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Correct Shifting Technique?


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#61 leon_90

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Posted Oct 02 2017 - 10:23 AM

Donohue recalls driving a Ferrari 250 LM clutchless but only because Hansgen blew it during his turn. By the way he described the event it seems unlikely that it was something usual, but an emergency only kind of situation

#62 hagapito40

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Posted Oct 02 2017 - 12:12 PM

Not forget also that a racing clutch designed to work on a +400 hp is no equal to the one instaled on a street car. There is almost no slip AFAIK and the travel between clutch-declutch is short, making easy to stall the engine in first gear (witch was common on old races after pit stop).

Now i will ASK AGAIN! it is possible to disable autoblip in GPL to shift with 3 pedals+ sequencial shifter?

#63 John Woods

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Posted Oct 02 2017 - 02:21 PM

IIRC there is a no-blip patch somewhere, but not sure...

Spent a few minutes looking up "no clutch shifting race car transmission" and found these happy quotes:
(not a lot of info to be found easily).

Brendan on Vehicle Maintenance and Repair Forum:

"Basically, a dogbox allows instantaneous shifting without the clutch, but in a synchro box you have to put it in neutral, then match revs, then engage next gear. In a synchronized box, it is unnecessary to shift without a clutch (unless, for instance, your clutch is broken and you need to limp the car home/to a shop). This will result in increased synchro wear."

Evelrod on eng-tips.com, (automotive engineers forum)

"Nick, I have a rather laaaaaarge history with broken gearboxes from some 50 years of racing...I think I have broken just about every part that will fit in a manual box at one time or another.  "Dog boxes" are like all other manual transmissions, some good and some a lot better.  I have had a passing aquaintance with a Jack Knight four and a JK five speed...both shifted with a conventional lever and all upshifts were clutchless as it's extrememly difficult to do a proper up with a clutch...down I always used the clutch with a little 'heel toe'.

Milanoguy on eng-tips.com:

"Well I don’t have the precise answer for you, but clutchless upshifts are why people use dog engagement transmissions in the first place."

admc58 on Grassroots Motorsports:

"Been doing it racing for years and haven't killed a trans yet. I actually only do it for down shifts. Up shifts I still clutch."


So, for sure not definitive, but...


:D

Edited by John Woods, Oct 02 2017 - 02:31 PM.


#64 TurboMan

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Posted Oct 02 2017 - 02:52 PM

View Posthagapito40, on Oct 02 2017 - 12:12 PM, said:

...

Now i will ASK AGAIN! it is possible to disable autoblip in GPL to shift with 3 pedals+ sequencial shifter?

I never managed to disable autoblip with that setup but i have an idea that could work, will do a test this week (hopefully) and report back with the possible solution, if nobody figures it out :) .

BTW, do you know how are "crash gearbox" or "dog gearbox" called in Spanish (South America or Spain, i don't mind)? PM me not to get this too off-topic.

Edited by TurboMan, Oct 02 2017 - 02:52 PM.


#65 gliebzeit

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Posted Oct 02 2017 - 04:27 PM

"Now i will ASK AGAIN! it is possible to disable autoblip in GPL to shift with 3 pedals+ sequencial shifter?" - No.

#66 hagapito40

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Posted Oct 02 2017 - 08:44 PM

I will have to build my own h shifter then... :P
Turboman: the only term i know to describe a gearbox is "caja de cambios sincronizada" (sinchronized gearbox) or "caja de cambios no sincronizada" the opposite :blink:

thanks!

#67 TurboMan

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Posted Oct 06 2017 - 11:22 AM

View Posthagapito40, on Oct 02 2017 - 08:44 PM, said:

I will have to build my own h shifter then... :P
Turboman: the only term i know to describe a gearbox is "caja de cambios sincronizada" (sinchronized gearbox) or "caja de cambios no sincronizada" the opposite :blink:

thanks!

That's ok. I also did a quick search but it seems there's no proper translation neither for "dog box" nor "crash box". Thx :thumbup:

#68 John Woods

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Posted Oct 06 2017 - 03:15 PM

Caja de perro?
(google translator)

Perrocaja?


