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PostPosted: Fri Jan 28, 2011 7:09 pm 
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Location: Regina, SK
Should you replace or upgrade your head bolts when you pull the head? This thread is an attempt to help you decide.

The North American Swifts/Metros/Fireflys/Sprints that came with reusable head bolts are the G13 SOHC 16V engines. The rest originally had Torque To Yield (TTY) bolts.

TTY head bolts are currently in fashion with Auto Makers because they don't need to be 'retorqued'. The reason is that the bolt has a nominal torque rating. Most are simple 8.8 Metric rated bolts (basically Grade 5). The size of the bolts is usually M10(diameter) x 1.5(threadpitch) with varying lengths. They have a torque rating of about 38ft/lbs when dry and unlubricated. When you install them, you are supposed to oil the threads and set a final torque of 54ft/lbs. This causes the bolts to self lock as the threads engage the threads of the block, deform and shift, and takes the elasticity out of the bolt. Taking the elasticity out of the bolt is work hardening it. Unhardened bolts tend to be soft and bendable, which is why they will deform when abused or when expected to (during the torque process). Hardened steel sounds like a good thing, but it's a 'double edged sword'. The bolt is harder but at the same time it is more likely to snap (more brittle) so it can't actually handle as high of a load as an unhardened bolt. This is why TTY head bolts are so popular, they save the auto makers cost associated with having to retorque headbolts. Service techs at dealerships are expensive and most customers don't wish to return for an additional bolt torquing. TTY bolts tend to fail if an engine overheats, and some auto engines seem to fail prematurely due to use of TTY bolts.

Note: Torque ratings are done at approximately 65-70% of failure torque, if we apply that to 8.8's rating we get 52ft/lbs.

If you are debating whether or not to reuse them consider this: you can certainly pass a die over the bolts and cut the threads straight, but you still have a bolt that has been stretched and is no longer able to stretch; the worst possibility would be it would snap!

There are 4 downsides to the re-use of TTY head bolts:

1) Bolts may snap when setting torque or in the event of unexpected stress on the head.
2) Threads in the block being stripped, due to improper thread engagement.
3) Premature head gasket failure due to thread failure.
4) Head warp, due to the bolts/threads failing, and the head overheating while under torque in some places and no torque in others.
If you've decided to change your head bolts you need to decide which way to go...stock replacements are about $20 a set for the 89-01 G10 cars for example. They are TTY and need to be replaced every time after you torque them.
Suprfly sells upgraded replacements which are high strength and are fully re-usable though they are more expensive ($30 a set for the G10).
Some installation suggestions:
Block thread preparation-
Use a M10x1.5 tap to clean the block threads. I prefer the 'bottoming type' and avoid the 'taper type' tap. A 'plug' one will also work. Use this to clean out all the head bolt holes. This will remove any oxidation and straighten or cut any deformed threads into proper shape. Use a cutting oil; if you don't have any on hand, use a little ATF dripped on the tap. This helps to keep the tap moving smoothly leaving smooth threads behind as well as collecting most of the junk in the tap's flutes. Use a wire brush to clean off the tap between each hole and re-oil. Then use compressed air to clean out any remaining debris from the holes. I have used brake cleaner when I was in a pinch, and it worked well, just give it time to dry.
Head bolt lubrication-
In years past I used regular motor oil, but using engine oil doesn't work well when you want those bolts to come out. I suggest a good Copper or Nickle based anti-seize. It won't evaporate like oil, and it is very good at preventing corrosion or oxidization. Another benefit to using an anti-seize is that you also get a 10-20% boost in effective thread engagement, over the just dry or oiled 75%. If using anti-seize, a little goes a long way and it's always easier to to add more. Tighten the bolt till it is snug, then back it all the way out. Do this until it 'feels' the same going all the way in. You should notice quite a bit a difference compared to the first time you tighten the bolt. It usually take three full 'threadings' for the anti-seize to completely work it's way in, and sometimes you will have to add more.

