Reverse Gear

[ramkya1]

Hai BHPians,

Some of us were discussing about reverse gears..... some gery aeresa emerged. I have seen that techies here can explain complicated concepts simply and are really knowledable about the nuts and bolts of the engine, thank you. The questions:

1. Is it possible for the reverse gear to be engaged while the vehicle in moving forward? If that happens, will it not damage the gear box?

2. Is there some mechanism through the gear selecter to ensure this does not happen?

3. While the car is moving back, is it possible to engage 1st gear.

4. Is is necessary to come to a dead stop before engaging reverse gear?

Tnx in advance for inputs,

-- Ramky

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[Deeps]

Here are some answers on my behalf:

1. No, it isnt possible to engage reverse while moving forward. when attemoted, the gearbox makes a grinding sound and the stick offers resistance to enganging in the R position. This happened to me a few times when i was in a hurry trying to park...but now i let the car come to a dead stop before trying to get into reverse.

2. Well, the only mechanism is that position of reverse and 1st are so far apart. And in most european cars, you have the reverse and 1st in the same postion (not exactly in the same position) but have that ring that you have to pull to engage reverse...or press down on the head of the stick.

3.Yes, engaging 1st while moving backwards is very much possible.

4. From my experience, it is necessary...because only then will the gear slot in smoothly.

[sbasak]

For questions 2-4 my reply is same as ramkya1
For 1, I like to say following.
Modern cars usually have a mechanism to prevent that.
However, older cars, it is theoretically possible. In most cars (even 1980s) all forward gears are synchromeshed. Basically, they use helical gears which allows to combine two rotating shafts engaging each other. This process eliminated the double declutching system (which is still found in older buses & trucks). Double declutching ensures that before engaging gears, engine speed and gear shaft speed should match so that the gears engage without jerk.
Since reverse gear is without synchromesh, if you try to engage it when car is moving, you'll hear a grinding noise. Yes, it can damage gearbox and should not be done.

[v1p3r]

1. Not possible. It will damage the engine.

2. Yes, on certain cars only. The Europeans have a ring/push down reverse selection system. Hyundais will somehow refuse to slot from 5th to reverse directly. Marutis have no such hassles though.

3. Yes, very much so. Way easier to get a wheelspin too!

4. Yes, or risk damaging the gearbox.

[burjiis]

I dont recollect, but I have seen an SUV(in a movie) moving from Reverse position to forward position without stopping. It was an unbelievable scene wherein this guy is running away from the baddies in reverse and then when he sees the road getting wider, just turns 180 degrees and continues with the same momentum in the forward direction. Saw it years ago, maybe more that 10 to 12 years ago.

Burjis

[Samurai]

Originally Posted by burjiis

this guy is running away from the baddies in reverse and then when he sees the road getting wider, just turns 180 degrees and continues with the same momentum in the forward direction. Saw it years ago, maybe more that 10 to 12 years ago.

Actually I have seen it in many movies, always wondered when they shifted the gears from reverse to forward.

[Deeps]

Originally Posted by burjiis

I dont recollect, but I have seen an SUV(in a movie) moving from Reverse position to forward position without stopping.

yes, we have all said that this is possible. What is not possible/desirable is shifting from forward to reverse without stopping.

[viper]

Originally Posted by Deeps

yes, we have all said that this is possible. What is not possible/desirable is shifting from forward to reverse without stopping.

Hey,

I'm sure you guys must have all seen 2fast 2 furious. There is this scene where the hero forgot his name when he pulls the handbrake in a moving car(eclipse I think) without exactly halting and then speeding like crazy in reverse. Always wondered how they did that.

Viper

[tsk1979]

As for reverse gear, your car has to be stationary, ie the drive wheels have to be still. If you are rolling backwards or forwards there will be that grating sound.
If you want to engage reverse gear at high speed, you need to lock your brakes, and then shift into reverse.
The reason is that in cars the first 5 gears are synchromesh, but reverse is not.
Also if you engage reverse gear in a standing car, you can still roll forward by depressing the clutch,
However for synchronous gears you can engage even when car is rolling wether forward or backward. Infact thats how burnouts care done. engage reverse, get 10kmph speed reverse, and then depress clutch hit first floor the pedal and let go of clutch. Voila a burnout even in a santro'ish car.

[navin]

Originally Posted by Samurai

Actually I have seen it in many movies, always wondered when they shifted the gears from reverse to forward.

The 180 is simple BUT DO NOT TRY THIS ON OPEN ROADS AND WITHOUT TRAINING.

drive car in reverse at top speed so weight is on front wheels

lock brakes and turn car hard so that the weight is transfered to the rear wheels but the car still wants to go inthe direction it was moving. since the weight is now on the rear wheels the car spins 180 deg.

engage forward gear and gun the engine

it takes a lot of practice. use an old car!

[Surprise]

http://www.team-bhp.com/forum/techni...t=REVERSE+GEAR (Is it possible to shift into reverse at a high speed?)

Same topic discussed here. Get additional inputs here

[DRC]

I have a video clip of Saab rally team doing the same.. Would have shared it witth you, but dont know how to ??

[tsxei]

Originally Posted by viper

Hey,

I'm sure you guys must have all seen 2fast 2 furious. There is this scene where the hero forgot his name when he pulls the handbrake in a moving car(eclipse I think) without exactly halting and then speeding like crazy in reverse. Always wondered how they did that.

Viper

I've seen this movie. His name is Paul Walker. And he does this in the Evo, not the Eclipse. Maybe they filmed the scene in parts.

[Deeps]

Re you sure it was an EVo? I cant remember...was so long ago. Because i believed Tsk when he said that with the hand-brake the rear wheels must have been locked and the reverse would have been engaged? But this theory wouldn't apply to the Evo 'cos its 4wd.

[tsxei]

Originally Posted by Deeps

Re you sure it was an EVo? I cant remember...was so long ago. Because i believed Tsk when he said that with the hand-brake the rear wheels must have been locked and the reverse would have been engaged? But this theory wouldn't apply to the Evo 'cos its 4wd.

I am pretty sure that it is the Evo. Tyrese Gibson who is the black guy drives the Eclipse and I remember he shouts out something like "crazy white boy" when he sees Paul Walker perform this stunt.

But I have no idea about how this stunt was performed. My guess was that it was filmed as bits of scenes with one scene of the car going straight and making a 180 degree turn and the next of the car driving in reverse. It will be interesting to hear some theories about how this can be done in one shot.