Engage or Disengage Clutch at a Stop


#1

One mechanic has told me that you should keep your clutch engaged at a stop. A friend of mine has advised against doing that since he claims that it is hard on the throw-out bearing. What is best for the clutch, to keep it engaged or to disengage it and put the car in neutral at a stop? Thanks for your input.


#2

I’ve been driving manual transmissions for over 40 years. Be it my own vehicle or a big rig.

The throw out bearing is designed to hold the clutch out at a stop. And that’s the way I use it.

I’ve never replaced a clutch because the throw out bearing wore out. It has been because the clutch itself wore out.

Another urban myth.

Tester


#3

On the other hand, I HAVE seen clutch failures caused by frozen or broken throw-out bearings…These sealed bearings must survive on the lube provided at the factory…“Riding The Clutch” is not a substitute for shifting into neutral…JMHO…


#4

This discussion comes up every once in a while. The answers always seem to be about 50-50.

Personally I’ve never been one to sit at a light with my foot on the clutch. Ever. I have ridden with idiots who held their cars on hills by slipping the clutch. UGH! I have replaced several clutches, and I can attest that the throw out bearing was a cause for failure at least part of the time. Even when you have your foot on the clutch, there may still be minimal spinning contact between the clutch and the pressure plate and flywheel.

Why put extra unnecessary wear on any car component? Watch for the yellow light for the cross traffic, and slip it in gear. If the yellow light is not visible, so what if you take half a second to put your car in gear once you get a green light? That’s how you make a clutch last the life of the car.

See also: http://community.cartalk.com/discussion/2274401/extending-clutch-life

And: http://community.cartalk.com/discussion/2296636/tips-for-babying-a-clutch-transmission

There are more if you want to do a search.


#5

Conventional wisdom is that holding the clutch in increases throwout bearing wear.

OTOH, it is in the interest of safety to be able to quickly accelerate away from a dead stop if and when the drunk/texting/whatever car behind fails to stop.

IMHO, what really trashes TBs is riding/slipping the clutch, not fully depressing the clutch pedal. I view the safety issue on a sliding scale based on vehicle weight/visibility/maneuverability (i.e. I always keep it in gear on a M/C, but I–generally–don’t in my F150).


#6

I no longer drive standard shift vehicles but when I did…I released the clutch through a long light. I was diligent however and was on the clutch when the light changed. A lot of people though…just seem to sit there and wait on another shade of green. If you can’t be alert…keep the clutch engaged through the light since it won’t hurt a thing. +1 for @Tester .


#7

When I had vehicles with a clutch, I would put it in neutral and let the clutch out at stop lights.

But I always watched the cross traffic’s light. When their light went to Yellow, I’d push in the clutch and wait in 1st gear for my light to turn green.

yosemite


#8

MG McAnick We may be Brothers from a different Mother! My Father gave me his old 1954 Chevy when I was 13 years old and taught me how to operate a clutch. That was 49 years ago. I have owned well over 40 motor vehicles. Maybe 10 were automatics. At a stop sign I usually leave the vehicle in gear with clutch disengaged unless I anticipate having to wait more than a few seconds. At a red light I always wait in neutral with my foot off the clutch. I also keep the brakes on so any driver approaching from behind will (hopefully) see my brake lights. When the light turns green I quickly shift to second then first. This is an old habit from owning/driving BMC cars with non syncro first gear.


#9

To each their own but my vote is for neutral and shifting into gear as the light changes. I’ve gone into a number of clutches with noisy throwout bearings on comparatively low mileage cars and the common denominator was city driving although it was not often known how the driver operated the vehicle at the lights.

There’s also the side issues of glazing the clutch disc if the clutch hydraulics are a little weak or the clutch is out of adjustment a bit along with the possibility of what happens if the hydraulics decide to let go or a clutch cable snaps as the driver is sitting there.

A young man whom I worked with at a Subaru dealer owned an older Subaru that he had modded and took a lot of pride in. The clutch cable snapped on that car one day as he was sitting in the parking lot, in gear, and talking to someone for a few minutes. The car lurched into the side of one of the used cars parked there. There wasn’t a lot of damage but the point could be made that if his car had lurched into moving traffic things could have been much worse.


#10

One thing that has to be consider is that with the clutch disengaged, the crankshaft is being thrust foreward with that same force on the throwout bearing. Although I have never encountered abadly worn crankshaft thrust bearing or crank thrust surfaces, it could happen and would be very expensive to correct.

