When I rev match towards a stop light and find a great majority of people are brake light watchers. You know the type who only brake if they see red taillights. . They cannot judge distance or perspective for ****.. and will literally run into you if you don't tap on the brakes to show them the red taillights their so familiar with.
So be careful if slow down the car by rev matching and going down the gears.

When I rev match towards a stop light and find a great majority of people are brake light watchers. You know the type who only brake if they see red taillights. . They cannot judge distance or perspective for ****.. and will literally run into you if you don't tap on the brakes to show them the red taillights their so familiar with.
So be careful if slow down the car by rev matching and going down the gears.


that is an excellent point!

there are two ways to heel-toe. you perform a simple revmatch, or you perform a full double clutch. read this thread from another board, we discussed it recently in details.

http://www.corner-carvers.com/forum/...ML/000576.html


[Modified by frank@b16a.com, 3:12 AM 12/25/2001]

Rick's Speedy Transmixer Run-On: The clutch disk is splined to the input shaft which is geared to the countershaft which is simultaneously geared to the 1,2,3 and 5 change gears (in a T5) which spin at different RPMs while they freely revolve on the mainshaft (pant, pant). Synchros reside between the free spinning change gears and the mainshaft to provide speed matching during the shift. The input shaft lies inline with the mainshaft and can also be synchro engaged to the mainshaft, the 1:1 4th "gear¨ position. Shifting involves an ordered dis/engagement of the engine and transmission at the clutch, and the changing of gear ratios with the shifter. Changing gear ratios includes changing geartrain RPM, and the gear sets' synchro assemblies help narrow the change gear-mainshaft RPM difference and provide final splined gear-mainshaft engagement. During this short shift interval, the car's speed doesn't change much, and likewise the transmission's driven mainshaft RPM doesn't change much. After the clutch is reengaged (let out) the geartrain RPM change must be reflected at the engine's RPM.
Downshifting involves changing from a lower numeric ratio, say 1.0:1 (4th) to a higher numeric ratio, say 1.29:1 (3rd). This 1.29:1 ratio nomenclature means that the engine spins 1.29 revolutions for one mainshaft revolution when in 3rd gear. From the 1:1 4th gear direct drive RPM, the engine must spin up to this 1.29 times higher 3rd gear RPM at some point during the short 4th gear to 3rd gear downshift interval. Looking at the 3rd gear synchro relative speeds between 4th and 3rd gear is also instructive. While in 1:1 4th gear at 3500 engine/mainshaft RPM, the 1.29:1 free spinning 3rd gear sees only 3500/1.29 = ~2700 RPM. After the 3rd gear downshift, assuming the mainshaft is close to 3500 RPM still, the engine RPM must have increased to 3500*1.29 = ~4500 RPM. The 3rd gear synchro rose ~800 RPM to the mainshaft 3500 RPM level, while the engine rose ~1000 RPM.

Wish said

quote:
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Cannon, that blip throttle is a downshift thing, and technically not needed with a double clutch, that's why you let the clutch out the second time to let the input shaft spin up to the same speed as the engine.
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Sorry, but this confused me, somewhat more than normal I think double clutch downshifts add to synchro work UNLESS engine RPM is raised while the clutch is out to match the new gear's higher RPM. The double clutch downshift without blip throttle doesn't accomplish anything of value. For example: in 4th gear, the engine spins the input geared geartrain at some RPM. Letting the clutch out after disengaging 4th gear just reconnects the engine to the input shaft geared geartrain at the same or lower RPM in neutral instead of 4th. No Work is done, although you have exercised your leg. Since the closed throttle engine RPM probably drops faster than the mainshaft RPM, the double clutch alone may even INCREASE the 3rd gear-mainshaft RPM difference that the synchro must still overcome...

To complete a 4th to 3rd downshift, while in neutral, the 3rd gear synchro RPM must either be sped up by


the engine's blip throttle back through a clutch engaged input shaft, or
the mainshaft speed forward through the 3rd gear synchro and geartrain to the clutch disengaged input shaft (recalling that the mainshaft stays close to the previous RPM).
If you blip throttle with the clutch out while the transmission is in neutral, the engine spins up the geartrain back to the 3rd gear synchro. The subsequent downshift into 3rd can now take place with little RPM difference across both the synchro and the clutch; smooth, baby. If the mainshaft speeds up the 3rd gear synchro alone prior to downshift, then the synchro has done the heavy lifting while the RPM mismatch still exists. Congratulations, the synchro RPM difference has just moved upstream to the clutch. Letting the clutch out engaged in 3rd gear while traveling at 4th gear speeds forces the car's rear tires to spin up the engine's RPM. This can upset the braking/turn-in balance and can cause lose of car control.

Downshifted gearboxes usually respond well to throttle blipping, with or without double clutching. Mastery yields smoother transitions and longer synchro life.

Plus, it just sounds right!

Rick

[EDIT]File type conversion errors[/EDIT]


[This message has been edited by Rick Kean (edited 11-27-2001).]

I actually can't heel/toe, I have to toe/heel... heel on brake and toe on throttle...

My foot won't twist enough for my heel to touch the gas pedal..

BTW Lloyd - your quote rocks. canibus is so sick it's not even funny. My favorite: