I see, I think i'll just stick with heel and toe.

 

Well when you talk about double clutching and bliping the throttle when you do it, this is how your suposed to. What happens whe you do the double clutch without bliping the throttle. Thats how he double clutches and I want to make sure hes doing it right so he wont mess the car up any more. But trust me there is nothing wrong with his syncros.
Charles

 

I think we're all willing to beleive that the synchros are ok, so let it be. It sounds to me like your friend would be better off driving a mini-van (no clutch to worry about). If he's grinding gears, don't worry, it wont be long 'til he CAN'T mess it up any more.

Yes, when downshifting (double, single, or no clutch) you are best off blipping the throttle lightly.

 

If you double clutch DOWNSHIFT, and DON'T blip the throttle, then you are defeating the purpose of double-clutching, and since you are slowing down the input shaft when double clutching(and not blipping), then you are actually wearing your syncros MORE so than by shifting normally.

 

O.K. Thanks that helps. Its going to be hard getting this threw his head. He is curently running the car with a bad turbo, numerous vaccum leaks, Bad alternater, And a cracked exhaust manifold with a SMALL hole in the exhaust. And when reving high you hear the turbo bearings start to grind when in boost. He has wrecked the car and got it fixed, the driverside window doesn't work, and the driverside key hole is broken. The interior is all messed up. He is running on tires that have went past the wear marks. But the horrible thing is that this car was in perfect condition before he got his hands on it. Oh and now the tranny is going out as of this morning. Man when I got my GTU it had a low compression motor and bad interior, ran mega rich, I redid the whole motor got new tires and changed just about everything on the car except the suspension and steering. Then the steering on the right front tire when when I was conter steering from a low mph slide I got into with gravel I didn't see and I hit a pole. Damn I loved that car. Totaled it.
Charles

 

Does anyone else think it's funny that a guy named Vin Diesel(spell?) talks about double clutching in The Fast and the Furious. Hehe, his last name is diesel.

By the way, to the best of my knowledge, big rigs don't have synchros in their gearboxes, so they have to double clutch every time.

 

I think there is some misconceptions.

I would think double clutching is good for the clutch, when used properly. My Camry's clutch is slipping, and needs to be replaced. Whenever possible, I'll double clutch, to match gears. I would believe this extends clutch life.

Someone mentioned they'll stick to heel and toe. I was under the impression heel and toe is "double clutching" in a corner.

If your going hot into a corner, I trail brake, then to get a smooth acceleration throttle out of the corner, I heel, toe the gas to drop to the next lowest gear.

Without double clutching, there would be the jerk of just downshifting, which depending on where you are in the turn, could be very bad, and I would think throw off your cars traction off.

 

hehe ya they got big rigs like that. must be fun when they got low and high gear as well as the standard gears to switch between on some of em. ive heard of them guys racing each other and double clutching with a hand on both sticks. that must be fun

 

aze cheese I know " granny shifting not 2x clutching like you should" what crap is that???? **** even I dont know crap about cars but I know that. stupid writers trying to look like they know somthing. but yeah I hatfta 2x the SHO the syncros are goooooooooone, my mom completly lets the rpm's drop b4 shifting, for every shift. so now the synco is gone and its not very fun to drive, 2x clutching takes sooo long for me, for I am not very good at it.oh well its better than walking

 

Its not.

 

NASCAR uses dog-ring transmissions with straight cut gears, not syncromesh trannies like street cars.
They don't use the clutch becuase you dont have to. You just slam it into gear, keeping the gas floored. It has nothing to do with clutch style.

 

I dunno what they are doing playing with their "other" stick while driving...
Most transports now have a switch on the gear shift, allowing them to 'split' gears (high and low range...) (clutchless too, to the best of my knowledge...)

As well, unless they were carrying a load, there would be no reason for them to use the low range gears....

