Screws for turn signal cancel ring

[TommyV]

As I work on getting my 71 911 on the road (2.5 years into this project) it seems like I encounter a new problem everyday. The good news is I found the harness I needed from the Emergency Flasher switch to the 6 pin plug in the firewall. Connecting that and tying in the turn signals means I now have all lights, flashers and blinkers working!! Yay!!!! This is a big deal because I'm much more mechanically oriented and have never been talented when it comes to electrical, but I persevered and overcame!

Today's problem is I had the wrong wheel when I got the car, so I recently bought a 914 wheel that fits, but had no turn signal cancel ring. I purchased that and the harness mentioned above from Tom Butler (thanks Tom!). Then I realized that I needed screws to attach it. I found a couple that fit as they were holding the 914 base (which I don't need) to the wheel. Unfortunately, then are not countersunk, they have a small serrated washer on them. I took them to the local hardware store to day figuring they were 4mm. When I check though, they are smaller than 4mm by just a little and much bigger than 3mm. Now the 4mm nut I was trying to test it with was too coarse, but it walked down the screw without having to turn it. The online Porsche PET calls is a 4 x 8 countersunk-head screw, but it seems to be NLA. Is it a fine pitch 4mm? Anyone have a couple they want to sell me or a source for them?

[37yrold911]

if you can determine the actual size (and it may just be flashing or cross-threading on the female part) try Bel-metric, Amazon, etc.

[SIMI BOB]

If you buy a set of metric taps and dies (I bought a Craftsman set a very long time ago) it should include a gauge that will tell you the "pitch" of the screw. Even the cheap Harbor Freight set includes one. If you are doing a lot of work on your car, this is a must have item (not just the gauge).
Measure across the threads with a micrometer and you will get within .002" or .003" of the metric size of the screw. I have a large chart on my wall that shows metric and SAE drill sizes and compares metric and inch sizes up to 1 inch. Also a must have item, IMHO. You may be able to get one from any quality tool supply store in your area. Mine was free. Sorry about the rotation and slightly fuzzy pic, but you get the idea.
Bob B

[andyjboy]

They're std M4 thread - you can buy suitable screws from Sierra Madre (although the originals were slotted not Phillips head):

http://www.sierramadrecollection.com...12-p20039.html

[SIMI BOB]

Go to this page and look at the chart "ISO 261 STANDARD PREFERRED THREADS" and you will see that the "preferred " pitch for a 4MM screw is 0.7MM (or about .028") between threads. It also gives the number for "fine" pitch threads (but some of these are hard to find with the smaller dia. screws).
Most of the nuts and bolts on the Porsche are "preferred" pitch, but some exceptions are Valve adjuster screws (8X1.0) and the larger size bolts in the front and rear suspension (ball joint nuts).
Bob B

https://en.wikipedia.org/wiki/ISO_me...thread#ISO_261

[TommyV]

I found a set and got them today. They are definitely a finer pitch than the standard .7mm, probably the .5mm fine pitch mentioned in your link Simi Bob.