Torque value between Aluminum and steel

R Q

R Q

Well-Known Member
Joined
Apr 4, 2005
Location
Charlotte
I have a part that I'm mounting and for the steel equivalent the torque value is 30-35 ft-lbs. I made an aluminum part to replace the steel one so is there a torque value equation that would give me the difference between two two metals? The aluminum is threaded with 3/8" course threads.
I don't want to strip the aluminum part.
 
What percent thread depth do you have? How much thread engagement? Torque values I've seen are typically based on the fastener size and material. According to a calculator I found, based on you having a grade 5 bolt, 6061 t-6 aluminum with around 1/2" thread engagement, they recommend 25 ft-lbs with a max of 35. Depending on what it is, you might need the extra clamping force of keeping it around 30. Honestly, if your threads are cut well, it should take a good bit to strip that out. I've tightened the crap out of some 3/8-16 bolts in aluminum building jigs and whatnot. It's pretty tough.

Here's the calculator I used. Handy tool for prototyping! http://www.futek.com/boltcalc.aspx
 
Thanks. I failed to mention that the part was 1/2" thick. I ended up putting some lock tire on and tightening it up good and snug. It made it 500 miles to Daytona yesterday so I guess it worked
 
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