:D

#69 Bob Simpson

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Posted Oct 06 2017 - 06:34 PM

The "dog" term has nothing to do with animals, I'd think.

It's probably more to do with the verb -

follow (someone or their movements) closely and persistently.
"photographers seemed to dog her every step" synonyms: pursue, follow, track, trail, shadow, hound;


informaltail
"they dogged him the length of the country"

Edited by Bob Simpson, Oct 06 2017 - 06:36 PM.


#70 Saiph

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Posted Oct 06 2017 - 07:41 PM

I'd disagree Bob. I think it refers to the way that the teeth on the "dog" firmly lock a gear to its layshaft, the same way a dog-type animal firmly grips its prey.

#71 Pete Gaimari

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Posted Oct 06 2017 - 08:24 PM

A dog is just another word for teeth on a gear.

#72 John Woods

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Posted Oct 07 2017 - 11:02 AM

Lathe Dog


Just guessing wildly, the first auto transmissions were derived from machine lathe gearboxes?

#73 Warren Hall Jr.

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Posted Oct 07 2017 - 04:07 PM

I'm not sure how the dog gear term came to be. I can tell you the gears have interlocking dove tails. Just like in good furniture or desk drawers.
The only difference is there's lots of space between them when engaged. It's the interlocking angled dogs (dove tails) that keep you from just moving the gear lever. The throttle or pressure on the gears has to be released in order to change gear.
Perhaps Bob will remember when he visited here I showed him actual dog gears and a fully functional main shaft from a Hewland MK8.
Warren

#74 John Woods

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Posted Oct 07 2017 - 05:47 PM

Dog Box Description from Honda Tuning Magazine, (published by Honda? Or superstreetonline.com, not sure...its from somewhere)

Quote

"Dog Box transmissions have fewer teeth, but they are larger and much straighter. They use far fewer parts than OEM transmissions while still retaining reliability. These gears are made to handle fast shifts in high horse powered vehicles. To some extent, the straight-teeth design creates a unique, almost whining sound inside the car. Not all Dog Box transmissions sound the same, but for the majority, the gears produce a sound similar to the noise a stock reverse gear makes when in use. Less parts and dog teeth make this upgrade a highly effective item for any serious racer.

Although these transmissions can be driven on the street, they're intended for racing. In order to shift, the user must unload a little torque to ensure the dog teeth are not lined up. This can be done by tapping the clutch or letting off the gas similar to shifting a stock transmission. The majority of racers with bigger budgets utilize a strain gauge to unload power. A strain gauge sends a signal to the ECU to stop the ignition which in turn unloads power long enough for a super quick shift. Though these tranny's are strong, that doesn't mean they can't be improperly used. That's why caution is strongly urged in using this transmission for daily driving. Grocery duties are better left to a backup beater.

Most racers with cars producing over 300 WHP opt for a Dog Box after they get tired of replacing their stock transmission. Repeatedly replacing transmissions and the parts involved is time consuming and costly. A few blown transmissions resulting in "Did Not Finish" scores and several thousand dollars in repair costs can entice even the most thrifty competitor."

All images alleged to be dogboxes:

Street transmission gear on left, dogbox gear on right: http://image.superst...h_gear_shot.jpg

http://image.superst...tdown+gears.jpg

http://image.superst...ars-in-case.jpg

Note in the attached pic reference to "dog rings."

Attached Files


Edited by John Woods, Oct 07 2017 - 05:58 PM.


#75 TurboMan

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Posted Oct 08 2017 - 12:27 PM

Some good pics there John, helps to understand what's going on inside these gearboxes.

View Posthagapito40, on Oct 02 2017 - 12:12 PM, said:

...

Now i will ASK AGAIN! it is possible to disable autoblip in GPL to shift with 3 pedals+ sequencial shifter?

Although Greg already confirmed it is not possible to disable autoblip with your configuration, i wanted to try something, which didn't work. So you'll need to get yourself an H-shifter :)




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