Some suggestions on installing head bolts-
Try to torque your bolts in several stages.
Here's an example:

a.) 21ft/lbs <- Initial torque
b.) 32ft/lbs
c.) 43ft/lbs
d.) 54ft/lbs <- Final torque

The pattern will vary depending:

G10 3 cylinder with 8 head bolts:
5 - 1 - 3 - 7
6 - 4 - 2 - 8

G13 4 cylinder with 10 head bolts:
7 - 5 - 1 - 3 - 9
10 - 4 - 2 - 6 - 8

Torque specs:

G10 1989 - 2000
TTY Bolts: 54ft/lbs
3Tech Bolts: 50ft/lbs

G13 8V SOHC 1989 - 1997
TTY Bolts: 54ft/lbs
3Tech Bolts: 50ft/lbs

G13 16V DOHC and SOHC 1987 - 2001
Stock Bolts: 50ft/lbs
3Tech Bolts: 50ft/lbs

Torque and Thread lubricant remarks:
Anti-seize will attempt to behave just like 30w oil, but there are variances. Refer always to the Technical Data Sheet of the anti-seize you are using. It may give you a K value. Usually K is 1.0 for steel into steel and 0.80 would be a 20% reduction of the friction from normal. For Permatex anti-seize products, reassemble parts to their normal torque. I tend to run a 10% reduction on torque when it comes to any bolt that isn't supposed to be oiled according to the manual.

There is a HUGE spectrum of anti-seizes and thread lubes, Here is a handy chart:
Image
Comments on Bolts-
(Strength)
Metric bolts have the strength of the metal stamped on the cap. Unlike SAE bolts, this information is labeled in the form "X.Y".
The first number, X, is one percent of the bolt's tensile strength in Newtons per square millimeter (1 N/mm2 equals 145 psi). The second number, Y, is ten times the ratio of yield stress to tensile strength (X). A class 8.8 metric bolt's tensile strength would be 8 x 100 = 800 N/mm2. Its yield stress would be its tensile strength divided by Y, in this case 800 x 0.8 = 640 N/mm2.
Practical application-
Common classes of metric bolts are 5.8, 8.8, and 10.9. These numbers are roughly equivalent to SAE grades 2, 5, and 8, respectively. You can also find metric bolts of class 12.9.


I have received a PM asking to explain why the 3tech head bolts require less torque than the TTY ones. This has partly to do with the bolt threads actively changing their engagement with the threads in the block, creating more friction. Another part is that as you overload the bolt it stretches permanently to create 'a fixed' amount of clamping force. With non-stretch (reusable) bolts you don't need to torque the bolt as much to get the same effective clamping force. You are in still in their elastic range, which means the bolt can handle sudden load increases and still return to form. The TTY bolt, which when subjected to an additional load (or heat) may stretch. This may cause a blown head gasket or warped head.

Here's a sketch:

Image

The narrowing is permanent, and explains why TTY bolts are designed for single use.

I would like to thank Phil&Ed for graciously offering to edit and clean up my post.

_________________
My cars:

J. McBean: '98 Suzuki Swift 1.3L 16v SOHC 5sp+ "Mk5" Made in Canada
The Mini Rattler: '94 Suzuki Swift .993L 6v SOHC 5sp+ "Mk3" Made in Canada *The Winter Beater*
B. Berry: '90 Chevrolet Turbo Sprint 1.0L 6v SOHC 5sp+ "Mk2" Made in Japan

I got 18MPG in a 3cyl with a 5 speed manual 4dr, '93 Metro! :yeahyeah


Last edited by gamefoo21 on Sun Jan 30, 2011 11:08 am, edited 3 times in total.

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PostPosted: Sat Jan 29, 2011 2:02 am 
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looks like someones got too much time on their hands... snowmobile break down?


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PostPosted: Sat Jan 29, 2011 7:14 am 
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Joined: Thu May 24, 2007 9:35 am
Posts: 57
Location: Etch-A-Sketch, Ohio
How 'Bout Studs ??..... :D


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PostPosted: Sat Jan 29, 2011 12:02 pm 
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Joined: Mon Dec 01, 2003 12:47 pm
Posts: 11669
Location: columbus, ohio
i'm a stud. :ez_pimp:

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1991 Blue Geo Metro Convertible highly modified 1.0L Turbo3 5 spd. - 1991 Red Geo Metro Convertible customized with a Twincam 5 spd.

My Turbo3 Project
My Cardomain Page -Ol' Blue
My YouTube Channel
My Photo Gallery
SAAB Sonett II


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PostPosted: Sat Jan 29, 2011 11:30 pm 
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Location: Regina, SK
earthtoad wrote:
How 'Bout Studs ??..... :D


Studs apply to the same rules, but will generally require a bit less torque, to get to the same clamping load. Bolts are twisting and pulling at the same time, while with studs most of the force is being applied to stretching the stud.

