Is it better to downshift, or......

Simply because of the costs in the long run. I don't want to mess with my Tranny setup or clutch! Brakes are way cheaper and easier to repair!

 

Use your brakes to slow down and stop. Down shift to be in the correct gear for when you take off - either from a stop (1st gear), or from a slower speed (whevever gear is necessary).

 

KENCO- Put the transmission in neutral, let out the clutch and brake to a stop. No wear on clutch or throw-out bearing that way. The only time you need to downshift is to be in the correct gear for a corner so you can keep power on to stabilize the rear end and to be in the correct gear for best acceleration out of a corner or to match speeds with slower traffic ahead. Downshifting for stop signs or stop lights results in unecessary wear on clutch and driveline parts, even if it does sound heroically cool.

Taz
Terry Phillips

 

Your question is too black-and-white. Mostly use the brakes, but doing one GENTLE downshift into 3rd or 4th to get some better engine braking as you decellerate is OKish IMO if you're coming down from 5th -- but you don't do this downshift immediately.

 

I leave the car in gear, use the brakes and de-clutch (put car in neutral) only when I don't have much braking left to do.

Downshifting through the gears wears the clutch and probably isn't the easiest thing on the drivetrain unless you rev-match very well. Brake pads are cheap.

 

It's FAR easier to take off a wheel and caliper to service my brakes then to pull the trannie and line up a new clutch plate.......

Just my 2 pips....

 

if you're driving these cars "like they're meant to be driven" you should have no choice but to use the brakes . . . but then it's really bad to leave your foot on the brake when you come to a complete stop after you just baked a bunch of heat into 'em . .. so it really depends

edit: it's a good time to practice rev matching and heel/toe'g if your interested in learning to become a better driver . . . that's why the pedals are so close together .

 

as another side note the 308's I've driven in stock trim seemed to have very low engine vacum at idle and the power brake booster liked a bit of engine rpm ... could've been other problems but I thought others have noted low engine vacum at idle??? . . could just be 2vi cars with the kjet causing problems though which is what my experience is with.

cheers

 

Dangerous thought and illegal if I remember correct! If the wheels are rolling make darn sure its in a gear for that moment you need to get out of harms way.

The wear on the clutch and sincro's vs brakes is so minimal (90% of the clutch wear happens on take off from a stop) it isnt worth the discussion. Learn to double clutch and heal and toe and have a hoot, thats why you bought the car.

 

Roger that!

 

Sometimes it is good to downshift just to help assist the brake

To me brake is more important, I rather see my tranny fail over

an overheated brake pads and injure someone. Specially down hill.

 

+100 though I have to admit to a downshift once in a while just to enjoy the blip and sound (I have stick shifts).

Dave

 

some times I gear down to 3rd or 2nd then in nautal the rest of the way

 

Dave- Maybe it takes you longer than me to put the car back in gear and let out the clutch, as one does when the light changes or something else happens. Another skill learned is choosing the appropriate gear and matching the revs perfectly before letting out the clutch. Neutral works on F1 transmissions, too, except all you have to do is hit upshift if you need power. To each his own.

Engine braking provides negligible stopping power on street cars. Jump on the brakes of a Ferrari with ABS at 100 mph and you can stop in around 5 seconds. Try downshifting only and see how long it takes.

The engine sound is glorious on a well executed downshift, but multiple downshifts are wasted when coming to a full stop. Downshifting one or two gears to keep the engine running smoothly is certainly an option. Afraid I do not agree on the negligible wear on synchros and throw-out bearing. If you are double-clutching down through the box (you are not, Phil Hill did), you can negate most of the synchro wear, assuming you do it correctly.



Taz
Terry Phillips

 

For me: a gentle coast to a stop in neutral, with gentle intermittent brake application ... followed by a gentle move off after the stop.
I'd rather spend money on fuel than pads or clutches.

Btw, would someone mind replying to my post on TR tool size? Thanks.

 

jungathart- Hopefully you got your question answered on TR tools. Completely unqualified here.

Taz
Terry Phillips

 

+100.

I havnt seen a driving manual anywhere that didnt mention coasting in neutral being illegal. If you need to accelerate suddenly you need instant power.

I also agree the gearbox is a pretty tough animal. Get one of these on a twisty hilly road and clang the shifter up and down through the gate, its the most fun you can have on four wheels. I have to work on heel and toe, never quite mastered that.

 

Virtually all driving manuals these days are written for automatic transmission cars. Putting a prndl in neutral while you're moving is probably a bad idea -- those don't respond very quickly. But mostly what's illegal is coasting in neutral with the engine off. You have no power steering or power brakes without the engine.
(Of course, hybrids are designed to do exactly that -- coast with the engine off. Wunnerful stuff, this "green" tech, ainna?)


But on "real" cars, if you're coming to a full stop, that's what brakes are for. And the gearbox is going to come to a stop in any gear.

Remember that the clutch disconnects the engine from the gearbox input shaft. The gearbox output shaft is permanently connected to the drive wheels though the differential. The gears connect the input and output shafts. When you're in neutral with the clutch engaged, the input shaft is freely spooling, and the output shaft is being spun by the drive wheels.

