Home fork stud-bolt extraction

[ReSanti]

Hello, I over-torqued a nut and broke one of the two stud bolts that secures the axle rod to the right fork of my '82 GS1000EZ. I have tried tapping vise-grips with a hammer as well as good ol' fashioned muscle, but the grips are just chewing the bolt up. I also tried warming the fork up with a really hot towel. I was going to buy a mini-butane torch, but the guy at Ace said be careful if the fork is aluminum, you might melt the bugger.

Any one ever had this problem and successfully extracted the stud-bolt out themselves? I'm debating being a test pilot and riding the moto at 15 mph to the shop to pay the mechanics to do it, but I wanted to try every avenue before I fork out the cash for that solution.

Thanks ladies and gents.

[bwringer]

Very common problem. A hot towel won't do it. You will need fire to get the stud hot -- give it 20-30 seconds or so on the stud, just enough to loosen the thread locker, then clamp down VERY HARD with VERY LARGE vice grips and it will come right out. Don't fart around with small vice grips.

The HW store guy is sort of an idiot... you would have to really overdo it to melt the aluminum, especially with a mini butane torch.

The good news is that any real hardware store will have 8mm studs. You might as well replace the other studs while you're at it. Try your local Ace or Do It Best. Get studs that are the same length or slightly longer than the old ones, along with new nuts and washers. (Hint: Home Desperate, Meantards, and bLowes are not real hardware stores.)

As I said, this is very common, but easy to fix. I keep 8mm studs around for this exact reason.

[Normk]

+1 to the previous post. The problem with loosening a steel, cad. plated steel fastener from aluminum is that they "marry" over time. Moisture, oxygen and other corrosives cause the differing materials to become an amalgum of the materials which bonds the stud to the aluminum. If there is any significant amount of stud locking material left from the factory assembly (assuming they used which I doubt), it will aid you as it tends to exclude corrosives.

As said, heating is the trick and you need not be concerned with over heating by a mini-butane torch. The problem is that heating needs to be done very rapidly because simply making everything uniformly hot has only a small benefit in releasing the corrosion seized fastener. The trick is to heat the stud to red heat, very quickly. This accomplishes several things, the most important of which is to cause the steel stud to expand more quickly than the aluminum. You need quick expansion and high heat because you want the steel stud to become plastic as well as to be prevented from expanding by the aluminum threaded hole.

A steel stud, heated into the plastic range tries to expand radially (become bigger in cross-section) but, if restrained by the surrounding aluminum hole, the stud cannot expand. Since the expansion pressure due to the expansion is so great, and the steel heated into the plastic range, the steel begins to flow axially (lengthwise). In this way the steel stud becomes longer but since the amount of material within the stud remains the same, the stud, when cool, is reduced in diameter.

A smaller diameter stud has more clearance and usually released from the hole with little effort. Welding a nut to the broken stud accomplishes this as well as to provide a means of turning.

I recommend using a larger torch such as a propane plumbers torch to rapidly heat the stud. The mini-butane torches are OK for soldering smaller items but lack the BTU's (quantity of heat) to rapidly heat an object of this size effectively unless you are fortunate. I always reach for the larger propane (Bernz-a-matic and similar) rather than my little butane, FWIW.

If it's a stubborn one I run it up to a friend's machine shop and use his oxy-acetelyne. It's not worth the space for me to keep tanks for mine these days as do so little bigger stuff and the propane works well for most.

Get a propane torch onto the stud, heat the snot out of it until it's red hot, let cool while melting a parafin wax candle against the threads as close to the aluminum surface as possible. Give the end a few solid smacks with a hammer to help loosen but don't go crazy as you want to loosen the threads and not drive the stud deeper. Hard taps with a small hammer rather than heavy blows with a large one is the ticket.

Clamp on you 10" vise grips, stud extractor or other holding device and work it loose. If it won't move, heat again, wick in some candle wax, tap and try to turn. Try to avoid loud use of "technical language" as it frightens the children.

I used to obtain supplies of old castings and components with siezed fasteners as practice for training new technicians in the college. They were not happy but learned to remove seized and broken such that they were never troubled again by the issue. Fork leg studs are not the ideal beginning but that's what you got.

