Car rolling when in gear after driving on track

[Alicks]

So I was at nurburgring, came in and parked up. Obviously didn't want to put the handbrake on. Put the car in gear and the car still rolled against the engine. Anyone had this before? Only did it when it was hot. Wasn't sure if it was

A. Hot thin oil reducing compression?
B. Perhaps clutch was hot or is wearing out?

Still drives fine, doesn't use oil, no smoke or anything when it's running. It was just pretty annoying obviously.

 

[blueguy]

Hate to ask the obvious, but are you sure you had it in the right gear at the time?

 

[Alicks]

Yeah mate 100% came in from one lap, put it in first and it rolled. You could feel the resistance of the engine. And then did another lap half hour later, came in, exactly the same thing again

 

[integraleo]

First gear If facing slight incline or reverse if facing down on a slight incline

 

[Alicks]

I can't see how first or reverse would make a difference tbh as the engine will crank either way. Regardless I reversed up, and put the car in first. And it still rolled.

 

[ste01]

Try parking on a hill and leaving the car in first, then in reverse. You'll see the difference when you take the handbrake off

 

[hondamad2204]

stupid question.....are we talking car on or off here???

Are you saying that with the car switched off, when you leave it in gear it rolls as if its in neutral?

 

[Brecht]

Think with the engine off that is , it's normal for it roll a little and then stop..
But with your car it just keeps on rolling like it's in neutral ?

 

[Rom]

It does matter which gear your in.
You want to be in the opposite directional gear than the slope.

Even then, with enough inertia, it can still roll, it just need to over come the resistance.

 

[Alicks]

Right I probably wasn't too clear. So I drove round track. Reversed into a parking space in the car park which was on a small decline. Switched off my engine. And because of heat in read pads etc I didn't want to put the hand brake on, I put the car in first gear with the engine off. And the car still rolled forward with very little resistance and when I say rolled forward I mean if id of left it it would've just rolled away. So much so I had to put a block under the wheel. Just seemed a little odd that's all...

 

[hondamad2204]

Thats it then, if you had left it in reverse it would have jolted and stopped itself if you driven up the incline front forward and put it in first it would have stopped it.

 

[dave7368]

these will help...

 

[Alicks]

Lol I give up. Front end was pointing downhill. I'll just keep a brick in the boot while I'm lapping ring next time

 

[emmsyDC5xx]

If your facing downhill - put it in reverse.
If your facing uphill - put it in first.

 

[Linus27]

If your facing downhill - put it in reverse.
If your facing uphill - put it in first.

I never knew that. I always leave in second regardless.

 

[Rom]

Lol I give up. Front end was pointing downhill. I'll just keep a brick in the boot while I'm lapping ring next time

This is what were saying. You should have put it in reverse. Not first.

 

[integraleo]

And it's irrelevant if the car is hot or cold it's the same. If you leave it in a forward gear that gear allows the car to roll in that direction but not backwards,if it's in reverse gear the car can roll backwards but not forwards. Try it on any hill with the car off and take handbrake off and you will see. I think something like this should be taught by every driving instructor

 

[Alicks]

Care to explain the logic behind that? I was under the impression you should leave it in the gear that would cause the least damage if it was to start? Uphill would be reverse. Downhill would be first. All that holds the car on a hill is the engines compression. Plus any auxilleries. An engine has the same compression which ever way it's cranked; and a gearbox will rotate in either direction? Thus, the only thing affecting the holding force of the engine is the ratio of the gear which is engaged surely? I will try it but I just don't get the the mechanical logic behind this. Also IMO heat is the biggest factor? Hot oil has a lot less resistance than cold oil. Which in turn will reduce compression. And also a hot clutch I would imagine has less holding force than a cold one. These being the two biggest factors and a both heat related

 

[Dan34]

My driveway slopes ever so slightly downhill, I always leave mine in first and it never rolls away. This thread has confused me now lol.

 

[El_Boomo]

Unless the K20a is different to the majority of engines, it will rotate backwards as easily as it will forwards.

Depends who you ask, some will say leave it in gear opposing travel (believing the engine won't run backwards) some will say same direction to stop damage if it does move (ie hit by a car and forced)