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Does any one know the maximum torgue on a 8mmx1.0 grade 5 cap screw. Will this screw handle 25 lb ft.
Thanks Gary
gl krukoski

I think you're in the wrong place
Will Munns

This cap screw is a alternate for the gudgeon pin clamp bolt on a TD engine. I need to know if a grade 5 is strong enough at this location.
gl krukoski

Again, wrong place unless you have a k-series engine, all our bolts are metric, grade 5 means not very much to us (11ish in metric? - I know 3 is 8.8)
Will Munns


Gary, your best bet is to type something like 'torque "grade 5" 8mm' into Google and then follow the most promising of the couple of hundred hits. Unfortunately I don't have the time to look myself.

Good luck, Kes.

Kes, MGFs and mgtfs are different cars to MG TF and TD which were made in the 50's. MGFs and MGTFs are cars made in the 90's and 00's. Try the other BBS on T-series TD-TF. Good luck
d mottram


It's a standard engineering question which isn't specific to any vehicle.

I have found this website - = which indicates that SAE Grade 5 is 120,000 psi Med. Carbon Heat T. Steel. Comparing this to the metric and other tables the nearest spec gives a max torque of around 20 ft/lbs.

So I would say that the 8mm x 1.0 grade 5 cap screw won't handle 25 lb ft safely, especially in a gudgeon pin clamp bolt.

I'm no engineer, just a Google-looker.

Regards, Kes.

This thread was discussed between 09/02/2005 and 10/02/2005

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