16

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 acting as a cathode pulling electrons from the anode (the aluminum threads) and causing them to corrode. Since there isn't much metal in the threads, and since a ...


13

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 drill necessary for drilling before tapping threads into the hole. There is also a metric section off to the side. 1/4 20 would be a #7 drill bit or 0.2010 ...


13

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 and alloys thin threads (both male or female) This applies to both loosening and tightening. Take the example of spark plugs and head bolts, which screw into ...


12

"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 that described the Torx design. "Torx Plus" is also a trademark. The Torx Plus design was developed to handle more torque and that design is under a patent ...


9

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 being of your family and yourself, not to mention those around you should any of these bolts fail? As for T2Y bolts, here is what Fel-Pro says about them: T-T-Y ...


8

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 = .3125 . Metric is even simpler you don't use the reciprocal at all... M8x1 is 8-1 = 7mm M5x.8... 5-.8 = 4.2mm. Of course, many of the SAE sizes require odd-ball ...


8

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


7

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 seizing. This is further exacerbated with aluminium which is a relatively soft metal but with hard surface oxides also the difference in hardness between ...


6

Yes, 9 is the stem length in the graphic you have pictured.


6

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 tension in the fasteners. This is, more or less, the same as over torquing and may lead to failures of the fastener (or the part, or the gasket). Lubricants can ...


5

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 filler material and a release agent. You fill the hole with one of the materials of the kit. The bolt is coated with a second material, a release agent that keeps ...


5

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 stretch the hose, pulling it to the screw area. In smaller sizes, screw clamps leave a flat spot under the screw fitting; this leaves low pressure areas at the ...


5

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 loosening the bolt may do. As a result there are less accidentally loosened head bolts. If you are a DIY person, which I am, I don't have a real issue with ...


4

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 you don't have the freedom of movement to rotate it 1/6, this way you can find the position that suits you best. Hope I've been clear enough, sorry if I have ...


4

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. If you use a castle nut with a cotter pin, it should stop the nut from removing itself.


4

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 Caledonia Rally of 2006 (in which I competed as navigator in this glorious Lancia Flavia Coupe) one on the competitors encountered a problem out of the road that the ...


4

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 the fastener and whether it is left hand or right hand thread. On the ends the tool also includes files meant for internal threads. There is a size limit to ...


4

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 the aftermarket picks up the slack for fasteners. If not, then you'd have to go back to the dealership. If they don't have any, you can got to an alternative ...


4

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? For a conventional bolt, ignoring the torque required to overcome friction when you tighten it, there is a linear relation between the amount of torque and the ...


4

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 effective if the parts are not clean. Tabs work if the parts are clean or dirty.


3

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 they'll self-lock effectively. When purchasing a new balljoint, replacements for these are almost always provided. Your local dealership should charge you no ...


3

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 are using double-hex heads to allow for greater torque, despite the complexity of having different tooling. Otherwise they would use simple outer hex bolts. Such ...


3

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 bonus question goes, I would agree with your gut. There is no way a spring clamp is going to clamp any better than a worm gear clamp. You would be able to get ...


3

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 support bracket, and it's the bracket itself that has the threaded hole. This bolt hole felt so loose because there aren't threads; it's drilled to the full ...


3

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 ratchets to downgrade from 1/2" to 3/8"? Yes. 1/2" to 3/8" adapters are readily available on all the tool trucks, and most other places that sell tools. Here's ...


3

I have only ever had/used 1/2" drive air impact guns. The reason is simple: I can produce as much/more torque with a 1/2" breaker bar than a 3/8" impact drive can produce. If I need to use an impact wrench (which usually works really well on rusty bolts), I'll grab the 1/2" drive and have at it. For me, there usually is no reason for a 3/8" impact drive, so ...


3

The 1/2"-drive can withstand more torque than its 3/8" sibling (due to its larger moment of area). Since the question clearly states that this is needed to undo really tight or stuck bolts, the 1/2"-drive impact wrench makes more sense. As for recommendations, there will always be someone recommending Brand A over Brand B and vice versa. That said, I'm ...


3

Best practice for all fasteners is clean and dry threads. There are three exceptions. If your using thread locker use the same torque. It is generally assumed that thread locker does not change the torque value. Fasteners that require thread sealant, such as ones that go into water jackets, have torque that is already compensated for the sealant. For ...


3

Use a collet block These are designed to take a collet and tighten down on a rod. It works just like collets in a lathe or the spindle on a mill. You can hold the block in a vise, install the appropriate collet, tighten it down, then get to work without damaging the stock material. EDIT: Alternatively, use V blocks. These are less preferred because they ...


3

Yes, part of the function of a washer is to spread the load. If the manual or parts list lists them then they should be there - someone in the past may have made a mistake and left them out...


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