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71 Z differential front mount


7tooZ

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The mounts are quite different in shape and I've seen no one claim that the later mount (easily available) can be used in place of the earlier mount (NLA).  Here are some pictures (posted by someone, somewhere -- apologies for not knowing who to credit)...

S30 Differential - Front Mount Insulators - OE - 240Z early vs late - top.jpgS30 Differential - Front Mount Insulators - OE - 240Z early vs late - bottom.jpg

 

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What counts here is the offset between the mount holes and that stud. As you will notice, that spacing looks identical 

With the early diffs farther forward than the later ones by an inch or so, this offset must be reflected in this spacing. But what you see in the picture, and I see as well when I check my part examples, is that these two have the same spacing....

Ignore the fact that the two blues and two red line spacings appear to not be same. The close up has significant paralax. Notice the stud orientation between the two.

1F40ABF3-FCEA-4375-8B1C-E793876FC167-1469-000000B7B863A7DF.jpeg

So what's up?  How can they be? Well if you turn one around, since the center stud has to stay in the same place on the car, the diff mount holes magically move to required position

It is my opinion, that if you just rotate a new mount 180 and put it in, it will fit on a (here we go..., deep breath...) a series 1 car.

You could also just reverse the moustache bar so it puts the dff back and use a new insulation in its correct orientation, like,  (dare I? sure...) on like a series 2 car. 

Edited by zKars
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I hope you're right, Jim.  The only early front diff mount I've seen advertised was on a Japanese website back in July and the asking price was a cool 28,000 Yen ($300+).

p.s. It's ok to call it a 'Series 1' car.  You're with friends here.

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Thanks for the information zkars & namerow. I should know this. I converted my 71 to the later location some 20 years ago. My current 72 has an R200 that I am taking out and opting for a lower diff gear.
So the current 72-78 mount should work. Think I’ll order one to see.
Changing to a Subaru R180.


Sent from my iPhone using Classic Zcar Club mobile

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  • 3 years later...
On 11/27/2017 at 8:39 PM, zKars said:

What counts here is the offset between the mount holes and that stud. As you will notice, that spacing looks identical 

With the early diffs farther forward than the later ones by an inch or so, this offset must be reflected in this spacing. But what you see in the picture, and I see as well when I check my part examples, is that these two have the same spacing....

Ignore the fact that the two blues and two red line spacings appear to not be same. The close up has significant paralax. Notice the stud orientation between the two.

1F40ABF3-FCEA-4375-8B1C-E793876FC167-1469-000000B7B863A7DF.jpeg

So what's up?  How can they be? Well if you turn one around, since the center stud has to stay in the same place on the car, the diff mount holes magically move to required position

It is my opinion, that if you just rotate a new mount 180 and put it in, it will fit on a (here we go..., deep breath...) a series 1 car.

You could also just reverse the moustache bar so it puts the dff back and use a new insulation in its correct orientation, like,  (dare I? sure...) on like a series 2 car. 

Is this theory or is it truly that easy?  I’m getting fed up with the clunk and really don’t want the change everything around it if possible. 
thanks

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I'm at that point in the reassembly of my 5/71.  Wanting to replace all things rubber after 50 years, I ordered a new diff mount, going on Motorsport Auto's claim that you can just retrofit a later mustache bar and rear crossmember to shift everything backwards to the later driveline geometry.  During reassembly a few months ago, I discovered that shifting everything back caused the OE diff strap to be positioned right above the front diff mount bolts, which obviously doesn't work.  I went back and forth with MSA about this conversion and the inherent issues, and basically they had no real-world information on how to make this work, so I eventually gave up.  Fortunately, my original diff mount still seems ok, and the original mustache bar bushings don't look terrible, so I'm going with all original pieces for now.  If things clunk once I get the car back on the road, well, then I'll revisit the various conversions.

To your question - one of the options I looked at when I was going back and forth with MSA was test-fitting the new diff mount 55415-N4301 rotated 180 degrees, keeping all of the other suspension pieces unchanged.  It looked like the front crossmember bolt holes would line up, but I didn't go any further with it than that at the time, as I was trying to make the full conversion work.  One thing I did notice is that the top plate of either diff mount, when installed as intended by Nissan, is not perfectly horizontal - there is a slight angle where the rear edge is lower than the front edge.  When the later diff mount is rotated 180 degrees, it will now angle slightly where the front edge is lower than the rear edge.  I'm not sure if this is significant, it probably just puts a different stress on the diff mount rubber bushing.

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Interesting and thank you for sharing that information. I was concerned about the drive shaft length in that conversion, seems like it would be pulled back too much. 
My existing mount still has the rubber in place it’s just separated from the steel. I honestly have more of a chirp than a clunk. I wonder if it’s possible to some how reattach the two components. 

Thanks for the feedback 

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