Engine protection device??? electrical "box", lockout to prevent wrong gear choice?? Options

[Mueller]

We don't read about people shifting into the wrong gear too often which ends in costly repairs, but when we do hear about it, it gives everyone a sick feeling knowing that big money is about to be spent.

Now it seems it wouldn't be too difficult to have a "box" that monitors engine RPM as well as what gear the driver is in and MPH. Of course the "box" is going to have to have some logic control with user inputs for different variables.

Basicly what we want to do is have the "box" tied to an electrical/mechanical device that will not allow you to put the car into a gear which the "box" has deemed unsafe.

So if you are in 4th @ 6500 and want to go to 3rd which will raise the rpms to 7000 (borderline redline)
the "box" will "okay" the gear choice and not interfer....well, due to some odd reason, the driver picks 2nd gear instead, the "box" knows that 7500 rpm is way too high and it gives a signal to the electrical/mechanical device and "blocks" the gear selection.

Now the only way the driver can put the car into a gear is: Stay in 4th or, shift into 5th or slow the car down enough so that the road speed will match the RPM/gear/MPH safety combination which is the "box" will be programmed for.

This is nothing new, Porsche used this logic on thier PDK transmission and RUF had this for his clutchpedal-less manual shifting cars.AFAIK, no one has this as an "add-on" device or to be used with a clutch pedal

[Mueller]

another brain fart: instead of having the device prevent the transmission to go into the wrong gear, it could instead not allow the clutch to engage until the correct combination is achieved(?????)

[Aaron Cox]

one word: UNSAFE

you cannot prevent someone from making gear choices, if you need to downshift/explode your motor to avoid a collision...more power to ya. i think this 'box' woul lead to accidents...etc

[Mueller]

"For competion use only"

does that make you feel better?? (IMG:style_emoticons/default/smile.gif)

an over-ride switch could be added...besides how safe would it be to grenade your motor, have hot oil splashing onto the exhaust or onto the tires giving you 0 traction???

one word: UNSAFE

better get off the road then, there are millions of cars out there that are unsafe, lots of automatic cars will not allow the car to be downshifted into a lower gear which could cause damage.....

my description might not be perfect, but like I said before, RUF offers this on some of his cars, he is considered a "manufacture" and if it was unsafe, he would not be allowed to do it on his street cars.

[ss6]

If you're going to be making a doodad that blocks a shift, that probably means some solenoids or other electrically active components.

If you're in that "league", why not kill two birds with one stone, and instead of using moving parts to block shifts, use the moving parts to implement shifts, ie solenoids or servo's (or etc) activating the tranny. Your activation logic can discard "dangerous" gear selections, AND eliminate the sloppy shift syndrome, AND possibly speed up the shifting. Think of it - shift paddles on the steering wheel and evrythang...

[Mueller]

SS6, trust me, I've thought about it.......the RUF version used to be available as an add on item for about $10K

the reason I like just the "wrong-gear avoidance box" is that it would (or should be) an item that could be legal in all racing classes. There is no performance advantage, it could be considered an "insurance" device similar to an Accusump.

[airsix]

Mueller, check your PM's NOW!

[lapuwali]

I can't think of a single instance where downshifting will save you from a collision. This is tantamount to a biker insisting they had to "lay her down" (which is a completely silly concept I'm not even going to bother to argue). If you're using the gearbox and clutch as a brake because of brake failure, use the handbrake instead. If both your hydraulic system and the handbrake have failed, I suppose that's it's slightly possible a downshift might help, but that's got to be a pretty rare case.

To Mike's point, I'd think this would be fiendishly difficult to implement. How do you prevent the clutch from engaging? How do you detect which gear the car is in? Neither of these are trivial problems to solve reliably. It's much easier to do gear detection with something like a sequential box, where a simple up/down microswitch can detect shift drum movement. Not so easy on most H-pattern 'boxes. On the clutch, some solenoid/pin arrangement is the only thing that leaps to mind, preventing the clutch arm from moving far enough to release the pressure plate. On the gear detection, supplying a Ferrari-like gate at the shift lever and using switches to detect position in the only thing I can think of that could be done at a reasonable cost.

I'll have to dig it up, but in a back number of Racecar Engineering, they described what I have to say is the most brilliant gearbox idea in quite some time. Imagine, instead of the synchro/slider/dog gear system, you had a set of small hydraulically actuated multiplate clutches (hydraulic fluid acting directly on a pressure plate inside a housing splined to the shaft, just as the slider is). Think of several little brake pistons pressing against the gears to tie them to the shaft. These little clutches can be operated by (relatively) inexpensive solenoid valves, which can be computer controlled. To engage a gear, just open one of the valves. To engage neutral, close all of them. Not a complicated control program.

Now, there's no more dog ring/gear/synchro wear, as those parts are gone. By varying the speed at which the valves open, you can have the shift action be slow and smooth, or quick and hard. If the hydraulics fail, the system either remains in gear (as long as the pipe between the engaged clutch and the valve isn't the leak), or goes into neutral. If the electrics fail, all of the valves open, and the 'box goes into neutral. Since there's a computer controlling the valves, it's easy to program in rev limits. You could arrange it as a "pre-selector", so you push a lever, say, 2 times when in fourth, and the computer shifts down to second only when the revs are matched to your speed, rather than exactly when you push the lever. The main clutch would only be used for starting from a stop, and wouldn't have to be touched otherwise. The best thing is it can be retrofitted into nearly any existing gearbox.

