Add-on to prevent manual transmission from stalling

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Old 05-15-20, 01:05 PM
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Add-on to prevent manual transmission from stalling

about 8 years ago I was in Texas visiting a buddy of mine who had installed some part to prevent his manual transmission from stalling. It may have been an upgrade to an existing component where the side effect was the car wouldn't stall.

I didn't pay attention since I don't stall out my car but now that I have a kid about to drive I'd want to install this stall-prevention gizmo so I don't have to start shopping for another car.

Anyone know what this is called? Can't find anything on Google
 
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05-15-20, 03:34 PM
Hal_S
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now that I have a kid about to drive I'd want to install this stall-prevention gizmo so I don't have to start shopping for another car.
Just teach the kid how to drive a stick.

Here's how I would do it.
If the kid can learn to use the BRAKES to come to a smooth STOP, then they can learn to use the CLUTCH to make a smooth START.

Mechanically, a car's BRAKES and CLUTCH are mechanically identical- mechanical pads grab a rotating steel disk. The clutch is default ON, and require foot pressure to disengage. The brakes are default OFF, and require foot pressure to engage.

You can teach a kid the "FEEL" of how to lightly engage a clutch, by teaching them how to lightly disengage the brakes.

Find a sloping driveway or parking lot. Put the car in park w/ parking brake.
Let the car roll forward and then have the kid use their RIGHT foot on the brake pedal to learn how to slow the car until they are going so slow that the BRAKES groan/chatter, and you are JUST moving forward. This will generate a distinctive groan or whine. Have the kid learn to keep the brakes just barely engaged so they can go ~50 feet with "moaning" brakes. This usually takes a few days to master braking with the RIGHT foot. When they're done, the kid should be able to go from moving to a gentle stop using the RIGHT foot on the brake pedal that is SO SMOOTH that stopping is imperceptible.

Next, do the exact inverse with the LEFT foot on the brake. Starting from a dead stop, the kid should learn to JUST release the brake pedal enough so that the brakes moan and the car moves imperceptibly forward.
Repeat for a few days until the kid can use their left foot to "feather" the brakes and keep the brakes just partially engaged.

Finally, have the kid try the clutch with the left foot. Because the muscle memory for "feathering" the brake is basically identical/inverse to the muscle memory for softly letting out a clutch, the kid should already be able to keep the clutch partially engaged at very low speed.
After you learn how to "feather" a clutch and keep it partially engaged, it's a simple matter of learning the shift pattern, because once you're moving at speed, shifts from 1st to 2nd, 2nd to 3rd etc are generally much simpler 1) clutch-to-the-floor 2) switch gates 3) release clutch slowly, which is much easier to learn.
 
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Old 05-15-20, 01:52 PM
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I can't think of "a part" that you could add to keep the car from stalling.
Early 50's Chrysler products had a torque converter system in their manual transmissions for a little while on some models - very poor system.
 
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Old 05-15-20, 03:08 PM
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It was called an fluid drive transmission. You didn't need to operate the clutch to stop the car if the gear selector was in the correct position. Chrysler Corp. used these transmissions in their vehicles in the 50s. Doubt many are around today or even 8 years ago.
 
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Old 05-15-20, 03:11 PM
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I've only seen stall prevention programmed into race cars but in those the computer also controls the clutch. In that situation the computer activates the cutch to prevent stalling or does not allow a downshift if it will over rev the engine. I don't know how you could have a device to prevent stalling in a car with a manual clutch since there is no device to actuate the clutch. That only leaves increasing the throttle but that might be dangerous causing the car to lurch forward more quickly than expected.

Personally, I'd put my new driver in an automatic so they can focus more of their attention on safely driving and not divert some of their precious attention to operating the third pedal and wiggle stick.
 
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Old 05-15-20, 03:34 PM
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now that I have a kid about to drive I'd want to install this stall-prevention gizmo so I don't have to start shopping for another car.
Just teach the kid how to drive a stick.

Here's how I would do it.
If the kid can learn to use the BRAKES to come to a smooth STOP, then they can learn to use the CLUTCH to make a smooth START.

Mechanically, a car's BRAKES and CLUTCH are mechanically identical- mechanical pads grab a rotating steel disk. The clutch is default ON, and require foot pressure to disengage. The brakes are default OFF, and require foot pressure to engage.

You can teach a kid the "FEEL" of how to lightly engage a clutch, by teaching them how to lightly disengage the brakes.

Find a sloping driveway or parking lot. Put the car in park w/ parking brake.
Let the car roll forward and then have the kid use their RIGHT foot on the brake pedal to learn how to slow the car until they are going so slow that the BRAKES groan/chatter, and you are JUST moving forward. This will generate a distinctive groan or whine. Have the kid learn to keep the brakes just barely engaged so they can go ~50 feet with "moaning" brakes. This usually takes a few days to master braking with the RIGHT foot. When they're done, the kid should be able to go from moving to a gentle stop using the RIGHT foot on the brake pedal that is SO SMOOTH that stopping is imperceptible.

Next, do the exact inverse with the LEFT foot on the brake. Starting from a dead stop, the kid should learn to JUST release the brake pedal enough so that the brakes moan and the car moves imperceptibly forward.
Repeat for a few days until the kid can use their left foot to "feather" the brakes and keep the brakes just partially engaged.

Finally, have the kid try the clutch with the left foot. Because the muscle memory for "feathering" the brake is basically identical/inverse to the muscle memory for softly letting out a clutch, the kid should already be able to keep the clutch partially engaged at very low speed.
After you learn how to "feather" a clutch and keep it partially engaged, it's a simple matter of learning the shift pattern, because once you're moving at speed, shifts from 1st to 2nd, 2nd to 3rd etc are generally much simpler 1) clutch-to-the-floor 2) switch gates 3) release clutch slowly, which is much easier to learn.
 
