a) the pressure on the disks is NOT even.. that's why there a proportioning valve in the hydraulic system.
b) the brake torque produced by a given pressure is NOT even... larger radius brakes in front lead to more brake torque for a given line pressure.
c) with less traction available, less weight transfer will take place.
hth ken
...to the betterment of Subaru mechanics everywhere
In some regions you MUST use engine brake (the Alps in Austria and Switserland): if you drive down from a "col" (San Gottardo, Simplonpass, ...) without engin brake your brakes are overheated and you will have almost no braking power left when you arrive in the valley (if you will arrive there!). It is also clearly indicated by roadside panels.
"Daya" schreef in bericht news:c01d1a$11gqb8$ snipped-for-privacy@ID-223567.news.uni-berlin.de...
"Dave Null Sr." wrote in news:Xns9488BCB912B50lrowoy@66.11.168.195:
If you can match your engine speed to the transmission speed you're basically doing the same thing. I think that what you are talking about is a PART of engine braking.
-S.S.-
On Sun, 08 Feb 2004 17:21:50 GMT, SkaredShtles wrote in news:Xns9489696FE7715elanmbx1NOSPAMyahooc@216.196.97.132:
No, I'm talking about the need to downshift at all.
Proper habit is to make sure you always have engine revs in a usable powerband: ie: not 700 rpm at 20km/h in fifth (or whatever that works out on your car.) so you can (on the commute road) escape a difficult situation under power, or (on a windy road) accelerate away at a satisfying rate.
I should also point out an assumption that you never brake with the clutch in in normal circumstances. The only exception is in extremely slippery conditions where you want full control from the brakes without worrying about the fronts locking up (FWD or auto AWD) and causing lack of braking or stalling the engine.
Downshifting to slow down the car to 'save' the brakes is not a rational thought with today's braking systems. Nevermind that I do it at every stop. :)
"Dave Null Sr." wrote in news:Xns9489B2BF198D9lrowoy@66.11.168.195:
Ahhh... but I live near and drive often in the mountains. I will agree that "speed management" is the goal that I'm working towards. Maybe I don't do any "engine braking" per se at all...... I just use the appropriate gear to manage my speed up & down steep slopes.
-S.S.-
So why would you want to prolong your brake life at the expense of your engine? Brake pads are cheap compared to internal engine parts. I'm just trying to point out the other side of this often discussed, yet never really solved argument. There are times when you should use the brakes and times when using the engine is the best, most of the time the best is a little of both. I should point out that I live in a mountainous area and you can always tell a flatlander has been around when you smell those brakes cooking!
I, too, use quite a bit of engine braking. But there is one thing that I haven't seen mentioned that I think it worth pointing out: In wintertime, you can find yourself in a situation where your engine braking is too much for the available grip. I'll grant that it doesn't happen often, but it can happen. In such a situation, you won't have anything "automatic" like ABS to prevent the car from going into an uncontrollable 4-wheel slide (for AWD vehicles). The appropriate response when you sense a loss of grip under engine braking is either apply more throttle or depress the clutch. If you're at a relatively high speed and in a higher gear, you can probably get away with the former option. At low speeds and in a low gear you're probably best off depressing the clutch and switching to brakes, as it would be easy to apply *too much* throttle and make the situation worse rather than better.
- Greg Reed
If you rev-match on the downshifts, you won't cause any undue wear to the clutch disk.
generally a good rule of thumb is to be going downhill in the same gear as you would use when you go up the same hill.
ken
What??? Do you know ANYTHING at all? Downshifting (enigne braking) is one of the biggest benefits of a manual transmission. Saves brake life, provides better winter traction when slowing down (no chance to lock the brakes). The clutch can totally handle this, that's what it is designed for!
One of the dumbest things I've ever seen is people who have manual transmission and use their brakes to slow completely down. If you have any skill at all, you can slow almost to a stop using the transmission and just use the brakes to totally stop the vehicle.
Chris
Not ture. If you downgear on slippery conditions and there is not enough available grip, it's not like the tires will lock up, they'll just slide a bit. Unless you are a very unexperienced driver, you'll be able to keep the car straigh until the tires catch up to the speed of the car, or the car slows down enough.
Some people may argue that engine braking eliminates ABS, but that's only because you don't need ABS for enigne braking. ABS is only for COMPLETE MORONS who don't know how to drive and stamp on the brakes, locking all four wheels. I've disabled the ABS on my car because it's absolutely stupid.
ABS = Training Wheels for Adults.
Chris
It's not a matter of clutch disc wear.
When you use engine braking, you're applying force in the opposite direction, which is ordinarily OK. I use engine braking too. But if you do it excessively, you can make your clutch vibrate & chatter. I think the problem is wear in the pilot bearing.
Not true. I've smoked the brakes in a couple of medern cars in spirited driving, both automatics. Also, I've seen several cars smoking at the bottom of a popular shortcut heading west from Yosemite. I even saw a full-sized Bronco smoking at the bottom of that hill, and I always expect big trucks to have excess braking capacity for towing. It's that only hill I can think of where I'll engine brake even with an automatic. My first time down, I was driving an automatic, and had almost no brakes left at the bottom, Smoking from at least 3 of 4 corners. The braking didn't come back properly as things cooled down. Pads glazed, calipers leaking, rear brake shoes cracked. I'm happy to have a stick shift now, as I don't think engine braking with an automatic is such a good idea (IIRC I needed a trans fluid change after one descent).
manual-transmission
My father taught me how to shift in an old International Pickup. No clutch. Try being a 4/ 1/2 ft tall 14 yr old learning how to drive in that thing. LOL GRIND!
Rob
Sounds like your car needed some work to begin with.
Rob
Nope. And I only smoked brakes there once, but I've seen others do it several times. In fact when we see cars at the bottom, it's nearly even odds their brakes will be smoking.
Dave Null Sr seems to be the only one who understands the true benefit of engine braking, i.e. to be in the proper gear to accelerate when the need for stopping ends.
How about using both the breaks and the engine? Not as much wear on the breaks and you get in a habit of downshifting, which can help a lot in difficult road conditions, such as in winter when it's slippery. If you don't downshift as a rule, who's to guarantee that you're gonna do it right when you really need it?
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