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Inner Fulcrum Torque

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62Migit

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Could anyone please recommend a torque for the nut on the inner A-arm fulcrum pin/bolt? I dialed the torque wrench to 40ftlbs (same as the trunnion or upper fulcrum) and I stripped the threads right out. The manuals I have (Haynes and the restoration manual) do not include this torque, so I simply guessed the torque for these bushings would be similar as the upper link. My bad. I bet the nylock type nuts are much weaker than the standard.

While I'm at it, is there a helpful online list of torques that might include the ones my manuals missed? It's frustrating to guess wrong. /bcforum/images/%%GRAEMLIN_URL%%/frown.gif

Thanks,

Mark
 
62Migit said:
While I'm at it, is there a helpful online list of torques that might include the ones my manuals missed? It's frustrating to guess wrong. /bcforum/images/%%GRAEMLIN_URL%%/frown.gif
Click to expand...

https://www.spridget-tech.com should have it in there, good luck.
 
Torque is baised upon the size of the bolt. There is a list in the front of the Haynes manual for example.
 
Baz said:
www.spridget-tech.com should have it in there
Click to expand...

I can't see it there, IIRC the top trunnion bolts are quite a bit bigger than the inner fulcrums - I think top trunnions are about 3/8", but the inners are 3/8" stepped down to 1/4" nuts, so the torque will be much less. (Only rough figures as it's all from memory)

I have to say that apart from big ends & mains and head bolts I subscribe to the Roger Menadue theory that with experience you know how to tighten things up correctly - if you use the correct size spanner, you will only be able to get them to roughly the right torque (that's why spanners get longer as the a/f gets bigger ;-).
Torque wrenches and socket sets have their uses, but they do tempt you to overtighten things.

Roger was braver/more skilled than me as he did head bolts that way as well!

Anyway, to answer your question,I would do them up as tight as you can with a spanner, but so that you could still just talk while doing it (ie jaw is not locked shut as you try to squeeze the max tightness). Maybe that's why it's called a torque (talk) wrench /bcforum/images/%%GRAEMLIN_URL%%/grin.gif
 
john_j said:
Maybe that's why it's called a torque (talk) wrench /bcforum/images/%%GRAEMLIN_URL%%/grin.gif
Click to expand...

/bcforum/images/%%GRAEMLIN_URL%%/lol.gif "You torque too much, you worry me to death" /bcforum/images/%%GRAEMLIN_URL%%/devilgrin.gif
 
jlaird said:
Torque is baised upon the size of the bolt. There is a list in the front of the Haynes manual for example.
Click to expand...

I would normally rely on this table, but suspensions tend to have some wacky materials and higher torques (grade 8 instead of 5) so I thought it was best to match something of known value. The trunnion and inner fulcrum have very unique bolts, but the threads are exactly the same size and pitch. That's why I applied 40ftlbs to each. All I can figure is that the castlelated nut on the trunnion might be hardened, and the nylock nut on the inner fulcrum is standard grade 5. I suppose torque is even less imporant since that little nylon sleeve will prevent it from backing out.

At least the car is painted and I've finally entered "assembly mode." /bcforum/images/%%GRAEMLIN_URL%%/smile.gif

Mark
 
Material quality and nut thickness will determine the torque and when the nut will strip. 40 lbs sounds like too much for a standard nylock nut, I would think no more than 30. Check the specs for a standard bolt that size. Then go out and buy a new one. I would be confident in saying that the trunion nut is hardened.
 
I think those are 3/8" fine thread nuts. If it is grade 5 the recommended torque is 26 ft-lbs, if it is grade 8 it would be 37 ft-lbs. Since I don't know what the fulcrum pin is I use grade 8 nylock nuts and torque to 30 ft-lbs. A generic torque table can be seen here.
 
Chris, you are right, the inner fulcrum pins are 3/8"-24 (fine). Assuming that the provided nyloc nuts are grade 5, I torqued them to 26ft-lbs and it worked splendidly. With these unique fasteners that aren't marked for grade, it seems like a bit of a guessing game. Time to tape that table to the garage wall.

Thanks for the help!

Mark
 
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