Urban myths about cars

[syncro.]

Rollcage said:

TallPaul said:

syncro. said:

... I'd rather not load up the un-lubricated thrust bearing in the engine then turn it over. Much better in my oppion is to slightly increase the stress on the starter and wait till the thrust bearing is lubricated before loading it up!

How does the thrust bearing get lubricated?

I dont think he quite knows what he is talking about!

Thrust bearing is not part of the engine ,for a start.

Certainly wouldnt be an issue with it being lubricated or not - its just a bearing, like any other, but just more difficult to get at!

I think I do, sound more like its you who doesn't fully understand how an engine works.

I don't mean the clutch release bearing I mean the cranshaft thrust bearing, usually located either side of the crankshaft centre main bearing. This also gets loaded when you press the clutch, it is the place the force applied by the clutch release bearing is reacted, these are typically splash lubricated so don't get any oiling until the engine is rotating. There is also a very high change of this bearing being almost completely devoid of oil if the engine has been stopped for any period of time. The thought of pressing two plain bearings together with a resonable amount of force when they arn't lubricated doesn't sit well with me. Obviously the clutch release bearing is a completely different matter as you say as its a sealed bearing.

[The Wookie]

syncro. said:

I think I do, sound more like its you who doesn't fully understand how an engine works.

I don't mean the clutch release bearing I mean the cranshaft thrust bearing, usually located either side of the crankshaft centre main bearing. This also gets loaded when you press the clutch, it is the place the force applied by the clutch release bearing is reacted, these are typically splash lubricated so don't get any oiling until the engine is rotating. There is also a very high change of this bearing being almost completely devoid of oil if the engine has been stopped for any period of time. The thought of pressing two plain bearings together with a resonable amount of force when they arn't lubricated doesn't sit well with me. Obviously the clutch release bearing is a completely different matter as you say as its a sealed bearing.

Err... When the clutch is disengaged there is no force on the engine thrust bearings. The thrust bearing is loaded by the pressure of the clutch on the flywheel when the clutch is engaged, hence it being good practice to put your foot on the clutch when you're starting the engine.

[Dave_ST220]

The Wookie said:

syncro. said:

I think I do, sound more like its you who doesn't fully understand how an engine works.

I don't mean the clutch release bearing I mean the cranshaft thrust bearing, usually located either side of the crankshaft centre main bearing. This also gets loaded when you press the clutch, it is the place the force applied by the clutch release bearing is reacted, these are typically splash lubricated so don't get any oiling until the engine is rotating. There is also a very high change of this bearing being almost completely devoid of oil if the engine has been stopped for any period of time. The thought of pressing two plain bearings together with a resonable amount of force when they arn't lubricated doesn't sit well with me. Obviously the clutch release bearing is a completely different matter as you say as its a sealed bearing.

Err... When the clutch is disengaged there is no force on the engine thrust bearings. The thrust bearing is loaded by the pressure of the clutch on the flywheel when the clutch is engaged, hence it being good practice to put your foot on the clutch when you're starting the engine.

That is how i understood it too, which maybe explains why many manufacturers recommend it!

[syncro.]

The Wookie said:

syncro. said:

I think I do, sound more like its you who doesn't fully understand how an engine works.

I don't mean the clutch release bearing I mean the cranshaft thrust bearing, usually located either side of the crankshaft centre main bearing. This also gets loaded when you press the clutch, it is the place the force applied by the clutch release bearing is reacted, these are typically splash lubricated so don't get any oiling until the engine is rotating. There is also a very high change of this bearing being almost completely devoid of oil if the engine has been stopped for any period of time. The thought of pressing two plain bearings together with a resonable amount of force when they arn't lubricated doesn't sit well with me. Obviously the clutch release bearing is a completely different matter as you say as its a sealed bearing.

Err... When the clutch is disengaged there is no force on the engine thrust bearings. The thrust bearing is loaded by the pressure of the clutch on the flywheel when the clutch is engaged, hence it being good practice to put your foot on the clutch when you're starting the engine.

So lets follow the load path, the clutch release bearing presses on the pressure plate which inturn presses on the flywheel which magically stays still and reacts all the forces... no. This force is passed through the flywheel to the crankshaft which is reacted by the thrust bearings in the crankcase.

[The Wookie]

syncro. said:

So lets follow the load path, the clutch release bearing presses on the pressure plate which inturn presses on the flywheel which magically stays still and reacts all the forces... no. This force is passed through the flywheel to the crankshaft which is reacted by the thrust bearings in the crankcase.

No you mule, the clutch release bearing presses on the diaphragm spring which is reacted by the pivot and pulls the clutch away from the flywheel. The clutch's natural state is with the spring pressing it against the flywheel

ETA - Why not have a play with the little flash app on this page

http://auto.howstuffworks.com/clutch1.htm

ETA Again - Twas in fact I who is a visually unappealing, intellectually challenged beast of burden

Edited by The Wookie on Wednesday 16th June 10:57

[syncro.]

The Wookie said:

syncro. said:

So lets follow the load path, the clutch release bearing presses on the pressure plate which inturn presses on the flywheel which magically stays still and reacts all the forces... no. This force is passed through the flywheel to the crankshaft which is reacted by the thrust bearings in the crankcase.

No you mule, the clutch release bearing presses on the diaphragm spring which is reacted by the pivot and pulls the clutch away from the flywheel. The clutch's natural state is with the spring pressing it against the flywheel

Draw a FBD of the pivot, something has to support it and react the force there, to reitterate pivot -> pressure plate -> flywheel -> crank -> block

[The Wookie]

I have drawn an FBD and you are in fact right, I take it back

[syncro.]

