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F Body tunnel mount hardware size?

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Old 08-12-2017, 02:03 PM
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Default F Body tunnel mount hardware size?

Hey guys,

Just curious if anyone knows the bolt size and thread pitch for the 4 bolts that you'd attach a tunnel mounted torque arm crossmember or drive shaft safety loop to? I removed the stock cross member to make clearance for my true duals and now have no clue where that hardware went. Figured someone may know off the top of their head and be able to tell me before I dump out my bucket of random bolts and start trying them, and then proceed to throw them around the garage until I can find one that fits. Thanks in advance.
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Old 08-12-2017, 02:49 PM
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I may be wrong but I'm thinking they are 14mmX1.5mm
Definitely metric tough.
Good luck, I had a hell of a time getting my Tq arm to clear the exhaust and to line up with the holes. Had to use some strong persuasion skills both verbally and physically lol.
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Old 08-12-2017, 03:01 PM
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Ok great! Thanks a lot... Yea I am going to be installing my new s60 tomorrow and/or Monday, for now I am going to TRY to keep my QA1 trans mounted torque arm as is and install the Midwest Chassis tunnel mounted driveshaft safety loop that I got, and hope to god it all clears my TSP exhaust and that the QA1 arm fits the s60 without a ton of modification... If it doesn't, well then I guess Midwest Chassis tunnel mount torque arm with the true dual crossmember gets ordered and I sell the safety loop since that crossmember has one built in. Thanks again for the help.
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Old 08-12-2017, 08:44 PM
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If you referring to the original sheet metal brace that goes across the tunnel and bolts to a pad on each side,the bolts are 8mm by about an inch long.
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Old 08-13-2017, 01:33 AM
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Originally Posted by FirstYrLS1Z View Post
If you referring to the original sheet metal brace that goes across the tunnel and bolts to a pad on each side,the bolts are 8mm by about an inch long.
thats exactly what I am talking about. Thanks for both replies.
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Old 08-14-2017, 10:20 AM
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yep, 8mmx1.25 20mm
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Old 08-14-2017, 09:30 PM
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Originally Posted by BMR Sales2 View Post
yep, 8mmx1.25 20mm
I thought I saw 8mmx1.25 30mm mentioned here:

https://ls1tech.com/forums/suspensio...bolt-size.html
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Old 08-15-2017, 10:14 AM
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30mm is what we include with our aftermarket arms due to the added thickness of the bracket. The stock bolt I believe is 20mm or close to it. If you go with too long of a bolt, it will bottom out against the floor pan and not tighten down correctly. 20mm should be plenty of length for full thread engagement through the brace and not bottoming out into the floor
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Old 08-15-2017, 10:23 AM
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^^^ length isn't critical,a 20-25 long will do. I've got SLP subframe connectors and driveshaft loop tied into those points also so I used longer bolts. Also used SS bolts as things tend to corrode here in the rustbelt.
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Old 08-15-2017, 11:34 AM
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Originally Posted by FirstYrLS1Z View Post
^^^ length isn't critical,a 20-25 long will do. I've got SLP subframe connectors and driveshaft loop tied into those points also so I used longer bolts. Also used SS bolts as things tend to corrode here in the rustbelt.
25mm it is! Thanks
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Old 08-18-2017, 02:59 PM
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20mm worked perfectly for my application for anyone interested. Thanks for all the help and replies guys
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