Questions tagged [terminology]

For questions about words, phrases and definitions that are specific to maintenance and repair of motor vehicles.

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1
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1answer
34 views

Ride stiffness vs roll stiffness

What is the difference between ride and roll stiffness? Are they separate or closely related?
1
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1answer
50 views

AC service valve/hose sizes

Every time I find myself needing this information, searches turn up wrong or incomplete information. What are the standard sizes for automotive air conditioning service valve and hose fittings for ...
2
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2answers
29k views

CV Axle vs drive axle, vs cv shaft, vs drive shaft

I feel like I'm hearing a bunch of terminology that sounds like it may be the same thing or at the least related parts of a sub-assembly. The part I know for sure on my car is labeled as the CV Axle ...
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5answers
8k views

What is the stick shift called in an automatic?

In a manual transmission car, the transmission control is generally called the "stick shift". What is it called in an automatic car?
9
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2answers
11k views

Crank vs turn over vs start vs whatever

I see conversations like the following a lot: A: My car won't start. B: Does it crank? A: Yes but it won't turn over. B: Wait, I'm confused. So, it tries? A: Well it makes a sound. B: ...
4
votes
2answers
111 views

Renewed brake pads

I am new to the automotive world and especially in services. I did some research on some things, but others I cannot find definite answer. I bought a car which has had "renewed brake pads and discs"...
10
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3answers
5k views

What exactly is a jackshaft?

The Wikipedia entry for the Ford Cologne 4.0L SOHC describes the use of a "jackshaft": It uses a jackshaft in place of a camshaft to drive a timing chain to each cylinder head. Three timing chains ...
4
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1answer
3k views

What is an orbital motor?

I came across this word on a particular type of hydraulic motor, but I do not understand what is so "orbital" about orbital motor. Essentially, to my understanding, it is just a motor powered by ...
12
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4answers
24k views

What is the large metal bar that sits behind the bumper?

I've seen a few vehicles with their plastic bumpers off recently. They all seem to have a large metal crossbar sitting in front of the radiator. What is this called? Update: And a sideview of the ...
12
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3answers
47k views

What's the meaning of a “lean” vs “rich” air fuel mixture

I'm learning about vacuum leaks on engine intakes and I'm hearing this terminology of lean air fuel mixture. I thought I heard of a rich mixture before too. What's a normal mixture referred to as? A ...
7
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1answer
8k views

Which side of the engine is the “front”?

Maybe this is a silly question, but what is the technical definition of the "front" vs. the "rear" of the engine? On my vehicle, from the context of part names, the "front" is the side with the ...
5
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5answers
2k views

What do you call the distance driven on a vehicle?

In the US (and I suppose other places where distances are still measured in miles) the term is mileage. But what about the rest of the world? Is there an SI term for mileage? Or is mileage still the ...
6
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2answers
818 views

Term to indicate how much force one needs to exert to steer the wheels of a car

What is the proper term to indicate how much force the driver needs to exert to steer the wheels of a car?
15
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2answers
6k views

Is there a difference between a sunroof and a moonroof?

The sunroof tag here states: The opening in the roof of a car. Usually a glass panel that opens by sliding down and back. However, the owner's manual of my 2006 Mazda 6 refers to the opening only ...
11
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4answers
58k views

What are the “1” and “2” or “L” gears used for on an automatic?

In a car with an automatic transmission, we are normally greeted by the acronym PRNDL, or in some cases (older cars) PRND21. I know that the L, 1, or 2 will cause the transmission to stay in a (L)...
6
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2answers
14k views

What does NM@rpm mean in car's spec sheet?

I checked my car's specs sheet this morning and in it I noticed: Torque NM@rpm: 145@4600 What does NM@rpm mean?
4
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1answer
1k views

What does BHP@rpm mean?

In my car's specs sheet I noticed: Power (BHP@rpm): 117@6600 What does BHP@rpm mean?
2
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0answers
101 views

Calculated vs absolute engine load [duplicate]

The OBD-II protocol (SAE J1979) has a couple of PID's that relate to engine load: +------+-----+---------------------------------+ | Mode | PID | Description | +------+-----+------...
12
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1answer
3k views

What exactly are fuel trims?

What is meant by the term "fuel trim"? Why are they so important in diagnosing engine operation issues? How do short-term fuel trims differ from long-term fuel trims?
21
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3answers
11k views

What is valve float and how does it impact engines?

The Wikipedia entry is hard to grok: Valve float is an adverse condition which can occur at high engine speeds when the poppet valves in an internal combustion engine valvetrain do not properly ...
1
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2answers
163 views

What is OSHA/NIOSH?

I have heard both OSHA and NIOSH mentioned in answers here what are they and why do I need to be concerned about them when it comes to working on my car? This is inspired by a question from Wyatt ...
3
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1answer
862 views

Shortblock vs Longblock

What is the difference between a shortblock and a longblock? Both terms are used to refer to the engine, but what's the difference between them?
18
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3answers
178k views

What exactly is a “burnt valve” and what causes it?

I've come across this term a couple of times in the context of diagnosing engine-related issues, but don't know what it refers to. Here is an example from an automotive forum I frequent: I gotta ...