Why alignments need TTA method with TTY bolts?

[cwebster]

Al,

Why did engineers choose TTY bolts and the torque-to-angle method for alignments on the Camaro 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 to visit 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.

Thank you for your feedback and insights!

--Cal

[HDRDTD]

Originally Posted by cwebster

Al,

Why did engineers choose TTY bolts and the torque-to-angle method for alignments on the Camaro 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 to visit 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.

Thank you for your feedback and insights!

--Cal

Ask that same question to the bolt manufacturer ARP and no doubt you'll get a detailed explanation of the different methods of torqueing a bolt.

I've heard the explanations in the past, I just can't remember them well enough to explain it here.

Basically TTY or TTA are far more precise than your normal torque wrench.

[cwebster]

Originally Posted by HDRDTD

Ask that same question to the bolt manufacturer ARP and no doubt you'll get a detailed explanation of the different methods of torqueing a bolt.

I've heard the explanations in the past, I just can't remember them well enough to explain it here.

Basically TTY or TTA are far more precise than your normal torque wrench.

I understand the methods and the difference between them. I'm just looking for an explanation why the GM engineers chose to use them in this specific application.

[HDRDTD]

For those that are curious, here is an explanation of the various torque methods explaned by ARP.

http://www.arp-bolts.com/p/technical.php

[HDRDTD]

Originally Posted by cwebster

I understand the methods and the difference between them. I'm just looking for an explanation why the GM engineers chose to use them in this specific application.

Accuracy ???

[cwebster]

Originally Posted by HDRDTD

Accuracy ???

I'd like to hear that from GM, as well as whether the decision was based on testing they've done and what they think of not complying in terms of maintainability and safety. Please read my entire question and consider that I'm asking on behalf of all the other Camaro owners who are facing this dilemma, some of whom have spoken in the thread where this topic was raised.

ZL1 Rear Camber and Toe Alignment Bolts Question

If you really want to know my position, my posts in the above discussion are: 7 10 13 16 23 24 27 28 31

--Cal

[iPODFAN11]

I'm definitely going to be voting for this one.

[vtirocz]

TTY and TTA allow for a more consistent (and sufficiently high) clampload at the bolted joint interface. They must have needed this method to hit their clampload targets.

[waterman]

Subscribed.

[cwebster]

Originally Posted by vtirocz

TTY and TTA allow for a more consistent (and sufficiently high) clampload at the bolted joint interface. They must have needed this method to hit their clampload targets.

"...a more consistent (and sufficiently high) clampload at the bolted joint interface" for what, though? On a cylinder head it would be to maintain the gasket seal in the presence of extreme pressure and heat, especially for differing expansion of dissimilar metals.

For our application it would presumably be to maintain the wheel trim, right? Given the vibrations and torsional stress from the drive train, the eccentrics would seem more likely to shift. A higher, more consistent clamping force should therefore equate to more stable, persistent settings, right?

Anecdotal evidence from members in this forum does not seem to bear this out. Many drivers claim to have been doing it the traditional way without any negative effects. These drivers seem to be satisfied that their alignment settings are sufficiently stable using "tried-and-true" methods they've always used. For them, it only adds time and expense for little if any benefit.

One could argue that the more you subject your suspension to vibration and stress, the more TTY/TTA would benefit you. Under this theory, a car used strictly for daily driving would see little if any benefit whereas one that is strictly a track car would virtually require it. Considering the science behind it, I would have to agree. In practice, however, it is difficult to see the proof.

For example, hawk02 only uses his car for daily driving. He had a 4-wheel alignment done last Summer using the traditional method. An alignment check done a few days ago shows it still within specs. There are many other drivers who use their cars exclusively or mostly for racing who claim to have similar results doing it the "old fashioned" way. On the other hand, my first alignment since delivery in 12/16 done a few days earlier showed my suspension substantially out of spec. Assuming the prescribed methods were used at the factory, one might expect settings to remain more stable.

Given that I've used my car mostly for drag racing, I probably should have taken mine in for an alignment check before now. Even the most rock-solid connections can loosen with enough vibration and torsional stress. Still, one could be forgiven for wondering whether it's worth the time and expense. Would a simpler, cheaper method applied more often be just as good or better than the one prescribed?

I think it would be worth it to hear what Al and his engineering team think...

--Cal

P.S. The A10 shudder issue seems more urgent that this one. There are other issues that seem to have more traction too. By the time the next poll or two roll around I doubt this topic will rise to the top. At least more people are thinking about it now. In the meantime, for safety sake, if you do choose to use the prescribed TTA method DO NOT REUSE the old TTY bolts. If you don't use TTA then just be prepared to possibly align more often.

[Stephen12ZL1]

A simple visit to the alignment shop should not be a huge ordeal with replacement of these lower control arm bolts. I understand the factory used a TTY method to set these bolts instead of a standard torque method. After the initial stretch of these bolts given the diameter of them, what is the harm with a simple retorque as the stretch has already occurred? Are these large diameter bolts indeed “weaker” after this factory tightening? Should we continue the practice of just a simple retorque? Two mechanics I have interviewed contend that the bolt has already been stretched so a simple retorque is all that is necessary. The torque will remain constant. Enlighten us please as eager minds want to know. Thanks!