Thread: Engine braking
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Old 04-13-2011, 07:43 PM   #28 (permalink)
jtbo
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Quote:
Originally Posted by justjohn View Post
Thanks for all the good replies. I'm definitely learning.


I think there must be some fundamental flaw in my understanding of the system though, because rev-matching seems counter-intuitive in terms of wear to me. Oh wait, I think I may have just made a breakthrough. Hang on and tell me if this is right.

"It's not using the clutch when RPMs are high that's hard on it, it's when there is a large difference between where the engine speed is and where it 'should' be for whatever gear you're going to."

If that's right then I've got it. Cause when I learned that keeping on the gas during upshifting was bad for it, I originally assumed the logical link was simply "high RPM = bad for the clutch." Assuming that's wrong, then that's where most of my confusion was coming from.

I always thought rev-matching was just for clutchless shifting, which I have wanted to learn for a while as well, but I've been stuck with an automatic.
Remember that there are box input shaft rpm and engine rpm, it does not matter if engine rpm is high or low, it matter what speed difference is between two. Well when speaking of wear, also clutch slipping at high speed wears more than at slow speed, but that also is more like difference in those two rpm than exact engine speed.

You can have engine at low rpm and box input shaft at high rpm and again you get more wear than would be optimal.

Gearbox input shaft speed depends from which gear is in.

That is how I understand it, but also gearbox internals have bit mystery to me.

edit: One thing I remembered, some engines do burn oil when engine braking at high rpm, so that is good to remember, frequent oil checks are not bad thing if engine braking near redline.
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