downshifting on hills

[Toyboomer]

I felt I was clear on this but it still comes up. My vehicle is 4-R 2006 V-8 Sport. I live in the CO mountains and my house is two miles up a hill on a paved road with a 35 mph speed limit. Shifting down to third when descending to the valley keeps me off the brakes most of the time. I also downshift to 4th when descending downhills on the interstate. This procedure seems preferable to using the brakes all the time.

I have heard some say that brakes are cheaper than a transmission but info. over the years tells me the transmission is not harmed by downshifting on hills. Some years ago I lost a Ford Taurus transmission at 50,000 miles. The tech asked if I downshifted for hills as that could have been the reason for the failure.

Can anyone confirm my opinion on this matter as my wife recently asked me again if this procedure was ok? She has an 04 4-R.

 

[pipspeak]

I am of the same opinion as you, but am no technician so could be wrong.

Downshifting that causes the engine revs to jump excessively is probably not good, but I often shift to 3rd (of 4) when going down a long hill and the revs never go much above 2K - less than when I'm cruising on the freeway OD. I can't see how that is harmful to the tranny.

I'd be more worried if I was heavy on the gas pedal when accelerating, pushing the engine and tranny hard that way.

And consider manual transmissions... That's all I used to drive, and engine braking to me is an inherent part of driving a stick and is in no way frowned upon by technicians. Why should it be any different for automatics?

 

[SlowYourRoll]

doesn't seem like the engine or transmission would be working very hard at all if you downshift to mantain speed down a hill. Your just coasting so no big deal, much better than riding the breaks.

 

[tomhaney1]

doesn't seem like the engine or transmission would be working very hard at all if you downshift to mantain speed down a hill. Your just coasting so no big deal, much better than riding the breaks.

I do the same thing and have in many other trucks, especially when towing. The 4Runner transmissions are electronically controlled anyways so I figure it will decide how to safely [down]shift. I also hate riding my brakes, it is costly and wears the system down, especially on a nearly 4,000 lb. vehicle.

 

[jpalaska]

I'd be interested too to hear from an experienced mechanic or mechanical engineer about using lower gears in an automatic tranny to brake the vehicle.
When I first got my 911 about 10 years ago, I was told not to downshift to slow down the car too much in racing situations, or going down a hill.
They said the same thing mentioned earlier, "brake pads cost a lot less than a gearbox."

JP

 

[khaug]

I regularly tow a 4,000# trailer (Porsche 911 on an open trailer) and have used a '98 4Runner and our current '03 as tow vehicles. I've probably done 35,000 or so tow miles with these two 'Runners.

I always downshift when descending grades, shifting into a lower gear that will let me stay completely off the brakes. With the '98, this was absolutely necessary to avoid total loss of braking due to brake fade. The '03 is much better in this respect, but I still avoid heating the brakes as much as I can.

I sold the '98 at 5 years of age with 75K miles on the clock, and my '03 currently has done 62K miles. The transmissions in both vehicles have operated like new the entire time.

IMHO, this is the correct way to operate a tow vehicle.

 

[JP4RNR]

As long as you are not exceeding the speed for the given gear, downshifting should not harm the transmission in anyway and as long as the transmission is properly maintained. Gas mileage will suffer a little. What harms the transmission is constantly overrevving the engine on the border of the redline. The front oil pump on the trans is not designed to withstand in excess of 5000 rpm's for any extended amount of time as this generates alot of heat and could cause premature deterioration of the trans fluid and premature failure of the oil pump. I can see that if you down shift into 3rd at 80 mph that would be hard on the transmission. On the V8 with a 5 Speed auto you can downshift from O/D into 3rd at 60 MPH and the RPM's will climb to about 3500 RPM

 

[HiVel-JR]

So why even put brakes on a vehicle? Just use your engine, that would alleviate the brake cost all together. :beer:

I have heard downshifting to slow down is not good for anything, but we all still do it because it feels and sounds cool. I also think it depends on the vehicle. Also JP has it right, if a porsche mechanic says not too, I think I would listen to him/her before a toyota or ford mechanic...(my father was a porsche mechanic after he retired, but that is not saying much for him) lol

I would use the brakes, unless the road was slippery...

 

[jpalaska]

Let me clarify what I meant in my '911' post.
The experienced Porsche people I know here and the 'lower 48' warned me about shifting into lower gears to slow the car when, for example, coming off a highway at 80 mph onto an exit ramp (sounds cool, but use the brakes instead), or going down hill too fast and then shifting to a lower gear to slow down during the descent. (use the brakes to get slow, then downshift to hold a slower speed).
As for the downhill descent, there's a difference between slowing down from a high speed by shifting down (bad) and holding a slow descent with a low gear (probably OK), especially for a long hill, where you can get the brakes too hot by constantly applying them on the way down.

JP

 

[pipspeak]

I have heard downshifting to slow down is not good for anything, but we all still do it because it feels and sounds cool. I also think it depends on the vehicle.

I don't know about you, but when I was learning to drive (in Europe) I was taught that downshifting (a stick) while braking was an inherent part of slowing down under control. Whenever I drive a stick I still use the engine and brakes together to slow down.

Basically you have far more control of the car when the engine, not the brakes, is controlling speed. I can underatand that some people might downshift too much or too soon because they want to sound like a nascar driver, but using the engine in conjunction with the brakes to maintain speed is the best way to stay in overall control, IMO, even with VSC and ABS and other gadgets.

