Wheelbase predicament

[Patcon]

Ok, so I went and measured the car in the shop. The pinch welds on the bottom of the rocker panels appear to be parallel. It's a little hard to measure the front because the floor supports interfere with a straight measurement. The rear was easy and measures out at 51 1/4". The under floor pan frame rails are close to 30" outside to outside but get a little wider near the front of the floor board. I wonder if that is because there are more layers of metal there.

For center line in the rear there seems to be a list of good candidates. Center of mustache bar bolts, center of control arm bolts, etc. All of these seem to be centered off of the wheel wells.

The front is more difficult. I agree that everything forward of the firewall is suspect. I ended up concluding that the center of the hood latch bracket is a good candidate for a center line. It seems to measure very close to center from the top of the fender supports. If the hood latch is not centered anymore then you probably have bigger problems. Not much else there to work with...

[Namerow]

Charles:

Would you mind also measuring between the centre of the front shock towers, if convenient?  FSM says 913mm. 

Interesting that your measurement of the pinchweld separation distance (51.25" = 1302mm) is smaller, rather than larger, than the 1326mm value I got from scaling off a screen blow-up the FSM diagram.  The difference is almost exactly 1.0"...  which makes me suspicious.

 

Edited May 26, 2018 by Namerow
comment added about FSM vs. actual dimensions

[Elliott000]

I appreciate all the help guys. I gotta work all weekend but on Monday I'm going to spend some time going over these numbers.

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[Patcon]

12 hours ago, Namerow said:

Charles:

Would you mind also measuring between the centre of the front shock towers, if convenient?  FSM says 913mm. 

Interesting that your measurement of the pinchweld separation distance (51.25" = 1302mm) is smaller, rather than larger, than the 1326mm value I got from scaling off a screen blow-up the FSM diagram.  The difference is almost exactly 1.0"...  which makes me suspicious.

 

Yes I will try to get a center to center on the front shock towers.

I measured inside to inside on the pinch welds. I will get an outside to outside and see if that is more in spec. It would make sense they would work on outside dimensions and leave the error for the inside. There are a number of metal layers there so the flange is fairly thick

[Patcon]

Outside seam to outside seam is 51 9/16" or 1310mm

Center to center on the front shock towers is 35 7/16" or 900 mm

It looks like the FSM has 913 for this dimension. Will be interesting to see if my hood and fenders fit correctly when I set it off the rotisserie??? That's a pretty big "bust"!

 

Edited May 26, 2018 by Patcon

[CanTechZ]

C/C Shock towers on my '70 measured 905mm.

Edited May 26, 2018 by CanTechZ

[CanTechZ]

I did a hi-res scan of the FSM chassis drawing and then did a raster to vector conversion.  For those who are interested, I am attaching the cad file (.dwg format) that most cad software should open, as well the same drawing as a pdf.  I scaled the .dwg file as close as I could to 1:1. One thing I noticed was that when I scaled such that the horizontal dimensions were accurate the vertical dimensions were plus about 3%. See the dims in green that I added for reference.

Mike

 

 

240Z Chassis Dimensions - Source 1972 FSM Dated 10SEP71_Scaled_26MAY2018.pdf

240Z Chassis Dimensions - Source 1972 FSM Dated 10SEP71_Scaled_26MAY2018.dwg

[Elliott000]

Outside seam to outside seam is 51 9/16" or 1310mm
Center to center on the front shock towers is 35 7/16" or 900 mm
It looks like the FSM has 913 for this dimension. Will be interesting to see if my hood and fenders fit correctly when I set it off the rotisserie??? That's a pretty big "bust"!
 

My buddys car has the same 900mm as does mine and his hood fits beautiful. I would not sweat it .

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[Elliott000]

Sweet! My lower pinch welds match up at 51 1/4 front and rear. I'm going to go with that for my front and rear centre reference line

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[Patcon]

33 minutes ago, Elliott000 said:

Sweet! My lower pinch welds match up at 51 1/4 front and rear. I'm going to go with that for my front and rear centre reference line

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That's fabulous!

[Elliott000]

Definitely nice knowing I have a dead to nuts center line. Tomorrow I'm going to triple check the car is level them plumb some points down and ensure everything up front is square at least within reason. Once I fi ish the driver side frame rail and tie a bit more in on the floors, the structure will be done and then the next step is replacement panels for the rockers and rear lips. I also need from fenders, always prowl g Craigslist so if you guys see a decent factory set of steel fender s let me know!

What's everyones take on fiberglass fenders? Stay away or what

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[Patcon]

6 minutes ago, Elliott000 said:

Definitely nice knowing I have a dead to nuts center line. Tomorrow I'm going to triple check the car is level them plumb some points down and ensure everything up front is square at least within reason. Once I fi ish the driver side frame rail and tie a bit more in on the floors, the structure will be done and then the next step is replacement panels for the rockers and rear lips. I also need from fenders, always prowl g Craigslist so if you guys see a decent factory set of steel fender s let me know!

What's everyones take on fiberglass fenders? Stay away or what

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Depending on what you need for rockers. There is a member on here that makes some of the parts that are NLA.

@disepyon

you aught to read his build thread