fine gentleman, Mr. Ross Corrigan and his Modern Motorsports, from whom I ordered wheel bearings and related parts some years ago.  Rest in peace, Ross!  Ross' 5-lug hubs are mentioned in Jon Mortenson's celebrated FAQ on Datsun differentials (http://forums.hybridz.org/topic/49194-differential-cv-lsd-hp-torque-r160-r180-r200-r230-diff-mount/) as "the strongest option". 

 

Several newcomers, such as Techno Toy Tuning, offer front-end 5-lug conversion.  But the front end is easier than the rear, at least when it comes to Datsun-Z suspensions.

 

I've found two options on the current market for rear-end S30 5-lug conversion:

 

1. Silvermine Motors.  Stock stub-axles redrilled for 5x114.3 are offered here: http://www.silverminemotors.com/datsun/datsun-280z/brake-upgrades/5-lug-hub-stub-axles-for-240z-260z-280z .  This, in my opinion, is a very reasonable price, and the simplest solution.  The caveat is concern about structural integrity of the two studs that end up being so close to the edge of the stub-axle face.

 

2. Chequered Flag Racing offers a brand-new 4 or 5 lug (dual pattern) stub axle, which is not an OEM redrilling, here: http://www.chequeredflagracing.net/Datsun.html . White Head Performance appears to be selling the exact same thing.  (http://whiteheadperformance.com/products/whp-billet-chromoly-stub-axles-27-spline-datsun-240z-260z-280z/ ) .  It looks impressive, but (1) doesn't have the studs pressed in, (2) the dual hole-pattern does nothing for strength, and (3) the price is $730 per piece!!!  Also, Modern Motorsports appears to still exist in some form, offering Chequered flag, here:  http://www.modern-motorsports.com/stub-axles.html . 

 

As far as I can discern, the Chequered Flag stub-axles are NOT the same thing that Ross used to sell; his units only had the 5-lug single pattern.

 

Questions:

 

1. Are there any other suppliers that I may have missed?

2. Is anyone still selling the exact same parts that Ross used to carry?

3. Does anyone have personal experience with the Silvermine redrilled stub axles behind a high-torque engine?

 

By way of context, I have a 461-cubic-inch big block making an estimated >500 ft-lbs of torque, a Doug Nash 5-speed manual transmission with a 3.27:1 first-gear, 3.7 R200 rear-end (welded), and I plan on running slicks.  That's over 6000 foot-pounds of torque at the rear axle, plus the shock-loading of a dumped clutch at 4000 rpm.

Edited September 8, 2015 by Michael

[RebekahsZ]

Michael-Those are big torque numbers!

What has been your experience with axle strength? I think you will find that your ae stubs will break (inside the diff) before your wheel flanges will break. From what I have heard, the aluminum 5-lug front hubs push the front wheel offset out toward the fender. You might be ok with skinny front tires. If running wide tires, I would look into having stock 280z hubs re-drilled to try to maintain stock offsets. In the rear, with that kinda torque, you might as well consider a solid axle like an 8.8 or 9".

[Phantom]

Check out the 5-lug hub set-ups at Arizona Z Car. You'll need to scroll down toward the bottom of the page to see them and I'm not certain they'll sell the hubs by themselves. 

http://www.arizonazcar.com/brake.html

[Michael]

Thanks, Phantom and Rebekah.  The reason for going to 5-lugs is for expanding options for wheels, rather than for structural strength of rear-end components.  If anything, I see redrilling of the stock stub-axles (27-spline 280Z) as a weakening, not a strengthening.  And there is indeed accumulation of evidence that the weak-point is the splines of the stub-axle or the U-joints of the halfshafts, rather than the wheel-studs.

 

Arizona Zcar offers what looks like a comprehensive rear strut assembly, but I was unable to find any documentation specifically of the stub-axles.  Their stub-axle scheme appears to be very different from anything native to the S30, which means that individual components could not be fitted to an otherwise stock setup, even if they were sold separately. 

 

Local machine shops have been leery of redrilling my stub-axles for the 5-lug pattern.  They're worried about being able to hold tolerance, and on top of that, expressed concern about the two bolt-holes (of the 5) that end up close to the edge of the stub-axle face.  When I showed the the Chequered Flag aftermarket stub axle, both shops that I visited recommended that I buy the new units, instead of trying to modify the stock ones.

 

Swapping to a solid rear-axle is another perennial idea that's been discussed now for 15 years.  In my case, there is already an extensive roll-cage (effectively a tube chassis) that would have to be substantially modified.  Also, we've seen several examples in recent years of folks running 9's in the quarter-mile, on nominally stock rear suspension.  Two brothers who go by "JnJ" come to mind (see http://www.jnjdragracing.com/ourcar.htm). They used to post actively a few years ago.

 

I hasten to add: while indeed many parts are liable to breakage, especially with sticky tires and proper alignment-setting (that is, good traction), the aim is to learn incrementally, by breaking parts incrementally.  After all, broken individual parts bespeak a strong motor and good traction; otherwise there is a more benign failure, which paradoxically represents less progress.  However, all of this is contingent on good tires, and good tires require suitable wheels.  I find myself fretting over lug-patterns and wheel-selection before sorting out many details of the suspension (though the infamous spindle-pins have various bushings have been duly replaced).  Yes, this is a misallocation of priorities, but an unavoidable one, when so many increments of progress are cascading and sequential.

Edited September 12, 2015 by Michael