why are we all wasting money on TTY head bolts?

[turbonator]

okay, after my trip to the engine shop a week ago, they told us that they re-use the factory head bolt and have no failure rate with the 100-150 diesels that they build every year.... so has any one looked at the possibility of finding a good replacement bolt that can be re-used like a stud? i know that the mazda millenia uses a super hard bolt to hold the girdle on the bottom of that motor... not the same size, but they are an excellent bolt to use when the starter bolt holes get too damaged, just pass the taps in the holes and drill out the starter and voila.. new much stronger bolts with an allen head...:thumbsup: anyways rant over...LOL

 

[Matt Bachand]

Are all the head bolts they re use TTY? I thought the bolts physically stretch.


I guess if it doesn't snap when re-torqued you may be all right.....????

I like the stud idea better anyhow.

 

[6.2 turbo]

I have a bunch of 12.9 allen bolt's if you are interested.

 

[turbonator]

i am just saying that one of the vendors could make some decent coin if they brought out head bolts the same strength as ARP studs and sold them $50-$75 cheaper than the studs... and they would be re-usable at least twice.... we re-used the head bolts on our 3500 6.2l and it has 60,000 km on it now and no problems..... it seems kind of like a scam to have to throw away bolts..... i am going to look into this a bit and try to find a price on a set to see if it is viable....:thumbsup:

 

[Matt Bachand]

I think it may have something to do with studs you are only moving the NUT, the threads of the stud are NOT twisting to torque.

With TTY or any bolt, the head, and EVERY thread is moving always, causing much less torque???? Or differently spaced torque pressures???

 

[ak diesel driver]

one of the biggest advantage studs have is the abilty to use all the threads in the hole. when you use bolts you have to be shorter to keep them from bottoming out.

 

[JiFaire]

You can certainly re-use non-TTY head bolts, but I am not sure I'd want to re-use the TTY ones. jim, are you sure your engine shop is talking about GM 6.5 diesels? Cummins, powerstroke, or CAT would likely be different... it wouldn't be the first time that the diesel mechanics didn't know their Azz from a hole in the ground when it came to our particular kind of engine.

 

[turbonator]

It was Jeff that began this thread, but I will respond now. When we were in the shop, one of the guys was beginning to reassemble a 6.5L. He had all the pieces gathered and just was to install our cam bearings, then move on to the 6.5L. I noticed that he had a box of used head bolts with the rest of the pieces and had to ask him. The bolts are all collected from old blocks and re-used. Originally the 6.2L did not use a TTY bolt, did not think to ask him if these were the bolts that they had gathered. One thing he did mention was that they had some problems with the newer TTY bolts and less problems with the used.

As Jeff mentioned, before we knew any better (or worse...LOL), we re-used our head bolts. We busted two in the install, I figured it was a little to do with my torque wrench at the time (since replaced and need a new one again). This motor is special to us as it was our intro to the 6.2/6.5L. It has over 70,000km now, is our daily driver, our go to puller and #1 work truck.

 

[turbonator]

You can certainly re-use non-TTY head bolts, but I am not sure I'd want to re-use the TTY ones. jim, are you sure your engine shop is talking about GM 6.5 diesels? Cummins, powerstroke, or CAT would likely be different... it wouldn't be the first time that the diesel mechanics didn't know their Azz from a hole in the ground when it came to our particular kind of engine.

they have a fair bit of experience working on GM 6.2/6.5l at this shop(53 years of experiance) you might say that these guys are the "bill heaths" of quebec.... they are true builders, i find that it is particular to throw away bolts everytime a head is removed, actually it fits well into our consumer driven culture, all i am saying is that it is possible to find a better alternative than torque to yield, and cheaper than studs..... and the only difference i see in using better reusable bolts is that they are reusable. TTY bolts pull the threads the same as a reusable bolt would, in my mind it makes good sense to use something that will give a better return on investment, leaving money to do other things with.

 

[JiFaire]

OK, I think I have this JIM and jeff thing sorted out now... sure would be nice if you guys signed your posts or used different coloured smilies or something... or just used turbonatorJIM and turbonatorjeff or something...

And please tell me if I got it wrong again and I'll keep trying

I guess what we're going on here is the GM engineers' decision to use TTY head bolts and the uneqivocal manufacturer's warnings to NOT re-use those. Could you use other head bolts in place of them? Yeah, if you found the right ones. Would I re-use TTY bolts? nope.

Lots of guys here have rebuilt these bad boys, and I've never yet heard that reusing TTY bolts was a good idea.

If you want to, by all means go ahead, but I think I would follow the expert's recommendations. Just sayin'

 

[turbonator]

OK, I think I have this JIM and jeff thing sorted out now... sure would be nice if you guys signed your posts or used different coloured smilies or something... or just used turbonatorJIM and turbonatorjeff or something...

And please tell me if I got it wrong again and I'll keep trying

I guess what we're going on here is the GM engineers' decision to use TTY head bolts and the uneqivocal manufacturer's warnings to NOT re-use those. Could you use other head bolts in place of them? Yeah, if you found the right ones. Would I re-use TTY bolts? nope.

Lots of guys here have rebuilt these bad boys, and I've never yet heard that reusing TTY bolts was a good idea.

If you want to, by all means go ahead, but I think I would follow the expert's recommendations. Just sayin'

(the jeff) i am not disagreeing with the do not reuse, i just think it is time for someone to bring out an alternative between the studs and the disposable bolts, jim talked to one of the ARP guys last week and the headsstud came up.... did you know that this is an incredibly oddball combination? it came about from one man who was searching for something better..... now they are sold everywhere..... could do the same thing with a better quality bolt.....maybe it is arp that needs to be contacted again....

