Suspension Issue

[SySt]

Alright, I am so close to having my suspension project done. Just FYI, I had both subframes out, took off all arms and put in poly bushings, new ball joints, new steering rack, new steering shaft and new tie rod ends. Everything went well so far, until I decided to torque down the eccentric bolts on the rear subframe. I know the torque spec is 136lb/ft. I set my torque wrench to that number and started torqueing. I ended up stripping the threads on the two bolts I tried to torque. It never reached torque spec. Note, I have yet to torque the front eccentric bolts as my torque wrench does not go high enough but I am afraid the same thing will happen... Of course I ordered new bolts and nuts. I am wondering if anyone else has had this problem. Does the anti-seize I put on the bolts play a role in this? At first I did think my torque wrench was mis-calibrated but then I borrowed one from work which I KNOW is calibrated and the same thing happened.

Please, any advice or comments anyone can give is very much appreciated.

 

[Allan_MA70]

yes anti-seize will require you use a lower torque, AFAIK dont use anti-seize on those bolts.

if you live where they salt the roads i would cover the bolts with some grease after you do them up

 

[SySt]

Why does it require a lower torque? I did put anti-seize on most of my suspension bolts and they all torqued to spec fine. I do live in MN so they do salt roads, though I would never drive my Supra in the snow. But alright, the anti-seize thing was on my mind. Only one question, why does the anti-seize require lower torque? What exactly does it do? Just make it more slippery so that treads collapse easier?

 

[Allan_MA70]

no makes for less friction on the threeds so you require less torque to turn the nut but clamp the items tighter or the threeds fail, id suggest new bolts all round as you may of streached the others to a point near failing

 

[SySt]

Well, I suppose that makes sense. Thing is that I am not going to go replace all the bolts. That would mean a few new control arms and such. Does kinda suck that I do not have much other choice. If it breaks it breaks and I will have to fix it.

 

[Asterix]

Wow. Impressive. I've torqued those bolts down with antisieze and they did great. New bolts surely are in order. You should doublecheck that torque value. The large bolts on the front lower arms may be as high as 136, but the smaller ones in the rear may only be 90. Checking the online TSRM... Well, whadaya know. Rears are 136; fronts are 177!. It's always possible that the previous owner of the car put in substandard bolts. Good thing you're getting new ones.

Torque is a really bad way to specify bolt preload. What you're actually looking for is a specific amount of stretch to the bolt to provide the clamping force. Because the torque to turn the nut depends greatly on the friction between the threads and between the nut and mating surface, the final bolt stretch is very hard to predict based on torque. The torque spec is probably with dry threads, so lubricating them with antiseize will give you the same stretch for less torque. There's lots of info on this out there in places like Carroll Smith's "Nuts, Bolts, and Fasteners" book, or any decent mechanical engineering handbook. The TSRM has a section at the back that describes standard torque specs for the different bolts; read that and make sure your bolts look like those shown there.

Asterix

 

[SySt]

Those bolts were brand new. But yeah, i'll just coat the non-threaded section with anti-seize.

 

[SySt]

Well, I tried to torque another bolt down. This time I wiped off the anti-seize. The bolt stripped once again before it reached torque spec. Granted there could still have been anti-seize residue on the threads. Do you think that would be enough to lubricate it that much?

Who has torqued these bolts before? Have you torqued them to spec? What methods have you guys used?

 

[mkIIIman089]

Are these still new bolts that are stripping? Or is it another used bolt?

 

[Asterix]

That is strange. I've torqued those bolts to that spec at least a couple of times now, even with antiseize. My torque wrench is the simple Craftsman beam-type one. What I probably did on the front lower arm bolts is tighten them to the limit of my wrench, which is about 140ft-lb, then put my breaker bar on and push as hard as I could. They surely ended up over 150ft-lb. I'm sure I did the rears to 136 like the book says.

I'd say those bolts are suspect if they can't take the torque. You could head to a junk yard and practice on some. If they pass your test, take them home and use them.

