[camaro5]

Good info that NOBODY is going to know up front.

Some humans work on the "If I can't see it, it isn't there" theory.

I would get a set of these, and keep them handy for any alignment.

TTY!

[cwebster]

Just got back from my 4-wheel alignment. Of course there's a different crew on Saturday and they know nothing about yesterday's discussion & findings. When the car is done I make a remark thanking them for getting the bolts so quickly to do the alignment. Suddenly heads pop up... "Bolts? What bolts? We don't know anything about any bolts." Even after I recounted my entire discussion with the crew from yesterday, emphasizing that the requirement was verified and bolts were ordered; the mechanic is positive it's not true. Once again I urged him to check his manuals. He comes back admitting that "apparently it's true". At least he didn't apply the TTY procedure so the existing bolts weren't over-stressed. The bolts never came in so, they said they'll get the bolts on order and call me when they're in. Based on what I've seen so far, I'm not depending on that. I'll have to call periodically to check.

Here's my spec sheet from the alignment:
They said I had 3 choices, one (flat) for normal driving and two for high-performance track. I chose a "flat" alignment for straight-line driving, not an aggressive camber "angled" alignment for corner carving. Before going to a road track I'll get it re-aligned. Otherwise the tires wear too fast and unevenly.


--Cal

[Stephen12ZL1]

Originally Posted by cwebster

Just got back from my 4-wheel alignment. Of course there's a different crew on Saturday and they know nothing about yesterday's discussion & findings. When the car is done I make a remark thanking them for getting the bolts so quickly to do the alignment. Suddenly heads pop up... "Bolts? What bolts? We don't know anything about any bolts." Even after I recounted my entire discussion with the crew from yesterday, emphasizing that the requirement was verified and bolts were ordered; the mechanic is positive it's not true. Once again I urged him to check his manuals. He comes back admitting that "apparently it's true". At least he didn't apply the TTY procedure so the existing bolts weren't over-stressed. The bolts never came in so, they said they'll get the bolts on order and call me when they're in. Based on what I've seen so far, I'm not depending on that. I'll have to call periodically to check.

He blasted them with his impact and they are perfect!

[BMWM.D.]

Just to play devils advocate on this.... BMW has a very similar rear suspension setup and also calls for replacing these bolts. I’ve never seen anyone replace one or anyone have an issue with failure.

The main issue I see is that it can be pretty hard to get your adjustments perfect on the first torque. Sometimes the eccentrics move, or the angles simply change a bit when everything is tightened. This means your “one time use” bolt is getting torqued again. And keep in mind that these aren’t TTY bolts like a head bolt or LS crank bolt. I believe the main reason for recommending replacement is that the nuts are a locking style.

Do what you’re comfortable with, but there’s a good chance your new fasteners are going to get tightened and loosened a couple times during an alignment procedure. As OCD as I am with my own cars, this is something I’ve never worried about.

[BMWM.D.]

On a side note....man, that rear toe was pretty far out. How many miles are on that car? I think I need to get mine up on our alignment rack soon.

[Mr. Wyndham]

These bolts have been TTY for some time, including on the 5th gen. Same for the brake caliper bolts!!...Yet people re-use them all the time, because like someone mentioned many people don't know - including the service people.

Should you reuse them? No, obviously...but it's done all the time, and I haven't seen anyone's rear arms coming apart.

I think the idea behind the bolts being TTY is so they will not come undone once the alignment has been set. Or will at least, resist doing so.

I'm going to have an extensive alignment done in the spring, to determine where everything sits on this car in both the track setting, and back to street, again. I'll probably request to have new bolts put in. I will have it realigned two track days (and several months) later, at least to check on it...if the alignment has changed, I do not see myself replacing these bolts each and every time I have one done..............

[seanblurr]

Not saying this is right, but I adjusted the rear toe and camber on my SS1LE multiple times last track season on the same bolts. I wasn't going to replace the bolts every damn time I made an adjustment. I did not, however, know about the caliper bolts being TTY. Definitely didn't replace those ones either...

