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Old 11-25-2010
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Jim Pace Jim Pace is offline
Skippy Instructor
Entry Speed Demon / Advanced Member (100+ Posts)
 
Join Date: Jun 2006
Location: Ridgeland MS
Posts: 168
Re: Gearbox question - new SB Formula cars

Stuart,
Good question. Different shifting techniques are better suited for different types of cars depending on the reason behind the procedure. Depending on the cars you drive you can use different techniques to keep the shifting smooth and efficient.

#1. A Sequential box will shift up & down without the clutch just fine and the "heel toe" portion is "needed" to blend the speed of the engine with the road speed to prevent upsetting the rear tires when the lower gear is selected (think turn 17 Sebring). In this case a simple heel-toe blip of the throttle will do just fine. Some cars (Skippy Formula among them) will respond better using the clutch on the downshift to avoid shocking the driveline and adding a little forgiveness to your technique (again Sebring 17). Most Skippy Formula guys will suggest the clutch on the downshift but not on the upshift. Yes on Heel-Toe. It will of course go into gear no matter how bad your technique and certain guys can Go Fast no matter what they do.

#2. A Non Synchro box (Hewland style being very popular) needs the Heel-Toe to match the actual gear revs before the lower gear can be selected. In that case it is recommended to do a proper Double Clutch Downshift, the essence of which is to Rev the engine in Neutral with the Clutch out. How you arrive at Neutral and what you do after is not so important as long as the Blip occurs in Neutral with the Clutch out. Many variations exist on the double clutch theme but again the essence is Blip in Neutral with Clutch Out. Many Non Synchro drivers only use the clutch to get started and stopped. Once this proper Double Clutch technique is learned you can drive most anything with or without the clutch. Street car, race car, vintage cars, trucks...pretty much anything besides a Sequential. Again with enough force even bad technique can be overcome and many drivers do just that. Problems occur not on every shift but on the occasional bad shift while passing or other traffic issues where poor fundamentals generally jump up and bite you on tail. Many stories of exceptional SKippy guys making the next step into higher level cars only to find they had poor shifting fundamentals and paid a high price to learn in the new cars. Engine over revs and broken trannys cost staggering amounts at that level!

#3 A Synchro box in a street car (typical H pattern) can be Double Clutched to save wear on the synchros but not needed. In this case the Heel Toe is needed to blend the engine speed to the road speed like with the Sequential. These are great for double clutch practice however and with patience you can "FEEL" the synchro working less when done correctly. The gear selector is not forced into gear but rather you feel it when the revs match and then it "falls" into gear. The Mazda MX5s (all the Mazda school cars) are very good for this practice and asking an instructor to show you is a good idea.

Up shift or down, regardless of the box, try to feel what is going on inside the tranny and you will be better intune with the car.
Best of luck in your school! Feel free to ask questions.
Regards,
JP
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