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| Author |
Message |
nharmon
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No Engine Brake
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Jun 30 17:06 UTC 2006 |
I was riding my motorcycle through Blissfield, Michigan yesterday and
coming into town there were signs saying "No Engine Brake" and "Engine
Braking not Permitted". I found this quite strange because on a
motorcycle you use the engine to slow the bike down.
It turns out that an "engine brake" is something entirely different and
mostly found on semi-trucks.
http://www.dot.state.oh.us/dist3/Planning/Traffic/NoEngineBrakes.asp
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| 12 responses total. |
tod
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response 1 of 12:
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Jun 30 19:30 UTC 2006 |
Nice way to burn a clutch
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cyklone
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response 2 of 12:
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Jun 30 19:45 UTC 2006 |
Engine braking (on bikes) is also a good way to wear out the valve train
prematurely. As an honest mechanic once pointed out, it's cheaper to replace
brake parts than valve parts.
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nharmon
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response 3 of 12:
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Jun 30 20:01 UTC 2006 |
That does makes sense. Weird, in my class engine braking was taught as
an effective way of saving brake life, but it seems it is at the expense
of the engine.
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tod
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response 4 of 12:
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Jun 30 22:51 UTC 2006 |
If you have a drivetrain warranty or something then maybe that's the
ticket..you pay for brake pads.
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nharmon
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response 5 of 12:
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Jul 1 02:08 UTC 2006 |
When you break-in a racing engine (in a car) you do a lot of engine
braking because it keeps the piston rings rotating (preventing them from
wearing into the cylinder in the same spot).
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cyklone
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response 6 of 12:
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Jul 1 03:07 UTC 2006 |
I can understand that for a break-in. I just wouldn't make it a habit. I
always prefer to save engine braking for emergencies. Learn to brake
properly without it, and then use it only when really neccessary. That way
you're building in a margin of safety.
Having said that, I confess to sometimes flicking off the overdrive when
I'm coming off a highway ramp in my car. But I usually don't do it until
I'm down to about 1000 rpm, so I only bump up to about 1500.
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gull
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response 7 of 12:
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Jul 4 18:42 UTC 2006 |
For me it depends on the situation. I don't engine brake on highway
ramps, but I routinely downshift to engine brake when coming down
mountain grades. The tradeoff there is the extra wear of one
downshift, versus dragging my brakes for miles and potentially
overheating them. To me it's a safety issue, especially when driving a
truck. Once you've experienced brake fade you won't want to go there
again. On one automatic U-Haul I drove this actually seemed to be
built into the transmission's shift logic -- the harder I got on the
brakes, the more aggressively the transmission would downshift.
I tend to think that, at reasonable RPMs, the extra wear on the engine
is pretty minimal. (This may be different on bikes, which seem to run
high RPMs all the time.) On manual transmissions the additional wear
will be to the clutch, and will depend a lot on your skill at matching
revs while making the downshift.
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cyklone
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response 8 of 12:
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Jul 4 19:00 UTC 2006 |
You're definitely right about the mountain grades. I think the problem
with automatically popping down a gear to slow is more than just about
engine wear. For one thing, there's the possibility of over-revving and
getting near the redlne. I also recall from my biking days that a
downshift on a less than perfect road surface can make the back end
twitchy.
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nharmon
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response 9 of 12:
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Jul 5 02:41 UTC 2006 |
I have adjusted my stopping behavior to better fit the recommendations
of my motorcycle owner's manual. It says to slow in gear until just
before the stall point and then downshift.
I spoke to a few knowledgable motorcycle people and the general
consensus seems to be to stick to what the manual recommends. At high
RPMs the rev limiter would be unable to stop the engine from speeds that
would damage itself, and slowing while keeping the engine speed matched
and in gear with the road allows for quick evasive manuevers (including
speeding up quickly) if necessary.
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n8nxf
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response 10 of 12:
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Jul 7 17:09 UTC 2006 |
That sounds more like it. The only way I can see doing in the valves by using
the engine to brake is by over-revving the engine. I use to downshift my cars
all the time but found that I was wearing out the clutch prematurely and
clutches cost more to replace than brakes. On most motorcycles, downshifting
is a good idea and clutches are pretty easy to get at and replace, for the
most part. Another term for the engine braking truckers use is "jake-brake".
The diesel is pretty noisy when using the engine brake so it's often
discouraged in noise sensitive areas.
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gull
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response 11 of 12:
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Jul 12 01:00 UTC 2006 |
Re resp:8: Yes, that makes sense, especially on a motorcycle. I've
never had a car get squirrelly due to a downshift...while it certainly
could happen, in most situations cars don't have enough engine braking
relative to the amount of traction they have to break the rear end
loose that way. In a car, using a good heel-toe technique will also
smooth things out a lot. ( And it's fun when you pull it off
well. :) )
Re resp:9: That's pretty much the technique I follow in my stick-shift
car, except that if I'm coming to a stop I'll often just shift to
neutral or hold in the clutch. Downshifting in that situation does
have the advantage of putting you in the correct gear to accelerate
again if you need to, which is nice if you're in a situation where you
want to drive a bit aggressively.
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cyklone
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response 12 of 12:
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Jul 12 02:55 UTC 2006 |
As for that last part, I admit that "sporty" or competitive driving
involves those things. I think when you enjoy that kind of driving you're
willing to accept a little increased wear and tear across the board (good
tires aren't cheap either!). However, nate said he was a beginner on his
bike, so he should probably start with the basics first.
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