[Stephen12ZL1]

Voices of reason finally join the discussion...

[cwebster]

Originally Posted by BMWM.D.

On a side note....man, that rear toe was pretty far out. How many miles are on that car? I think I need to get mine up on our alignment rack soon.

I was a little surprised too. It's never been aligned except (I hope) at the factory. It's currently at 5500 miles after 14 months, most of that to and from the tracks. It's not my daily driver and I seldom hit a pothole - there's just not that many of them around here. Obviously something has thrown it off, though. That could account for a lot of the wear I was seeing.

--Cal

[cwebster]

Originally Posted by BMWM.D.

Just to play devils advocate on this.... BMW has a very similar rear suspension setup and also calls for replacing these bolts. I’ve never seen anyone replace one or anyone have an issue with failure.

The main issue I see is that it can be pretty hard to get your adjustments perfect on the first torque. Sometimes the eccentrics move, or the angles simply change a bit when everything is tightened. This means your “one time use” bolt is getting torqued again. And keep in mind that these aren’t TTY bolts like a head bolt or LS crank bolt. I believe the main reason for recommending replacement is that the nuts are a locking style.

Do what you’re comfortable with, but there’s a good chance your new fasteners are going to get tightened and loosened a couple times during an alignment procedure. As OCD as I am with my own cars, this is something I’ve never worried about.

The procedure does not call for applying the TTY until the alignment has been checked and re-adjusted. In your BMW example or any of the other anecdotes mentioned in this thread, how do you know how much torque was applied? Was it actually getting "torqued"? What torque value do you think they used? Could it have been snugged down or tightened to whatever the mechanic "felt" was enough? Could it have been cranked down with an impact gun? Even if it were torqued to the specified (1st Pass) value I wouldn't expect the self-locking nut to come loose. That's not the concern I would have.

These are torqued using the TTY procedure at the factory so they've already been "stretched" the point of plasticity. If someone were to apply the correct procedure a second or third time to the same bolts I would be concerned about catastrophic failure from metal fatigue. If they're just "snugging them up" there would, of course, be less chance of that happening but more of a chance that the alignment wouldn't hold.

Originally Posted by Mr. Wyndham

These bolts have been TTY for some time, including on the 5th gen. Same for the brake caliper bolts!!...Yet people re-use them all the time, because like someone mentioned many people don't know - including the service people.

Should you reuse them? No, obviously...but it's done all the time, and I haven't seen anyone's rear arms coming apart.

I think the idea behind the bolts being TTY is so they will not come undone once the alignment has been set. Or will at least, resist doing so.

I'm going to have an extensive alignment done in the spring, to determine where everything sits on this car in both the track setting, and back to street, again. I'll probably request to have new bolts put in. I will have it realigned two track days (and several months) later, at least to check on it...if the alignment has changed, I do not see myself replacing these bolts each and every time I have one done..............

Originally Posted by seanblurr

Not saying this is right, but I adjusted the rear toe and camber on my SS1LE multiple times last track season on the same bolts. I wasn't going to replace the bolts every damn time I made an adjustment. I did not, however, know about the caliper bolts being TTY. Definitely didn't replace those ones either...

If you watched the torque value during that additional 75-90 degrees you would see it reach a plateau. Continuing beyond that point does not increase the torque. It only weakens the metal. If you've ever snapped off a bolt you get the idea - except most bolts aren't designed to stretch and give like these, which is why it's easier to snap them off when over-torquing.

Maybe someone will step up and actually test this to see how many TTY applications it takes to make it fail. Or whether you can maintain the adjustment using a single torque value(??). Maybe someone already has?

I don't know any more than any of you why the engineers made the decision to use these bolts, but they did. Maybe someone close to GM could ask them. I doubt such a question would gain enough momentum to rise to the top of the "Ask Al" list, given the opposition from more longstanding members.

Maybe a better question would be... As seldom as it has happened or is likely to happen, what would be the consequences of control arm coming apart? -or- Do you feel lucky?

