View Full Version : Another torque question
wareaglescott
11-20-2017, 03:47 PM
OK so say I want to go back and check the torques on my bolts.
Rear CV axle nut calls for 98 lb-ft and then 45 degrees.
How would you check this after the fact?
Obviously cant put a torque wrench on it to check because I don't know what the initial resulting torque equaled after I did the additional 45 degrees. What do you do in this situation?
Thanks
Gromit
11-20-2017, 03:51 PM
Mark it with a paint stripe at installation and visual inspect for moment.
Just my $.02 for those torque and turn bolts.
Chris AKA Gromit.
scottiec
11-20-2017, 04:29 PM
Does the axle nut get staked?
wareaglescott
11-20-2017, 04:30 PM
Mark it with a paint stripe at installation and visual inspect for moment.
Just my $.02 for those torque and turn bolts.
Chris AKA Gromit.
Yes that is great had I done it at installation. Wish I would have. Another rookie mistake where I didn't know what I didn't know at the time. 3300 miles later what do I do?
BEAR-AvHistory
11-20-2017, 05:08 PM
What he said market them with a paint stripe.
You might be able to reach some of the bolts in question so on those set your click release wrench to the proper torque & see if they release/clicks. If so you most likely did the right thing to start.
The bottom line is are the saying in & the stripe will tell any future slippage from this point forward The only other thing you can do is back them all out & start over, not something I would do.
Here's what you want to use:https://www.mcmaster.com/#tamper-evident-paint/=1acc45i It comes in different colors. There are other products out there, some with higher heat range and some that are oil resistant and even some that are legal for use in the regulation choked state on the dark side of the Colorado River across from AZ.
We used to call this stuff torque stripe. It shows any movement or loosening of fasteners as it drys brittle and easily cracks. A quick visual inspection will show if the fastener is loose. No crack = good to go.
Gromit
11-20-2017, 10:37 PM
Ok my personal opinion about just the big axle bolts on the IRS. If you did it right the first time I wouldn't be too worried about it. The wheel is held on by the bearing retainer the spline transmits the torque of all of the suspension fasteners this one is probably the least critical
And, I don't think Ford is sneaking into mustang owners garages and re torquing that nut after 3000 miles. Or ever I'd mark it now and only glance at it when I've got the wheels off.
There are a lot of other fasteners to worry about
Chris AKA Gromit
wareaglescott
11-21-2017, 06:17 AM
Ok my personal opinion about just the big axle bolts on the IRS. If you did it right the first time I wouldn't be too worried about it. The wheel is held on by the bearing retainer the spline transmits the torque of all of the suspension fasteners this one is probably the least critical
And, I don't think Ford is sneaking into mustang owners garages and re torquing that nut after 3000 miles. Or ever I'd mark it now and only glance at it when I've got the wheels off.
There are a lot of other fasteners to worry about
Chris AKA Gromit
Ya brings up another interesting point. I have never checked any torques on fasteners on any car I have ever owned and have never had anything fall off. Yet on the Cobra I seem to want to check everything every 1000 miles or so. Not really sure why. I guess I am just guilty of over maintaining.
I also wonder why the big bolts on the front wheels had a torque spec only and the rears had the lower torque plus 45 degrees.
CraigS
11-21-2017, 07:04 AM
The front wheel hubs are from a 1995 design when all we did was plain torqueing. Since then the 'angle torque' procedure is being used more and more. Personally I don't care for it. Unless one has a special tool, and the room to use it, in reality, most angles are measured by eyeballing them. I'd rather rely on a click type wrench. On your axle nuts, you could loosen them completely, and redo the procedure, and apply the paint.
rich grsc
11-21-2017, 08:52 AM
OK so say I want to go back and check the torques on my bolts.
Rear CV axle nut calls for 98 lb-ft and then 45 degrees.
How would you check this after the fact?
Obviously cant put a torque wrench on it to check because I don't know what the initial resulting torque equaled after I did the additional 45 degrees. What do you do in this situation?
Thanks
Where did you get this info, is this on the new IRS? What I have is 250# on the rear axle nut. The first I've seen this spec.
wareaglescott
11-21-2017, 09:05 AM
Where did you get this info, is this on the new IRS? What I have is 250# on the rear axle nut. The first I've seen this spec.
yes page 109 of my build manual has a list of all the IRS torque specifications. The manual I am referencing is revision 4B from December 2015
Jeff Kleiner
11-21-2017, 09:07 AM
....On your axle nuts, you could loosen them completely, and redo the procedure, and apply the paint.
Then again, to muddy the waters further, these may be like the one time use OEM Ford torque to yield rod bolts whare once torqued (and therefore stretched) the torque & angle procedure can not be repeated with consistent results.
