Automatic W Paddle Shifters-Rev Matching->WHY?

[Husker]

Automatic with Paddle Shifters (Select-Shift 6-speed)
Rev Matching - Redesigned Case With Lighter Internals

I'm trying understand the difference between a regular Automatic With Paddle Shift & one with Rev-matching.

My current DD has Auto with Paddle Shift.

When I down shift, from lets say 4th to 3rd @ 4K RPM the RPMs go up and the car slows down which is why I down shift in the 1st place.

Now what is gonna happen when I do the same thing with the Rev-Matching Auto & Why is it a desired feature?

Will it slow down or pick up speed momentarily?

Is the feature designed for racing & not normal everyday driving?

If anyone knows of a thread (Yes I searched-Probably not the right way) or a site that explains it, Lay it on me...I really wanna learn.

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[Todd15Fastback]

rev matching allows less abuse to be placed on the transmission. You are matching RPM's, so when the shift is made you don't get a herky jerky feel.

Reduces stress on the drive-line
Prevents forward weight transfers when down shifting
Reduces engine braking and chances of wheel lock

 

[Trackaholic]

I remember trying to answer this in a previous thread, but can't find it either, so here's the deal.

When you downshift, the engine will need to reach a higher RPM. There are a couple ways to do this (I will explain based on a manual, but the reasons and process are the same for the automatic).

First method: put in clutch, select lower gear, release clutch. When you release the clutch, the rear wheels will be forcing the engine to spin up to the higher RPM and the engine will be resisting this due to its internal friction and inertia. Therefore, if you want to shift quickly and let out the clutch quickly, you will put shock into the wheels and drivetrain which can upset the balance of the car, cause a lurching feeling for the driver and passengers, and put unnecessary load on the components.

So you change the process to: push in clutch, select neutral (but don't release clutch), blip the throttle as you pass through neutral, select the lower gear, then release the clutch. Now you've brought the engine to the correct RPM before releasing the clutch, which allows for a quick release without upsetting the balance of the car or adding additional stress to the drivetrain. You will also have a smoother shift without lurching.

In both cases you will have increases engine braking due to being in a lower gear, but the blip in theory can make everything faster and smoother. Plus it sounds cool.

-T

And Todd was faster.

 

[Grimace427]

It makes a difference in the auto in that it allows a quicker and sportier-feeling downshift. It honestly isn't all that important with the auto being how soft they shift nowadays. It would be more useful with the manual transmission.


Remember guys that with an auto transmission the driveline isn't necessarily locked at all times so what you guys are explaining doesn't always apply.

 

[MUSThavaSTANG]

I wouldn't advise using your engine to slow your car down. Brakes are cheaper to replace than a tranny.

 

[Fomoco15]

Should be a great upgrade from my fusion. Wish it had it

 

[Grimace427]

I wouldn't advise using your engine to slow your car down. Brakes are cheaper to replace than a tranny.

Engine braking puts zero wear on the transmission.

 

[Backorder]

I remember trying to answer this in a previous thread, but can't find it either, so here's the deal.

When you downshift, the engine will need to reach a higher RPM. There are a couple ways to do this (I will explain based on a manual, but the reasons and process are the same for the automatic).

First method: put in clutch, select lower gear, release clutch. When you release the clutch, the rear wheels will be forcing the engine to spin up to the higher RPM and the engine will be resisting this due to its internal friction and inertia. Therefore, if you want to shift quickly and let out the clutch quickly, you will put shock into the wheels and drivetrain which can upset the balance of the car, cause a lurching feeling for the driver and passengers, and put unnecessary load on the components.

So you change the process to: push in clutch, select neutral (but don't release clutch), blip the throttle as you pass through neutral, select the lower gear, then release the clutch. Now you've brought the engine to the correct RPM before releasing the clutch, which allows for a quick release without upsetting the balance of the car or adding additional stress to the drivetrain. You will also have a smoother shift without lurching.

In both cases you will have increases engine braking due to being in a lower gear, but the blip in theory can make everything faster and smoother. Plus it sounds cool.

-T

And Todd was faster.

So if a manual transmission is supposed to have rev matching it will throttle up automatically as you downshift?


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[Grimace427]

So if a manual transmission is supposed to have rev matching it will throttle up automatically as you downshift?

Yes. The 370Z and C7 'vette have the feature. It uses sensors on the clutch pedal(and shifter maybe?) and along with other parameters and algorithms will blip the throttle as you are making a downshift.

 

[MUSThavaSTANG]

Engine braking puts zero wear on the transmission.

If you downshift into too low a gear and the wheels lock up it does. But now I'm talkin manual.

 

[BackInBlack]

Otherwise known as "heel and toe" shifting...

 

[Grimace427]

If you downshift into too low a gear and the wheels lock up it does. But now I'm talkin manual.

The thread is all about rev-matching. You aren't going to lock up the wheels if you are rev matching on downshifts, and you aren't doing any wear and tear on anything other than your left leg by using engine braking to slow the car. Nobody is advocating downshifting to 1st gear while going 50mph.

 

[souprmage]

Still, the point is the same. Brakes are made for slowing you down, the motor isn't. Different motors behave differently in respect to the braking effect. The 5.0 will have a larger effect than the EB and the 'wear-and-tear' will be different as well.

That said, it may or may not be consequential, at least as long as you keep the revs below red-line. I trust you're all smart enough to not go over red-line with a down-shift. Right?!?!

 

[w3rkn]

If you drive an automatic, then nothing discussed is of any concern. Rev-matching is usually for manuals..

Otherwise, an automatic does this regardless as it has a TQ converter.

 

[jimmypop13]

Still, the point is the same. Brakes are made for slowing you down, the motor isn't. Different motors behave differently in respect to the braking effect. The 5.0 will have a larger effect than the EB and the 'wear-and-tear' will be different as well.

That said, it may or may not be consequential, at least as long as you keep the revs below red-line. I trust you're all smart enough to not go over red-line with a down-shift. Right?!?!

Engine braking saves from having as much brake wear and is worth it to me, also bc I'm in gear to accelerate if I need to. Sticking it in neutral and stopping with just the brakes seems like a half baked idea to me. Considering I've got 100k miles on my turbo 4 banger, have only had to replace my brembo pads once and that was at 95k, and had zero engine issues or loss of power, I'd say engine braking is a non issue and good idea for anyone with a manual transmission

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