986 Forum - The Community for Porsche Boxster & Cayman Owners - View Single Post - ARP accessory studs for race seat mounting

Quadcammer · 02-18-2020, 06:23 AM

996SeatInstall

I copied and pasted the key point below. Less of an issue with studs but still

This seemingly innocent little fellow is a factory 996 seat mounting bolt. Other than the fact that it has a 6-point external head, and a "self-centering" tip, it doesn't look much different than most bolts.
Looks are once again deceiving!
This car came to me with "regular" 10mm x 1.5 thread pitch grade 8.8 bolts in place of most of these OE bolts. Inexplicably, two of the OE type were still used in the passenger's seat. I noted that the replacement bolts did not seem to move particularly freely in the holes when I took them out, and that the threads were slightly rounded off on their edges. I ran the threads with a die, and the situation did not seem terribly urgent.
I had the seats in and out at least a-dozen-and-a-half times trying to get all of these Big Problems worked out, and by the time I could see the light at the end of the tunnel, I suddenly found that I had
concurrently reached the end of the life span of the threads in the floor!
This on top of everything else?! #@%&@# !!
After the shock wore off, I got to looking at these odd little bolts. I tried to clean one of them up by running the threads with a die. It lurched in a tight-loose-tight rhythm. Strange. I threaded it into my finger tips. This does indeed not have a regular thread! It is sort of triangle-shaped. A trip to the local pro fastener outlet put order to my findings. These bolts are not normal, not even self-tapping. They are THREAD FORMING BOLTS. "Triodal" by name, if I remember correctly (?). The holes in the car floor are blank inserts, and these bolts, with their self-centering tip and special shape form their own threads as they are FORCED into the holes in the floor. These are not normal threads, and only work to whatever degree that they do with the OE bolt in them. Other bolts will not quite interface well with them, and if they are asked to come in and out too many times... POOF! Goodbye threads!
Oddly enough, the failures only occurred on the front holes. The rear threads remain rock solid. ???
Problem solved by drilling out the inserts and re-tapping them to the next closest size... 1/2"-20 SAE.
REAL THREADS this time. SOLID!

02-18-2020, 06:23 AM	#5
Quadcammer Registered User Join Date: Dec 2016 Location: Clifton, NJ Posts: 1,135	996SeatInstall I copied and pasted the key point below. Less of an issue with studs but still This seemingly innocent little fellow is a factory 996 seat mounting bolt. Other than the fact that it has a 6-point external head, and a "self-centering" tip, it doesn't look much different than most bolts. Looks are once again deceiving! This car came to me with "regular" 10mm x 1.5 thread pitch grade 8.8 bolts in place of most of these OE bolts. Inexplicably, two of the OE type were still used in the passenger's seat. I noted that the replacement bolts did not seem to move particularly freely in the holes when I took them out, and that the threads were slightly rounded off on their edges. I ran the threads with a die, and the situation did not seem terribly urgent. I had the seats in and out at least a-dozen-and-a-half times trying to get all of these Big Problems worked out, and by the time I could see the light at the end of the tunnel, I suddenly found that I had concurrently reached the end of the life span of the threads in the floor! This on top of everything else?! #@%&@# !! After the shock wore off, I got to looking at these odd little bolts. I tried to clean one of them up by running the threads with a die. It lurched in a tight-loose-tight rhythm. Strange. I threaded it into my finger tips. This does indeed not have a regular thread! It is sort of triangle-shaped. A trip to the local pro fastener outlet put order to my findings. These bolts are not normal, not even self-tapping. They are THREAD FORMING BOLTS. "Triodal" by name, if I remember correctly (?). The holes in the car floor are blank inserts, and these bolts, with their self-centering tip and special shape form their own threads as they are FORCED into the holes in the floor. These are not normal threads, and only work to whatever degree that they do with the OE bolt in them. Other bolts will not quite interface well with them, and if they are asked to come in and out too many times... POOF! Goodbye threads! Oddly enough, the failures only occurred on the front holes. The rear threads remain rock solid. ??? Problem solved by drilling out the inserts and re-tapping them to the next closest size... 1/2"-20 SAE. REAL THREADS this time. SOLID!