Jeff
wareaglescott
11-21-2017, 09:16 AM
Then again, to muddy the waters further, these may be like the one time use OEM Ford torque to yield rod bolts whare once torqued (and therefore stretched) the torque & angle procedure can not be repeated with consistent results.
Jeff
That was a concern of mine. I don't think I what to attempt to loosen them.
I may just stick my torque wrench on it and adjust it upward and see where it stops clicking. IF I am in the range of what the front suggest and RICH GRSC suggested for the rears I will mark it and consider myself good. I really don't think it is an issue anyways. Just me looking for things to worry about I think!
Another thought on a topic we are already beating to death. I remember when I torqued down my fronts I had to wait until the wheels were on the car and it was sitting on the ground to be able to generate the torque without the suspension moving around on me. In my attempt to prevent the knock offs from having issues I did the set screw from the side trick but also siliconed them in place. In order to have access to the front nut and put that kind of torque on it I guess I will have to take the siliconed center piece of the knock offs out!
Why the heck was I not smart enough to mark these properly the first time!!! doh
Jeff Kleiner
11-21-2017, 09:39 AM
...Why the heck was I not smart enough to mark these properly the first time!!! doh
Well, even if you had marked 'em you wouldn't be able to see the marks with the wheels on ;)
Jeff
TexasAviator
11-21-2017, 10:05 AM
If you have some time and you WANT to do it you can reuse TTY bolts. When you pull them, measure them. If they are new they can be reused at least 2 more times. SAE repair manuals that I have state that they are good for 3 uses. You wont be stretching them out of yield if you are using the specs that they were in. If you have the time, you could remove and set them up for your piece of mind.
I built a 500hp 2.0 turbo motor with a ton of TTY bolts and reused on a teardown. That little engine is still racing in Florida on 28lbs of boost.
edwardb
11-21-2017, 10:59 AM
Personally I would not loosen a previously torqued bolt for diagnostic purposes only. Especially the TTY variety. For disassembly, repair, whatever, OK. But not just to see if they're still tight. Mark as suggested. I inspect all the suspension bolts as part of annual maintenance. If in doubt, might put a wrench on one. But I'm not taking stuff apart and then re-torquing. Not necessary IMO. I just finished doing the winterization (:() and inspection of #8674. I did put a big breaker bar on the IRS axle nuts. They were still tight with no signs of movement. Those nuts were notorious for loosening on the older style IRS. At least so far, looks like the newer 2015+ style is OK.
I'm with edwardb -- no need to loosen a fastener to ensure it's tight. Use torque stripe and visually check it.
Also, I used to be an engineer working in an environment where fasteners were critical components and failure could have catastrophic results including injury or death. I've learned over many years NOT to reuse critical fasteners that have been torqued. The first couple threads take most of the load and tend to deform (yield -- plastic phase) and never return to their original form. Yes I know, you will find even auto manufactures claiming you can reuse TTY fasteners x-number of times. But I've seen enough failures to support my tactic of replacing any critical fastener that has been torqued. Another thing many folks do when welding (and I used to as well when I was a pipe fitter) is run a ground lead so that the current runs through a bolted assembly. Again, seen way too many failures attributed to this practice. Replacing fasteners is cheap insurance.
Avalanche325
11-21-2017, 04:21 PM
I agree, just set your torque wrench and make sure that they are not loose. Don't loosen them.
No time to chat....
I am going to the garage to short my electrical system out to do a fuse test.:p
CraigS
11-22-2017, 08:15 AM
I thought about the TTY stuff as it applies to things like head or rod bolts. But in this case, if it were TTY, you would be stretching the stub axle. I don't think that is happening. I had never seen the 98# + 45deg spec so my 2015 IRS axle nuts my sn95 front axle nuts are both at 200#. I marked the rears and after about 11 months and 20 autocrosses on hoosiers they haven't moved. This was a huge problem on the old t-bird IRS but Ford has apparently solved it on the 2015 version.
Almost everything you wanted to know about fasteners but didn't know where to find it -- just follow the link (or Google it): Fastenal Technical Reference Guide (https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwiGrKeqp9LXAhVJ_mMKHU_KD08QFggrMAA&url=https%3A%2F%2Fwww.fastenal.com%2Fcontent%2Fdoc uments%2FFastenalTechnicalReferenceGuide.pdf&usg=AOvVaw3N3lr2a9mNnQfdb0zU_-9w)
For most this will be a dry read but if you plan to reuse fasteners start at the bottom of page 27 "Reuse of Fasteners" and pay close attention to what testing has shown about re-torqueing fasteners and the reduction of clamp load. This will help explain why reusing fasteners can lead to failure. You're simply not achieving the same clamp load when re-torquing to the same spec. As the threads wear and deform it takes greater torque achieve the same stretch.
Other good sources of technical information on fasteners (and safety wire) are any of the military branches of aviation technical manuals on the subject. These are free (your tax dollars paid for them) and a google search should turn up several choices.