Asterix

 

[mrnickleye]

OK...After sitting here reading these threads, I have to let you know....(and I'm not being a smart ass, just trying to help get things straight)

Anti-seize is NOT going to change the torque values. Torque is applied to a fastener for ONE simple reason. To keep the parts coming together at a pre-determined load. Think about a head gasket for a moment. You are TOLD to insure clean, "lightly oiled" bolts are thread into a "clean" hole, then torque the bolt to a spec. To hold the head to the block at a certain tension.
ALL fastners (except cheap little screws from the hardware store) with torque values required are manufactured to a spec for the application they're to be used in, with stretch, twist, and tensil strength calculated in.
I know these things because I was an aerospace engineer for several years. (sometimes I wish I would have been a bartender, more time, beer & women)

Now my question is...do the bolts thread into the holes (nuts) by hand??
Are all the threads (Male and female) in good condition?? Are you very sure of the torque wrench??? It would seem that if those torque values are correct, and those are the correct bolts (Toy dealer??) , then your wrench must be off.

 

[IJ.]

Also NOT trying to be a smartarse but ARP list 2 different torque values for different lubricants used with the same studs......

 

[mrnickleye]

Also NOT trying to be a smartarse but ARP list 2 different torque values for different lubricants used with the same studs......

It seems you are correct. Thanks. I like to learn new things, that's what keeps life interesting. Aircraft fastener applications are quite different.

http://www.arp-bolts.com/pages/tech/tech.html

Including this....

http://www.arp-bolts.com/pages/tech/images/fasttorq.pdf

And

2. The lubricant used is the main factor in determining friction, and therefore, the torque for a particular installation. Motor oil is a commonly used lubricant because of it’s ready availability. If less friction is desired in order to install the fasteners with less torque, special low friction lubricants are available. With special lubes, the required torque can be reduced as much as 20 to 30 percent. It is important to keep in mind that the reverse is also true. If the torque value has been specified for a particular fastener on the basis of low friction lube, installing the fastener with motor oil will result in insufficient preload; the torque has to be increased to compensate for the extra friction caused by the motor oil.

 

[IJ.]

MrNick: LOL You're welcome!

I've been building motors going on 30 years now and still manage to learn something new almost every day!

That's what makes a resource like Supra Mania so useful once you filter out all the crap you're left with some real gems!

There are a lot of very bright knowledgable people here and it would be stupid to not take advantage of what they know.

 

[p5150]

What kind of torque wrench are you using (needle-point, break away, digital)? Do you have a universal or "wobbley" attatched to an extension? Are you using a crows foot? Are you setting the torque wrench to foot pounds or newton? Are you holding the back of the wrench or applying all of the torque from the handle? Are you torquing from the bolt or nut side? All of these things can change the torque reading.

In addition, if you are at the extreme upper or lower limits of the torque wrench you are using, it will not read correctly.

one way to test the wrench is to measure its length from the socket attatchment to the handle. Lets say for example that it is one foot long. Now clamp the 1/2 drive socket attatchment in the vise and place a weight on the end appropriate for what it is set for. A 50 pound weight should cause it to break away if the wrench is set at 50 ft/lbs. (you also need to consider the weight of the wrench in this experiment) Torque applied = weight x length

So, in summary, to apply 100 ft/lbs of torque on a 6 inch lever, you would have to use 200 pounds of force, and on a 2 foot lever you would need 50 lbs of force. On a 1 inch lever you would need 1200 lbs of force.

The purpose of anti-seize, primarially, is to prevent the bolts from rusting together. The bolts, when lubricated and torqued, provide a more well-distributed and even clamping force. If the bolts have any type of restriction on the threads, you will have an indicated torque of what you want, but the bolt/nut will not provide the clamping force that you want. Not all bolts are designed to "stretch", although I dont know for sure if these do or dont. Im going to guess that they dont. I always lubricate bolts before I put them in - ESPECIALLY on the chassis where they are exposed to a lot of moisture. The grease/anti seize will help to keep the moisture out.

Truthfully, I dont think that you are applying the correct torque.

 

[mk3forme]

im not familiar with the bolt in question but what does it thread into? A backing nut or just a threaded hole? Either way check the threads of the hole this bolt is going into. I say this because I build Toyota's for a living and I see, all the time, a bolt that will shoot in its intended hole but not tighten up.Just spin out.The threads might not be in tact. Sometimes retapping the hole will do it and sometimes it wont. Just another idea for ya