Double clutching to prevent synchros wear

[swalve]

I'm not altogether experienced with manual transmissions, but I have used these common sense things with my '99 Ford Contour, and it's made it to 120,000 miles without any troubles...

1) Use the brakes to stop- slowing by downshifting only is fun and you can get better performance doing it, but it doubles (or more) the wear on the clutch, and is unsafe in traffic. Drivers behind you don't know you're braking because your brake lights don't go on. Brakes are cheaper than a clutch.

2) Let the synchros do their job- don't slam the stick into gear. This causes the synchros to work very hard, very fast, creating more heat and wear. On my transmission, I just lightly touch the gearshift to the next gear, and after a half second or so it just slips right into gear because the synchros have been allowed to do their job.

 

[tdi-rick]

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Can you please make a step by step description of heel-toe braking and rev matching while skipping the clutch?

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Kilou, check my post at the top of page two

 

[JHZR2]

I was wondering about one thing... Say youe double clutching, but for whatever dumb reason you overrev the engine, i.e. rev it faster than it will need to be for your speed/gear.

It seems to me that there would be a LOT more wear on synchros from having to bring the speed down, as compard to up...

Granted, they do it somewhat if youre shifting up through the gears fast enough, I suppose.

Any thoughts?

JMH

 

[Audity]

I think Swalve has it right -

Use the brakes, not the drivetrain, to slow down. Downshift only to be in the right gear for when you go back to the throttle. Pads and rotors are dirt cheap compared to transmissions and clutches.

Treat your transmission gently. I'm actually not familiar with domestic manual transmissions, especially ones bolted to big V-8's, but with imports I've driven (and I've been lucky to have driven dozens) shifting is a two- or three-finger activity, actually a fingertip operation.

And on downshifts, a wise person once told me "downshifts should he heard but not felt".

 

[Mickey_M]

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Of course, by double-clutching, you're trading decreased synchro wear for increased wear on your throwout bearing, cluth slave, and clutch master cylinder..

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Only if you use the clutch.

If you do it right, you can bypass the clutch.

I usually get 140-180,000 miles on a clutch.

 

[brianl703]

I don't double clutch but if for example I'm going from 5th to 3rd, I step on the clutch, shift from 5th to 4th to 3rd and then release the clutch. Going directly from 5th to 3rd seems to be hard on the 3rd gear syncro based on the amount of effort it would take to put it in 3rd gear.

 

[XS650]

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I think Swalve has it right -

Use the brakes, not the drivetrain, to slow down. Downshift only to be in the right gear for when you go back to the throttle.

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A good rule of thumb is to use the brakes to slow down, downshift to maintain speed on a downgrade.

 

[Shannow]

I normal shift on the way up, and double on the way down (usually 5th to third). brakes do the braking, matching recvs means no snatch when I'm coming out of the corner.

Never knew what I could do until I tore my anterior cruciate ligament, and had to drive home sans clutch at all. A few minutes, and I was pretty smooth both up and down. Traffic lights were "engage first, floor accelerator, turn ignition key to start".

 

[XS650]

Shannow, I've driven a motorcycle and car many miles home without using the clutch because of broken clutch cables. Same technique as yours except light throttle when starting out from a stop with the starter.

 

[Shannow]

XS650, mine was a hot 6 with triple CD carbs. needed maximum DP across the slide to catch...was a tad exciting when it did, 'though.

 

[Yuk]

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Anyone else ever skip the clutch and just rev-match???

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Yes, often.

When I wear my big steal toe boots I have trouble working the clutch in my little old Sentra (I actually have to turn my left foot sideways to work the pedal). So... I shift up and down (except when I’m pulling away from a stop sign/red light) without the clutch. Downshifts require rev-matching, throttle blips or else I get major grinding and really nasty looks from surrounding drivers. Done properly, I can get seamless, clutchless shifts all the way down to first.

 

[sprintman]

Good drivers always double clutch. Bad drivers don't. Simple as really. Can my wife double de clutch? Next question..s