...yay or nay??? I went from a 6MT to a 5AT, and I got into a habit of downshifting to slow down and also get the RPM up so I can have a better take off if needed...but in doing so, it also increased the mpg and life of the brakes of the car, but that's not that important to me. My question is, is it good to downshift in the manumatic? There are many advantages to downshifting in the 6MT, and it doesn't wear the engine/tranny...but on an automatic, what's the effect on the engine if you downshift to slow down or downshift for power? I've heard people say it's not good to downshift in 5AT at all, so why the hell they put that in the first place? if it's made just so you can TOW, why the hell did they put it in this car? it's meant for spirited or raced style driving....and some even said that switching between manumatic and full auto is bad for the tranny...WTF??? If that's the case, then why the hell would they put that in a car like this, egh???

I really liked downshifting to slow down in the 6MT and sometimes, I felt it was safer to downshift than to step on the brake...

Can someone clear this up???

 

Manumatic is designed to be used, for the enthusiast, to have better control of the car, for all of the reasons you mentioned. It is VERY stressful on the engine, trans and differential to trans brake the car (downshifting to slow down). It is bad for an MT as well, but not AS bad.

The amount of sudden torque gain on the drivetrain will beat it up and heat it up more as well. Also, your suspension take a big load hit as well, so possible premature wear on bushings and components as well.

If you are going to do this, I would recommend your service intervals be as follows:

Oil - every 2500-3000 miles - religiously
Trans and diff - drain and refill every 15K, not 30K.

Now - with all that said - I do it all the time, and try not do...but likely 1/2 the time I do it as well.

Rick

 

so putting it into manual mode and upshift at redline is OK, but downshifting is not good for your engine? or is it bad both ways? which is the lesser of two evils?

 

OK -

So racing your car and shifting at redline is what it is. When you race the car, you put additional stress on it over normal driving. If your racing the car all the time, then expect issues and do frequent fluid changes to be safe.

Downshifting is likely, in my opinion, worse, because the SUDDEN change it dramatic to the drivetrain. Up-shifting, from high RPM to lower RPM is nowhere near as stressful...

 

The car came with BRAKES... they are used for BRAKING.

The car came with an ENGINE... it is used for ACCELERATING.

Unless you are on the track trying to turn quick times, or on your local twisty canyon having fun I suggest using the above components appropriately, otherwise you will be shortening the life of those components.

You do not need to be at peak RPM/HP when driving on a regular basis.

But then again, we do drive a Z!

 

I remember back about 10 years ago when Honda tuning was popular, I was told that in a manual transmission, shifting up and down doesn't affect the tranny because your gears go thru neutral gear before you go into another gear. Whereas when you manually shift an automatic, it doesn't go through neutral thus it was bad for your automatic tranny, for what reason I don't remember...so when these tiptronic shifters came out, I was wondering if they did anything extra to protect the tranny or did they just slap that onto the same auto tranny and just make it easier for you to shift instead of having to pull your shifter up and down and side to side...

 

Downshifting/engine braking are techniques that drivers have been using ever since there were cars with transmissions. Its one of the first things I was taught when I learned to drive.

And it can be done on an auto trnny as well as a manual tranny. And it will not harm the vehicle.

"ENGINE BRAKING is a method of slowing down an automobile without the use of the car's friction braking system. It works best on cars with a manual transmission, though cars with automatic transmissions experience the effects as well. Some automatic transmissions may compensate for it to some degree, however, which may not be what you want. In the case of either type of transmission (Though it is more useful with a stick) one can downshift in order to increase the effectiveness of this technique, though it can be observed at any time by simply letting off the gas.

If you let up on the gas in your car you will start to slow down. This is in part due to friction. Let off the gas pedal all the way, and you slow down more than you can explain by loss due to aerodynamics and rolling friction, however. The explanation is that your car is no longer putting energy into causing compression, but the road is. Your engine now works specifically as a compressor, being driven by the road, and going through a fairly significant ratio conversion in the process. The compression (and regular friction of course) creates heat, which is dissipated by the engine's cooling system. However, a lot of the energy is also expressed back into the road via the expansion of gases.

