Datsun-240z Vs Fairlady-z432

[Gav240z]

On 5/27/2017 at 9:55 PM, kats said:

Thanks Blue and Alan, 

We want to know what purpose does these nuts have for ?

Kats

Since we're on the topic, I feel like someone may have mentioned this before. But I can't recall now. What is the purpose of these brackets on the lower radiator support panel?

The photo is car HS30 00836 - yes she's seen better days...

[HS30-H]

32 minutes ago, Gav240z said:

Since we're on the topic, I feel like someone may have mentioned this before. But I can't recall now. What is the purpose of these brackets on the lower radiator support panel?

Apparently they were part of a short-lived factory air con prep, relocating the horns to make more space for the condenser.

74820-E4201 was a factory replacement 'one size fits all' front crossmember/lower radiator support panel which incorporated them. It was superseded in 7/72.

They are a little odd because they seem to be more often seen on cars that have had replacement crossmembers/lower rad supports fitted than on cars that left the factory with them... 

[bartsscooterservice]

8 hours ago, kats said:

Thanks everyone, 

 bartsscooterservice, I am looking at ZT website, seems to me the roller bearings are good for the butterfly moving, they will give much smoother and almost trouble free for years to come. 

I saw ZT's 920 gold 240Z at Las Vegas convention 2000, I took my Blue 240Z there too.

I am afraid my SU's shafts are sucking air due to wear. 

And how is everyone doing with the SU damper oil? 0-20W is stiff for the pistons movement, I will try much thinner oil.

Kats

Manual says: Use Mobil SAE 10w30 for damper oil, do not use SAE 30 or higher weight oils

[240260280]

3 hours ago, HS30-H said:

Apparently they were part of a short-lived factory air con prep, relocating the horns to make more space for the condenser.

74820-E4201 was a factory replacement 'one size fits all' front crossmember/lower radiator support panel which incorporated them. It was superseded in 7/72.

They are a little odd because they seem to be more often seen on cars that have had replacement crossmembers/lower rad supports fitted than on cars that left the factory with them... 

 

 

Hurray Alan!!! Finally an answer!!!  Mystery solved.

[240260280]

10 hours ago, kats said:

 

And how is everyone doing with the SU damper oil? 0-20W is stiff for the pistons movement, I will try much thinner oil.

Kats

 

Hi Kats,

The pistons can bind  if the domes are out of alignment. The way to check is to remove the plungers then lift and drop the pistons with your fingers in the throat on the bottom of the piston lifting it up and down. You should be able to feel any binding.  The final calibration check is to lift both up to the top and release at the same time. They should "clunk" on the bottom at the same time.  If not, it is possible that the margins have carbon or that the domes and pistons were mixed up at some time (or the springs are not matched or the nylon stop washer is missing in one).  Sometimes you can swap the two pistons and the fall calibration will work better.   Pistons and domes are matched in the factory but wear and mix-ups do happen.

Binding is usually caused when screwing down the domes. If the dome is clocked (rotated) too much from its natural position, or if one screw is tightened too much at one time (to tilt the dome toward it) then binding will occur.  The trick to optimally installing a dome is:

 

1. Fit the dome w/o screws and rotate it cw and ccw while visually noting the stopping points. You can mark with a pencil. Usually there is ~ 1mm of arc in each direction from the center.

2.  Insert the screws to their middle depth (ensure no pressure on dome flange) and repeat the rotating the dome to note the stopping points.

3. Turn all 4 screws down evenly and in a cross pattern (like lug nuts on a wheel) but again, do not tighten so that the dome can not be rotated. You just want the screws to apply minimal pressure and just kiss the flange so that you can still rotate the dome but this time with a slight resistance caused by the screws.

4. Rotate the dome while lifting and dropping the piston. Note that in the center of rotation, the piston will not bind. This is where you want the dome to be.

5. Once the dome is in the sweet spot, Turn all 4 screws down evenly and in a cross pattern (like lug nuts on a wheel). Be sure to give each only a 1/4 to 1/2 turn at a time.  Continue lifting and dropping the piston to ensure all goes well.

6. After both domes are screwed down, do the drop test to ensure both fall at the same rate.

7. Add oil and the plunger then repeat the drop test to ensure both fall at the same time.

 

Finally, when considering an oil,  the important item to note is what the damper does: It only slows transitions of the piston to smoothly meter fuel. 

