16 votes
Accepted

Stainless Steel Fasteners

Stainless and aluminum are pretty far apart in the galvanic series of metals with aluminum at the anodic (corroded) end. This means that in the presence of an electrolyte the stainless bolt will be ...
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  • 14.3k
14 votes
Accepted

What fasteners should not be loosened using an impact wrench, and why?

As the name suggests, impact wrenches have the ability to impart high amounts of momentum change. The delivery of this momentum change is hard to meter, so it is quite easy to damage: soft metals ...
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  • 39k
13 votes
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What size hole should be drilled for an individual tap?

https://engineering.purdue.edu/ME463/Course%20Documents/Design%20Resources/starrett-inch-metric-tap-drill.pdf This is my favorite chart for tap drill sizes. The chart incorporates tap sizes and the ...
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  • 15.9k
12 votes
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Torx vs. Star Fasteners

"Torx" is a trademark, i.e. a name for a company and can be renewed indefinitely. The Torx design used to have a patent that expired in 1990. After the Torx patent expired, ISO 10664 was created ...
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9 votes
Accepted

"Always Replace" (torque-to-yield) Bolts

I cannot tell you directly if the bolts you are using are Torque to Yield (TTY or T2Y) bolts, but if Bently says to replace them, you bet I'd do it. What are three bolts in comparison to the well ...
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8 votes

What size hole should be drilled for an individual tap?

There is a formula for it.... take the nominal size (.250") and the reciprocal of the threads per inch (20TPI = .05). .250 - .05 = .205, the drill size. Here's another 3/8-16.... .375 - .0625 = ....
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8 votes
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Securing exhaust manifold studs?

According to their datasheets Resbond 970TS is capable of withstanding 2100°F Another method would be the use of locking wire on the studs
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  • 7,828
7 votes

Stainless Steel Fasteners

The most immediate issue is galling. Stainless steel typically contains a lot of suspended carbides ie very hard particles in a soft matrix. This means that stainless threads are prone to galling and ...
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  • 1,586
7 votes
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Removing rusted partially broken engine fasteners

Your best bet is to use heat. Take a torch (propane will work just fine) and heat the stud portion until it is cherry red. Then douse it in PB Blaster or WD40 or just about any other lubricant. Then ...
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6 votes

Spring vs worm gear clamps?

Great question. Spring clamps have several advantages from the engineers point of view. They apply even pressure around the joint, screw clamps do not. Screw clamps pull from one side and this can ...
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  • 11.5k
6 votes
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In a clip, what does the "Stem Length" mean?

Yes, 9 is the stem length in the graphic you have pictured.
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6 votes
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Torque specification thread lubricant best-practice as specified by manufacturers

In general, the assumption is that you are not using a lubricant. When a lubricant is specified, obviously then you use it. Using a lubricant will result in the same torque readings, but higher ...
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  • 14.3k
6 votes

Removing rusted partially broken engine fasteners

Not exactly what you're asking for, but maybe a different solution. I had similar problems with a couple of Chevys. More-or-less, I cut the studs flush, and used a pair of 'split flanges' to join ...
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  • 887
5 votes

Why do manufacturers use different bolt types on cylinder heads?

From what I understand the answer to this very simple and logical. When someone might be attempting to DIY a fix and have a particular socket that fits a nut, they may just turn it not realizing what ...
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  • 32.8k
5 votes

Bolt reaches end of hole but threads don't grip

Loctite thread repair product #: 28654 (also known as Form-A-Thread) may help your problem. I wouldn't suggest using it on a headbolt but I think on a timing cover it would work. Basically it a ...
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  • 19.7k
5 votes

Removing rusted partially broken engine fasteners

These bolts can be very difficult to remove due to the rust and heat they are exposed to. The threads are rusted both externally and internally. I've had some success with the following: Soak with a ...
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  • 9,459
4 votes

Alternatives to left-handed thread without resorting to specialist tools

Left handed nuts are typically cut that way so the spinning of the motor/engine will not loosen the nut over time. A right handed nut will likely loosen over time from the torque of the motor starting....
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  • 8,413
4 votes

Alternatives to left-handed thread without resorting to specialist tools

The specific repair you describe; repairing a radiator fan without the correct fixings, can be done in a number of ways. One of the most creative ways I've ever encountered was on La Carrera ...
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4 votes
Accepted

Alternatives to left-handed thread without resorting to specialist tools

There is a tool known as a thread file. While it is a semi specialty tool, it is common for garages to own one. A thread file only depends on the thread pitch and independent of both the diameter of ...
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  • 15.9k
4 votes

Spring vs worm gear clamps?

The one simple reason manufacturers use spring clamps instead of worm gear clamps: Cost It costs far less to mass produce spring clamps and use them than it does worm gear clamps. As far as your ...
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4 votes

Why do manufacturers use different bolt types on cylinder heads?

Having had to work in tight spaces, I say it's very useful to have a bolt which you can turn in less than one-sixth turn. What I mean is, that bolt can be turned with a common hex tool, but sometimes ...
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4 votes
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Sources of Torque-To-Yield bolts?

The TTY bolts need to be specific to the application, but don't need to be sourced through the dealership. Fel-Pro makes a lot of bolts which replace the stock bolts in a TTY application. Usually ...
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4 votes

"Always Replace" (torque-to-yield) Bolts

The other question I'd love an answer to is why are the bolts "always replace." Does the torquing process (20 Nm + 90º) weaken the bolt, or is it not reproducible? Or something else altogether? ...
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  • 2,929
4 votes

Air trapped inside threaded "blind" hole vs. hole integrity

Air usually will not cause this issue. It will compress quite a bit without the worry of it causing issues. If thread locker is use, it would be trapped. Without it, it will escape past the threads ...
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4 votes

Con rod fastener's washers: tabbed or spring washers?

I would use the tabbed washers : they don't affect the torque reading as once the nut is torqued, they bend easily and just lock the nut into place. Loctite - if available - may not always be ...
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  • 34.4k
3 votes

"Always Replace" (torque-to-yield) Bolts

The actual reason to replace the bolts isn't specifically the bolts, it's the nuts. These are self locking (i.e. Nyloc) style nuts and after they've been removed and refitted, you can't be sure that ...
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3 votes

Why do manufacturers use different bolt types on cylinder heads?

Those are engine head bolts and need to be torqued precisely, in order to last their useful life. Since they are located in an awkward location and have to be assembled in a factory, I suppose they ...
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  • 259
3 votes

Spring vs worm gear clamps?

Spring style hose clamps are typically fabricated from steel alloy and plated with zinc for corrosion protection. Aluminum would not be a good choice for spring clamps due to low elastic limits and ...
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3 votes
Accepted

Is my Forester's caliper bracket bolt hole stripped?

Well, this was me being an idiot. Or, more charitably, not thinking the situation through. When I got around to reassembly, I realized that this hub assembly is between the head of the bolt and the ...
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  • 1,413
3 votes

Can 1/2 drive impact wrenches be adapted to use 3/8 sockets?

1/2" drive is the way to go, the only advantage to the 3/8" is it's going to be smaller and lighter. With the major disadvantage of much less torque. are there any adapters like in regular hand ...
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