1983 GL1100 HEAD BOLTS


Information and questions on GL1100 Goldwings (1980-1983)
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boudro
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1983 GL1100 HEAD BOLTS

Postby boudro » Sun May 05, 2013 1:11 pm



Where can I find a set of new head bolts for my bike. I'm pretty sure mine r streched out.
thanks



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trike lady
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Re: 1983 GL1100 HEAD BOLTS

Postby trike lady » Sun May 05, 2013 2:50 pm

I was going to suggest if you know the bolt sizes to see if NAPA auto parts has them or a Honda dealer that has been in business for a very long time may have some in a dusty box in inventory.
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dingdong
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Re: 1983 GL1100 HEAD BOLTS

Postby dingdong » Sun May 05, 2013 5:42 pm

The head bolts are torqued into aluminum. I seriously doubt if the bolts are stretched. I May be wrong though.
Tom

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SteveB123
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Re: 1983 GL1100 HEAD BOLTS

Postby SteveB123 » Sun May 05, 2013 5:54 pm

boudro wrote: I'm pretty sure mine r streched out.
thanks


How much elongation is there?
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WingAdmin
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Re: 1983 GL1100 HEAD BOLTS

Postby WingAdmin » Sun May 05, 2013 9:24 pm

dingdong wrote:The head bolts are torqued into aluminum. I seriously doubt if the bolts are stretched. I May be wrong though.


Head bolts are designed to stretch by design. The amount they stretch is dependent on the alloy used, and the amount they are torqued.

Actually, technically, every bolt stretches a tiny bit when it is torqued. If they didn't, you wouldn't be able to tighten them. Think about threading a bolt made of ultra-hard ceramic, into a hole also made of ceramic. When the bolt head reached the surface, it would simply stop turning - you couldn't torque it any further, and even if you gave it a huge amount of force trying to tighten it, it would take very little force to loosen it and remove it.

Metal bolts, when the head contacts the surface, can be torqued. The more they are torqued, the more the bolt stretches. This "give" in the metal is what allows the bolt to hold fast as a fastener. Eventually, you continue to tighten until the bolt's threshold is reached, and the bolt snaps.

What I would recommend is to try to source original OEM bolts if yours aren't serviceable. Non-OEM bolts may not have the correct stretch (different alloy), and could apply the incorrect amount of force on the head gasket even though they are torqued to spec.

Here is a short article on this that I found online, that describes it very well:


There are three types of procedures used for torquing: torque to yield/angle to turn; torque to maximum stretch yield; and torque to a specific torque number and hope it's correct.

Basically what it comes down to, is that torquing with just torque values such as foot-pounds or newton-meters is at best a guess at getting the torque correct. Depending on the type of fastener, materials used for both the bolt and the part it screws in to, cleanliness of the thread, lubrication used, TYPE of lubrication used, etc., the torque between two "identical" fasteners can actually vary by as much as 35% (or more) with the torque wrench having the same setting for both fasteners!

Many fasteners, such as wheel studs, water pump bolts, etc., are just there to make sure that the bolt is probably tight enough, and probably not too tight. These are the bolts that you reuse over and over without any problems.

Head bolts, as well as most of the bolts internal to the engine, are what are called stretch bolts (also known as torque-to-yield bolts). These are designed to be tightened to the point they physically start to stretch, usually by a few thousandths of an inch. This leaves them in a elastic condition, that allows very equal clamping forces to be applied to the part they're holding down.

When you tighten one of these bolts, the torque setting that is used is designed to get the bolt close to the point that it starts to stretch. The torque angle gauge is then used to put the bolt PAST the point it starts to stretch and actually start to stretch it. You just can't accurately measure this with a regular torque wrench, thus the torque-to-yield/angle-to-turn method. The Maximum stretch yield method doesn't apply here, since you need A) A very accurate micrometer to measure the actual bolt stretch, and B) Access to both sides of the bolt, which you don't have on head bolts.

The torquing process is quite simple. You simply torque the bolt using a normal torque wrench to a pre-determined torque. Then, usually you'll warm things up by running it at idle, then let it cool back down and re-torque again with the torque wrench. After that part is done, the torque angle gauge comes into play. The torque that the bolts are at after the regular wrench is theoretically just before the bolt starts to stretch. This accuracy depends of course on the factors mentioned above. To get the final torque AND stretch on the bolt, you tighten the bolt a given number of degrees of rotation. This is what the torque angle gauge is for, accurately measuring the degrees of additional rotation (typically accurate to a degree or so).

The Reason For Not Re-Using Stretch Bolts

The reason is quite simple. Once you have stretched the bolt once, it never returns to its original size. This weakens the bolt, and if you try to re-use it, you take a risk of snapping the bolt in two, leaving the threaded part in the block, the top in your hand, and a complicated repair required. It's just not worth the risk to try to re-use old bolts.

You can get replacement bolts that are not designed to stretch at the torque required to hold the parts together.

There are two good reasons for using non stretch bolts. You want to re-use them in the future, and/or you have an engine that is either forced induction or very high compression. Since the bolt is already at it's maximum stretch without losing strength, you don't want to put undue stress on it from a high compression engine and take the risk of a blown head gasket.

There is also a good reason for NOT using these bolts, and staying with the original OEM style stretch bolts. Non stretch bolts require re-torquing after a few heat/cool cycles (usually specified at around 5-6 cycles), and may have to re-torque them anywhere from every 30k to 70k miles, depending on application. If you have a normally aspirated engine, there's just no reason to have to do the extra work when normally you wouldn't touch the bolts again after they've been done properly with regular OEM stretch bolts. Also, stretch bolts tend to provide more consistent, even clamping pressure than the solid bolts do.

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dingdong
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Re: 1983 GL1100 HEAD BOLTS

Postby dingdong » Mon May 06, 2013 6:49 am

Very interesting. Something I didn't know.


Tom

A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.


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