 

Here are the key transitions:

 

1. Engine vibrations: without the damper, the pistons would shake in the dome and wear it out the edges.

2. Road bumps: without the damper, the pistons would clunk up and down when going over bumps and dips causing the fuel flow to change radically in short bursts.

3. Acceleration: the damper reduces the fuel metering during acceleration by keeping the needle deeper in the fuel jet orifice.  Another opposite effect of the delayed piston rising is the increase of  fuel flow caused by the manifold vacuum creeping forward of the throttle plate to draw more air over the annular fuel puddle. This also increases the venturi pull of the fuel as more air is now flowing over the bridge and through the smaller opened area above it.  The net effect is more fuel during the acceleration stage but not too much.

4. Deceleration: the damper increases the fuel metering during deceleration by keeping the needle higher in the fuel jet orifice.  Another opposite effect of the delayed piston falling is the decrease of  fuel flow caused by the manifold vacuum being stopped completely in the throat  by the closed throttle plate. The result is less air to draw from the surface of annular fuel puddle as the venturi pull of the fuel is low (Less air  is now flowing directly over the bridge and through the very large opening area above it.  The net effect is reduced fuel during the deceleration stage but not too little.

 

Ultimately the damper oil you chose will only be noticed during acceleration. Thicker oil will enrich the acceleration mixture, thinner oil will lean the acceleration mixture.

 

[HS30-H]

22 hours ago, 240260280 said:

Hurray Alan!!! Finally an answer!!!  Mystery solved.

I wouldn't close the file just yet. I still think there's more to be learned and understood about them and the story behind them. It's a mod/supersession that seems to have gone off half-cocked as far as I can see. I suppose we could surmise that the coming re-design of the rad support and lower crossmember (for the bigger radiator area) made the additional brackets obsolete, but I'm still curious.  

[240260280]

I asked Mr. Matsuo and he did not know their purpose.  Your idea makes sense.

Another similar mystery: My Honda Ridgeline has a funny piece of metal at the rear base of the driver side (LHD) front wheel well but it is not on the right. It turned out it helped compliance with front left-side head-on collision requirements..... so sometimes it is safety rather than function that can make the answer difficult to determine.

Edited June 7, 2017 by 240260280

[HS30-H]

14 minutes ago, 240260280 said:

I asked Mr. Matsuo and he did not know their purpose.  Your idea makes sense.

When I mentioned the factory 'Roll Over/Safety Bar' mount prep points to ('Kaku U' team member) Osawa san in a conversation about competition influence, he had no idea they were even there. When I asked chief chassis engineer (also 'Kaku U' team member) Hitoshi Uemura about them he said "not my department...".

It serves to remind that there was a cast of hundreds behind these cars.

 

[kats]

Thanks everyone, I really like these conversations, anything is well come here.

Gave, I too think the support member is generic , as Alan mentioned it has a part number Z432 code, E42 . That is strange because Z432 does not have air conditioning system.

And we see the member even has a small brackets for a Z432's air filter box. 

Would Nissan engineers have intended to put the two big rudders just for horns for Z432 with an oil cooler , and for a condenser for air conditioned car ?

"If you do not use it, just leave it" 

Kats

[kats]

Here is an oil pump for S20, this is a gear driven type only used for the early GTR. When Z432 was began to produced the pump was already switched to the chain driven type.

I took pictures with a chain driven pump for comparison.

An engineer said in an interview in a magazine, the change was made for reducing noise level. 

But later, many owners want the noise, we feel it as racing sound, we think it is music rather than noise.

Some car have altered with this gear driven oil pump, I want to here the noise in some day.

I found one terrible thing on the spare chain driven pump, a bolt head is scratched half ! What happened with this engine?? The car had an accident in the front section ?

Kats

 

 

[Gav240z]

Kats is that the noise we can hear on Ando San's Z432-R replica?

 

[kats]

Gave, I do not know that, I will ask Ando-san about it. R-Factory is the famous shop , the owner Aihara-san rebuilt the engine. Aihara-san has rebuilt so many S20 for customers. 

This yellow Z432 has an unique all gear driven mechanism (including cam shafts gear driven) which is produced by  

Aihara-san. You can hear different sound from other S20s.

Kats

By the way, do you know who is an owner of this car? 

Mr . Nakamura Shiro , a former senior vice-president of Nissan. He got this car a few years ago. He was a chief of styling department. I hope Nakamura-san tells designers "make S30 again! " .