nope...the auto tranny does not shift down to slow the engine down when you step on the brake because if you let go of the brake, it'll continue to run smoothly and dwindle down....it only shifts down when it's out of RPM range in case you need to take off, the tranny still searches for gear when you step back on the gas...now if you shift down thru the manumatic mode, it locks the car in that gear until it has to get into a lower gear...most of the time it will stay in that gear, and it slows down the engine...

 

I suppose that the

Should I downshift or should I brake?

conflict will go on forever.

 

and that's the reason why I want to know some facts on the effect on the tranny...

 

Read the "facts" in my post above, with a link to a relaible source. In part, it says:

"...it puts little or no more load on your engine than it would otherwise bear, but saves considerable wear on your brakes"

bill

 

I dislike the question (posted about once each moth) because it offers false choices: downshift or brake. Neither is a correct answer. A good driver uses the transmission, brakes, clutch and accelerator together to control the car.

 

I wasn't crazy about the 5AT in our cars. It didn't down or upshift when I wanted it to. It took about a second or two to downshift especially. The computer takes some of the control away. However, it is supposed to help take loads off of the automatic transmissions in these cars.

On a mountain road I'd rather have the stick.
In traffic the 5AT is much better.
Pick your tranny for the type of driving you do the most of.
I do not mine the stick in traffic. It gives me something to do. ;-)

 

I have a 90' 300zx MTrans
and a 2006 350z 5AT.

What I dont like about the AT is that when you step on it, the engine automatically downshifts, then gives you this almost uncontrolled amount of power, like you are being launched from a sling-shot, which can be dangerous if you are trying to pass someone and kind of over shoot the distance you are trying to go.

So to avoid this problem, if i need to step on it to make a pass on the freeway in a tight space, I slide over to the manuel mode, then downshift, giving me about 75% more control over what i am trying to do, it feels just like a regular stick shift when you do this, in terms of acceleration control.

(pointless post I know, Im sure everyone with 5AT does this, just thought Id share anyways)

 

actually, I haven't seen many threads concerning this issue...and any thread that's related or comes come to relating to this issue have mostly been hearsay, or what everyone THINKS should be done...bailey bill found that really interesting article regarding this subject...

I use a lot of engine braking on my sportbikes, and trust me when you're on a motorcycle, engine braking vs conventional braking can mean a difference between crashing or stopping in certain situation...

I'm gonna see if I can find more reliable sources of pros and cons on this topic...

 

I think you are talking about style more than proper technique.

Two racers at the track. One hits the brakes hard, spins the tires coming out of corners, ands hits the throttle hard. The other does everything smooth. All transitions from slow to acceleration, and acceleration to slow are seamless. Both have the same lap times. Neither technique is better. Both get the job done.

 

LOL, I had my z since January '07 and had a couple of close calls passing under acceleration while in automatic mode as you pointed out above (sling shot effect)....I prefer manual mode for control down/upshifting...I too am curious about the harm it does to the engine (if any)....

 

Posting for the 3rd time:

"...it puts little or no more load on your engine than it would otherwise bear, but saves considerable wear on your brakes"

Why would you think using the engine to DEcellerate would cause any more wer than using to ACcellerate.

When you lift, whether you downshift or not, the engine is coasting.

bill

 

Not one person commented about the rev matching after it was brought up?? I thought that was the purpose of the rev matching also to help with the strain you might get shifting down with the manumatic. Any one else think that or just two z owners out of ******* z owners (to many to count)........

 

Oh oh!! Me me!! I did. (Z MANIA raises his hand), I just did not say the word rev "matching".

 

If you're racing or driving sprinted while using the manual mode on the 5AT then both the engine & tranny are taking a hit to their longevity. If you're driving it normally and down shifting to delay using the brakes, and up shifting to better manage the gear your in then I don't think you causing any more wear but may want to change the fluid more often.

IMO, use the brakes unless your going down hill or a similar situation.

I have an 06 5AT and it appears to rev match to within +/- 200 RPMs.

 

ok, that has nothing to do with what I'm talking about...BUT if it does then let's say that race was done several days back to back for months...now that we know they both came in together...let's look under their engine and the wear and tear....don't answer me unless you know FOR SURE: which vehicle burned more gas? which vehicle has more brake life left? which vehicle has more engine wear? cleaner fluid? ...etc....

 

Just use the damn brakes! Pads are cheap and you save fuel from just braking.

 

wrong buddy...in a 6MT, you do not save fuel braking..you save MORE fuel engine braking...you burn fuel coasting and idling...

 

You use more fuel when engine braking because of the higher rpms.

 

Engine braking when done right ftw. I have 82,000 on my SS Silverado now with the stock brakes and pads and there is still 1/2 the pad left. This is the 1st auto I'v done it with but I'v had no problems. (and thats the longest lasting brakes I'v ever had :O)

 

No. When coasting to a stop fuel is keeping the motor running. When engine braking momentum is doing most of the work.