Datsun-240z Vs Fairlady-z432

[xs10shl]

Kats, here's a little more information.  For starters: AFAIK, original 7x14 Kobe Seiko wheels are designed to be used with the style of wheel nuts I've shown a few examples of, or the left-most wheel nut in your picture, with the large flat washer.  Id imagine that this was designed to help spread the forces over a larger surface area, due to the fragile nature of the magnesium.  I can only presume that it was determined that smaller wheel holes would not hold up to the stress of lateral forces by just using standard sized holes with tapered nuts.

The 7x14 Kobe Seikos that I have would also use the same wheel nut with flat washer, and could not safely use the tapered nuts, because the holes are too big for the studs, providing minimal contact without the special wheel nuts (picture 1). I believe this wheel would be the correct wheel and (almost correct) wheel nut for the Works cars as well.   As to my Works car- I've been using a 2010-era Kobe Seiko Mag replica which employs the tapered nut style, largely thanks to a steel insert in the casting which takes the bulk of the stress, and then distributes it to the magnesium hub (picture 2).  It's clearly a safer alternative for actual road use, but I don't know that it's strictly "as-original", though. 

 

 

 

Edited February 15, 2023 by xs10shl

[HS30-H]

Two basic different types of wheel nuts were used between the OEM '432' Kobe Seiko magnesium wheels and the Works 432-R/Works 'Rally Mag' wheel.

The (narrow) '432' type used what I believe is called a 'Sleeve Nut', with a long parallel shank and a corresponding parallel hole in the wheel. These centred the wheels on the studs by having a close clearance between the shank on the nut and the hole in the wheel, and clamping force was distributed by a thick washer on the outside face. Personally speaking, I don't like this fixing method. It always seems to raise questions of balance and poor centering.

The (wider) Works 'Rally Mag' type used a conventional nut with a (60 degree?) tapered washer that was pressed on - but free to spin to the short shank. The wheels had a steel insert with a matching taper. Clamping force was distributed around the tapered washer and centering was 'automatic' via the stud-centric nature of the tapered washers. These seem pretty much fool-proof to me. 

I've got a fairly big collection of Works Kobe Seiko wheels (7j x 14" Rally Mags, wide 15" 4-spoke circuit racing mags and 6j x 14" 'Violet' rally mags) and all of them use tapered steel inserts in the wheels to suit tapered nuts. 

Works rally cars started off in 1970 with open-ended wheel nuts, but switched to chromed dome nuts soon after.

 

[HS30-H]

Another angle. Works 240Z maintenance. Period photo:

[HS30-H]

12 hours ago, xs10shl said:

The 7x14 Kobe Seikos that I have would also use the same wheel nut with flat washer, and could not safely use the tapered nuts, because the holes are too big for the studs, providing minimal contact without the special wheel nuts (picture 1). I believe this wheel would be the correct wheel and (almost correct) wheel nut for the Works cars as well.  

My impression is that the 7x14" Kobe Seiko 'Rally Mag' wheels on your Works car are something of an anomaly, in that they use the same 'Sleeve Nut' style fixing as the OEM '432' Kobe Seiko mags. 

Of course, there was constant evolution within the specifications of the Works cars - even to the stage where there were differences between cars made in the same 'batch', and for the same event - so the concept of what may be 'correct' or 'original' for one Works car may not necessarily be applicable to another.

However, I have a pretty good collection of wheels made by Kobe Seiko for Nissan's race and rally teams (maybe 40+ wheels now) and they all - without exception - have a steel insert with a conventional (60 degree?) taper to suit wheel nuts with the same tapered washer. At least six of my Rally Mag wheels came from the batch of cars built for the 1970 RAC Rally here in the UK, so they have some provenance. From what I can see of the wheels, they don't seem to have been modified from parallel bore 'sleeve nut' fixing to tapered seat steel inserts. The inserts look original, and match the later wheels in my collection. 

Looking at period photos and original Works cars, I see plenty of evidence of tapered seat fixing. Doesn't mean that they were all that way, but it looks like majority share to me.

A couple more period photos, perhaps illustrating the destructive nature of top flight rallying (and drivers who insist on getting to the end of a stage despite having a puncture...). Tapered seats in evidence:

 

       

[xs10shl]

8 hours ago, HS30-H said:

My impression is that the 7x14" Kobe Seiko 'Rally Mag' wheels on your Works car are something of an anomaly, in that they use the same 'Sleeve Nut' style fixing as the OEM '432' Kobe Seiko mags. 

Of course, there was constant evolution within the specifications of the Works cars - even to the stage where there were differences between cars made in the same 'batch', and for the same event - so the concept of what may be 'correct' or 'original' for one Works car may not necessarily be applicable to another.