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Old 05-15-20, 04:58 PM
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to be more specific he wanted to use it as a track car, it was a subaru WRX, he'd described some system he put in and the added benefit is that it couldn't stall so his old lady could drive it as well. doesn't sound like there's anything like that available.
 
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Old 05-16-20, 06:38 AM
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Can you check with your buddy in Texas since he has installed one?
 
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Old 05-16-20, 07:25 AM
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I don't like that, if in fact it's available. Sounds like it could be dangerous.
 
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Old 05-16-20, 06:34 PM
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Finally got a hold of the buddy, said it was a "lightened crank pulley" which is meant to reduce mass to rev quicker and the side effect is that, while still possible for the car to stall, makes it much harder to stall. Again this is on a WRX
 
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Old 05-17-20, 03:17 AM
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That doesn't make sense: something is being lost in translation from hot-rod-talk to English.
Reducing the rotating mass of the engine/crank/flywheel reduces angular momentum/rotational inertia and make it EASIER to stall the engine with a lighter crank pulley/flywheel.
If you jack up a car and spin a heavy steel wheel when compared to lighter aluminum wheels, it is easier stop the lighter wheel from spinning than the heavier.
Sound MORE like the track car simply has sufficient horsepower/idling torque to weight ratio that at a high idle if you just release the clutch the car simply leaps forward, rather than stalling.

Postscript - Ok, now this 'sorta' makes sense (however I still think your racer friend is chasing phantom horsepower). New after-market-engine-trick Replace ALL of your steel engine accessory pulleys with billet aluminum pulleys, and you get FREE HORSEPOWER and FREE TORQUE
There IS a difference, perhaps 10%-15% but that is under full acceleration, mostly from 3,000 to 7,000 RPM. So the rotational inertia of the accessory pulleys would only matter to somebody who needs to shave off a tenth of a second from a quarter mile drag run.

A stick shift simply accelerating normally from a stop; I'd have to say 'no difference'.
 

Last edited by Hal_S; 05-17-20 at 03:45 AM.
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Old 05-17-20, 03:43 AM
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Teach him to use the clutch. Taught my daughter year ago and now she doesn't even think about a clutch type car. I was mechanic and we had several kids come in who could not drive a clutch car into shop.
 
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Old 05-17-20, 04:33 AM
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Lightened pulleys, undersized pulleys, lightened flywheels are the miniscule improvements made to performance engines to squeeze out tiny, and I mean tiny, amounts of horse power.

It has nothing to do with improving the drivability of a car!
 
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Old 05-17-20, 06:34 AM
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Teach him to use the clutch. Taught my daughter year ago and now she doesn't even think about a clutch type car. I was mechanic and we had several kids come in who could not drive a clutch car into shop.

This does not make sense. You taught her or not?
 
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Old 05-17-20, 04:47 PM
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so you're correct in saying that when you let off the clutch the car goes forward like an automatic when you let off the brake while in D.
at bone stock, when i teach people to drive a manual, I have them very slowly let out the clutch pedal and get the car moving until they can fully let out the clutch pedal.
this is basically the same principle but it's more forgiving when the clutch pedal is let out (doesn't have to be as slow/controlled)
 
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Old 05-17-20, 05:37 PM
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This does not make sense. You taught her or not?
Sure it does. Since she knows how to drive a clutch, she no longer thinks about it. She just does it.
 
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Old 05-17-20, 05:50 PM
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Originally Posted by Michael Chang
this is basically the same principle but it's more forgiving when the clutch pedal is let out (doesn't have to be as slow/controlled)
That doesn't make sense.
Lighter pulleys/flywheels make an engine EASIER to stall, e.g. LESS FORGIVING, when letting out the clutch. Again, a dragster / track car simply has an engine with MUCH MORE low-end torque so that it is HARDER TO STALL, even though lightening the pulleys/crank/flywheel makes the engine (marginally) easier to stall.

That WRX probably has the 2.5L high-compression boxer engine that generates 140 ft lbs of torque at 1,000 RPM. The high compression comes from a long stroke, which gives high torque. The opposed "Boxer" engine has individual crank throws for each piston, which gives even torque.

So, the WRX is a small car with a high torque engine; which makes it hard to stall. Adding aluminum pulleys won't change that, but make it microscopically EASIER to stall at low RPM.
Stalling a car is like bunting in little league baseball.
The bat connects with a 5oz baseball moving at 50 mph and stops it. Now imagine "bunting" with a 50 oz. bowling ball moving at 5 mph. Both are moving with the same energy (weight x speed) ~horsepower, but totally different torque (the "mass" component of the equation).

Claiming that aftermarket pulleys make it harder to stall a high-torque engine is like claiming that it's harder to bunt a bowling ball than a baseball because the bowling ball is polished with Turtle-Wax...
 

Last edited by Hal_S; 05-17-20 at 06:15 PM.
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Old 05-19-20, 06:35 AM
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This post has gone way off course and should be closed in my opinion.
 
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Old 05-19-20, 10:44 AM
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Nah-
This discussion helps explain the fundamental distinction between Torque (weight P in pounds lifted distance D in feet) and Horsepower ( weight P in pounds lifted distance D in feet, during time M in minutes).

Originally Posted by [url=https://www.caranddriver.com/news/a15347872/horsepower-vs-torque-whats-the-difference/
https://www.caranddriver.com/news/a15347872/horsepower-vs-torque-whats-the-difference/][/url]
Scottish inventor James Watt gave us this handy equivalency: one horsepower is the power required to lift 33,000 pounds exactly one foot in one minute.
 
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