Hello,

As the title suggests, are the bolts connecting the front strut assembly to the steering knuckle TTY (Torque To Yield)? I noticed that the nuts are a unique design, and are difficult to reinstall on the bolt by hand. After a little searching, it appears that the nut is crimped after initial installation from the factory. I'm assuming this is done to prevent the nut from backing off and causing a catastrophic failure resulting in loss of steering.

Also, I know on later GM cars (5th Generation GTO, C5 Corvette, and Pontiac G8), the strut to steering knuckle are TTY. I have combed over my 1988 Firebird GM Service Manual, but there is no mention of TTY bolts, but the torque spec is listed as 203 Lb. Ft. (275 N.m).

Does anyone have a Haynes manual or other GM Service Manual that states something different?

 

The nuts are locking nuts. It's cheaper to deform the nuts than make them with a locking insert.

 

TTY bolts had not been introduced by GM when these cars were built.

So no, they are not that.

The crimp appearance on the nut is the locking feature Drew speaks of. Lots of automotive lock nuts are made that way. In addition to what Drew mentioned, that locking system also doesn't melt, the way nylon does.

 

The early 3rd Gens used regular bolts. Sometime by '92 GM did use TTY bolts. I found out the hard way by not reading the FSM first (yea, they stretched/broke on torquing them to 203 ft/lbs).

I have no idea which year was the first for the TTY strut to spindle bolts (125 ft/lb, + 120° turn).

RBob.

 

Yeah the later service manuals give a hokey torque spec + additional degree turn. But does that conclusively indicate that the bolts are TTY? The book doesn't specifically say they're TTY. It doesn't say anything about replacing the bolts. Everything other than the torque spec is the same as the earlier manuals. Did the bolts really change or did GM/Helm just change the procedure for reaching final torque for greater accuracy or standard practices in GM service departments?

I suppose I could look up the bolts in the parts catalog and see if they changed... But then it's 2020, if there was really some off the wall torque procedure required to not damage the bolts, and safely retain the struts, would all the backwoods backyard hillbilly mechanics have known about it? Is there a rash of horror stories about mistorqued struts causing Joe ******* Wrenchturner to fly off some lonely overpass into a fireball of twisted metal?

What I'm getting at is that the data (as far as I'm willing to dig into it, because who cares?) is inconclusive, and people have been changing struts on thirdgens with blatant disregard for whether the bolts are TTY for decades, you'd think if it mattered we'd know about it by now.

 

From the '92 FSM, note entry #4. I can also post a picture of the stretched/broken bolts when I over torqued the factory OEM units.



RBob.

 

I don't see anything in the book that says the bolts are TTY. I see a procedure to torque the bolts to an angle, but is that really the same thing? I don't know, and don't care. Clearly it doesn't really matter since I'm sure hundreds or thousands of thirdgen struts have been changed without looking in ANY book, and struts aren't falling off thirdgens left and right. I'm not going to waste the time to get into it and search for an answer for the same reason people dont open manuals to replace a pair of struts.

 

Did you miss the part where it states "New strut-to-knuckle bolts, washers, and nuts?"

Also, the GM Firebird parts manual has the same bolts, washers, & nuts from '82 through '90. They then changed part numbers in '91, and same parts where also used in '92. The bottom line is, in '91 and '92 they are TTY.

There are quite a few things about these cars that are somewhat unknown.

RBob.

 

Yep, I missed that line because I wasn't paying close enough attention when I looked in the book before posting. I guess I better fire up the tyme muschine and go back to the year 2000 when new bolts, washers, and nuts were still available. Either that or never disassemble the struts since the bolts are one time use, and new bolts don't exist... Better to drive on worn out dampers than to cheat the torque spec on them thar fancy bolts.

The used bolts, torqued as close as possible to spec are going to be better than generic Chinese origin garbage from the local hardware store. It's not as though there's a lot of alternatives to reusing the old hardware.
See what I mean about how it doesn't matter?

 

Doing your work for you... it does matter and there are alternatives:

https://www.spohn.net/shop/1982-1992...dware-Kit.html

But the bottom line still is, yes, the '91 - '92 strut to knuckle bolts are TTY. And as such shouldn't be reused. Instead of being a fool and driving around on worn out struts, just get new bolts and throw away the TTY bolts that are also worn out. Jeez, why are you being so difficult?

RBob.

 

Oh yes, I'm sure every shadetree that replaces struts on a 91-92 thirdgen is going to go buy new bolts from Spohn.

Maybe you should ask yourself the same question.

You get that used bolts are still bolts, yes? Just because they've been torqued once doesn't suddenly transmogrify them into fresh dogshit. Assuming they were originally stretched short of the point they were damaged, and they weren't damaged by exposure to the elements, or by removal, they're still serviceable. We're talking about strut to spindle bolts, not cylinder head bolts, or rod bolts. As long as the bolts don't break, or come drastically loose, it's not the end of the world.

If you think that everyone, the majority, or even a reasonable fraction of people who've changed struts on a late thirdgen have done more than putting the bolts back in and zapping them with an impact, or leaned on them with a cheater bar, you're delusional. Most chain store mechanics aren't even going to bust out the torque wrench for a 1992 anything. They didn't even bother in 1995. Yet here we are without reports of the wheels falling off any 91-92 thirdgen. The evidence strongly suggests your concern is unwarranted.

 

Wow, just can't let go can you? TTY bolts are one time use, period.

Maybe you should bring some technical discussion to this thread instead of your rantings and ravings...

RBob.

 

On the "streets" I have learned that I can reuse the strut bolts for bazillions of cars as long as they have not been overtorqued. Thug life. Lol. I have reused the camaro bolts a bunch.

Replacing the bolts do be VERY careful of cheap quality ("chinese") junk parts. In this day and age, if I was replacing them I would go name brand.

 

Next time someone asks me why I do all my automotive work, I'll give them a link to this thread.

Note that I did answer the OP question...

RBob.

 

Why is it so hard for you to accept that people re-use the bolts all the time, without a problem? You would probably clutch your pearls with more force than you exerted trying to torque strut bolts 55 ft lbs higher than the requirement, if I told you that another forum I'm on regularly preaches reusing TTY head bolts on a turbocharged engine, at least once per set of bolts.

You don't suppose the reason you had a fastener failure is because you exceeded the required torque spec by 55 ft lbs, rather than a shortcoming of the bolt? Has that thought occurred to you? Because the rest of us have reused the bolts, without trying to torque them tighter than the Incredible Hulk wielding Thor's hammer, and haven't had any problems.




The way I'm reading it, as long as you reach 148+ ft lbs, it is good enough. Anything more is gravy. 203 ft lbs, in your case was clearly too much since the bolt failed. I.e. you failed.

Sorry, I just love a good debate.

 

Thank you all for your replies.

As my car is an '88, the bolts should be NOT be TTY, as they are listed with a single torque spec, not a torque spec and degree.

Also, for the torque spec, please reference the screenshot of the 1988 Firebird Service Manual.

 

Why in the world would they use a torque to yield bolt at a service point?

I might be able to find a new, high quality bolt if somebody can give me the specs.

 

You are correct about the '88 MY bolts not being TTY. As the FSM states torque them to 203 ft/lb. I would also put some Locktite on the threads. Blue at the least, red would be better. Then follow the FSM for torque specs.

RBob.

P.S. hey, just giving the facts...

 

Well,

I did a little more digging though the Service Manual (it's over 1,800 pages), and I found this chart under General Information



Yes, Prevailing Torque Nuts can be reused if not damaged or corroded! This is great news, as mine are cleaning up very nicely.

Thank you all for your help!

 

Funny how a thread can go around the block for three days, only to come back around and reach the same conclusion as the first reply given in under 10 minutes.

 

No.

Compare the two. It's unlikely the material changed, and IIRC, the thread size is the same.

Let's go over a few misnomers:
The service description advising to replace fasteners can be due to a number of reasons. "Use new fasteners" does not assure a fastener is true torque to yield. They may design a pre-applied thread sealant or deformation material to the threads (see above chart) or another feature that has nothing to do with torque value. Brand new deformed style locking nuts are a known quality. They can assure they will work a certain way at a certain torque. Used nuts run on and off of threads lose some of their locking capability.

The service description advising to torque to XXlb-ft plus YYY degrees is a way to assure a measurable distance of load, or pre-load of the fastener-set, or part assembly.
It is NOT an assurance of any sort a fastener is true Torque To Yield. You know a given thread and specific degree turn will move the fastener a specific distance. This method has the capability of a more consistent application of fastener load.

What makes a true torque-to-yield fastener?
Look at the shank and the threads. If the smooth shank is greater than the minor diameter of the threads, it's not a true torque-to-yield one-time use fastener. Period. That stops the mis-identification at the pass. Shank equal or smaller than thread minor diameter doesn't guarantee a fastener is of a material quality or otherwise qualified to be true TTY though.

A true torque-to-yield fastener uses a stretch of the non-threaded shank to apply a load greater than would normally be accomplished by that size fastener. In other words, a smaller, fastener torqued to a higher amount, can perform the job of a thicker, "stronger" fastener, by stretching it more than a non-TTY fastener would be. This design uses the material to a yield, or stretch point that prevents a reliable re-use of the fastener.

When it comes to thick shank non-TTY fastenever, there are TONS of rod and cylinder head bolts that are perfectly fine for re-use. Are you going to mic. each cylinder head bolt and rod bolt or just buy new ones, when a failure due to one of those would cost you a lot more than the replacement cost? Right, you're going to buy new.

Everything comes back to reasonable economy of time, and education of inspection. As we all know, rod and head bolts make sense to go new. Anything else needs an educated review, cleaning, chasing of the threads (not by a cutting die) and re-use. Let's be honest, we don't even inspect most bolts.

They didn't. So let's stop spreading misinformation.

 

To throw a wrench in this discussion, I read a post about a guy that works at one of those testing facilities tested used TTY head bolts against new ones and the conclusion was that it really didn't matter if they were used or not, they were still good enough used for the application as long as they weren't over torqued. Pretty much blew my mind

 

I spent about an hour reading about TTY fasteners over the weekend. I found multiple sources that said some TTY fasteners could be reused as many as five times in some applications. Even Fel-pro says that TTY head bolts can be reused, but that technicians should replace them with new since they have no way of knowing if they've already been reused. As I already mentioned, it's not like we have a lot of choice. Regardless if the bolts are TTY in 91-92, it's not as though there are a lot of places we can get new replacement bolts that are going to be as good as what came on the car originally. Obviously people have been reusing the bolts since 1991 and the only problem I've ever heard of is from one person.

So in conclusion....

1) OP's bolts aren't TTY, his car isn't a 91+. Wouldn't it be nice if a moderator didn't steer a thread into the weeds for some completely useless trivia that isn't relevant to the thread?
2) Even if they were TTY, it wouldn't matter for 99% of the people to whom the exception to the rule, would apply.
3) They're most likely not TTY at all, and if they were, it probably would still be fine to reuse the bolts using common sense.
4) It doesn't matter.

Who are you going to listen to? The folks who have reused the bolts with no problems, or the one guy that exceeded the required torque and broke a bolt...

 

Just a short note to thank you guys for this discussion. You may have gotten PO'd at each other -- but I learned something. In 25 years and 150k miles of ownership, I have replaced the struts on my 89 IROC-Z either twice or three times (can't remember) and never did anything to the bolts besides wire brushing them a bit.

 

And that's probably all they ever needed.

Just don't go too far... After all, rust is Mother Nature's natural thread locker.

 

I wonder if only TTY bolts have an extra turn spec? Non-TTY bolts just have a torque. TTY bolts, torque, plus a 1/4 turn, etc. That is based on thread pitch and a specific stretch of the bolt.

 

Believe it or not, I also own a couple of Studebakers. Studebakers provide a graduate-level course in rust.

 

There is Torque To Yield, and Torque To Angle. If you really want to know more, jump over to Google and start reading. Just keep in mind a lot of people are confused, so stick to sources that you can trust.

 

I read both service procedures and can clear up the confusion for you guys. This is one of those rare moments when my engineering knowledge actually helps.

275 Nm is considered "high torque" for a Class 10.9, M16 thread. It's about +15% above standard torque and is used for things like critical joints in structural members (like a strut mount). You're basically trying to get things as tight as possible without yielding the bolt. The torque is met by friction, so the actual clamping load could end up too low or too high depending on condition of threads, whether lubricant is applied, or maybe you're using up some of the torque just to squeeze the parts together (bad fitting struts).

The torque spec in the '91-'92 manual reads like a "Torque-Turn" tightening spec (not a "Torque to Yield" tightening spec). The Torque-Turn spec is used when more precision is desired because it reduces the effects of friction. The initial torque brings all the parts in contact (take up all the slop). Then the turns method achieves the desired clamping load. The number of turns are usually in 30° increments because it's easier to eyeball against the corners of a hex head bolt. And they're giving you a minimum torque of 200 Nm just in case the 120° turns doesn't achieve enough clamping load. It's a double check to cover your ***.

Basically, the later '91-'92 tightening spec is a process improvement, especially when reusing old bolts where the friction is not like new, and struts that don't mate up real well with the spindle.

 

And for people with ADD,

--> It​​​ is not torque to yield.

 

Thanks for taking the time to provide a detailed, easy to understand explanation. I learned something new today!