67 Fury leaf spring front hanger bracket nuts torque

[edbods]

On the 67 Fury, the front hanger bracket for the leaf springs - are the nuts meant to be torqued to 30 ft-lb? The FSM is a bit confusing on that. I tried to torque it up to 30 and snapped a stud...
I just got a similar nut and bolt as a substitute but I got paranoid of snapping all four so I just tightened them up by feel with a 1/2" ratchet.

 

[volksworld]

if they're 3/8 bolts 30 is about right...if they're 5/16 more like 15...subject to how rusty they are

 

[edbods]

Yeah they're 3/8 studs. I see repro sets for sale but at the moment I don't feel like paying 200 bucks for a set. Honestly 30 seems waaaay too high, and they weren't even that rusty either. I tried torquing up the others but it felt like the studs were stretching, usually you can feel when you're gonna reach the specified torque for a fastener but my torque wrench just kept going...it really felt like it was gonna snap. And the threads were definitely not greased or anything like that either.
I got a replacement 3/8 grade 8 bolt but it had UNF instead of UNC threads, I tried torquing that up to 30 and while I never actually reached it, I felt a lot more confident pushing it to that at least.

 

[Gerald Morris]

Yeah they're 3/8 studs. I see repro sets for sale but at the moment I don't feel like paying 200 bucks for a set. Honestly 30 seems waaaay too high, and they weren't even that rusty either. I tried torquing up the others but it felt like the studs were stretching, usually you can feel when you're gonna reach the specified torque for a fastener but my torque wrench just kept going...it really felt like it was gonna snap. And the threads were definitely not greased or anything like that either.
I got a replacement 3/8 grade 8 bolt but it had UNF instead of UNC threads, I tried torquing that up to 30 and while I never actually reached it, I felt a lot more confident pushing it to that at least.

Can you get your hands on a second torque wrench, as a sanity check? Sometimes old torque wrenches won't "click" at a relatively low torque setting. when in doubt, I use one with a simple bar and indicator needle, which is less prone to err with age or wear. 30 ft*# isn't huge torque for good steel, but keep "good" in mind....

 

[edbods]

I would if it were an old clicky one, but this is one of the fancier deflecting beam wrenches:

It's a different take on the older beam wrenches - these have the very useful feature of being able to hear and feel the click.
Accuracy is rated to ±2% whereas the cheaper clickers were ±4%. Very common to see rusty, beat up, 20-30 year old ones still well within spec. This one I've had for five years but it hasn't seen the use and abuse that a professional workshop would subject it to, so I'm still very confident in its accuracy.
30 ft lb is indeed not that large, but given the size of these studs I thought it was rather high for them. A quick google search shows that the recommended torque is 38 lb-ft for 3/8" UNC, and 43 ft-lb for 3/8" UNF. Might explain why the UNF bolt I got felt stronger when torquing it up.
I suspect that the reason the stud snapped was that the nut's washer got caught up or binded somehow and then way too much force got applied.

 

[Big_John]

I would if it were an old clicky one, but this is one of the fancier deflecting beam wrenches:
View attachment 745225
It's a different take on the older beam wrenches - these have the very useful feature of being able to hear and feel the click.
Accuracy is rated to ±2% whereas the cheaper clickers were ±4%. Very common to see rusty, beat up, 20-30 year old ones still well within spec. This one I've had for five years but it hasn't seen the use and abuse that a professional workshop would subject it to, so I'm still very confident in its accuracy.
30 ft lb is indeed not that large, but given the size of these studs I thought it was rather high for them. A quick google search shows that the recommended torque is 38 lb-ft for 3/8" UNC, and 43 ft-lb for 3/8" UNF. Might explain why the UNF bolt I got felt stronger when torquing it up.
I suspect that the reason the stud snapped was that the nut's washer got caught up or binded somehow and then way too much force got applied.

Wow... I've never seen a torque wrench like that. We calibrated hundreds of torque wrenches every year in our calibration lab too. I retired 10 years ago, so this may be too new... or it may be something we don't see in the USA.

But, yes, generally speaking, a beam type wrench is accurate and will stay accurate. You still don't want to use it as a breaker bar, but they are the best bang for the buck. One thing about torque wrenches are they are usually accurate in their upper 80% of the scale, but I didn't see that noted when I looked up this wrench (because I had to know!)

IMHO, what happened to you had nothing to do with torquing the nut in place. The stud was probably over tightened before or damaged when removing. Since these cars are 50-60 years old, lot's can happen with other guys working on them over the years. Including it was never right to begin with. I once had a used head bolt start to twist off..... and I wasn't done torquing it!.

 

[Gerald Morris]

I would if it were an old clicky one, but this is one of the fancier deflecting beam wrenches:

It's a different take on the older beam wrenches - these have the very useful feature of being able to hear and feel the click.
Accuracy is rated to ±2% whereas the cheaper clickers were ±4%. Very common to see rusty, beat up, 20-30 year old ones still well within spec. This one I've had for five years but it hasn't seen the use and abuse that a professional workshop would subject it to, so I'm still very confident in its accuracy.
30 ft lb is indeed not that large, but given the size of these studs I thought it was rather high for them. A quick google search shows that the recommended torque is 38 lb-ft for 3/8" UNC, and 43 ft-lb for 3/8" UNF. Might explain why the UNF bolt I got felt stronger when torquing it up.
I suspect that the reason the stud snapped was that the nut's washer got caught up or binded somehow and then way too much force got applied.

Looks like you're WELL tooled bro! Carry on and have a Fosters for breakfast.

 

[edbods]

Wow... I've never seen a torque wrench like that

...so this may be too new

I think these have been around for a while; I bought my first deflecting beam on Gumtree second-hand and it looked like it was made in the 80s or so. Sold it and got this one because I got sick of the non-ratcheting head. You guys also have them but they don't seem to be as popular, Powerbuilt sells a model that looks identical to what I have: 1/2 in. Dr. Deflecting Beam Torque Wrench
I think this one has a ratcheting head judging by the pics. It doesn't actually say though. Seems to be on sale right now as well - 95 bucks instead of 180, if you want to get one now might be the time especially since it says it's got 2% accuracy.
One disadvantage about these types of torque wrenches is that they only torque in one direction, if you've got a left-hand threaded fastener you'll need to use the regular beam wrench.
Didn't think about it being overtorqued prior to me getting my mitts on it. I wasn't anywhere near the torque spec when it snapped, was very surprising.

Fosters

haaa i don't think anybody drinks that here