--Cal

[Mr. Wyndham]

Originally Posted by cwebster

If you watched the torque value during that additional 75-90 degrees you would see it reach a plateau. Continuing beyond that point does not increase the torque. It only weakens the metal. If you've ever snapped off a bolt you get the idea - except most bolts aren't designed to stretch and give like these, which is why it's easier to snap them off when over-torquing.

Maybe someone will step up and actually test this to see how many TTY applications it takes to make it fail. Or whether you can maintain the adjustment using a single torque value(??). Maybe someone already has?

I don't know any more than any of you why the engineers made the decision to use these bolts, but they did. Maybe someone close to GM could ask them. I doubt such a question would gain enough momentum to rise to the top of the "Ask Al" list, given the opposition from more longstanding members.

Maybe a better question would be... As seldom as it has happened or is likely to happen, what would be the consequences of control arm coming apart? -or- Do you feel lucky?

--Cal

You're right, of course. And please don't mistake my comments as disagreeing with an obvious method of use for these TTY bolts....I'm just sharing the experience that 90% of people on here never knew they were having. This has been the case since Gen V.

Yet, the shops loosen the bolts while on the rack, make the adjustments, and then beat the $**t out of them with an impact wrench until they figure "good enough". Many, many alignments, and track days on the same bolts, and my suspension links have fallen off due to a snapped bolt...I think, because the loads are mostly transferred to the brackets attached to the subframes.




And as I said - I'll probably ask for the proper bolts to be replaced this May. Ask Al...see where it goes. Though I think we already know the answer:

"Replace the TTY bolts as instructed."

[BMWM.D.]

Originally Posted by cwebster

The procedure does not call for applying the TTY until the alignment has been checked and re-adjusted. In your BMW example or any of the other anecdotes mentioned in this thread, how do you know how much torque was applied? Was it actually getting "torqued"? What torque value do you think they used? Could it have been snugged down or tightened to whatever the mechanic "felt" was enough? Could it have been cranked down with an impact gun? Even if it were torqued to the specified (1st Pass) value I wouldn't expect the self-locking nut to come loose. That's not the concern I would have.

These are torqued using the TTY procedure at the factory so they've already been "stretched" the point of plasticity. If someone were to apply the correct procedure a second or third time to the same bolts I would be concerned about catastrophic failure from metal fatigue. If they're just "snugging them up" there would, of course, be less chance of that happening but more of a chance that the alignment wouldn't hold.




If you watched the torque value during that additional 75-90 degrees you would see it reach a plateau. Continuing beyond that point does not increase the torque. It only weakens the metal. If you've ever snapped off a bolt you get the idea - except most bolts aren't designed to stretch and give like these, which is why it's easier to snap them off when over-torquing.

Maybe someone will step up and actually test this to see how many TTY applications it takes to make it fail. Or whether you can maintain the adjustment using a single torque value(??). Maybe someone already has?

I don't know any more than any of you why the engineers made the decision to use these bolts, but they did. Maybe someone close to GM could ask them. I doubt such a question would gain enough momentum to rise to the top of the "Ask Al" list, given the opposition from more longstanding members.

Maybe a better question would be... As seldom as it has happened or is likely to happen, what would be the consequences of control arm coming apart? -or- Do you feel lucky?

--Cal

I was just going off my personal experience doing alignments (as part of my job) over the last 15 years. It’s pretty easy for your angles to change as you tighten things down. Or as you adjust the other side of the car. I find myself going back on a regular basis. On some cars, the toe will actually change every time as the eccentric is torqued. So you almost need to anticipate this before tightening everything down. If you don’t, it’ll be off once properly torqued. It’s like trying to hit a moving target.

I just aligned my ZL1 this afternoon, and the suspension and eccentric setup are extremely similar to the BMWs I usually deal with. And I didn’t change the bolts, just like I never have on my 335i. Is it the “right” way to do it? No, but I’m not overly worried about reusing them. But I also didn’t zap them with an impact like a moron, lol. Maybe I’ll replace them next time.

My car wasn’t as screwed up as yours, but it had double the recommended front toe (24 minutes or 0.4 degrees). The spec is 0.2 or 12 minutes. My thrust angle was off a bit due to the right rear being toe’d out. Total rear toe was still in the specified range, but far from perfect.

