danswofford

I installed an aftermarket aluminium gas pedal and then added a 1/4 aluminium plate to it which serves two purposes: to add height to the pedal and the plate is 3/4" wider than the stock location.

The setup for me is just perfect. I can get plenty of foot on the brake and rock the outside of my foot to tag the gas.

Dan

danswofford

Thanks for all the input. I think the concensus is that double clutching is not needed on modern cars with good syncos. I'm going to try to learn to just do a single clutch and rev match.

sleeper02Z06

Bingo, on both counts!



Joe

TGrits10

Well some people didn't pass it the first time around......

J/K (I keeed, I keeed!!) I've got a pedantic streak and it shows (thought I was being subtle enough not to ruffle feathers....obviously not the case). Guess I'm still idealistic/foolish enough to think I can change the world by eradicating poor spelling & grammar one post at a time.

TGrits10

96LT1

The vast majority of the cars that required a double-clutch to downshift (no 1-2 synchros) also had mechanical linkages for the clutches.

I'm not aware any newer cars that don't have hydraulic clutches.

That said the only time that a car might be prone to grinding is if the hydraulic clutch can't "keep up" and with modern hydraulics the only way that should happen is if their is a problem with the system (old fluid, low fluid, bad o-rings, etc)

fmrfast

With the clutch in there is still some connection this causes engine RPM's & transmission speed to climb together. When in neutral there is no connection, engine speed spools up without spooling up the trans.

96LT1

You also have to remember that almost all manual transmissions today have a constant-mesh gearbox. The main drive gear, cluster gear and all the mainshaft gears are always turning regardless of whether the transmission is in neutral or the clutch is in.

Kanmer

Either way you do it,(clutch in blip or clutch out blip) the purpose is to match the engine RPM's to road speed for the gear you are selecting. Not the transmission. The wheels, trans, shaft will all be turning in relation to road speed. You are trying to match the rpms to that speed for the gear you are selecting. Rpms too low and you squawk the tires and slow down drastically. Too high and you defeated the purpose of your braking. RPM matching is the reason and it will save the equipment.

Bob

Solofast

When you push in the clutch and disengage all the gears, the layshaft and input shaft start to slow down. That is fine on an upshift, since the next gear that you are engaging is spinning at a lower speed and the gear engagement pretty much "drops in".

On a downshift, the layshaft wants to slow down, but the gear you are trying to engage is spinning faster, so the synchro ring creates drag between the ring and the gear you are engaging, so that when the speeds are close enough the engagement dogs can slip into place.

When you are properly double clutching on a downshift you are spinning up the input shaft and layshaft to a higher speed so that the speeds of the layshaft and the gear that you are downshifting to and want to engage, match. That way the synchros's don't have to speed up the layshaft. Thus the shift is easier, and there is a lot less wear and tear on the syncro's.

In the C5 & C6 not only do the syncro's have to speed up the layshaft, and clutch plate, but they have to accelerate the long input shaft between the engine and the gearbox. This fundmental design means that the syncro's have to work harder to accelerate the additional rotating inertia of the shaft between the clutch and the gearbox. Porsche had lot's of syncro wear problems on the 928 for this very reason.

I was talking to a friend who works a Tremac and he said that newer cars are using carbon synchro rings instead of brass, to improve the wear in applications like ours. Not sure if our trannies have carbon syncro rings, maybe somebody who has had one of them apart can chime in on that one.

If you can do it right, and if you can do it quickly enough to not slow yourself down, go for it. I do it all the time on the street, since it reduces shift effort. If you are feeling high shift effort what you are feeling is the syncro rings creating drag on the shaft and matching the speeds so that the engagement dogs don't grind.... If the gears drop in really easily it was a good match, and no synchro wear. Going up thru the gears on the street you can find shift points that give you a really easy shift. What is happening there is that while you are going slowly thru netural the natural deceleration of the layshaft when you put in the clutch is matching the drop in output shaft speed and the shift is really easy. That minimizes wear on the synchros so that you can abuse them on weekends....

Obviously you have to match the speed of the engine to the road speed when you let out the clutch so as to not upset the car, double clutching is more for saving the syncromesh and reducing shift effort.

JiminFL

When I got my first C5 I already knew how to double-clutch, and always did. First time I went for a DE event I realized that since double-clutched heel toe downshifts were already 'programmed', changing to single clutching and reliance on the syncros to spin up the tranny for the sake of downshift speed was nearly impossible and definitely not faster, mostly just felt weird and seemed to be too much to think about under that kind of pressure.

Bottom line, I think d-c saves some wear on synchros, and downshifting saves brakes at the cost of rear rubber over time, but my advice is to go with what is natural and what you do in everyday driving. The less you have to think about shift technique under threshold braking, the better, IMO.


Jim

TGrits10

Amen. Practice like you play .

I've gotten so used to heel-toeing downshifts on the street that now it feels really odd to just brake with the clutch in and not be engine braking. The benefit is that on the track (or any other spirited situation ), the downshifts under braking require almost no thought, I just do it.