So if you step on the clutch and shift to neutral from fifth, the input shaft will slowly spin down from the engine rpm. But the output shaft will still be spinning at the car speed (wheel speed times the diff ratio).

Trying to shift from fifth directly to first immediately after stepping on the clutch, while the car is still tooling along at 55 mph or so, is going to require the input shaft to spin much faster than it's going -- possibly faster than the engine will turn. (Consider what engine RPM you'd need to hit 55 in first.) It's the synchros that try to make up that difference.

(The same thing happens, to a lesser degree, on any downshift -- the input shaft has to turn faster for the lower gear. Double declutching in neutral uses the engine to spool the input shaft up to an appropriate higher rpm before engaging a lower gear, so the synchros don't have as much matching to do.)

So you'll probably want to wait until the car has slowed from a fifth gear speed before trying to shift the gearbox to first gear, even with the clutch engaged.

But it's not a situation that comes up very often, for me. When I'm cruising along in fifth, I try to avoid coming to a full stop and then powering back up to a fifth gear speed. If there's traffic or a signal light ahead, I try to just downshift and slow so that the road obstruction can clear before I get there, so I won't have to come to a full stop.

Of course, it helps to look a bit further ahead than the bumper in front of you. (Unlike 99% of city drivers.)

One thing you notice in city traffic: the side scoops on a 3x8 are functional: The right side feeds the engine air intake, and the left side provides ram air to the oil cooler .... while you're moving. When you're stopped, you have no airflow to the oil cooler. And all that heat from the engine bay wafts forward into the cockpit, when you have the top off.

BMW ran some studies a while back. Throttled operation (running the engine in a vacuum) isn't a very efficient use of a piston engine. Piston engines are usually most efficient at WOT. So "idling" up to speed can actually take more fuel than a "rabbit start". ("Sunday supplement" science has never been very accurate.)

Of course, the way to save fuel is to avoid having to come to a full stop in the first place, so you don't have to put all that speed back on after bleeding it into the brakes. (Stop and go freeway traffic just converts fuel into brake heat.)

 

Yup, Im pretty slow these days. Are you sure Im not double clutching? I teach it to every new Ferrari owner to do it until engine temp is showing on the gauge, either going up or down in the gears.
Fact:
From the second the F1 equiped engines start the clutch is fully depressed and the TOB is loaded when still in "N".
Attempting to get an extra few hundred miles on a clutch over its life span (while not enjoying the car as it was designed to be used) is akin to not driving the car because it puts miles on it, decreasing its value.
If the discussion pertains to the most efficent method on a race track, the whole arguement changes and we agree on a few points. I raced old English cars for many years and if it wasnt for engine braking..... It was a hard habit to change when moving into tracking a 360 or the likes.

A matter of opinions, we each shared ours and all is well,

Dave

 

Growing up on worn out british cars taught me the double clutch shift both up and down. it's a habit I still have and few people notice but are amazed at the smooth ride in old 3x8 and 911s. In late cars like the 355/360s I brake hard, the downshifts are purely to select the correct gear for corner exit. On the street I may just grab neutral especially in traffic. Unfortunately modern electronics are negating heel/toe footwork, part of my driving pleasure on a spirited drive.

 

Fellows, I'm not sure why we're having this conversation. Coasting to a stop is not a good idea or recommended by any mechanic, high performance driving or racing instructor or professional school. I just learned that a chief instructor for a well thought of locla marque club school has been depressing the clutch near the beginning of the braking zone and coasting ALL THE WAY INTO THE CORNER! OMG! He's been doing this for EIGHTEEN YEARS! We were at a Ross Bentley Speed Secrets seminar and I thought the answer was obvious, but it's obviously not!

Brakes are used to slow the car. Downshifts are not used to slow the car. Downshifts are used as a timing aid on the way to selecting the best gear to get out of the next corner (1st, if coming to a stop). Do I go 5-4-3-2-1? No, but I go 5-4-3-2 or 5-3-1 coming up to an intersection.

Most all F-cars go between 20-25 mph in TOP gear at 1000 rpm, so unless you are slowing to a stop, you can leave the clutch engaged (foot off the pedal) until you are nearly stopped. If you downshift, you can leave the clutch out in the lower gears to walking pace, then depress the clutch as you roll to a stop.

A car is most stable when there is a connection between the engine and the drive wheels, as long as there is not too much of a differential in speeds between the two... You are doing no damage to the clutch or any portion of the drivetrain if the downshifts are executed correctly.

If you like, I'm available for lessons at VIR nearly anytime!

Honestly, it's best to downshift. It is never good to coast, except the last 3-5 mph to rest.

 

I always downshift into 4th and 3rd. I am VERY careful going into 2nd, it seems very hard on the syncro. I always rev match. I find the 308 to be the easiest car to toe/heal I have ever driven. Must be my size 8-1/2 Northern Itialian feet. They just seem to fit the car. If I don't downshift and keep the car in gear, it doesn't feel like I am driving it.