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Old 06-19-2013, 08:39 PM   #21 (permalink)
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Just enough clutch to get the engine spinning over. When perfected you will feel practically no change in inertia, it does not take much, remember when they were cranked by hand (engines that is).

On your long hill descent with obstructing traffic just leave it in gear and use engine braking to keep a safe distance. Most modern cars use no fuel when you have your foot off the gas and are engine braking.

I would probably use engine off coasting if I had .5 plus mile opportunities. In my Fiesta with the 6 speed powershift I just slip it in neutral and leave the engine on, unless I need to slow down, then I put it back in gear first then use the brakes only if I have no choice.

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Old 06-20-2013, 04:16 PM   #22 (permalink)
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My Honda Type "R" has a very sharp clutch, which is probably why my bump experiments this afternoon weren't universally smooth. By far the smoothest was when engaging from around 30 mph where the full engine revs are around 1500. I released the clutch as quickly as possible after I saw the engine catch, but in the 45 mph region I couldn't get it particularly smooth - it seems to "bump" immediately on engine fire up, if that makes any sense.

If I always bumped at 30 mph it'd be fine, but I'd be losing too much speed if I let it coast down that slow.
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Old 06-20-2013, 05:10 PM   #23 (permalink)
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I've bump started my Pan on a number of occasions; that is very tricky, as the engine is quite big for the weight. But even that can be bump started without much ado with a swift but delicate half-release. Top gear is a must.
I had a Suzuki Freewind 650 cc single cylinder. I could never get that bumpstarted in an orderly fashion; it did behave vile then, like a bucking bronco.
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Old 06-20-2013, 05:22 PM   #24 (permalink)
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Quote:
Originally Posted by RedDevil View Post
use top gear
I'd like to throw an asterisk * on that point.

I've had occasional trouble getting my Firefly/Metro to fire up using top gear when at low road speeds. I'm guessing the motor doesn't get spun up fast enough (RPM).
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Old 06-20-2013, 05:31 PM   #25 (permalink)
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True, there is a limit to how slow you can go. Obviously you cannot bump start in 5 when you're only doing 10 mph; the revs would be below idle speed. But then there's the starter motor.
That's the coast to the lights choice; bump start when they get green, but just stop with engine off when they stay red, and use the starter motor when it finally turns green rather that bump starting at the last remains of speed when the lights are still red.
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Old 06-20-2013, 11:17 PM   #26 (permalink)
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The first couple of posts here were in poor taste... Everyone here has had a light or stop sign jump out in front of them from time to time.

I think most people hit the nail on the head with their bump starting techniques. I will typically bump start a few gears higher as well too. Fifth gear is most common for me as that covers most speeds easily down to about 15 or so miles per hour. The starter will usually only turn the engine over at around 200-300 RPM but thats fast enough for the engine to catch and get going. Thats what I aim for as well. The trick is hitting the sweet spot on the clutch where the engine can spin without completely locking up and getting a feel for what it takes to start the engine. Once it is going I try and rev-match so you arent spinning up the engine with the car.

I never bump start the engine below 3rd. I have done it a couple times in 2nd as an absolute last ditch effort when coming to a stop and 1st on accident. That was violent and I feared that I had damaged my transmission. Stick to 5th gear in the beginning and get used to the feel before going in higher gears when you are moving slower.
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Old 06-21-2013, 10:35 AM   #27 (permalink)
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Quote:
Originally Posted by hawk2100n View Post
The trick is hitting the sweet spot on the clutch where the engine can spin without completely locking up and getting a feel for what it takes to start the engine.

I wonder if other people with really "sharp" clutches like mine can smoothly bump start? I'm going to have another crack today, but I reengaged the clutch the instant the engine fired on my first bump test run yesterday, couldn't get it smooth at speeds over about 35 mph, or engine revs c. 1500 rpm. I might have to just let the vehicle coast to that slow a speed, or go back to the usual starter method. Either that or I can get a whole lot slicker, but I suspect that my very sharp clutch may not permit it.


EDIT: Went much better.

Last edited by songman; 06-21-2013 at 04:22 PM..
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Old 06-24-2013, 10:56 AM   #28 (permalink)
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I'm not worried about wearing or damaging the clutch, but I am always worried about breaking a motor mount. One of the major weaknesses in Focuses are the motor mounts.

I have only done it two or three times on the focus. And that was in a traffic jam on a rolling hill; I didn't want to wear out the starter and I didn't want to waste a tank of gas idling in a traffic jam.

I would put it in 3rd gear, get rolling a bit then engage the clutch about half way to spin the engine than put it back to the floor. That seemed to do the trick every time. But I'm afraid of dumping the clutch and breaking something.

Most starter motors only turn 300 or so RPM - that's all you'd need to get the engine started.
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Old 06-24-2013, 04:59 PM   #29 (permalink)
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The starter motor has a mount too.
My driving instructor taught me to use the starter motor to move the car if the engine fails in a dangerous spot. Select second gear, don't touch any pedal especially the clutch. As soon as you turn the key so will the wheels, even when your tank is dry.

People get killed while trying to push their stricken cars from railroad crossings and busy highway lanes. Many could have saved themselves by using the starter motor.

So I practiced the in-gear start every once in a while in my old Civic.
One day it refused to start. It did not even click or what. Battery was fine, lights were bright. err...
Maybe a dead point on the brushes? Pushed it a bit in gear to rotate the starter motor. Nothing.
Up went the bonnet. Where the starter motor used to be were just a lead going straight down and the remnants of the starter motor bracket. The starter motor was dangling on the lead deep in the engine bay!

So even using the starter motor can cause damage, especially if you move the car by it.
It can save your life. It can kill itself.
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Old 06-25-2013, 05:59 PM   #30 (permalink)
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It's useful for emergencies, but it'll kill a starter motor pretty shortly. Without the weight of the vehicle, you don't want to crank a car starter for more than 15 or 20 seconds. Using it to move around a vehicle would significantly shorten it's life.

Diesel 18 wheelers have REALLY heavy duty starters - sometimes they're a real pig to start. It's pretty common to move them in and out of the shop when they are gelled up on the stater motor alone. They have some SERIOUS gear reduction in the transmission in the lowest gears ... so they don't really do anything other than drain the batteries.

My father had the clutch break on his truck during a rush hour traffic jam on the long island expressway. It wouldn't disengage. He would shut it off in 1st gear when traffic wasn't moving - then when traffic would start moving, he would start the truck in 1st gear then shift along without the clutch and just kill it in gear when he had to stop (brakes still worked).

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