Sadly there are too many people who just slam on the brakes at the last minute and wonder why they spin out. Plus, brakes can overheat and fade. I'd rather risk my tranny fluid than risk having no braking power left at the bottom of a long hill when I might really need it.

 

[Climb14er]

I felt I was clear on this but it still comes up. My vehicle is 4-R 2006 V-8 Sport. I live in the CO mountains and my house is two miles up a hill on a paved road with a 35 mph speed limit. Shifting down to third when descending to the valley keeps me off the brakes most of the time. I also downshift to 4th when descending downhills on the interstate. This procedure seems preferable to using the brakes all the time.

I have heard some say that brakes are cheaper than a transmission but info. over the years tells me the transmission is not harmed by downshifting on hills. Some years ago I lost a Ford Taurus transmission at 50,000 miles. The tech asked if I downshifted for hills as that could have been the reason for the failure.

Can anyone confirm my opinion on this matter as my wife recently asked me again if this procedure was ok? She has an 04 4-R.

An occasional (once in a blue moon) moving of the shifter to a lower gear won't hurt the tranny or drivetrain.

The 4Runner tranny is an 'automatic' and not a Tiptronic or manual.

Downshifting regularly puts a load on the tranny and drivetrain and in the long run, brakes are far less expensive to repair.

Drive it like an automatic rather than a manual and you'll have longer life for your vehicle's parts. :

 

[boston_kevin]

Couple of things to remember about downshifting...

1) If you downshift 1 gear and the RPM's jump near the redline - that's bad... If you downshift 1 gear and the RPM's jump less than 1000 RPM's, that's okay.

2) The use of downshifting is not meant to brake the vehicle, rather to hold it within a certain MPH range (and RPM range) to ease the use on the brakes (and tranny) This is especially important when towing.

Racers use downshifting to maintain RPM's when going into or out of a corner in order to keep the engine in the optimum torque band, but they all brake going into the corners to slow down.

I have downshifted for years (not for braking, but to maintain speed downhill or uphill) without any ill effects on any of my vehicles. Most trucks (including the new Tundra) have a tow button which locks out the top gear for towing, so as long as you remember what the purpose of downshifting really is, you should be fine...

 

[tomhaney1]

I downshift the 4Runner before I hit the downgrade. I would agree to do it while on the downgrade could be bad. I also have a 911 and I use the clutch to decelerate. I also heel-and-toe it out of corners and it still runs phenominally. IMO there are too many idiots that don't know how to do these things correctly and that's why there are so many warnings against doing them.

 

[TechWrench]

When debating this, you first have to consider the difference between the manual and automatic transmissions. From my years of experience as a transmission technician with both types of units, manually downshifting an automatic, or using a manual to downshift doesn't harm a mechancially sound transmission if it is done properly. As others have mentioned, large engine rpm changes caused by manually downshifting should be avoided if possible. When you do this with a manual, it isn't the best thing for the engine, and it causes wear on the clutch, but the internal mechanical components of a sound manual transmission most likely will not suffer from an occasional hard downshift. With the automatic, the torque converter takes most of the abuse, and the fluid in the converter absorbs most of the shock, but the internal components whould be able to handle the occasional hard downshift. Using the engine braking with a manual downshift on hills shouldn't damage a mechanically sound trans, and will save on brake wear and overheating. But, I don't see the value of manually downshifting on level ground, just to save brake wear while coming to a normal stop. Just use the brakes in sensible maner, and try to plan ahead for traffic conditions. Down shifting while towing also is a good idea to keep the engine rpms in the 'sweet' spot powerband. I think it should be fairly obvious that as you increase the stress on any mechanical device, you tend to shorten its lifespan. I'm sure there have been engineering studies on this, but I think it would be hard to quanitfy exactly how much one will shorten the life of an automatic trans if you downshift 50% of the time compared to 20% of the time.

 

[atomic punk]

DAC?

 

[Toyboomer]

downshifting with auto

Thanks for the great comments. These are sensible ideas and for the most part match my use of an automatic on downhills. I always brake first to prevent high revs so that's not a problem. One thing you have to watch with the Toyota because the transmission is so solid and quiet is that when you get to the bottom of a hill and hit the interstate that you don't forget to get out of 3rd or 4th. A few times I have been going down the road at 65-70 and noticed I'm still in lower gear although it has always been way below threshold.

 

[4by4th]

It seems as though the location and configuration of movement with the automatic transmission shift lever on the 4R console encourages downshifting. You can't accidentally downshift more than one position at a time without changing direction of movement with the lever. The lever is also in optimum location to rest your right hand on while driving, making it convenient to downshift. On the other hand, the shift lever on my F150 is on the steering column, making it difficult and impractical to downshift, except the overdrive is controlled by a button on the end of the shift lever making it very easy to get in and out of overdrive. I would hope the design engineers considered these things and whether or not downshifting was to be encouraged or not, but maybe I

 

[TechWrench]

DAC?

DAC is not applicable in the situations discussed here. We have been talking about highway hills and towing. DAC is designed to work in limited, low speed conditions. First, you have to come to a complete stop, put the vehicle in 4wd low range, start going down hill with DAC engaged, and you do not touch the brake or accelerator, just steer.