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914World.com _ 914World Garage _ Pressure plate bolt question
Posted by: Tdskip Jul 16 2020, 06:34 AM
Good morning.
Asking about Porsche 900-075-078-02 - the 6 pressure plate bolts.
Anything special about these or can I use quality ones from my local Ace? Not worth causing an issue by using an interior supplier, but from what I can see these are not under a whole lot of torque and appear to be off the shelf items that cross reference to exhaust bolts etc....
Thanks!
Posted by: GregAmy Jul 16 2020, 07:02 AM
I used regular bolts in mine. The plate's torque is generally taken up by the hardened pins.
I also committed a kapitalverbrechen by using 12mm socket head bolts from my Honda bolts stash. Allowed me better socket access in the confined space...
Posted by: ClayPerrine Jul 16 2020, 07:15 AM
You can use any class 8.8 (SAE Grade 8) M8x1.25 bolt, 18-20mm length. I like to use M8x1.25 cap head screws. I also add a lock washer and some Locktite red when installing. And I always use a torque wrench.
Posted by: cary Jul 16 2020, 07:30 AM
Or ones with 12mm heads. For socket fit.
Posted by: porschetub Jul 17 2020, 01:50 AM
You can use any class 8.8 (SAE Grade 8) M8x1.25 bolt, 18-20mm length. I like to use M8x1.25 cap head screws. I also add a lock washer and some Locktite red when installing. And I always use a torque wrench.
use 8.8 or more is fine.Posted by: Superhawk996 Jul 17 2020, 07:47 AM
Just a quick reminder. Metric 8.8 is equivalent to SAE Grade 5. As a general principle, there is no harm in going up a grade. Example. Metric 8.8 came out -- OK to replace with Metric 10.9.
No real worry about mixing Metric and SAE inadvertently due to obvious thread form differences. 
https://www.brightonbest.com/download/BBI_tech_poster_imperial_metric_bw.pdf
Posted by: ClayPerrine Jul 17 2020, 09:25 PM
Just a quick reminder. Metric 8.8 is equivalent to SAE Grade 5. As a general principle, there is no harm in going up a grade. Example. Metric 8.8 came out -- OK to replace with Metric 10.9.
No real worry about mixing Metric and SAE inadvertently due to obvious thread form differences.
https://www.brightonbest.com/download/BBI_tech_poster_imperial_metric_bw.pdf
Not saying you are wrong, but that is a completely different chart from the one I used.
Clay
Posted by: Tdskip Jul 18 2020, 07:14 AM
As usual this has been a very helpful discussion gentlemen. I appreciate all of the posts and will get a proper set and use some Locite.
Have a great Saturday and thank you again.
Posted by: Superhawk996 Jul 18 2020, 07:33 AM
Not saying you are wrong, but that is a completely different chart from the one I used.
Clay
No worries @http://www.914world.com/bbs2/index.php?showuser=1143 . I assumed it was an oversight.
In fact, there is a google chart that pops up from time to time on fastener searches that is blatently erroneous and doesn't reference tensile strengh. That's why I posted the chart and the source URL. It's a good reference by actual tensile strength and also had the common bolt and nut markings to help ID them. It's also easy to mess up the conversion between imperial units and metric when doing the conversions for comparision - been there done that.
I'm an engineer and have done quite a bit of fastener testing and you wouldn't believe how deep it can get with respect to fasteners. Proof load, yield, tenslile load. Torque vs. stretch? Physical measurement of stretch vs. ultrasonic measurement. Measurement of clamp load vs. torque. On and on.
Don't even get me started on AN fasteners (Army Navy Standards).
As always, I encourage people to double check me. I'm just another dope on the Interwebz.
Don't take what I say for gospel. Do your own homework when it really matters. Here is another datapoint from NAPA just to make sure I'm not fibbing.
http://knowhow.napaonline.com/common-automotive-fasteners-guide/
Posted by: ClayPerrine Jul 18 2020, 08:29 PM
Hey.. always double check me too. I am an ex-mechanic who is now a computer engineer. I never had the formal book Larnin' on bolt strength. That's why I look things up. If I got it wrong, then I will admit it.
Clay
Not saying you are wrong, but that is a completely different chart from the one I used.
Clay
No worries @http://www.914world.com/bbs2/index.php?showuser=1143 . I assumed it was an oversight.
In fact, there is a google chart that pops up from time to time on fastener searches that is blatently erroneous and doesn't reference tensile strengh. That's why I posted the chart and the source URL. It's a good reference by actual tensile strength and also had the common bolt and nut markings to help ID them. It's also easy to mess up the conversion between imperial units and metric when doing the conversions for comparision - been there done that.
I'm an engineer and have done quite a bit of fastener testing and you wouldn't believe how deep it can get with respect to fasteners. Proof load, yield, tenslile load. Torque vs. stretch? Physical measurement of stretch vs. ultrasonic measurement. Measurement of clamp load vs. torque. On and on.
Don't even get me started on AN fasteners (Army Navy Standards).
As always, I encourage people to double check me. I'm just another dope on the Interwebz.
Don't take what I say for gospel. Do your own homework when it really matters. Here is another datapoint from NAPA just to make sure I'm not fibbing.
http://knowhow.napaonline.com/common-automotive-fasteners-guide/
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