 

 

Good info - I'll have to re-calibrate my own thinking on the evolution of Works wheels and their likely dissimilarity to standard issue.  I spent some time looking for wheel pictures yesterday, and I could not find one which looked similar to the one I originally pictured above - entirely possible this is a non-Works Mag, and possibly not even original/authentic Kobe Seiko Mag. 

As an aside- I've poured over period pictures of my car before, and I have always thought that I could see open wheel nuts in some of them (which i could never understand how that could be, given what I thought I knew at the time), so I went with open nuts for last summer's shows.  Pictured are the 2010 replica Mags with steel inserts, and a couple of inexpensive open nuts.  Moving forward, there is clearly more investigative work to be done on my part, which is part of the fun.

 

 

[HS30-H]

2 hours ago, xs10shl said:

As an aside- I've poured over period pictures of my car before, and I have always thought that I could see open wheel nuts in some of them (which i could never understand how that could be, given what I thought I knew at the time), so I went with open nuts for last summer's shows.

There was definitely an observable transition/evolution from open-ended wheel nuts to the chrome domed-end wheel nuts during 1971.

Here's that 1970 RAC car (it is 'TKS 33 SA 696' by the way) again. Definitely open-enders:

 

 

[bartsscooterservice]

On 2/16/2023 at 12:03 AM, HS30-H said:

The (narrow) '432' type used what I believe is called a 'Sleeve Nut', with a long parallel shank and a corresponding parallel hole in the wheel. These centred the wheels on the studs by having a close clearance between the shank on the nut and the hole in the wheel, and clamping force was distributed by a thick washer on the outside face. Personally speaking, I don't like this fixing method. It always seems to raise questions of balance and poor centering.

Yes, this is the old style, I have them to on the z. It works but the clearance needs to be absolut minium or else vibration...

Back in the day they used to do a lot of finish balancing to get most out

 

[kats]

On 2/15/2023 at 10:37 PM, RIP260Z said:

HI Kats,

My only thought (maybe wrongly) that having a flat thick washer means the clamping force is spread over a slightly larger area, giving a greater grip. I presume a non moving washer would "bite" into the wheel, giving a better grip, whilst the spinning washer will keep moving until the torque/pressure from the nut finally holds the washer firm..... That is as far as my logic goes.....

As a side note, Kobe Seiko produced a tapered seat on their later Magolly wheels....

Thanks Ian, now I have got you. I am not good at Physics but I can understand how the thick fixed washer does for the magnesium wheel.

Then why did Kobe Seiko go to put tapered seat lately? I am wondering it like you. Also the Works car’s wheel too, put a tapered seat in a magnesium wheel.

Is this something like a compromised engineering? 
Or, did a newly invented nut with a spinning collar achieve for both good clamping force and centering the wheel?

 Mr.Namba - the general manager of the Works rally team - said “ we applied it for patents “.

I guess spinning collar would be nice because it doesn’t get scratched. Worn out-free collar is  always keeping correct clamping force. Wheels were so many prepared and provided in the rally , but wheel nuts might have always been with the car(just my guess, I think each car had spare nuts however) .

Kats

 

 

 

 

Edited February 18, 2023 by kats

[kats]

On 2/16/2023 at 7:01 AM, xs10shl said:

Kats, here's a little more information.  For starters: AFAIK, original 7x14 Kobe Seiko wheels are designed to be used with the style of wheel nuts I've shown a few examples of, or the left-most wheel nut in your picture, with the large flat washer.  Id imagine that this was designed to help spread the forces over a larger surface area, due to the fragile nature of the magnesium.  I can only presume that it was determined that smaller wheel holes would not hold up to the stress of lateral forces by just using standard sized holes with tapered nuts.

The 7x14 Kobe Seikos that I have would also use the same wheel nut with flat washer, and could not safely use the tapered nuts, because the holes are too big for the studs, providing minimal contact without the special wheel nuts (picture 1). I believe this wheel would be the correct wheel and (almost correct) wheel nut for the Works cars as well.   As to my Works car- I've been using a 2010-era Kobe Seiko Mag replica which employs the tapered nut style, largely thanks to a steel insert in the casting which takes the bulk of the stress, and then distributes it to the magnesium hub (picture 2).  It's clearly a safer alternative for actual road use, but I don't know that it's strictly "as-original", though. 

 

 

 

Thanks xs10shl, I am learning from you too. And more pictures, thanks!

 I didn’t expect that the Works wheel has a straight hole for the straight sleeve nut, it is interesting. 
 

For safety reasons, people don’t recommend using the old original magnesium wheel. Also Nissan says about care of it in the book “after driving in a salty water you must wash the wheel really well with the fresh water”

I know most of Z432 owners are still riding on their original magnesium wheels. Never heard of bad news. Maybe they don’t travel far away?

I know there is only one enthusiast who loves driving long-distance across Japan is Takeuchi-san, a PZR owner. I do drive like Takeuchi san, but he has been doing it from late 1970’s. 