Something to note with studs, the threads HAVE to bottom out, in the block. If the shoulder bottoms out before the threads it causes an improper load distribution, with the top few threads being completely loaded, which will result in thread failure and you have a very good chance of ripping the threads out of the block.

no_rust_vert wrote:
looks like someones got too much time on their hands... snowmobile break down?


Nah, just felt like sharing. Though I may have to request this get's moved to the FAQ section... Besides driving a sled that get's if I'm lucky 5 to 7.5MPG gets expensive. :lol:

_________________
My cars:

J. McBean: '98 Suzuki Swift 1.3L 16v SOHC 5sp+ "Mk5" Made in Canada
The Mini Rattler: '94 Suzuki Swift .993L 6v SOHC 5sp+ "Mk3" Made in Canada *The Winter Beater*
B. Berry: '90 Chevrolet Turbo Sprint 1.0L 6v SOHC 5sp+ "Mk2" Made in Japan

I got 18MPG in a 3cyl with a 5 speed manual 4dr, '93 Metro! :yeahyeah


Last edited by gamefoo21 on Sun Jan 30, 2011 11:10 am, edited 1 time in total.

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PostPosted: Sat Jan 29, 2011 11:37 pm 
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Joined: Thu Jul 20, 2006 7:17 pm
Posts: 1405
Location: Alberta, Canada
t3 ragtop wrote:
i'm a stud. :ez_pimp:


Real studs have big throttle bodies and tach clusters in their 16v cars... =)

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1995 Swift w/16V 4.39s, 3tech cam, Esteem t-body, Header, needs more.
1995 Gt Mustang "Boss Shinoda" package.
1999 F150 4x4 Supercharged
1967 Mustang 428 auto, never ending expensive project
1993 Civic si h22a, fell in my lap, couldn't resist!


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PostPosted: Sun Jan 30, 2011 5:10 am 
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Location: Palmdale, Ca
I drilled and tapped my block for much larger sbc ARP studs :ez_pimp:

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1987 Chevrolet Sprint Turbo under construction


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PostPosted: Sun Jan 30, 2011 10:08 am 
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Joined: Mon Dec 01, 2003 12:47 pm
Posts: 11669
Location: columbus, ohio
codyb76 wrote:
t3 ragtop wrote:
i'm a stud. :ez_pimp:


Real studs have big throttle bodies and tach clusters in their 16v cars... =)


ah, but that would be the wife's car and she's a vixen. :lol:

_________________
1991 Blue Geo Metro Convertible highly modified 1.0L Turbo3 5 spd. - 1991 Red Geo Metro Convertible customized with a Twincam 5 spd.

My Turbo3 Project
My Cardomain Page -Ol' Blue
My YouTube Channel
My Photo Gallery
SAAB Sonett II


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PostPosted: Sun Jan 30, 2011 11:01 am 
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Joined: Tue Oct 24, 2006 3:09 pm
Posts: 4998
Location: Palm Springs: Too hot from June to Oct.!
:blackeye:
Graduation from a College or University usually includes a course in 'Technical Report Writing'.
If you are a student, seriously consider this subject.
:idea: :idea: :idea:
The information as currently provided is a good referral source for future 'head bolt' questions.

"Got Head?"..............................................................................................(bolts) :lol: :lol: :lol:

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DIY Broken Bolt Removal: viewtopic.php?f=22&t=41042
DIY Clutch Adjustment: viewtopic.php?f=9&t=48281
DIY Wheel Bearings: viewtopic.php?f=2&t=29003
DIY Shocks: viewtopic.php?f=10&t=45483
DIY Wheel Align: viewtopic.php?f=2&t=42479
Once you get the cars dialed-in (compression, leaks, bearings, alignment, brakes) swap in new rubber and glass, you've got something which should last for years!


Last edited by Phil N Ed on Sun Jan 30, 2011 3:49 pm, edited 1 time in total.

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PostPosted: Sun Jan 30, 2011 11:12 am 
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Joined: Mon Jun 18, 2007 1:35 pm
Posts: 2433
Location: Regina, SK
Ugh!

That picture... I'll just get this thread deleted! :?

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My cars:

J. McBean: '98 Suzuki Swift 1.3L 16v SOHC 5sp+ "Mk5" Made in Canada
The Mini Rattler: '94 Suzuki Swift .993L 6v SOHC 5sp+ "Mk3" Made in Canada *The Winter Beater*
B. Berry: '90 Chevrolet Turbo Sprint 1.0L 6v SOHC 5sp+ "Mk2" Made in Japan

I got 18MPG in a 3cyl with a 5 speed manual 4dr, '93 Metro! :yeahyeah


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