Odd dimension on setback plates?????

Hello,

I'm in the process of drilling the holes in the setback plates, using the latest drawings from Greg for the plates w/o AC. I am wondering about the placement of the hole on the far right, looking at the first plate in the drawing. If you add up these dimensions: .5625+4.4063+2.75=7.7188 to locate the hole then it should also be located by adding these dimensions: 4.42+3.50=7.92 which is not equal to 7.7188.

Confused, I measured a couple of the dimensions directly from the printed drawing. The printed drawing I had turned out to have a scale of like .5854. I can take any dimension labeled and multiply it by .5854 and then take calipers and that new length matches the physical length of the dimension on the drawing. All the dimensions on the drawing scale like this EXCEPT for the 2.75" measurement. What's up?? which do I believe. I may be full of $hit, but I don't think so.

Here is the drawing I'm using:

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Thanks for any help, If the locations I drill now are wrong I can fill the holes and re-drill,
Luke

Don't worry about the 7.7188 measurement. Greg might have had a different Typ. Radius when he drew it. It make no difference. When you start your layout just layout the holes properly and the edges will be fine. That end could be 1/2" longer and it would not make any difference.

True dat.
Hole locations matter, outer radii and perimeter = no tiene importancia.

7.7188"?
Fo'git 'bout et.

Ok... so how do the two sets of holes reference eachother? The 4.42" dim is from the edge, therefore in order to use that to locate the first 3/8"-16 hole the .5625' radius is important. Either that or I use the 2.75" dim, which sounds like the right way to do it. I was just hesitant to use that because when I was trying to figure this out last night the 2.75" dim didn't scale properly on the drawing, I don't know why that is.

So the proper alignment is to have the first 3/8" hole .75" (3.5"-2.75") to the left of the last .45" hole?

That means I mis-drilled because I did 4.4063+.5625-4.42=.5488" to the left of the last .45" hole. Using the scale I found for the drawing this dimsion matched what was shown, .75 did not. Maybe SolidWorks just had a brain fart.

The holes are properly referenced here:

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The passenger side version you are fabbing is mirrored from the driver side plate.
The "AC" plates above have been machined from this drawing, exported as a .dxf.

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Great! I appreciate the time and patience. That clears it up!

I'm starting to really get excited the more constructive work I do rather than rip the car apart. I've got the money for a motor, so I should have that in the next two weeks. I just finished putting together my Ground Control coilovers today and they look great. The uprights are done, the spacers are done, the adapter plate is done, the setback plates will be finished really soon now. All the suspension parts are in. I've got a long ways to go yet, but I feel like it's possible now.

I'm still trying to decide what to do about a Diff, I don't like the looks of the stock 944 LSD but the Quaife unit is REALLY expensive. No diff is not really an option in my opinion. Have you ever seen a used Quaife? Are there any other helical gear type units made for the 944? I would rather have a gear type than a clutch pack, but I haven't ever seen a clutch pack for the 944 anyway. Let me know if you have any ideas.

Cheers,
Luke