k&b guy

hi everyone. 1st time poster. purchased a 2008 last june. love it my question is in regards to useing the downshift paddle when coming to a red light, turning, etc. useing the brakes only when necessary. i`ve replaced all rotors and pads, (saved on labor) just trying to get as much life as possible out of this set. my only concern is if i`m shortening the life of the tranny ? drive in sport mode. anyone else do this ? tnx.

CARTER

lobuxracer

iTrader: (2)

No, I don't do this. Brake pads are a lot cheaper than gearboxes without any regard for what car it is. With the lifetime ATF fill on the gearbox, being nice to it is even more important.

pc1990

^ Really...U certainly don't want to solely use downshifting as a way of slowing down, but I always thought that dropping a couple gears to slow down was ok. I remember a thread like this before and most of downshift to slow down. But its your car, use your best judgement.

edgeucated

iTrader: (4)

use your brakes. Downshifting to brake will surely put stress on your gearbox, and that can not be good.

huksa

While I was attending Skip Barber MX-5 racing school, one of the instructors (who is an ALMS driver) told us: "Let the brake do the braking. The purpose of downshifting (and rev matching) is to maintain the balance of your car and to have it ready for acceleration."

dinardalvi

on the spot, I never down shift to slowdown always brake then rev match downshift immediately and then blast through the curve. Boy i miss the track times.

boson

I guess i am going against popular opinion here, but I have been downshifting (engine-braking) in 60 miles of daily hwy traffic (chicago) since i bought my '08 as a daily driver. As far as I am concerned, it is the only redeeming quality of the paddles since no manual is offered. In fact, I often sing praises about this feature and how I don't think I could live without it - I now have to seriously consider this on my next purchase (car with manual vs. paddles preferred for engine-braking...)

I suppose I am putting my faith in the 'quality' of the Toyota powertrain - at least for the 3-4 years i plan on owning the car. It might some amount risk, but I am gambling on saving brakes vs. potential early tranny failure. (warranty??? - i can hope would cover failure...I am sure there are opinions about this...)

UCrazyKid

It's not a "quality" issue, its a simple fact of wear and tear. Cars are slowed by friction, turning mechanical rotation into heat. Your brakes are designed to this most efficiently and at the lowest cost. You don't want to intentionally add heat and friction to (probably second most expensive part of the car), the transmission. I have a sneaky suspicion that you are not an engineer.

Now I can whole heartedly agree that it is probably more "fun" to do the down shifting, and perhaps satisfying to hear the motor, but the reality it not the best use of the transmission. Yes, the paddles are there for down shifting on a track this more appropriate, but the brakes are still the primary method for reducing speed.

It's your car, do what you want. But you asked the groups opinion.

lobuxracer

iTrader: (2)

Maybe you missed what I said. It doesn't matter if it's an auto or a manual. Downshifting to slow is hard the gearbox period. You're doubling the amount of stress on the bearings and you're using the full mass of the car against them on downshift.

Duke02

iTrader: (2)

Not to pile on here, but as a trusted mechanic said to me once - "would you rather replace your brakes or your transmission". I think transmission braking is probably only advisable if you'd be riding your brakes otherwise (like going down a mountain) and you drive the car gently afterwards to let the trans cool.

joe0057

Is it not the engine that is taking the stress once the shift is made?

boson

Funny you should mention this - I am actually an engineer and am currently the Director of Engineering at a manufacturing company on the South side of Chicago...

As far as the physics of engine braking, I don't think I would rely on a mechanic's view of what is perceived to be happening, but you don't have to be an engineer to understand it, either (condescending, I know, sorry...). What you should understand is that a great deal of the resistance is due to the pistons lifting against a vacuum that is created when the engine is not under load but still firing, and very little (if any) is due to undue wear on engine parts - I know this very oversimplified but there is plenty more to read up on if you are into it...

Again, as far as the trans goes, understand I am talking primarily in 'general' traffic with rpm's around 2-4k - I'm not redlining all the way to work... I am sure you will discover that the trans is more than capable at dutifully handling downshifting on a regular basis without causing undue wear. I have driven with similar 'style' for 25 years (with certainly less reliable cars) and haven't had a tranny failure yet - even on the older domestics!

Now, I know this is not a win/lose discussion and I am not trying to change your mind or habits, - I am just relaying my opinion and experience.

tempest_is

Just to slightly echo boson's comment, the transmission is perfectly capable of assisting one in slowing down, hence the term "engine braking". I switched my heads up display to show the gear position while in Drive and I noticed that the ECU actually does some very slight engine braking while you're on the brakes, and you can even feel it slightly.

I personally enjoy this feature as well and I think that the context in which one is engine braking needs to be specified.

7No

iTrader: (1)

Boson. Higgs?

boson

__________