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A while back I reinstalled my seats using standard stainless socket head cap screws. I am not sure but it seems the passenger seat may be prevented from going all the way back as the screw heads are taller on a standard cap screw vs the original binding the track.
I went about ordering the short head screws. When I was looking at the original screws not only is the head shorter but the thread run-out is not right at the head of the screw but a short distance down the shaft. This suggests the bolt is a good bit stronger than one where the threads run out at the head radius.
Also from the pictures the short head non-OE aftermarket screw sets sold for seat mounting seem to have a smaller allen wrench socket size than the original.
Seeing that the seat belts are anchored to the seat on one side and the forces to the belt in a crash are therefore transmitted through the seat to the seat bolts is one compromising the safety of the system by not using caps screws just like the originals?
I'll just say that if a good quality/grade bolt is used, the forces required to shear the properly torqued bolt, are enough that, the seat coming off is probably the least of concern here.
A while back I reinstalled my seats using standard stainless socket head cap screws. I am not sure but it seems the passenger seat may be prevented from going all the way back as the screw heads are taller on a standard cap screw vs the original binding the track.
I went about ordering the short head screws. When I was looking at the original screws not only is the head shorter but the thread run-out is not right at the head of the screw but a short distance down the shaft. This suggests the bolt is a good bit stronger than one where the threads run out at the head radius.
Also from the pictures the short head non-OE aftermarket screw sets sold for seat mounting seem to have a smaller allen wrench socket size than the original.
Seeing that the seat belts are anchored to the seat on one side and the forces to the belt in a crash are therefore transmitted through the seat to the seat bolts is one compromising the safety of the system by not using caps screws just like the originals?
It's unlikely to be the bolt heads that are preventing travel.
The more likely cause is a lack of parallelism in the tracks, this commonly occurs when one or more of the track bolts comes loose.
To check loosen all the bolts and slide the seat around, be sure that it slides freely. Then re tighten and re check for slide freedom.
SS is necessary for the sliders, Use M8x20, grade 10, hex head cap screws
some use a mild Lok-tite
if you are concerned w/ corrosion use an anti seize and torque to spec
To add to Bill's comment, I have discovered, after installing and removing my seats many times, that it is quite easy to cause non-parallelism in the tracks when installing seats. I would cause non-parallelism myself if I did not start by tightening the rear inboard mounting first. This is because the other three mounting points have captive nuts that can move around in the holes. However, the inboard rear mounting points are fixed --- they do not move.
To add to Bill's comment, I have discovered, after installing and removing my seats many times, that it is quite easy to cause non-parallelism in the tracks when installing seats. I would cause non-parallelism myself if I did not start by tightening the rear inboard mounting first. This is because the other three mounting points have captive nuts that can move around in the holes. However, the inboard rear mounting points are fixed --- they do not move.
Great tip Jlaa, thanks for pointing this out. I've discovered through trial and error that it helps to install the rear seat bolts first, but now I have a clearer understanding as to why. I will also make sure to install the inboard bolts first from now on. I've not so much had alignment problems (perhaps setting each of the rails all the way back to start helps avoid this), but getting the seats to line up and bolt in correctly can be vexing at times. Again, thanks for the great pointer.
Great tip Jlaa, thanks for pointing this out. ........ but getting the seats to line up and bolt in correctly can be vexing at times.
You are welcome! You have no idea how relieved I am to hear that I'm not the only one in the universe that has cursed up a storm trying to get the seats to line up correctly!!! :-) :-)
Great tip Jlaa, thanks for pointing this out. I've discovered through trial and error that it helps to install the rear seat bolts first, but now I have a clearer understanding as to why. I will also make sure to install the inboard bolts first from now on. I've not so much had alignment problems (perhaps setting each of the rails all the way back to start helps avoid this), but getting the seats to line up and bolt in correctly can be vexing at times. Again, thanks for the great pointer.
That is a great tip, Jlaa! Never given it much thought till now.
I thought it might be helpful to post up a few pics and links comparing the OEM bolts to the Classic9 aftermarket "OEM" bolts. The OEM bolts are available from Sunset for $1.50 each. http://www.sunsetporscheparts.com/oe...he/90011903002 They're pretty notorious for stripping. Not surprising given their 8.8 hardness rating and take a 6mm Allen wrench.
The "OEM Type Low Head Yellow Zinc" bolts from Classic 9 http://www.classic9leathershop.com/s...inc-1985-1998/ are comparably priced, but there are some subtle differences. The Classic9 bolts accept a 5mm Allen wrench (more bolt, less hole), and most notably they have a hardness rating of 10.9 so they're less apt to strip (or shear I imagine). The thread run out is closer to the head on the Classic 9 bolts, which may not be such a good thing.
Edit: I neglected to mention the OEM bolts accept ball end hex keys, the Classic 9 don't.
OEM on left (6mm) Classic 9 on right (5mm)
Classic 9 on left, OEM on right (note difference in thread run out)
For the life of me I can't imagine why you would second guess the factory on such a critical component. The factory bolts are readily available, cheap, and extensively tested as a part of the overall seat/safety system.
Another tip is to understand that not all Allen wrenches are created equal. The "lesser" quality wrenches are almost always a looser fit to the bolt head than a quality tool such as Snap On.
My 968 had a huge number of socket head cap screws and I would often strip the socket head with wrenches or sockets made in China. At the suggestion of a great mechanic I paid a premium to purchase both Allen head and triple square sockets. I noticed immediately that the fit of the Snap Ons was noticeably more snug than my Chinese tools. And, honestly, I don't believe I have ever stripped a bolt since using the Snap Ons.
08-10-2016, 04:03 PM
Seat Mounting Bolts
