Notices
Stock JK Tech Bulletin board forum regarding issues with OE (original equipment) components of the Jeep JK Wrangler (Rubicon, Sahara, Unlimited and X) such as factory suspension parts, engine, transmission, body parts, interior fixtures and the on-board computer.

What's the point of downshifting?

Old Jul 9, 2014 | 08:20 PM
  #11  
bevan7170's Avatar
JK Enthusiast
 
Joined: Nov 2013
Posts: 494
Likes: 0
From: 16648, PA
Default

Originally Posted by SigEp418
Not arguing with your point. In the scheme of things I'm inexperienced at driving manuals and am looking for advice and pointers. But if I'm approaching a red light, shift to neutral and break, the light turns green, I'm at 25 mph and go to 3rd gear because I know that's the right gear in relation to speed and road conditions, then what's the difference?
Speaking from how I was taught to drive a manual this method is just down right dangerous. For those that ride motor cycles will confirm "your engine is only as good as your brakes". When you shift to neutral like this you have no real control over your engine/vehicle. I used to teach defensive/offensive driving for my old job. I've 17 years experience with a manual transmission and 7 teaching the above roles. Down shifting will not only slow the vehicle down but as stated above it'll put you in the right gear to pull around hazards when one arises. When speaking of down shifting there are various degrees of aggressiveness. If you're going to pop it into 2nd at 40 mph every time, yeah, you're going to have engine issues. If you match the speeds better you'll not only have absolute full control of the vehicle but you'll also save your brakes.
Reply
Old Jul 9, 2014 | 08:33 PM
  #12  
Roryslife's Avatar
JK Enthusiast
 
Joined: Jun 2012
Posts: 348
Likes: 3
From: Boise, Idaho
Default

http://www.edmunds.com/car-safety/bu...nsmission.html

http://m.cartalk.com/content/when-sh...l-transmission

Both sources agree you should not engine brake.

I do it wrong.
Reply
Old Jul 10, 2014 | 01:47 AM
  #13  
CombatDiver's Avatar
JK Enthusiast
 
Joined: Dec 2012
Posts: 228
Likes: 0
From: United States
Default

Downshifting is very useful in both declines/inclines as well as for regular stops. The transmission is more than capable of handling the shifting of gears whether it's up or down without a concern about excessive wear. The benefit I find of downshifting is control. Braking even with ABS results in decreased control. It is far more effective to downshift to slow your vehicle when you have lost control (such as black ice) than braking. Brakes are also designed to slow the vehicle down so you're not causing excessive wear on them if you decide to use them (I have heard some claim they downshift to reduce brake wear). Of course brakes have been known to overheat and fail in prolonged/steep declines but that is typically a problem in larger vehicles (such as 18 wheelers) and for that reason it is recommended/taught that you downshift for such conditions. Also, if you fully engage the clutch it can do what it's designed to do, riding the clutch or having it partially engaged is what does cause excessive wear. I hope this helps clarify things some.

Last edited by CombatDiver; Jul 10, 2014 at 01:57 AM.
Reply
Old Jul 10, 2014 | 02:01 AM
  #14  
Mark Doiron's Avatar
JK Jedi Master
Veteran: Air Force
FJOTM Winner
15 Year Member
Liked
 
Joined: Mar 2007
Posts: 14,800
Likes: 374
From: Midwest City, OK
Default

My technique: Keep the tranny in the gear appropriate to the speed I'm at (therefore it appears I'm downshifting), but use the brakes to stop while holding the clutch in. Unless someone is tailgating me, then I might let the clutch drift out a little to let him know he may not have bright lights in his face when I slow down. LOL. Anyway, taught my youngest son to drive that way, too. Then I learned why you should use engine braking to slow down your vehicle: Because when the driving examiner gives you that test, they insist on seeing engine braking by the examinee. Seriously, my son had never used engine braking, and she'd never given a test in a manual before. But her worksheet had a block to check off, and she made him do it. He had no idea at first what she was talking about. LOL.
Reply
Old Jul 10, 2014 | 02:57 AM
  #15  
tribulation138's Avatar
JK Freak
 
Joined: Nov 2012
Posts: 849
Likes: 1
From: CT
Default

I engine brake and use the wheel brakes at same time.

Im a daily motorcycle rider so I engine brake 85% of the time.

This topic is brought up on mc forums all the time
Reply
Old Jul 10, 2014 | 03:00 AM
  #16  
JeepaRoo's Avatar
JK Super Freak
 
Joined: Jan 2008
Posts: 1,306
Likes: 3
From: Columbus, Ohio
Default

I always am in SOME gear... I downshift to the gear correct for the speed as im slowing down but not going to brake with the engine as a rule..

downshifting was taught for engine braking years ago before ABS and when most cars were RWD..

it was common in a panic or near-panic stop situation to lock up the rear wheels because of the vehicle's weight shifting to the front as you brake hard. you typically had to let off the brake pedal some, which your front brakes partially released as well.

downshifting was a way to keep all 4 wheels spinning thus much better control of your car.. your engine was "braking" but also your rear wheel brakes had to overcome the driveline inertia to lock the rear wheels...

with ABS its a whole different ballgame now..

obviously anyone in the commericial driving business is taught to engine brake on heavy trucks or busses as a way to keep the brakes cooler and more effective should a panic situation arise.

