Nut Calcs?

[Paul Schooley]

Been away and was wondering if anyone ever took the time to list each bolt with size/part #? Sometimes I run into things on my car that don't make sense until I come out of my coma and realize it's probably standard thread used where a metric's supposed to be. Reckon the PO just did what had to be done in a few cases and I'm trying to return things to what they're supposed to be one small case at a time. Any help is appreciated.

[911pcars]

PAG did this in their parts catalog. Get a copy of PET and have at it.

Sherwood

[304065]

I'm working on a "fastener log" which lists:

Headmark
Diameter
Thread pitch
Length
Finish

for my engine. For example, looking at the workshop manuals (the definitive reference for concours) and the remaining finish of the fasteners on my 901/05 engine, it appears that all the small studs were black oxide passivated, and the other hardware finished in clear zinc. Over the years, this changed to cad or yellow zinc on the studs and nuts, as black oxide has relatively poor corrosion resistance (as I am discovering 41 years later)

I suspect that a similar log exists in the notebooks of the best restorers, but the labor involved probably makes it a highly guarded secret.

Here's one 356'er who posted some info:

http://www.brown-house.net/356project/hardware.html

[Grady Clay]

John,

Good for you!

PET is OK but not necessarily the only source. The other issue is Porsche specs much hardware with a DIN category in addition to the basic size. Many times I have to look in PET and several paper parts manuals to find the dimensions in print.

For example, Porsche lists the washer under the screw for the fuel level sender (900.025.003.30) as “5.3 DIN 125-Al.” What is missing, without a lot of researching DIN Standards, are the OD, thickness and the type of aluminum. For this washer the OD is smaller than “normal” and the material is very soft aluminum as it is a sealing washer where the screw tension is limited by the cork sender gasket. A lot can be learned from the part number; the 900 indicates a DIN spec part and the 30 indicates aluminum material.

DIN is Deutsches Institut für Normung e.V. (German Institute for Standardization), ~1917-1975. DIN was absorbed into the ISO standards (International Organization for Standardization) in the mid-‘70s

If you are disassembling a 911, label and measure every piece of hardware. Whenever possible, it is useful to measure the ID, OD and thickness of washers; dimensions and head markings of bolts, etc.

When I judged engines (early 911 and race cars) at Parade concourse, I noted the hardware type, finish patina and orientation. Even for a non-show car, it is very satisfying to have all the hardware correct. In some places it is critical (like seat mounting socket head cap screws).

Best,
Grady

[37yrold911]

what is critical about the seat cap screws?

- the bolt grade / hardness??

[Paul Schooley]

So, then there is no definitive chart (that anyone's willing to share) on the 911's hardware? I'm a little surprised at that considering how many hardcore detail concourse phreaks we have around here. I've been trying to resolve most issues with the PET but it doesn't always specify with clarity.

[911pcars]

Are you trying to identify the specs for every fastener in a 911? Sounds like a lot of time is needed to devote to this. Big job for every car part, but it's easier starting with one component at a time.

Sounds like a topic for a concours forum section.

Sherwood

[Grady Clay]

Here is the seat rail mounting socket head cap screw
(upper left). It has the short head to clear the other
hardware holding the rail to the seat and is 10 G/10.9
grade. The parts manuals specify; 900.119.042.02,
Zylinderschraube – Cheese-head screw, M6x15,
DIN 6912-10.9 vers.

This becomes a critical issue when Porsche mounted the
seat lap belt on the seat frame starting in ’69. I think
’74 is the first year where the belts went back to chassis
mount.

For comparison, here are short head 8 G/8.8 grade (upper
right and lower left). Also here is a 8 G/8.8 grade standard
height socket head cap screw (lower right).

Attachment 29058

BTW, these are original finish from the early '70s.

Best,
Grady

[37yrold911]

Thx - the correct cap screw is shown in the upper left and lower left ??

[Paul Schooley]

Maybe we could take each component and list them in this thread, then compile it all into one permanent thread. I'm sure there's a ton of guys that could put usefull info like this to work.