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Anyone know torque value for lock nuts on front upper balljoint?


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Not the nut that holds the upright to the balljoint, but the locknut that holds the upper balljoint to the upper control arm. I had one go loose on me and hopefully I didn't damage the threads too bad. I can't find the prescribed torque value anywhere.

 

Thanks

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I just looked in my assy guide and didn't see a torque posted.  That nut is just a locknut to hold the upper ball joint in orientation with the upper control arm so I would think 'good and tight' should work.  Similar to the outer tie rod locknut on the steering rack.  If you did have a torque value you'd have to use a crows foot wrench and calculate the torque for the center to center distance of the wrench or turn it 90 degrees.  

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I think he's looking for the the torque for the locknut circled here.  I've never seen that torque figure listed.

 

Knifey - Can you check the surface of the UCA where the lock nut hits and make sure there's not an uneven surface that would prevent there from being full contact for the full circumference?  Something like excess weld, etc.  That could cause an issue with it loosening.  Also check that the ball joint moves freely.

 

UCA.png

Edited by 11Budlite
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58 minutes ago, 11Budlite said:

I think he's looking for the the torque for the locknut circled here.  I've never seen that torque figure listed..

 

 

Correct. I'll take a closer look and see if there is any irregularity there. After thinking about this, I realize that after assembly, I had the car aligned, and the nut came loose on a trackday after that (I think the 2nd trackday after alignment). So it's likely that they undertorqued it, not me. Still, it'd be nice to have a target tightness. 

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Just a thought on loose fasteners--- locknuts come as various types and some are prone to degrade in locking ability with reuse. I expect manufacturers have engineers that understand which types to use. However, if any critical ones seem to come loose, then you want to consider extra measures. Of course correct torque is essential since bolt stretch is supposed to preload the assembly and that should be designed in. On critical items where failure would be a disaster, additional measures like safety wire ( properly done) or correct use of Loctite may be appropriate. If Loctite is to be used on parts that may need to be taken apart later it is important to know which grade to use.

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This is a good general article on locking fasteners: https://grassrootsmotorsports.com/articles/how-right-fastener-can-prevent-hardware-failure-tr/

 

At my work in the jet engine business, there's been a big shift in usage from safety wire to safety cable.  It's a lot easier to install and real easy to inspect for acceptability.  It can't be used in every application, there's still some applications where safety wire is the only option. 

Edited by 11Budlite
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 Great article-----The book mentioned in the article should be considered a "must read" for anyone building from scratch or substituting hardware that is not purchased to meet the exact spec. of the original ( I like to use better than original if a failure was encountered or is anticipated).  7s tend to be driven less conservatively than most cars, thereby heavily loading fasteners and vibrating, so should be treated to racing/aircraft grade hardware and assembly techniques for safety and reliability.

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The drawing above shows the nut but cuts of the torque spec. Nylon lock nuts are a one time use unless you get the aircraft ones. My ball joints are double nutted. If you know the size of the nut you can look up the torque spec on a general torque chart. Trying to get a torque wrench on the nuts, especially the upper one will be a trick.

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