Just a thought.


#11

The reality is that keeping the clutch pedal in at stoplights keeps the throwout bearing under load and putting the tranny in neutral and releasing the pedal does not. Whether it manifests itself as premature wear on the throwout bearing will vary widely depending on the vehicle and on how much in-town driving the owner does.

But, since holding the pedal in MIGHT lead to premature throwout bearing failure, and not doing so definitely won’t, I see no reason NOT to put the tranny in neutral and let the pedal out. You have everything to gain and nothing to lose.


#12

Every time the clutch is operated, slippage occurs between the clutch disc and the pressure plate/flywheel. There’s no getting around this. This slippage removes some of the friction material from the clutch disc.

So if I hold the clutch pedal down at stops, as opposed to stepping on the clutch pedal, shifting into neutral, releasing the clutch pedal, then stepping on the clutch pedal to put the transmission into gear, and then letting off the clutch pedal to go, I only cycle the clutch and throw out bearing half the number of times.

Tester


#13

Interesting point.

Researcher made an interesting point about thrust load on the crankshaft, too. I never would have thought of that. I highly doubt of it’s significant, but it is an interesting point.

I all may be that it’ll all vary wildly with the vehicle. And the differences may not be measurable… at least not on an internet forum.

But I think the biggest difference might be driving environment. If I live in an urban area and have to stop at 30 stoplights on my trips to and from work every day, I might suffer a throwout bearing failure, but if I live in an area in North Dakota where there are only stopsigns and no lights, I might never suffer a throwout bearing failure. I’d probably wear out the clutch first.


#14

depends on the vehicle too. my first 75 ford supercab had a clutch that took quite a bit of effort to hold down.

as my knees got worse I would put it in neutral more often.

I like manual trannys but would probably not buy another because of my knees and back


#15

ok4450 Around 1972 I was preparing to back my 1960 MGA out of a parking space. I pushed the clutch pedal to the floor and shifted to reverse. Before I could engage the clutch, it engaged itself and lurched backward I hit the brakes which killed the engine. The hydraulic clutch cylinder had blown a piston seal. Fortunately there was nothing or no one behind me. That is one reason I wait for traffic lights in neutral.


#16

If I’m at a stop sign, I depress the clutch. If I pull up to a stop light that’s just turned red, I’ll put in in neutral. Just my preference.


#17

When my dad was teaching me to drive a stick on my new 70 Maverick my parents bought for a graduation present , he always said when stopped at a light, put car in neutral with the clutch out to prevent excessive wear on the throw out bearing. I have had my 89 Mustang GT since new and always followed this procedure. At 80 K miles the bearing went and could not shift as clutch would not release…Changed out everything to new with the clutch and no problems as that was 10 years ago. Car now only has 114k on it…Go figure. I guess we will never have an answer to this question.
To each his own.


#18

Howie32703 I agree. I don’t think clutch in or out is that big of a deal and is mostly a personal driving style. I have only replaced 2 clutch assemblies in 30+ manual transmissions. Both were in good condition but engine and transmission were out of the car and I figured it was cheap insurance.


#19

I might add this to go along with Researcher’s comment about crankshaft and end play. This example is more extreme but could make the point.

The old air-cooled VWs would sometimes get balky on the clutches with premature wear, gear gnash, or a noticeable jolt when the clutch was engaged. This problem was due to excessive crankshaft end play which was caused by heavy use of the clutch and pressure of the crankshaft on the main bearing thrust surface.

The engine blocks are magnesium so the constant beating and pressure would dramatically increase the crank end play which in turn altered clutch operation.
When rebuilding an engine the main bearings were not only offered in journal oversizes of .010 and so on but were also offered with thrust surfaces that were thicker to account for the worn engine block due to clutch operation.

That’s also why when considering buying an old air-cooled the first step is raising the rear deck lid, grasping the crank pulley, and shoving it back and forth to determine how much wear and clunk there is…
A heavy clunk means an engine overhaul and iffy clutch operation.


#20

This is kind of a no-brainer really. Slip the tranny out of gear (via clutch or not, it’s easy) and let it in neutral while at a stop light or stop sign, the wear will be minimal. I’ve always done this and NEVER replaced a clutch in over 40 years of driving, never at least due to wear . . I would replace a clutch if I had the car apart to the point that it would be easy to change while repairing something else. My last daily had 585,000 miles on it when retired due to rust, original clutch. Stay safe, good luck! Rocketman