Explain to me where the force in red is being reacted, theres a force in balance there so you need a reaction force as the entire engine doesn't fly out the side of the car when you hit the clutch!

Just seen your post, thanks!

Edited by syncro. on Wednesday 16th June 10:34

[The Wookie]

Yes yes, I just agreed with you, you are right!

I'll just shut up now

[Drive Blind]

what about the guy driving home in his nearly new Jag.

Arrives first on the scene after a woman had crashed. Being a good guy he stops to help and suggests that she waits in his car until the emergency services arrive. Her car is a write off.

The ambulance guys arrive and ask if she's in any trouble. 'Just got a sore neck' she replies. They slap the neck brace on her and then get the fire brigade to cut the top off the car to get her out.

Insurance doesn't cover it, Jag man is 30K out of pocket.

[Trommel]

The Wookie said:

No you mule, the clutch release bearing presses on the diaphragm spring which is reacted by the pivot and pulls the clutch away from the flywheel. The clutch's natural state is with the spring pressing it against the flywheel

Starting a car with the clutch in most definitely causes wear on the CRANK thrust bearing, which is what is being discussed here. With the bearing pushing or pulling against the crank before the engine rotates the thrust side is loaded without any oil film, then you turn it over on the starter.

Anything putting pressure on them, in either direction, will obviously cause them to wear.

Edit - I see you've changed your mind.

Edited by Trommel on Wednesday 16th June 10:42

[off_again]

Drive Blind said:

what about the guy driving home in his nearly new Jag.

Arrives first on the scene after a woman had crashed. Being a good guy he stops to help and suggests that she waits in his car until the emergency services arrive. Her car is a write off.

The ambulance guys arrive and ask if she's in any trouble. 'Just got a sore neck' she replies. They slap the neck brace on her and then get the fire brigade to cut the top off the car to get her out.

Insurance doesn't cover it, Jag man is 30K out of pocket.

I was pretty sure that was a true story....

My brother used to work opposite a Ford dealer many years ago. Woman picks up her BRAND NEW Ford and screws up leaving the garage - shoots across the road, smashes into a parked car and gets hit by another car. Total write off and carnage for a few other cars - obviously covered by insurance, but barely drove 3 metres on the public highway before a crash...

Made the local paper that one!

[The Wookie]

Trommel said:

When you were criticising the shoddy engineering in the Bristol Fighter you said you were an engineer. Are you sure?

Bloody hell how long have you been waiting for that one!

Pardon me for having a bit of brain fade in the year since I shared my opinion on Bristol!

[Trommel]

[mnkiboy]

Drive Blind said:

what about the guy driving home in his nearly new Jag.

Arrives first on the scene after a woman had crashed. Being a good guy he stops to help and suggests that she waits in his car until the emergency services arrive. Her car is a write off.

The ambulance guys arrive and ask if she's in any trouble. 'Just got a sore neck' she replies. They slap the neck brace on her and then get the fire brigade to cut the top off the car to get her out.

Insurance doesn't cover it, Jag man is 30K out of pocket.

Don't believe it for a minute. Far too many holes in that story for it to be true.
Why would they rip the roof off an obviously undamaged car?
Why would a woman who only has a sore neck not point out the obvious error until they start ripping the roof off?
Why would the owner of a new £30k Jag walk so far away from the scene that he was unaware of what was going on.
Why should we beleive that a member of the public these days would actually stop to help at the scene of an accident?

[Chunky La Funga]

Drive Blind said:

what about the guy driving home in his nearly new Jag.

Arrives first on the scene after a woman had crashed. Being a good guy he stops to help and suggests that she waits in his car until the emergency services arrive. Her car is a write off.

The ambulance guys arrive and ask if she's in any trouble. 'Just got a sore neck' she replies. They slap the neck brace on her and then get the fire brigade to cut the top off the car to get her out.

Insurance doesn't cover it, Jag man is 30K out of pocket.

Why is Jag man in any way liable?

[Lefty 200 Drams]

Chunky La Funga said:

Drive Blind said:

what about the guy driving home in his nearly new Jag.

Arrives first on the scene after a woman had crashed. Being a good guy he stops to help and suggests that she waits in his car until the emergency services arrive. Her car is a write off.

The ambulance guys arrive and ask if she's in any trouble. 'Just got a sore neck' she replies. They slap the neck brace on her and then get the fire brigade to cut the top off the car to get her out.

Insurance doesn't cover it, Jag man is 30K out of pocket.

Well, it's his car the fire brigade have just chopped the roof off...

Allegedly.

Why is Jag man in any way liable?

[nogsk]

That someone in the USA sued the manufacturer of his RV as after he put it in 'cruise control' on a long straight road, he went out back to make a coffee - the pilotless vehicle crashed and he successfully sued for negligence?

[Garett]

Hear this one from a guy at work yesterday talking about a new engine being run in.

"they don't reach the maximum efficiency until the there's been a built up of carbon to help reinforce the seals"



Errrrrr, you what mate?!

[omgus]

As it had been debunked on this thread I now feel the world is a worse place now I know that the Mitsi Starion wasn't the product of a telephone error.

Although first heard from Clarkson (so pinch of salt already taken) I would like to know if it is true that TVR just ignored euro rules about ABS for the Sagaris because they "didn't get the memo" or if low volume manufacturers had a different set of rules to follow. I really want that to be true.