 

[JiFaire]

Ah, I see what you are getting at... sorry, I mis-read your intent to start with. Yes, getting in touch with ARP or another fastener outfit might save us some money. I think I like the idea of studs better for clamping force application, though they are expensive, no question.

 

[buddy]

And lets not be ultra conservative when discussing possibilities. Im not sure that a bolt can't provide the same clamping force as a stud. One advantage of the stud is you can seal it all you want and not worry about its affect on torque value. You may also have more accurate torqueing because there might be less yield on the stud when torqueing the nut on top of it, due to the length. But if the bolt is hard enough it should not be any differnt on anctual clamping force than a stud. Perhaps better even force across the whole head with the stud.

One disadvantage of the stud, can you pull a head out while its in the truck? Does it have a head to grip it to back it out without destroying the top threads?

I have read the advantages of TTY bolts and I dont really trust in that.

 

[6.2 turbo]

The studs have an allen head, and they are 1/2 inch diameter except for the end that threads in the block is 12mm. I used to remove all the studs,then remove the head.

 

[schiker]

Not sure about this but I think you can make a stud stronger more economically than a bolt due to how its made. A Stud can be turned or roll threaded then heat treated, cryo'ed etc ??? out of most any metal fairly easily. But a bolt has to be forged to make the head (or machined and that is more expensive takes time). At least its easlier to drill and broach an internal hex in the end of a stud. So I think its more economical to make high strength studs than bolts ???? Nuts can be made easy too. I think the hard part is mostly about getting the strenght in the head/shoulder transition and having acceptable uniform properties of strenght along the length I think ???

I imagine TTY can be made from a more forgiving alloy to the mfg process and reduces cost with lot sizes/quality control ???

The market price for stud and bolt differ due to market demand/mfg competition/ name brand etc. We don't see the price break for studs due to market not mfg costs.

 

[WarWagon]

Too cheap for the job... One of the reason's the 5.7 Diesel was so hated was reuse of the new technology TTY bolts. Use of the engine with too few head bolts in the design caused them to stretch and yield in use. Reuse of the now stretched/yielded bolts would break bolts down the road or allow the bolt to stretch more and pop the head gasket down the road. A head gasket failure should let you know the bolts have stretched.

Re-use was thought to be acceptable as the bolts did not yield during tightening - just close to it - if and only if the tightening was done perfectly with clean and chased threads with proper lube. Repeated engine failures from bad design that pushed the bolts past their yield limits during use has changed this to a more practical throw them away. Head gasket companies get tired of warranting engines from apparent failures of their product when stretched bolts are the cause. In other words re-use made the 5.7L Diesel more of a design failure than it already was. Many TSB's and memo's from head gasket companies came out to where your 6.5/6.2 Fel-Pro gasket set has a warning about TTY - get new bolts on it.

TTY was invented to be better than a standard bolt for clamping force. A simple bolt will not deliver the same clamping force and elastic principals the TTY bolt offers. Your grade 8 SAE bolts have a tensile strength of 150,000 psi. ARP's base head stud sets have a tensile strength of 200,000 psi.

TTY is an attempt to eliminate the once common head bolt re-torque after the first use. This TTY allows a seal when a gasket relaxes - because the bolt will keep the same clamping force with slight gasket collapse. It also puts the bolt close to it's limit where events like high cylinder pressure from ether, advanced timing due to IP dirt ingestion, etc. can take the bolt to it's yield point where the bolt looses it's elasticity/clamping force. In extreme cases the bolt will break, but it is not very far from simply doing so after loosing it's elasticity.

You will break/shatter the rod and piston, blow the crank out of the bottom end or ruin the bolt holes before you break the ARP studs. I have seen firsthand a shattered piston and (the now irrelevant to longer engine life) stretched TTY head bolts with a failed/lifted head gasket that resulted after the initial engine failure.

I seal the ARP's with blue or red locktight in the block, depending on what I have on hand, to eliminate the disadvantage of studs - leaks. I have no illusions about pulling the engine being easier than in frame for pulling the heads. I did pull a head off to see how things were doing after totaling the truck and only had to change the head gasket not the ARP studs before reusing the engine elsewhere.

I imagine a non-TTY bolt solution would have you retorque the head bolts after first use. Not something that is an advantage with 8 IP lines in the way for cost savings over ARP or advantage over TTY's single use.

 

[Acesneights1]

I am not sure what the 6.2's used but I reused the bolts not knowing any better at the time(10 yrs ago). The truck was fine. After my last head pull on my Dually , I used ARP's and will never use anything else. They are worth the money.

 

[great white]

I am not sure what the 6.2's used but I reused the bolts not knowing any better at the time(10 yrs ago). The truck was fine. After my last head pull on my Dually , I used ARP's and will never use anything else. They are worth the money.

Can you get the heads on and off with it in the chassis?

I seem to recall mention that you have to pull the engine to get the heads off with studs...

 

[Acesneights1]

That was what I originally thought. You put the heads on first and then screw in the studs. They have an allen key on them to screw them in. I love them.

 

[bk95td]

With everything being made in china these days I wouldn't trust any TTY bolt. Arp studs are well worth the price. The heat and mostly vibration of a engine really taxes the principal of tty. The heating/cooling cycles can't help either.