There are a number of reasons you might want to engage in engine braking. The first is that it puts little or no more load on your engine than it would otherwise bear, but saves considerable wear on your brakes. This leads into the next reason, primarily in the case of racing, but also when going down long hills; Frequent use of brakes not only wears out the pads but also heats them up. This leads to brake fade (most brake pads do not grip well when hot) and to boiling of the brake fluid, which does not work properly once it has been boiled. Brake fade is only a problem during overuse of brakes, such as going down long, steep hills, or during "aggressive" driving. The third reason, also primarily significant in sports driving, is that you want to decelerate into turns and accelerate out of them. Downshifting increases the effectiveness of engine braking, and increases the number of RPMs at a given speed, which tends to assist in acceleration."

http://www.everything2.com/index.pl?node_id=1181314

bill

 

I tried to use mine but stopped. Two reasons, when down shifting, it felt like I was hurting the engine, and it lags when shifting up.

 

Didn't the automatics come with rev matching since the 05 model, where the car automatically bumps up the engine speed when you downshift? If so, there shouldn't be that much additional stress to the drivetrain. I'm not a big fan of using the engine to slow the car down to save the brakes.

My old boss was proud that his brakes lasted over 30,000 miles because he engine braked all the time. True, he was saving the brakes, but at the cost of his engine. Brake pads are $250 a set. Even with new rotors, it shouldn't cost more than $1600 for a complete refresh. How much does an engine overhaul cost? I always wanted to point that out to him, but he was a know-it-all so there was no point in arguing.

But I do use engine braking at the track to help cool down the brakes if they start to fade.

 

IMO, downshifting while slowing down is a complete waste of time on a 5AT. It is always ready to downshift when you need to perform a defensive driving maneuver. It reminds me of the time when my buddy bought a brand new '98 Accord V6 and wanted to race with it, but it was an auto. So he was lead to believe the car would launch faster if he revved it in neutral while holding down the brakes before shifting to drive.

For 6MT, it is second nature for me to downshift when I slow down. It's not just for engine braking, but for safety as well. If I worry about wearing out the drivetrain, I might as well not drive at all.

 

Yes it is a technique... but for everyday driving it is just putting wear and tear on the engine/transmission that is not needed. It is a lot easier/cost effective to replace worn out brakes rather than a worn out engine/tranny.

My ... people can drive how they want.

 

I grew up in some places where if you didnt trans/engine brake to help slow down you would have no brakes left because of huge hills and heat. Its actually useful for more than just racing.

 

a lot of people say dowshifting in an auto "FEELS" like it wearing the engine, but does it really wear the engine if it's slowing the engine down? I don't care how it feels look seems like, but is it a fact that it wears the engine???

Are there any mechanics or someone who really knows FACTS instead of hearsay?

Good thing about the manual mode in these cars is that it locks you in the lower gear if you don't shift up, so that when you accelerate from it, it doesn't gear search. One of the things I hate so much from the automatic engine is that it takes forever to gear search...yes, I shoulda stayed with a 6MT...I know....

 

Downshifting can shorten your braking distance by a long margin.. but I do believe that everything comes at a price (increased wear).

 

How so? If you're threshold braking, you're not going to get anymore grip out of your tires by downshifting.

 

IMHO.. That is an unsubstantiated urban legend... unless of course you have no brakes Downshifting going down a hill IS a useful technique, especially if you have a big load.

 

it is not needed on a 5AT, since when you are brakein got stop, the car shifts down for you anyway. now if you wanted to downshift like in curves or to make a pass for a quick burst of speed in the next lower gear, it should be fine to do that.

 

i guess im wrong. its just that i feel the car goes slower when i downshift, so i assumed braking + downshifting at the same time would reduce the distance.. ie. when i try to brake in 5th gear it feels really heavy

 

All I can say is that some auto transmissions, most any late model Mercedes, are _designed_ to use the engine as brake. It is a very strange feeling indeed as the cars do NOT free spool when you get off the gas on a downhill grade.

 

If you are in 3rd and brake to stop without down shifting, the car remains in 3rd until you are nearly completely stopped. It will then automatically put the car in 1st preparing to go. Personally, I always down shift being careful of not over rev the engine while doing so. Hell...that's have the fun.