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Old 01-16-2013, 06:08 PM   #1
wlfpck
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Auto Transmission Mechanics Question

I have a question for you gurus out there...

I got into an argument with a buddy of mine. We were debating whether or not revving an automatic is bad or not.

This got brought up because I just got the TRD exhaust for my tC. He wanted to hear it after I installed it so I gave it a little rev to 3k. He wanted me to rev higher and I said that I wasn't interested in destroying my dd.

He claims that an auto in park or neutral when revved to redline won't have any damage to it. The damage can only occur to the engine if it goes past redline.

I called B.S. on this and did NOT do this. Just want to make that clear.

Out of curiosity, I'd like to know if this is true or not. Not that I would go and do this, but more of curiosity behind the mechanics. I have always heard that you shouldn't rev an automatic in park/neutral. However, I never actually knew the mechanics behind it.

Would there be any damage to the auto transmission by doing this?



edited to include the same question but about the transmission.
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Last edited by wlfpck; 01-20-2013 at 06:11 PM. Reason: Edited to include transmission in the question
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Old 01-16-2013, 06:41 PM   #2
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I think I remember seeing Deev make a post a couple months ago to a guy asking a similar question. Anyways he said that revving any car in park or neutral is not good as the engine isn't under load and you could destroy your engine bearings.
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Old 01-16-2013, 07:01 PM   #3
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hm... That's interesting. I didn't think about that. Didn't think about the engine bearings.

Is there any down side for the auto transmission? I just figured that revving in neutral/park would just burn up the auto transmission fluid or something. That was the only explanation that I could think of that made sense with my limited knowledge.
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I swear, if I hit a raccoon I'll just keep pushing him, there's no way he's going to fit underneath the car

Last edited by wlfpck; 01-16-2013 at 07:04 PM.
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Old 01-16-2013, 07:43 PM   #4
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You will NOT damage the transmission by doing that..
Not saying you will NOT look like a fool though
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Old 01-16-2013, 07:45 PM   #5
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Lol. I did not do it and will not do it. I was just curious as to what mechanically could be damaging to the transmission which causes people to say that.
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I swear, if I hit a raccoon I'll just keep pushing him, there's no way he's going to fit underneath the car
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Old 01-16-2013, 09:24 PM   #6
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I call bullshit on reving it in park, it should make no difference if there is a load or not. What are the bearings magically more stressed out by less of a load : headscratch:

I've reved my automatic in park and neutral, i've never had any issues with it.
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Old 01-16-2013, 09:36 PM   #7
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Tippey, I dont think it was said that reving the car in park or neutral will damage the transmission bearings. IIRC what was said is that free reving the engine can damage the engine bearings. You kind of missed that he was talking about the engine and not the transmission.

IMO Reving an automatic in neutral or park wont damage anything in the transmission. But it can damage the engine.

Reving an auto just makes people look like a dumbass.
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Old 01-16-2013, 09:37 PM   #8
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I'm referring to the engine in my first statement, i think its bullshit. There is no way in hell you're going to damage an engine because its not under load.
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Old 01-16-2013, 09:40 PM   #9
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^^^ What? How do you figure that?
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Old 01-16-2013, 09:47 PM   #10
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^^^ What? How do you figure that?
Since yours is a more exaggerated claim, how do you explain why the engine would get damaged from free revving it? Why would the bearings be damaged? Why do they need a " load ".

A bearing should fit perfect and have 0 play, therefore if its oiled properly it shouldn't mater what forces are exerted upon it.
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Old 01-16-2013, 10:04 PM   #11
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Since yours is a more exaggerated claim, how do you explain why the engine would get damaged from free revving it? Why would the bearings be damaged? Why do they need a " load ".

A bearing should fit perfect and have 0 play, therefore if its oiled properly it shouldn't mater what forces are exerted upon it.
Um, no. Your not doing that to me. I know how you are. You came in here calling bull shit. You explain your self.
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Old 01-16-2013, 10:06 PM   #12
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Um, no. Your not doing that to me. I know how you are. You came in here calling bull shit. You explain your self.
I can't explain something i don't believe in. You need to explain why you think its going to damage the engine

You can't create a theory and then ask someone else to disprove it without giving any supporting details.



