Manual Parking Question! Truck walking forward slowly while in gear without parking brake

Hi!

New to the forum! Been lurking, but this is the first thing I didn't immediately find an answer to since I got my tacoma about 6 months ago.

SO. Parked in the driveway, relatively flat. Turns out I had left it in 3rd gear, but forgot to pull the parking brake. Yes, that's a problem.

But!

When I looked out the window about an hour later, the truck was about 15 feet from where I'd parked it. I went out, realized what I'd done, but then wondered why it 'walked' down the driveway.

So I sat in it for a few minutes, and in 3rd gear, on a practically flat driveway, maybe a very slight downward slope, it would every so gently move forward about an inch. Then it would sit there for 10 seconds, and do it again. Did this in 1st, 2nd and 3rd gears, but not in reverse.

No problem with the parking brake on, it just stays...well...parked. This is the first manual I've owned that ever did this.

Is this 'normal'?

 

Try 4th gear, it's a bit taller and would require more to overcome the engine compression.

 

Makes sense. I'll give it a whirl out of curiosity!

 

That's pretty normal, when a manual transmission is in gear with the engine off the only thing keeping it from rolling is the resistance of the engine. The only thing that makes significant resistance in the engine is the compression when the cylinders come up but that will slowly bleed off thus it "creeping" when in gear on an incline without the parking brake on.

When parking in gear leave it in 1st or reverse, this will give the greatest resistance to "creeping"

Actually 4th gear would offer less resistance as it can turn the engine easier.

 

Backwards, 1st or 2nd would require more. 4th will be worse. Lower gear selected in the transmission means the wheel has less mechanical advantage against the engine (and vise versa, the engine has more mechanical advantage against the wheel). For example, if you were to choose 6th gear for parking, the wheels would essentially have an under drive ratio to the engine. Whereas in OD the engine has an overdrive ratio against the wheels.

edit: just realized the post above me clarified that. Didn’t see the second part.

 

Brain fart on my end, thanks!

I usually leave it in a taller gear because if I jump back in the truck and forget it's in gear, the truck lurches forward or back less.

 

It's late in the day......convinced myself that 4th would be better too without much challenge....

I could just use the parking brake consistently too.

 

What @Dm93 said- use a lower gear. The weight of the truck is enough in those shorter, higher gears to turn over the engine slowly an allow the truck to roll even on a small slope.

 

Did you also bypass the clutch safety switch?

 

Nope.

 

Should definitely always be using the parking brake, but putting it in a low gear is also a good idea on top of the brake.

 

I've driven manuals for so long including tractors and farm equipment that I instictively set thw parking brake on everything with a manual.

I typically leave it in neutral unless I'm on a significant incline.

 

I had a buddy that used to do that, until he was alerted in class that his car was in the lot below,,,, with a parking lot light pillar parked in the middle of it. We suspect not enough brake. At the time; He thought the slight incline didn’t justify any other measures.

 

Always 1st or reverse

 

This is the reason why I park it in gear along with using the parking brake. Parking it in gear is an extra safe measure just incase your parking brake decides to fail.

Kinda like parking an automatic in Park instead of Neutral is how I think about it

 

Ok. Confirmed 1st or reverse, no walking with the parking brake off.

I normally put it in 1st and I put the parking brake on out of habit about 99% of the time, but depending on the level of screaming children when parking/exiting the vehicle, I've missed pulling the brake 2 or 3 times..... normally catch it before I walk away from the truck, but not today. Luckily it didn't make it out of the driveway!

 

For sure. My other car is 08 Saab 9-5 Sport Combi Aero with 5spd. Saab engineers were smart. You have to put tranny in reverse and leave it there before you can take your key out. So 1st or reverse. Parking brake is a must for me as well.

 

More effort than my dad makeshe won't use the parking brake on anything, he typically leaves the tractors in gear when he gets off but alot of them are partial powershift so they will roll regardless of being in gear or not.

We don't have much of any hills around here so it isn't gona go far if it does roll a bit.

 

Why would you park it in 3rd gear? 1st for uphill, reverse if parked downhill. When you get to 300k like I did, 1st and reverse alone will not hold the truck since the engine compression is lower at high mileage. 1st or reverse with the brake