How to smoothly bump start / clutch start an engine

[Jammer]

Originally Posted by taredog

Have to put in my thoughts.

There should be no bump involved. Do not "pop" the clutch. Think of the way you go up through the gears when accelerating. Unless you always give your passengers whiplash and chirp the tires when you shift up. Gentle is the word and use the same gear you would use when accelerating at the speed you are at. Having knowledge of what is actually happening when the tranny is in or out of gear and what happens when you push the clutch in helps. Oh and how the engine is involved in all that.

I have used this technique a lot over the years due to being too poor to waste gas, having a dead battery and no funds to replace it or just having to drive a POS the wouldn't idle well.

As far as reverse tourque harming the drive train, if done correctly it is the same as taking your foot off the gas when decelerating. In other words the clutch is designed for reverses in forces. That's why many clutch plates have springs in them.

As to EOC, I never thought about the pilot bushing (is it really a bearing now in cars/light trucks?) but you should never keep the clutch depressed for long periods of time. Shift to neutral and let the clutch out. Less wear on the through out bearing.

I have known and ridden with people who pushed the clutch in every time they let up on the gas. Why? They were told to by someone. Believed the car would stall otherwise, even at speed. Never was successful at converting any of these people.

So do your EOC right, enjoy but know you didn't invent it. Been around since there were cars with clutches.

And be gentle restarting it using the proper gear and don't "pop" the clutch.

I have heard the same concerns about over using the clutch in such a way, and I try to not keep my clutch pushed down for more than needed to shift, and if needed, I'll go to neutral. I really do feel you have a good point on that one because I have been told this same advise from many mechanics.

As far as what gear to shift too I see both sides here. I agree about seeking a smooth ride- I feel what is most important is that when we go from EOC to starting our car back we don't have a big jolt, we all seek as smooth of a ride as we can get. I have found that 5th gear often works out pretty good but I prefer to go to neutral and stay there instead of ridding the clutch more than a second or so. However I also have used 4th gear and found it to be very smooth, and I really can't explain why other than the RPMs and my speed were a good match. It's more of feeling the road than anything else and not really being able to say exactly why I feel going to 4th then to neutral to restart sometimes works for me as well or better than going to 5th.

The method described in this thread does work, but I avoid using the clutch as much as possible and go to neutral as much as I can, so I'm not doing the "bump start" EXACTLY as worded here because I have been taught by mechanics my entire life not to use a clutch in such a manner- I believe some call using a clutch in such a way "slipping the clutch" which any mechanic will tell you is not good for long term use. Not to mention, most drive trains have a very long warranty on them, and that's for a good reason. I do not feel it's very easy to damage the drive train, but the clutch is another matter.

I used to drive a motorcycle in EOC for years- but I never dreamed someday would come that it would have a NAME for it. This method works double good for people on cycles.
* Please see my next reply in this thread, it could be important for some drivers.

[cfg83]

taredog -

Originally Posted by taredog

...

So do your EOC right, enjoy but know you didn't invent it. Been around since there were cars with clutches.

And be gentle restarting it using the proper gear and don't "pop" the clutch.

There was one intro by a Vet from WWII. He said they taught EOC for Jeeps so that you could coast in stealth mode. I'll bet they used it when they were low on gas too.

CarloSW2

[taco]

i find out in my truck

stiffer clutch 11lbs flywheel( compared to 28ish stock)

that it is the smoothest if i select a gear to bump start that puts my rpms near 1500. lower than that i get axle wrap and a jerk, higher than 2000, well it tries to lock up.

[Jammer]

I feel this is very important to append here:

I have discovered a situation when it is better to bump start in a lower gear as opposed to 5th gear. If I am going EOC down a steep hill and then start to go UP HILL a bump-start works much better by shifting to 4th or even 3rd gear depending on speed and how steep the incline upwards is. I feel this needs to be pointed out here in this thread. 5th gear is not going to work well if you have already started going up a steep hill in EOC, you will kill your engine FAST. This is based on first hand experience that has proven true multiple times for me.

[cfg83]

Jammer -

Thanks, I'll keep that in mind. Now that I think of it, typically I restart at or near the bottom of the hill, so I don't think I've ever tried it.

CarloSW2

[PaleMelanesian]

In that situation, I would still bump in 5th, but then immediately clutch in and shift to 4th. I do it all the time. 5th gives a smoother bump, and then a second later I'm in the gear I need to tackle the hill.

[user removed]

Ideally when you get a real feel for the percentage of engagement of your clutch that you need to just turn the engine over and get it started, the gear selection will not be that important as long as it is not lower than the gear you need to use for acceleration.

In the scenario of steep hills where you might not want to bump in 5th and then go to 3rd or 4th, the choice may be different that bumping then changing gears immediately.

In no case when bump starting should you completely let the clutch out and the time it is semi engaged is very small.

When done properly, as Pale stated earlier a passenger in the car would not even feel the change is velocity of the car. That is much easier in the highest gear, but can be accomplished in the top 3 gears with some practice.

regards
Mech

[Jammer]

Originally Posted by PaleMelanesian

In that situation, I would still bump in 5th, but then immediately clutch in and shift to 4th. I do it all the time. 5th gives a smoother bump, and then a second later I'm in the gear I need to tackle the hill.

I am speaking of very remote and extremely steep incline going up mountains. I do not live far away from such mountains, and it's not uncommon to find yourself in EOC going down hill just fine and dandy and suddenly you are going up an extremely steep incline with curves. It can happen so fast you may not have time to bump start until your already going up an incline so steep you feel you are pointing to the moon. In such a case the car's speed will slow down drastically and very fast- In my car it is all but impossible to use 5th gear when trying to climb a wall that the car needs to use 2nd gear just to find the power to get to the top.

I am speaking of very large mountains that suck the life out of small engines just to reach the top. It is less common, but it is a situation in which shifting to 5th gear and slipping the clutch is simply not a good option for me, it's way to easy to kill the motor as soon as it starts and when driving up such inclines one needs to get the power from the engine back on and turning the wheels in a low gear as soon as possible. I admit, these are remote locations and dangerous places to be practicing EOC going DOWNHILL because the brakes may not last long enough- Instead I find it's better to let the engine idle and use a combination of neutral and low gears (to keep from over heating the brakes as you ride them down the mountain to keep from going 80MPH around cliffs. However, at first I was speaking of going UPHILL, so I hope I didn't confuse anyone.

[taredog]

It's all about knowing your vehicle and having an idea what's actually happening with the drive train when you do something, not just that "this works sometimes when I do this, why".

Get to know your vehicle, don't do it if you are not comfortable, and if you can't do it without taking your eyes off the road, DON"T. It should be natural to you.

Every vehicle, driver and situation is different.

[user removed]

Jammer when you are in hills or mountains where you need to use the brakes to keep your speed down then use the gears instead of the brakes. If you can slow down using the gears then you should not be using any fuel anyway.

Driving through Blacksburg on the Interstate I did that for 3 miles alternating between 4th and 5th in my Honda. I was behind a line a big rigs and if I stayed in 5th I was going to run into the rear of the truck in front of me at over 85 MPH.

I never use brakes going down any grade unless it is the last resort. Using engine drag is the same as turning the engine off and you avoid the restart issue altogether when you need to go back uphill. In fact up to a point you would be in the correct gear when you started back up the grade.

Now if you were slowing down too much use neutral at the last part of the downhill slope. Then select the gear you need to climb the upcoming grade.

regards
Mech