Parking in-gear

corolla
#1

I have 2005 Corolla, manual. My wife just discovered that it does not hold the car in the driveway when parked in reverse without handbreak engaged. It would roll back. It will hold for a few seconds, then jerk back a few inches, then hold, jerk. I used to have a Saturn, which held in gear with no issue at the save driveway.



I would like to know if this is indication of problem, or if it is normal for Corolla.

#2

My manual trans cars did not do this but I always used 1st.

You need to use the park brake, do not rely on the trans alone.

#3

Please use the PARKING brake and first gear. Your car won’t jerk you around anymore.

#4

You should always use the parking brake in a manual and also after you turn the car off of course put it in first. Usually it even says to apply the parking brake and put your vehicle in first.

#5

It is only an indication that you are thinking the parking brake is an emergency brake. That is why you have a parking brake.

It should be used ever time the driver leaves the car.

The difference in the cars is just that, a small difference in how much of a hill it takes to allow it to more. Don’t trust ANY car to stay where you park it without using the parking brake. That includes cars with automatic transmissions.

#6

I agree with the others who pointed out that the parking brake should always be used when a car is parked, no matter whether the car has an automatic transmission or a manual transmission.

That being said, I want to point out that your car’s behavior could be an indication of poor engine compression. While this is not a call for panic by any means, you might want to have your mechanic check the engine’s compression when he is next working under the hood.

If the engine’s compression is weak, that could be an indication of waiting too long between oil changes or it could just be the result of having driven very many miles.

#7

Parking a manual transmission car in gear is an old chestnut that originates from bygone times when cars were much heavier and parking brakes were marginal to say the least.

Parking the car in gear relies on the expectation that the gases compressed in the cylinders will stop the engine from rotating, but in fact only 1 cylinder will be on the compression stroke at any one time, added to this piston rings aren’t a mechanical seal, they will always leak over any period of time, this can be measured by a leak down test.

Simply put, your starter motor has to overcome the engine compression to start the car, there’s no reason why a ton of car parked on a hill won’t overcome the same compression. If the compression was that high, you would never be able to push start a manual tranny car.

So no, a single engine cylinder under compression shouldn’t be relied upon to hold the car on an incline. Use the parking brake, that’s what it’s for. If the car won’t hold with the parking brake on and a gear engaged, it’s more indicative of parking brake rather than engine problems.

#8

Another point is that you could easily damage the transmission by relying on it alone to hold the car in place.

#9

It’s not engine compression that keeps a manual trans car in gear from rolling down an incline; it’s static friction within the engine from pistons, crank and cam(s). I suggest that the OP’s driveway is steep enough to overcome static friction from within the engine. If there were no static friction, then any manual trans car would roll down any incline in lurches in any gear as compression leakdown occurs.

Either first or reverse gear is appropriate, depending on the gear ratio of each. You can estimate this with a speedometer that reads in both directions and a tach. Observe the vehicle speed at a given RPM in first and in reverse. The gear that moves the car more slowly is the one to park in. Otherwise it’s a safe bet that first has a lower ratio than reverse. Uphill or downhill does not matter; without ignition and fuel, the engine will not start. On small inclines, parking in gear and static friction will keep the car stationary.

In a situation where someone might bump against my car, even on a level spot, using the parking brake will reduce stress on the transmission. In such a situation, I might even park in neutral with the parking brake applied.

#10

Errrr…No.

I admit you had me going for a few seconds there but I have all of the ingredients to verify that. I have a 1000 yard driveway that runs up to the house before it levels out. I put my 76 Jaguar at the top of the incline, switched off, selected first gear and released the parking brake. The car moved a couple of inches and held.

3 hours later the car had moved 2 feet ~ and yes I had chocks 3 feet in front of the car and chalk marked the wheel positions.

I re-applied the parking brake and pulled the spark plugs (probably the only easy job on a Jaguar) dropped the parking brake with the car again in first gear. The car just rolled down the hill with the engine cycling.

