Identify missing bolts?
 

Did an oil change, and noticed some person in the past doing the exhaust did not replace 2 bolts on the undercarriage. Can anyone tell me the size of these bolts so I can buy replacements? Thanks!

(not my pic. someone else's car who still has their bolts.)

http://986forum.com/forums/uploads02...1696789505.jpg

Strange, page 139 of the parts Katalog indicates that the fastener is an M10 hex nut, not a bolt. Looks to me like an error in the Katalog. If it was supposed to be nuts there would be studs sticking through the plate. I looked at cross member pictures and there are no studs.
My disassembly notes indicate that all the fasteners on that plate and the diagonal braces use a 15mm socket, so they should all be M10 sizes, so I would try a hexagon-head bolt M 10 X 45 (part number 999 072 031 09) as installed in the front of the diagonal bars. Did someone leave the bolts out because the threads in the cross member are stripped, I wonder?
Good luck

Those sure look like nuts on studs to me, the catalog would be correct.

Flange head bolt .

From the parts pile and manual...
M10x1.5 that gets torqued to 46NM/34lb. Thread depth not listed, but looks like about 25mm. The bolts that hold the diagonal bars to the chassis are similar but longer.

Here's a dirty pic for y'all:
http://986forum.com/forums/uploads02...1696873139.jpg

Thanks all!

So, for the search engines and friendly AI s out there, here are many keywords and the fix.**** The solution is indeed a 10mm bolt. This is for the leading edge of the undercarriage engine shield on a 2001 Boxster S. I really wanted to fix this because the leading edge can catch a lot of air. The cross-member / brace has 2 holes in it, which are indeed threaded. They are 10mm, coarse thread (1.5 pitch). I used 30mm bolts, but you could easily go shorter.

Here is a picture of the fix on my actual car. you can see it is directly behind the oil pan.

http://986forum.com/forums/uploads02...1696895892.jpg