[cwebster]

Originally Posted by Mr. Wyndham

You're right, of course. And please don't mistake my comments as disagreeing with an obvious method of use for these TTY bolts....I'm just sharing the experience that 90% of people on here never knew they were having. This has been the case since Gen V.

Yet, the shops loosen the bolts while on the rack, make the adjustments, and then beat the $**t out of them with an impact wrench until they figure "good enough". Many, many alignments, and track days on the same bolts, and my suspension links have fallen off due to a snapped bolt...I think, because the loads are mostly transferred to the brackets attached to the subframes.

(I assume you meant "have not fallen off")

Of course, I do understand. If they had never subjected their TTY bolts to to the torque-to-angle method then they would never get over-stretched; and therefore would be unlikely to be unsafe. I would expect that the alignment just would not hold stable as long. This is presuming, of course, that the GM specified method is in-fact better at keeping the settings stable. Given how far my settings were off, I'm not sure this is the case. Without empirical data from a direct comparison or answers from GM engineers we can't really know.

Originally Posted by Mr. Wyndham

And as I said - I'll probably ask for the proper bolts to be replaced this May. Ask Al...see where it goes. Though I think we already know the answer:

"Replace the TTY bolts as instructed."

I was not suggesting we ask whether or not we should follow the requirement. I was thinking more along the lines of:

Why did engineers choose TTY bolts and the torque-to-angle method for alignments on the rear suspension instead of normal bolts and traditional single-torque values? Was there evidence that traditional bolts and methods were insufficient to keep alignments stable?

For those of us who re-align frequently for different track and street uses, these requirements add significantly to maintenance costs and effort. Many of us are finding it difficult to justify the added trouble and expense, given that we haven't seen any down-side from doing it the traditional way.

None of our members has yet visited a service department or repair shop that is even aware of the requirement. Please share with us the potential benefits of using the specified methods and what, if any, potential drawbacks we might expect from using traditional methods.

--Cal

[cwebster]

Originally Posted by BMWM.D.

I was just going off my personal experience doing alignments (as part of my job) over the last 15 years. It’s pretty easy for your angles to change as you tighten things down. Or as you adjust the other side of the car. I find myself going back on a regular basis. On some cars, the toe will actually change every time as the eccentric is torqued. So you almost need to anticipate this before tightening everything down. If you don’t, it’ll be off once properly torqued. It’s like trying to hit a moving target.

I just aligned my ZL1 this afternoon, and the suspension and eccentric setup are extremely similar to the BMWs I usually deal with. And I didn’t change the bolts, just like I never have on my 335i. Is it the “right” way to do it? No, but I’m not overly worried about reusing them. But I also didn’t zap them with an impact like a moron, lol. Maybe I’ll replace them next time.

My car wasn’t as screwed up as yours, but it had double the recommended front toe (24 minutes or 0.4 degrees). The spec is 0.2 or 12 minutes. My thrust angle was off a bit due to the right rear being toe’d out. Total rear toe was still in the specified range, but far from perfect.

Sure, I completely understand your justification. I don't think that applying single-torque values or "just-right tight" methods to the TTY bolts will be unsafe. If the bolts aren't repeatedly stretched past the point of plasticity they're unlikely to snap. Anyone who has tightened thousands of nuts and bolts in their life has a good "sense" for what is tight-enough in the absence of specified torque. I've done this myself many times. It becomes unsafe when you follow the torque-to-angle procedure without replacing the bolts.

I have my doubts, as I told Mr. Wyndham, whether these TTY bolts and torque-to-angle method actually work in our case. I'm assuming here that the purpose of these special bolts and method is to hold the alignment stable. It's unlikely they're used to better support the loads induced on the suspension. TTY bolts are designed for a tension load, not a shear load. They wouldn't be any better at handling a shear load than a traditional bolt. As someone else already pointed out the loads from suspension travel and thrust (both shear) are transferred up through the suspension components.

--Cal