The car may be a 76 but it has 9,000 miles from new, this is a prototype car I bought directly from Jaguar racing developments at Browns Lane, Birmingham. The engine is the prototype ‘siamesed’ engine that came with the car, it is new, not rebuilt and has has 2000 miles on it. I rebuilt the 4 speed OD transmission 2000 miles ago and the complete IRS rear end 200 miles ago. So everything is fairly new.

Maybe I need more friction or something.

#11

!!!

Why?

You’re saying the transmission is strong enough to propel the car, but not strong enough to hold it still?

#12

Yes, I was going to recall a time I had the plugs out of my old Toyota pickup with the marginal parking brake… luckily it gave way while I was in the truck and I could stop it!

However, with a manual transmission car in good working condition it shouldn’t do what the OP is saying where in the low gear it only holds for a matter of seconds. Low compression is a possibility, but I think if it were that bad they would be seeing drivability issues. I think the issue is more likely a close to worn out clutch that’s slipping a little as it tries to hold the car in place.

#13

First off…USE THE PARKING BRAKE. Second…when parking on a incline put it in either first or reverse, depending on what direction the front end is facing. If facing down hill then put the car in reverse. If facing up-hill then put it in 1st.

#14

Scudder–Thank you for verifying my opinion that compression is the “force” that would hold a car in place while it is in gear, without the parking brake being applied. I agree with Greasy Jack that a slipping clutch is a possibility, but without sufficient compression (as you demonstrated by removing the spark plugs), even a good clutch will not prevent a car from rolling under these conditions.

#15

“If facing down hill then put the car in reverse. If facing up-hill then put it in 1st.”

I have to disagree with this, Mike. If the engine turns over, it will run backwards. That could cause a timing belt to jump a tooth. You should put it in reverse if you are facing uphill, and 1st if you are facing down hill.

#16

In addition to having the vehicle in park or in gear with the parking brake set, there is an additional precaution that everyone is supposed to take. Turn the front wheels in the direction that will guide the vehicle in the direction that it will do the least damage if everything lets go.

#17

I’ve heard the park in reverse if you’re pointing downhill way suggested on older diesels where there’s a possibility if the car rolls away the engine might actually start, but I agree that the opposite is probably better for a car with a timing belt.

#18

Static friction within an engine plus initial tire rolling resistance with a manual transmission in the lowest gear without using the parking brake can keep a car from rolling in many situations but is not guaranteed with a steeper grade.

Engine compression is not a factor with holding the car as cylinder leakdown happens quite rapidly even with an engine in excellent operating condition. After a few seconds, there is no compression pressure remaining in a stopped engine so static friction is what will hold a car from rolling if the hill is not too steep.

I repaired my fractured English.

#19

Wha Who? You should really try the experiment that Scudder said that he tried before repeating your friction theory. I am certain that you are incorrect. The other factor - initial tire rolling resistance, is virtually nil compared to even a mild grade.

With regard to the original question, the fact that this car moves and the Saturn didn’t is not a clear indication of a problem with this engine. I would not worry unless there were other indications of excessive engine wear or valve problems.

The first gear if downhill and reverse if uphill theory to keep the timing chain/belt from jumping a tooth is not valid. If the chain/belt is that loose, it will certainly jump a tooth when you blip the throttle.

First and reverse have the same gear ratio on every manual tranny I have had apart, but I can count those transmissions on my fingers, so my sample is too limited to make a generalization in that regard.

I think that we all agree that it is important to use the parking/emergency brake when leaving the driver seat on a manual transmission car. The only exception might be when it is around freezing and there might be liquid water in the parking brake cable or drums. Many northerners (including me) have gone out to their cold cars to find that the parking brakes were frozen solid and would not disengage. In those instances, park on the level or use a curb to keep the car stationary.

#20

Timing belts are more apt to jump when the crank us turned backwards. Tensioners all seem to be on the slack side of the belt… when the engine is running. Turning backwards, the tensioner will be easily displaced, allowing the belt to jump.

And, when assembling even a big block, the crank can be turned by hand with the plugs out, but compression will make turning impossible without a great deal of weight on the engine stand and at the end of the breaker bar.