I think driving your car naked will cause the engine to overheat

Disprove it without understanding anything about it.
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Old 01-16-2013, 10:13 PM   #13
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agreed it wont damage anything, unless you accidentally drop it in drive
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Old 01-16-2013, 10:53 PM   #14
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hey since theres well versed honda people paying attention here, what seals can i get to in a jdm auto/lsd before its in the shell. how hard is it to change the internal filter if i can even get to it relatively easy. any other refurbishment ideas/checks for it before its put back into service, also this by no means will be done in a shop nor access 2 1 easily, basically my uncle in laws corner of the kitchen
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Old 01-16-2013, 10:54 PM   #15
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I think driving your car naked will cause the engine to overheat
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Old 01-16-2013, 10:55 PM   #16
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agreed it wont damage anything, unless you accidentally drop it in drive
lol neutral drops..the death of amany pubescent reigned hondas.
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Old 01-16-2013, 11:30 PM   #17
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hey since theres well versed honda people paying attention here, what seals can i get to in a jdm auto/lsd before its in the shell. how hard is it to change the internal filter if i can even get to it relatively easy. any other refurbishment ideas/checks for it before its put back into service, also this by no means will be done in a shop nor access 2 1 easily, basically my uncle in laws corner of the kitchen
I would personally speak to some of the OEM honda retailers online for help, if they cant help find someone whom speaks japanese and have them skype one of the repair shops in Japan. Maybe theyll send you a kit. Best of luck I too wanted a AUTO LSD H22 before I wrecked my other car. I hate driving stick lol.
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Old 01-16-2013, 11:38 PM   #18
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My theory, its not the RPMs that are hard on the bearings, its partialy the sudden increase and rapid acceleration. There isnít as much of a load to hold things in place during a free rev. The engine bearings also are a "cushion". With that being said one can see how it could be hard on the bearings.

Also with the increase in RPM there is an increase in oil pressure. A really rapid increase in RPM and the bearings might not see the proper oil pressure immediately.

EDIT, I forgot about something but it has nothing to do with bearings. I used to race Karts when I was in my early teens. I had a very well known engine builder who did all the work on my engines. He said that he could tell who free revved their engine a lot and who didnít by the marks on the side of the cylinder walls near the wrist pins. IDK why because I never asked.
Can you name those things (parts) that would be held by loading on engine? I am trying to understand what you are saying, you know.

Also, I cannot agree with statement saying that bearings are "cushion". Rather, oil is acting as "cushion" on plane bearings. This is one of four key functions of oil, IIRC. It's been more than 30 years since my college days.

Oil pump is over pumping oil to internals of engine at all times during engine operation. Oil pressure regulator is dumping excess oil pressure at all times during engine operation. On engine with normal operating temp, there should not be oil starvation at the bearings because of over pumping oil pump.

In my opinion, you can free rev your engine to red line if you want. Doing so should not harm engine, provided that you do it with the engine in normal operating temperature. Doing so may accelerate engine wear for no good reason on most part and may make you look like an ass.
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Old 01-16-2013, 11:38 PM   #19
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I would personally speak to some of the OEM honda retailers online for help, if they cant help find someone whom speaks japanese and have them skype one of the repair shops in Japan. Maybe theyll send you a kit. Best of luck I too wanted a AUTO LSD H22 before I wrecked my other car. I hate driving stick lol.
Ok lol, Ill ask Honda here & the dude at HMO when I set up the order and see what he says. I dont mind manual's I just dont feel like doing a conversion, its gonna be tits though regardless
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Old 01-16-2013, 11:43 PM   #20
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Can you name those things (parts) that would be held by loading on engine? I am trying to understand what you are saying, you know.

Also, I cannot agree with statement saying that bearings are "cushion". Rather, oil is acting as "cushion" on plane bearings. This is one of four key functions of oil, IIRC. It's been more than 30 years since my college days.

Oil pump is over pumping oil to internals of engine at all times during engine operation. Oil pressure regulator is dumping excess oil pressure at all times during engine operation. On engine with normal operating temp, there should not be oil starvation at the bearings because of over pumping oil pump.

In my opinion, you can free rev your engine to red line if you want. Doing so should not harm engine, provided that you do it with the engine in normal operating temperature. Doing so may accelerate engine wear for no good reason on most part and may make you look like an ass.
i agree with this guy! that is the same thing Spartan taught me
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