I just got a CX5 Grand Touring w/ Premium package and am new to paddleshifters. Would it make any sense to downshift for braking or is that going to be hard on the tranny?

 

Being gentle with it is fine. I try not to rev above 3,000rpm

 

I always use engine brake, you spare your brakes, why rpm should not be over 3000, I can not see a logical explanation for, if you use as I, adaptive cruise control, rpm often goes well over 4000 rpm, - same scenario in sports mode.

 

Cost to replace brake pads < cost to rebuild engine. Just watch out for big Rev jumps. YMMV.

 

The automatic transmission won't do a money shift like you can do with a standard. With a standard, you have to weigh the cost of the clutch against the brake pads and factor in that if you miss 4th while downshifting from 5th, you may hit 2nd and damage the engine. It happens even to experienced drivers now and then.

 

Mine does the downshift itself as I brake. Even if I don’t brake, and let it just roll to a stop; it will downshift all the way through to 1st as it slows down. Kind of like it up shifts from 1st to 6th as I get up to speed from a stop.
Occaisionally I’ll use the paddle to put some engine braking in there to assist the service brakes.
If you use the paddle to downshift from, say 6th to 5th, the D display will change to the gear you’re in. As you apply the brakes and slow down, you’ll see the gear number drop through to 1 as a full stop.
At least that what’s I’ve seen since day 1 in my 2020 6 AT.

 

The normal downshifting as you slow down is not engine braking, the subject of this thread. All auto transmissions will down shift as you slow down, what the OP is asking is about using engine compression to supplement/replace braking when slowing down. I’ve done this with all of my auto transmission vehicles for over 30 years, but the real reason was to insure that I am in the correct gear to accelerate out of the turn. Never had a transmission issue in the last 10 vehicles.

 

Can't say that I've had a paddle-shifting vehicle for more than 100Kmi, so I have yet to see any longer-term negative effects from downshifting prior to braking.

Have done this method most of the time, for ~70Kmi in a Mazda3 2.5 S GT. Have done this method frequently in a 2016 CX-5 GT. Did this method for years in a manual-shift (not paddle-shift) early Miata, for ~150Kmi, without negative effects on transmission, clutch. I try to avoid huge RPM's when doing so. I keep the transm. oil relatively fresh (every 50Kmi, more or less).

IMO, if you're reasonable in your use of the transmission and brakes, I would think you should see increased life of both. They're both wear items, eventually. But judicious use of the transmission to downshift can ease the load on the brakes; the transmissions might not be overbuilt, strictly speaking, but they're certainly capable of operating effectively so long as you put reasonable loads on them.

 

When you always use your engine to brake you are putting stress on the engine rings. It is a bad idea. And when you buy a turbo you are also putting more stress on the engine rings. Also the transmission is being stressed. Brake pads are cheap.

 

If using ACC, this is exactly what the system does - downshifts to slow the vehicle and doesn't apply the brakes unless engine braking is insufficient.