Careful Of Incorrect Torque Settings

[65-Fstbk]

So I'm bolting up my upper control arms to the shock towers and I reference my "trusty" Mustang Restoration Handbook for the torque settings. Says 75 - 100 ft/lbs so I first torque both nuts to 70 and then go for 85. First one fine, second one keeps turning as I had a feeling through the wrench that something was amiss. Threads on nut #2 have stripped.

I then go to my laptop and check the Ford Service Manual and it says 55 - 75 ft/lbs in there. The new shafts in the UCA's are from Moog so I'm surprised the threads in the nuts would strip at 85 ft/lbs.

I have decided to use the Service Manual torque settings and am going to clean up and re-use the original nuts from the old shafts.

 

[Rusty67]

The nuts that hold the upper control arm to the shock towers are beefy. I wouldn't think 85 ft/lb would strip them. Maybe the nut was defective ? How do the threads on the shaft look ?

 

[horse sence]

is the nut stripped ,or is the whole bolt turning in the controll arm shaft
they are just pressed in and some times break loose,if it is you can hold it with a wrench while some one tightens the nut. thats only a 1/2 inch bolt 80 lbs sounds
like a lot to me

 

[Rusty67]

Grade 8 1/2" SAE bolt is good for 107 ft/lb.

 

[horseballz]

I would bet those bolts are not Grade 8, likely Grade 5, maybe 7. I would think that this would not be the the best place for a Grade 8, due to the shock that it can endure and the brittleness of the Grade 8.
Gene

 

[Rusty67]

http://redesign3.mu.snapshotdesign.com/itemdy00.asp?T1=CAB2+01

Shows bolts being grade 8.

 

[65-Fstbk]

The bolt wasn't turning in place, it was definately the nut. Really weird. I managed to get it off with a little muscle as it didn't want to come off either. The old nuts look different and have a collar around there base (to be honest the old nuts look stronger than the new ones).
I have attached a couple of pics. The old nut is on the left, new nut on the right. Old bolt torqued to 85 w/o issue. Really weird.

 

[Rusty67]

I notice you are using a flanged lock nut (OEM style) and a regular nut with a split washer. I would use a flange lock nut on both but if you aren't going to use the flanged lock nut you should put a regular washer in there to spread the load more evenly and then put the lock washer in. Also it looks like you dropped the arms. If you can, you should weld the original holes shut for strength.

It looks like the motor is out of the car. If you are going to weld those holes shut, maybe you can lay a bead down on the shock towers for some added strength.

 

[dennis112]

Whenever the front alignment is done, I seriously doubt if the tech will breakout the torque wrench. They'll put a 3/4" or so wrench on them to make em' "gutentight."

 

[65-Fstbk]

I notice you are using a flanged lock nut (OEM style) and a regular nut with a split washer. I would use a flange lock nut on both but if you aren't going to use the flanged lock nut you should put a regular washer in there to spread the load more evenly and then put the lock washer in. Also it looks like you dropped the arms. If you can, you should weld the original holes shut for strength.

It looks like the motor is out of the car. If you are going to weld those holes shut, maybe you can lay a bead down on the shock towers for some added strength.

I'm going to use the OEM style from my old arms on all 4 UCA bolts. I just put that pic up so you can see the diff. The old ones definately feel stronger. I may try to weld the old holes. Does just a plate over each one work?

 

[Rusty67]

A plate for strength is better then nothing. I haven't seen anyone do that but it would be much better then no plate at all. Welding is of course best.

As for reusing the stock nuts, that is fine as long as they haven't been taken on/off too many times. The locking capability of the nut weakens each time it is removed and reinstalled. Some say never to reuse them but this car doesn't fly or float. I don't know to reuse them more then 5 times a piece. If they go on as easily as a standard nut, its time to replace them.

 

[65-Fstbk]

Yup I agree thx.

For the holes I was thinking of just grinding and then welding a small plate over each hole. I suppose I could do the plug thing and then weld/grind and spray to make it disappear.

 

[robbz28]

Sounds like my uncle wrote your trusty restoration book...he wanted to tighten everything 5 to 10 lbs over the manual...until one day he tightened the rod bolts an extra 10 lbs and the oil couldn't get in the bearing and lubricate the journal properly and blew up a motor...

 

[bartl]

I wouldn't worry about the old stock location holes, they'll be fine. If you do want to weld them up, get some 1/2" tap-in galley plugs or equivalent, put them in from the outside and hold with a magnet, butt weld in on both sides, then grind off the lip left on the outside.