Can you identify this stub axle?

[coop]

After years of racing without a DNF, I finally sheared a stub axle on the race car. That axle had even been cryo-treated. So, I dipped into my spare parts bin and found two stub axles that look like they would do the trick. But wait, it appears like they are slightly different. The threaded ends have the same thread pattern but the diameter of the threads are slightly different and I mean slightly! The stub axle with the larger diameter has a lock nut on it which is identical to my sheared axle. The axle that has threads ever so slightly smaller in diameter has a castle nut on in which BTW, makes sense as that same axle also has a hole through the end.

Here is my problem. I have several good lock nuts for the larger diameter axle but the castle nut is cracked and the larger nuts wobble too much to be useful on the smaller diameter axle. Duh!

So - why are these axles different in this way? In the Black Dragon catalog, only one nut is listed and it is good for all Zs 1970 - 1978.

I'd really like to get a few good castle nuts that would fit properly - Anyone?

Also, anyone want to sell me an axle and nut combo?

One can't have enough spares.

Thanks all!

[Carl Beck]

Hi Coop:

Do they both have the same number of splines? Will the same companion flange fit on either one?

Carl B.

[coop]

This is where it get really weird Carl. Basically, I have three different axles. I'll call them axles A, B and C.

A - small diameter SPLINES and LARGE diameter THREADS (sheared on track)

B - small diameter SPLINES and small diameter THREADS (cotter pin hole with cracked castle nut)

C - large diameter SPLINES and LARGE diameter THREADS (good lock nut)

I also have two types of companion flanges, small for A ad B, large for C.

Note that the same nut works on A and C.

Just guessing here but perhaps A and B are from a 240 Z and C is from a 280 Z. Then someone may have used a die to alter the threads on B. Don't know but it is strange that B has the same thread pattern as A and C but is smaller in diameter(slightly).

Also, all bearings and spacers are identical.

Thanks.

[Carl Beck]

Most likely mentioning what you already know - but just to recap...

Yes - it sounds like "C" is what is called the 280Z stub axle. Perhaps it is the larger companion flange that is "stronger" - rather than the stub axle itself.

Spacers are stamped "A", "B" and "C" - and they are about 0.020" longer than each other. I believe that was a way to adjust for the casting and machining tolerances, of the bearing seats within the strut housings.

So in effect - whatever size spacer was used by the factory with a specific strut housing - it should be kept the same size - so that the end play comes out correctly when the axle and assembly are torqued down. So far I haven't found any documentation related to the specific distance between the inner and outer bearing seats within the strut housings. {sure would be helpful to know what that should be}.

If your stub axle "A" had no washers on each end of the spacer - then it was either a early 240Z stub axle that was assembled incorrectly - - - OR - - - it was the later {after 08/73} axle that required no washers.

Given that the bearing seats within the strut housing are fixed in place - It is a mystery to me as to how the space previously occupied by the washers, was filled when not using them. Unless much longer spacers were used - - but that doesn't seem to be the case.

In 1973 Nissan added a copper washer, under the washer/lock-nut that is torqued down on the axle. The service bulletin said that was to eliminate noise...

Nonetheless- I'd say that your axle "C" with a good nut would be the way to go...

FWIW,

Carl B.

[coop]

That is exactly the axle I am about to install today. Wish me luck. It would just be nice to get a replacement nut for my backup axle. I guess I need to spend some time at the fastener store.

BTW, all three of my bearing spacers have the "B" stamped on them so re-installation should be a no-brainer.