Keep in mind that the hardware guy likely works there because he knows a bit about hardware and that sort of thing but isn't a machinist or tech. He's likely doing his best to help you with what he knows so be grateful and polite. Neither of us could likely step in and do his job either.

None of that makes him an idiot or deserves the slander. Let's play nice and share, folks.

[bwringer]

You don't need to heat these particular studs to red hot, at least not on a Suzuki GS.

The factory did indeed use thread locker on the studs -- you only need to get them hot enough to soften the thread locker (somewhere above the boiling point of water) and they'll come out just fine.

Of course, for other machinery, heating to red-hot is excellent advice. It's just not needed in this special case.

[ReSanti]

Many thanks!

A big thank you to bwringer and Normk for the advice. You guys gave me the confidence and tools I needed to get that broken bolt out. Now to get the new bolt stud in...

Thanks!

Reid S.

[chuck hahn]

Metric thread exhaust studs from any auto parts store...just did one yesterday.

[Normk]

I know that it is obvious but one should (actually "Must") consider the tensile strength of any fastener which one considers for replacement. Using a low grade item in brakes, steering or suspension applications may be a great mistake.

I think that few non-technicians appreciate the issue to any significant degree. Since virtually every aspect of motorcycle service relates to fasteners it woudl be well for everyone to spend time to understand at least the basics: sizing, main type identification, tensile strength, methods to achieve proper tension/clamping force, loading (i.e. shear, tension, bending, etc.) which affect application, tension as it affects fatigue, material compatability, locking devices, etc.

Selecting a stud of the same length and thread pitch from a hardware store rack may be a very bad decision if that item cannot exceed load requirements. Having an axle clamp stud fail could be more than inconvenient....

I'm not suggesting that the stud in question does or does not meet the requirements but simply hoping that someone will consider the issue.

[elrico]

Well appreciated info. from all.Have had/done fork axel stud break and extract/replacement also.yrs ago.Having reliable,accurate torque wrench to go w/bolt,stud whatever fastener, invaluable tool to have also. Normk,everyone thanks for your posts on this.

[bwringer]

I know that it is obvious but one should (actually "Must") consider the tensile strength of any fastener which one considers for replacement. Using a low grade item in brakes, steering or suspension applications may be a great mistake.

I think that few non-technicians appreciate the issue to any significant degree. Since virtually every aspect of motorcycle service relates to fasteners it woudl be well for everyone to spend time to understand at least the basics: sizing, main type identification, tensile strength, methods to achieve proper tension/clamping force, loading (i.e. shear, tension, bending, etc.) which affect application, tension as it affects fatigue, material compatability, locking devices, etc.

Selecting a stud of the same length and thread pitch from a hardware store rack may be a very bad decision if that item cannot exceed load requirements. Having an axle clamp stud fail could be more than inconvenient....

I'm not suggesting that the stud in question does or does not meet the requirements but simply hoping that someone will consider the issue.

Excellent advice as always, Norm.

In the case of these particular studs, as well as many other fasteners infesting our beloved steeds, it's apparent that Suzuki used the very lowest grade of pressed cardboard, cheddar cheese, and pencil shavings to form them -- they're very soft and strip far too easily.

Another example would be the 6mm studs holding on the oil filter cover. These are of the very worst quality imaginable -- every GS will need to have these replaced at some point.

Of course, where it really counts, Suzuki did use high-grade fasteners. For example, brake caliper bolts, axles, engine mount bolts, etc. But wherever they could get away with it, they used crap.

In other words, I've found that hardware store studs are much stronger than OEM Suzuki. And if you're really worried, you can always visit an auto parts store for a set of higher grade 8mm exhaust studs.


On a related note, it's also worth thinking carefully about which fasteners you replace with stainless steel. Stainless is very strong, but brittle (it won't tolerate elongation, bending or stretching), so it's best to avoid using stainless in highly stressed brake, engine, or suspension components. As long as you use anti-sieze, stainless replacements are perfectly fine on anything 6mm or smaller, and most 8mm applications.

[Normk]

Another area in which to beware of stainless is into exhausts because stainless becomes harder than glass then heated. Some rocket scientists at Cummins specified stainless exhaust studs into their highway truck diesels, for example! Nasty doesn't begin to describe!

I used to sell carbide drill bits (Usually Garr 1500 Series) and have found a file to be easier to drill than some stainless studs which have been heated.