Kats

[kats]

On 2/16/2023 at 8:12 PM, HS30-H said:

My impression is that the 7x14" Kobe Seiko 'Rally Mag' wheels on your Works car are something of an anomaly, in that they use the same 'Sleeve Nut' style fixing as the OEM '432' Kobe Seiko mags. 

Of course, there was constant evolution within the specifications of the Works cars - even to the stage where there were differences between cars made in the same 'batch', and for the same event - so the concept of what may be 'correct' or 'original' for one Works car may not necessarily be applicable to another.

However, I have a pretty good collection of wheels made by Kobe Seiko for Nissan's race and rally teams (maybe 40+ wheels now) and they all - without exception - have a steel insert with a conventional (60 degree?) taper to suit wheel nuts with the same tapered washer. At least six of my Rally Mag wheels came from the batch of cars built for the 1970 RAC Rally here in the UK, so they have some provenance. From what I can see of the wheels, they don't seem to have been modified from parallel bore 'sleeve nut' fixing to tapered seat steel inserts. The inserts look original, and match the later wheels in my collection. 

Looking at period photos and original Works cars, I see plenty of evidence of tapered seat fixing. Doesn't mean that they were all that way, but it looks like majority share to me.

A couple more period photos, perhaps illustrating the destructive nature of top flight rallying (and drivers who insist on getting to the end of a stage despite having a puncture...). Tapered seats in evidence:

 

       

Thanks Alan, I am so glad that you are sharing your fantastic pictures here, I appreciate it so much. 

We can see a lot of details, I can just stare those pictures all day long. 
 

What a shocking picture that is!! Broken apart wheel!! I just hope that never happens to me. 
 

By the way, do you think the reason why the open type spinning collar nut became dome type head nut would be to prevent studs from dirt and soil? I would like to know how about Works cars on the circuit at the same time frame. 
 

Kats

Edited February 19, 2023 by kats

[xs10shl]

3 hours ago, kats said:

Thanks xs10shl, I am learning from you too. And more pictures, thanks!

 I didn’t expect that the Works wheel has a straight hole for the straight sleeve nut, it is interesting. 
 

Just to clarify here - based on Alan's data and my inability to find a corroborating period photo of a sleeved-nut wheel on a Works car, I'm now thinking that Works cars likely couldn't have used sleeved nuts and wheels, and that this wheel I pictured may be from some other application.  I'll add: the period use of tapered nuts instead of sleeved nuts is corroborated by the images Alan and I have of early Works cars using open wheel nuts. 

To explain: @HS30-H 's  info has resolved a problem in my mind that I could not figure out until now - namely: "is there such a thing as a wheel nut that is both sleeved AND open-ended?"  For my prior assertion to be correct, such a part would have to exist.  Alan's data suggests the opposite is true - the part that didn't exist in the open marketplace is actually the specialty Works wheels with tapered steel inserts. That doesn't mean that open-ended sleeved wheel nuts don't exist. I've just personally never come across one (although I could make one using a sleeved acorn nut and a grinder.)

Edited February 18, 2023 by xs10shl

[HS30-H]

3 hours ago, xs10shl said:

Just to clarify here - based on Alan's data and my inability to find a corroborating period photo of a sleeved-nut wheel on a Works car, I'm now thinking that Works cars likely couldn't have used sleeved nuts and wheels, and that this wheel I pictured may be from some other application. 

Never say never. I should remember that myself...

I think it is hard to discount it, knowing the provenance of your Works car. It may be the exception that proves the rule. I'm trying to think of any scenario(s) where a wheel using the classic tapered seat fixings might have been 'converted' to sleeve nuts, and have so far drawn a blank. I can't help thinking that it is more likely - citing Occam's Razor - to be original and correct for the car, and/or perhaps the whole '71 Monte Carlo Rallye batch (except RHD ex-'70 RAC car '694'...).

The logistics of a Works team participating in a certain event dictate the it makes sense for all of the team cars to have the same method of wheel fixing. An event like the Monte Carlo Rallye - with tarmac stages, ice stages, snow stages and changing conditions between all three - requires multiple wheel and tyre changes. There would have been dozens of wheels - shared between the cars - with the Dunlop tyre trucks stationed at strategic points changing tyres on wheels, and team service cars out at designated service points carrying wheels and tyres to be changed according to the upcoming stages. Big churn. Obviously it would make sense for all team wheels to have the same fixing method/nuts. Even the ice note/recce/fast service team cars would follow suit.

So without knowing for sure what the rest of the team cars used on the '71 Monte, I'd be reluctant to dismiss your sleeve-nutted wheels as 'incorrect'. There's even a slim possibility in my mind that they were something to do with the conditions on the Monte Carlo Rallye. Nissan's Works team had already contested the Monte Carlo Rallye several times before '71, so they knew what they were up against. There may have been some reasoning behind this...