I originally posted on my build thread about the different NOS Frame rails i have here:

@Patcon & @CanTechZ requested that i make a special thread for it, so you can discuss. so here is the same information again:

On 3/2/2022 at 5:05 PM, Namerow said:

Those NOS lower frame rails (and the LHS upper frame 'horn') are real unicorn pieces.  Where did you find them?

Also:  If time permits, it would be of interest to some of us if you can show some pictures of the internal details of the lower frame rails (reinforcement pieces, weld-nut fasteners, etc). 

Also: What metal gauge was used for those lower and upper frame pieces?

@Namerow: Since you cought my interest on this, i decided to have a deeper look into this. I have two different sets of NOS frame rails, one is grey and the other one black. one set is already sold, one grey item has already been cut up by my previous bodyshop to fix my chassis:
Here you can see the two sets with the partnumbers labelled on it.

The main differences are the mounting brackets (see red circles), some "wings" which were added on the grey version (see blue marks), and the extended length of the tension rod mounting "buckets" (sees green circles)
Otherwise the two are pretty much the same, aside from some small clamps and brackets which have been added:

-E4150 is used up to June 1972 according the european microfiches. and it also seems to match with my late 1971 production chassis i have.
-N4150 is not clear. i didn't find it in any of my parts list, it seems weither to be from the 2+2 nor any other model, but because of the part numbering system, i just think it's an July 1972+ item.

I didn't measure every single part, but wherever i checked on approx. 5 random spots, it was always 1,5mm thickness of sheet metal:

here are some additional photos, see additional cable clamp in the black version,

Additional "Wing" is well visible here:

extende shape of the inside reinforcment:

 

slightly different shape of the inside mounting bracket / reinforcement (left edge):

Here you can see the end "wings" on the grey one, but it seems like the "leftower" piece on t he black ones have just been bent up in the grey version.

Small additional bracket on t he grey version (center)

Here you can nicely see the different style of mounting brakets: (the center one of the grey one is bent, i t would look similar as the other ones on the grey one.
the additional "holes" on the left side are because the bracket on t he inside has been drilled out by the bodyshop, these wouldn't usually be there:

Here's a closeup:

Here the overall sisize difference of the tension rod mounting bucket is well visible:

From what i can see and what i've experienced so far, the KFvintagejdm parts (no advertizing here) come pretty close to the black ones from the picture. The only part missing here is the "bucket" for the tension rod:

they currently sell them only in two pieces, but if you look at the photos and drawings in the parts manual exploded view, you can see even the original ones where produced like this and then welded together. so in my opinion this is the best you can get if you can't find OEM ones. It's not well visible in my photos above, but even the "teeth" visible on this one seem to be as on the original ones (the part where the upper and the lower part join). Look closely in the last photo which i posted above, then you can see the "teeth" on the original grey one from a side view):

 

 

A great reference piece.  Thanks.

Can anyone tell me what these two M8x1.25 threaded holes are for? I see them in both the black and gray LH front frame rails above.

Here is a pic from an old ebay that has them and corresponding holes in the LH end of the lower rad support x-member. I don't see them on my 7/70 HLS30. These holes are on the replacement LF frame rail I have from KF.

 

 

In my spare time I have been creating a 3D cad model of my chassis and I have included these holes, I'm just curious about what they for. Here are a few images of my model, it is a work in progress.

Edited October 29, 20231 yr by CanTechZ

That's the attachment point for the towing bracket specific to the HS30-H model Fairlady 240ZG.

The stock short nose towing bracket could not be used on the 240ZG (the lower section of the Grande Nose covered it) so the factory created a 240ZG-specific towing bracket which allowed the tow rope to pass through the nose:

 

2 hours ago, HS30-H said:

That's the attachment point for the towing bracket specific to the HS30-H model Fairlady 240ZG.

The stock short nose towing bracket could not be used on the 240ZG (the lower section of the Grande Nose covered it) so the factory created a 240ZG-specific towing bracket which allowed the tow rope to pass through the nose:

 

Great info, thanks for clearing it up. After looking at images on BaT it looks to me that the extra reinforcement with the M8 x 1.25 threaded holes was added to all chassis production for the '72 model year. Here is an image of from HLS30-43540 (9/71) without the the holes followed by an image from  HLS30-52950 (10/71) that has them.

Edited October 30, 20231 yr by CanTechZ

8 minutes ago, CanTechZ said:

Great info, thanks for clearing it up. After looking at images on BaT it looks to me that the extra reinforcement with the M8 x 1.25 threaded holes was added to all chassis production for the '72 model year. Here is an image of from HLS30-43540 (9/71) without the the holes followed by an image from  HLS30-52950 (10/71) that has them.

HS30-H model Fairlady 240ZG went on the market in Japan around October 1971, so that would correspond.