Some Australian engineering student dreamed it up, and made a prototype or two, used in some racecars (rally cars, I think). Last I heard, he was looking for a manufacturing partner to make them in quantity. I think it's revolutionary, but unfortunately, it doesn't look to be attracting anything like the attention it deserves.

[Hi_Fi_Guy]

The safest system I can think of is a Sequential Adapter. This adapter fits to the lowe part of the gearshift (under the shifter boot) and forces you to shift sequentially UP or DOWN (forward & back), like on a motorcycle. I know these are currently available for newer porsches like Boxsters and carreras as well as some modern VWs. One would imagine it wouldn't be too difficult for one of these companies to make one work on a teener (might need to go cable shift though).

With this system a 5 to 2 downshift is still possible, but you would have to tug the lever back 3 times before releasing the clutch. One would hope that would not be a common mistake.

[JWest]

Imagine, instead of the synchro/slider/dog gear system, you had a set of small hydraulically actuated multiplate clutches (hydraulic fluid acting directly on a pressure plate inside a housing splined to the shaft, just as the slider is).

That just sounds like a run-of-the-mill automatic transmission, just made more complex by trying to package it with normal gears rather than planetary gear sets.

[JWest]

The safest system I can think of is a Sequential Adapter. This adapter fits to the lowe part of the gearshift (under the shifter boot) and forces you to shift sequentially UP or DOWN (forward & back), like on a motorcycle. I know these are currently available for newer porsches like Boxsters and carreras as well as some modern VWs. One would imagine it wouldn't be too difficult for one of these companies to make one work on a teener (might need to go cable shift though).

With this system a 5 to 2 downshift is still possible, but you would have to tug the lever back 3 times before releasing the clutch. One would hope that would not be a common mistake.

Vertical gate shifters were/are available for GM/Ford type 4 speed transmissions for drag racing. Basically the same thing - shift up and down one gear at a time.

I have never heard of anyone thinking of them as something you would want for a street car or for road racing.

[VegasRacer]

I've got a friend who races a 912. He blew his motor twice in the same year when he missed a shift and over reved the motor. His soulution was to spend more $$'s and install a Ferrari type shift gate. I don't know who the maker was, but I do remember he said the cost was about $3000.

[McMark]

It would be pretty easy to stop a hydraulic clutch from engaging. (IMG:style_emoticons/default/wink.gif)

[iamchappy]

It seems like it would be fairly simple to make a plate like shown above to guide it into the gears.

[JWest]

It seems like it would be fairly simple to make a plate like shown above to guide it into the gears.

It seems that everytime a read a Ferrari review, the shift gate is mentioned at annoying, balky, slow, only redeemed by the fact that it is so traditional.

Here is a snip from an article comparing a Ferrari and a Lamborghini:
Both are plagued with shift gates, which slow cross-gate changes without preventing-and perhaps encouraging-missed gears.

This does not seem like something I want to ADD to a car.

[lapuwali]

That just sounds like a run-of-the-mill automatic transmission, just made more complex by trying to package it with normal gears rather than planetary gear sets.

The devil is in the details. You still have a conventional clutch, so no power-sapping torque convertor. It's really just a different way to lock each gear to its shaft rather than using dog rings or dog gears. The good bit about his design is that it will fit comfortably inside any existing manual gearbox after you remove all of the existing synchro/dog assemblies and the shift forks. The hydraulic system actually ends up being simpler than an automatic transmission.


Converting an existing H-pattern gearbox to sequential is an expensive proposition. It also violates the rules for a number of racing organizations (as does the multi-clutch setup I've discussed). What might be simpler would be an H-pattern shift gate (ala Ferrari), with a set of lock-out plates that move based on wheel speed and the current gear position. Move into neutral, and the lockouts only provide the safe gear slots, the others being blocked until the wheel speed is low enough. Indeed, for the 914, you'd really only need a lockout for 2nd and 3rd. First is rarely selected by accident, and it's hard to blow up the engine by downshifting into 4th too early.

Another option along those lines might be a "lock in" plate, which doesn't allow the shift lever to be moved out of the 4/5 gate above a certain wheel speed. This could be accomplished with a single solenoid, positioned to the left of the R/1 gate, which extends so the shifter can't be moved to the left when activated. Even simpler, a slotted plate with a tongue and pin that, when the pin is extended, doesn't allow the slotted plate to move to the left. You could even use the existing lockout plate and modify it. The tongue points to the right, presenting a hole for a solenoid-actuated pin in the 4/5 slot. The pin is extended above wheel speed X, and retracted below that speed.

Wish I could draw some pictures of this...

[JWest]

Another option along those lines might be a "lock in" plate, which doesn't allow the shift lever to be moved out of the 4/5 gate above a certain wheel speed.

The Borg-Warner T-56 6-speed transmission (new Corvette and others) uses this for reverse. Below 7 MPH or so a solenoid retracts a pin to allow access to the reverse gate. The solenoid has a heavy spring, so it can be "crashed through" should the lockout fail.

The problem is no one is willing to pay for any of these ideas - even the Carrera GT had a problem of a missed shift blowing an engine during a demo. People want real shifters on real sportscars.