 

One of my friends brothers used to drive a rig and he went to the rig races in cali and thats how they did it. Both hands on the different gear shifts. He said that the steering in thoughs things are so tight that you can go ing a line for and hour and stay on the road if its straight without touching the wheel. He had an old really nice Freightliner. Oh god that was a sweet rig!!
Charles

 

No, double clutching helps extend the life of the of the gearbox, not the clutch.
No, you can double clutch on upshifts as well as downshifts. When double clutching on upshifts, you do NOT blip the throttle. When you downshift and double clutch, you don't HAVE to heel-toe, you can just blip the throttle while not braking. Heel-toeing is just the act of using your right foot to brake and blip the throttle at the same time. Double clutching, is simply shifting into neutral, releasing the clutch, disengaging the clutch, and selecting the next gear. It works for upshifts AND downshifts.
You are supposed to downshift in your braking zone, THEN trailbrake, that way you can get on the gas sooner without upsetting the balance of the car and trying to downshift on the exit.
Once again this isn't a problem if you do your downshifting BEFORE the turn-in point of the corner. Also, you can match revs by heel-toeing WITHOUT double-clutching just fine. I am currently racing Formula 2000's that use dog-rings instead of syncromesh so we HAVE to heel-toe to get the cars to downshift. I do NOT double-clutch on upshifts or downshifts, although if I was doing longer races I would to save wear and tear on the gearbox.

 

Just to let you know, the reason they don't have to let up when they upshift isn't because of the dog-rings. Dog-rings transmissions allow you to upshift without clutching very easily, but you still have to lift off the throttle. Also with dog-rings you HAVE to blip the throttle to match revs to downshift. In some pro series like Nascar and CART, the computer cuts off fuel automatically when you upshift, so thats why they don't have to lift when shifting.

 

Some thing wrong with his syncro's if he grinds on every shift...there is no way u can be that bad of a driver and grind on every shift...have u ever driven his car?? your gearbox and his are way way different (previous drivers driving habits). I have to double clutch only when downshifting into 2nd cause thats the only gear that grinds.

 

I didn't say that he grinds on every gear. just on alot when he is excited, which is most of the time. And yes I have driven his car which I stated before and No I didn't grind any gears.
Charles

 

god..this thread is so damn confusing

i stopped reading 6 posts ago because there is too much conflicting points...

 

What could possibly be confusing? The overwhelming majority say to single clutch unless your synchros are FUBAR.

As far as input shaft speed, upshifting: double clutching slows the input shaft; downshifting: double clutching speeds up the input shaft (if you blip the throttle).

Readers Digest Condensed Thread

 

For clarification, watch some in-car of a NASCAR race from Pocono. Not only do they NOT have a computer to cut the fuel on upshifts, they also do NOT match revs on the downshift from 4-3 going into Turn 1.

 

Hmm...I don't know about Nascar, but I know that in CART they DO have a computer that cuts fuel for upshifts, and they DO have to blip the throttle for downshifts. In any case, if what you are saying is true about Nascar, then all I know, is that the dog-rings are not what allows them to not lift while shifting, and they are not what allows them to downshift without matching revs.

 

Even at Pocono, it's rare for NASCAR drivers to shift once their up to speed. And if you really watch, on those occasions when they do shift, the clutch gets used. At Taladega earlier this year, the commentators made particular note of the fact that a driver (don't remember name) was actually resting his foot on the clutch after shifting, and that he'd be fixing that habit after seeing the tapes. NASCAR allows only a limited computer for telemetry purposes only. Engines must be naturally aspirated, carb'd, and of a particular displacement. Synchros way too much for race cars, and and these guys are very, very, very quick on their extremely rare shifts. They drive for a living, remember.

 

yeah he COULD be double clutching to speed it up, but he's missing a key point in that description.. when he lets it out, puts it in neutral, lets off the clutch, (then the part he missed.. blipping the throttle to the desired RPM in the next gear), then clutch back in, and into the lower gear.

I'm getting to the point in my Civic where I'm doing it regularly because my gears are starting to grind pretty bad, so I'm trying to save the synchros as much as I can.