-Christopher
Reply
Old Jul 10, 2014 | 03:19 AM
  #17  
metaldemon's Avatar
JK Freak
 
Joined: Jul 2012
Posts: 548
Likes: 0
From: United States
Default

I always downshift when coming to a stop. Most of the time I don't even touch the brakes until I am in first gear. Only the last two vehicles have been automatics. One was given to me, and my XJ I couldn't find a manual trans 4.0 liter in my area. My JK is a 2012, so it has a 3.6 liter. Using engine braking is they way I learned to drive on dirt bikes, and the trucks I drove on the farm.
The reason oil consumption goes up on the 3.8 liter engines is because it causes a vacuum in the cylinders went using the engine as a brake. It is the sign of the piston, and or rings not sealing properly, which I know is a problem with these engines. The 3.6 is too new to know if this will be an issue down the road.
I have been known to down shift my XJ automatic on long down hills, so I don't have to brake.
A downshift from sixth to fourth is also good when I have a tailgater behind me. Quick slow down, plus no brake lights. If that doesn't work I hit them with my LED fog/reverse lights. They are bright even in the daylight. LOL
Reply
Old Jul 10, 2014 | 04:55 AM
  #18  
GJeep's Avatar
JK Junkie
 
Joined: Mar 2011
Posts: 2,145
Likes: 4
From: Israel
Default

Originally Posted by Roryslife
Busting the Myths of Driving a Manual Transmission

Car Talk

Both sources agree you should not engine brake.

I do it wrong.

I drive auto now, but had been driving manuals for years.

Quote from the first link --

"..... if you're using the clutch to slow a car to "save your brakes" you better be really good with the clutch.
IF you're NOT smooth in your downshifting
, you'll be putting extra wear on the clutch.
"

It's not difficult to do it smoothly (mach the rpm). It becomes intuitive pretty quickly.
I had been downshifting to brake with different cars and 4x4's.
The first one was a VW Beetle. Never had to replace the clutch in 70,000 miles. Never had to replace a clutch in any other vehicle.

When driving through a city, the many releases of the clutch cause much more wear than correct downshifting, which causes negligible or no wear. So, if you downshift smoothly, you're doing it right.

Last edited by GJeep; Jul 12, 2014 at 06:52 AM.
Reply
Old Jul 10, 2014 | 07:23 AM
  #19  
Vt.rider's Avatar
JK Newbie
 
Joined: Oct 2013
Posts: 83
Likes: 0
From: Plymouth, Vermont
Default

I read the links on downshifting.....and have some doubts as to the accuracy of the article, especially when the author refers to the parking brake as the "E" brake....which I know is commonly (but incorrectly) used to describe the parking brake. Kind of like referring to a pistol or rifle magazine as a "clip". So IMHO it shows that the author isn't as knowledgeable as he thinks.

I've been driving (CDL) trucks, motorcycles and cars for going on 50 years. Never burnt out a clutch or ruined a drivetrain, and I downshift (not aggressively) when appropriate. I don't downshift on flat paved roads when coming to a stop, unless in traffic. And then, I'm usually dropping into 3rd gear, which a previous poster correctly noted that it gets you going again easily. I slowly downshift going downhill in snowy, icy, or muddy conditions and use engine braking because it allows overuse of the brakes on long downhill stretches.
Ever see the yellow road signs that say something like "7% Steep Grade Next 4 miles....Trucks use low gear"????
There's a reason for that. And it applies to anyone who wants to maintain good control and to extend the life of their brakes.

Downshifting when done incorrectly can cause damage to the vehicle and can even cause an accident. But when done correctly, is an appropriate driving method.
Reply
Old Jul 11, 2014 | 06:31 AM
  #20  
jk_sea's Avatar
JK Super Freak
 
Joined: Sep 2012
Posts: 1,564
Likes: 7
From: United States
Default

Not to turn this into an auto versus manual thread, but one of the advantages of a manual is it allows greater control of the Jeep because it allows you to shift predictively- you are able to see exactly what conditions are ahead and match gearing appropriately. Automatics are completely reactive and follow a "one size fits all" sequential shift program using inputs which only give partial information for what gear the Jeep really needs to be in based on throttle input, vehicle speed, etc. Just something to think about.

A good example of downshifting where a manual really shines is when you want to pass someone. I can go from 6th to 4th with a rev match and a seamless transition and get right back on the throttle in a perfect slice of the power band to complete a pass. Once I've made my pass, i can hit 5th for some additional velocity at reduced engine speed, or settle right back into 6 at cruising speed. In an auto, it has to make two shifts (5, 4) to grab the power I want, and will upshift (5,6) if I ease off the throttle (and I may not want it to do that).

Same thing going up a long grade, I can grab 5th well before I have to bury my foot into the accelerator and enjoy a nice slow burn between 2500-3000 rpm without any gear hunting.

The same things are "roughly" possible in an automatic. You learn the throttle points and at what pressures the transmission will grab the next gear in a downshift. I had a truck with an automatic and I'd find myself locking into 3rd gear (4 speed auto) to avoid the gear hunting on grades, and I knew when passing that a certain amount of throttle input would cause it to grab 1 gear, 2 gears, etc at certain speeds. But there's still a lot of flub in those situations, and the transitions aren't exactly smooth in a typical hydraulic auto...

At first I was taught to engine brake, and then I quickly discarded that practice in favor of keeping the car in an optimal gear depending on the speed.
Reply


All times are GMT -8. The time now is 03:22 PM.