philj

2019 RDX Advance. I have searched YouTube vids and this forum but have not been able to find the answers to these questions.
1. Best method for driving downhill on long, windy and steep grades in reference to brakes or transmission choices?
2. Which would you consider to be least costly on wear of engine, transmission and engine.
3. I have tried using the paddles going down the steep grades but unable to create smooth transitions.

Example : I am on a flat area coming up to a beginning of a long downhill grade. I am going 75 and start to increase speed due to downhill grade. If I use left paddle and pull up once
the rpm shoots up pretty high. Just sounds to high and doesn't feel right. On my old Acura TL I would put in manual mode and shift up and down and that seamed much smoother.
Not sure if this makes any sense to anyone but I know that there are many on this forum with better automotive knowledge than I.

NooYawkuh

I think first you should go to Sport +. If you're in Comfort, it will revert to automatic within seconds of using a paddle. In Sport, it reverts in about 10 seconds. In Sport +, it will stay in manual once you use a paddle. That's been my experience.

subin

I would just set the cruise control (ACC) to the speed limit and relax.

Or, with cruise control off, go to manual shift mode and use the combination of throttle and peddle shift to downshift/up shift to control the speed.
Keep the RPM below the red line and you should be fine.

robnalex

On the RDX, cruise control will not maintain speed whilst going downhill. It does not have that feature. The car will continue to gain speed due to gravity.

MT-RDX

The wheezy little four-cylinder, for all its advanced technology, does not provide much compression braking. On any significant downhill grade, the cruise control will not maintain the set speed without manual intervention.

Best solution I have found is use Sport driving mode (not Sport+), and put the transmission in Sequential mode. Then you can either drive without the ACC and use the paddles to select the gear appropriate for the grade, or let the ACC control the speed but use the paddles to shift down when the speed climbs over the set point. On a steep grade with curves, the manual method is my preference because using the brake (which may sometimes be necessary depending on the traffic, grade, and curves) will drop the ACC out and you have to keep resettiing it. Using manual mode you can simply drive using any combination of brake and gear just like in the olden days (when cars didn't try to think for you).

philj

Thanks all. MT-RDX helped me understand a little better. Bottom line I just have to go out there and play with it on mountain roads.
My older 2005 TL went through warped rotors which I contributed to the mountain downhill roads.

mrgold35

I've taken a lot of trip to AZ in my 08 RDX and 11 MDX and probably down the same roads you drive in your RDX. Transmission in Sequential mode+paddles are the best way up and down twisty mountain grades. The 10AT will probably try and shift to highest gear possible and take more time to shift/turbo spool if you don't use sequential mode. You just have to be comfortable with running the RDX in a much higher RPM range to get engine braking when needed, faster turbo spool time, sh-awd engaged, and quicker response time from the transmission since it doesn't have to shift 2-5 gears. My goal is to drive down the switchback without riding the brake and use engine braking+sh-awd+Acura handling mostly.

I've noticed my 5AT/6AT vehicles allow me to shift in sequential mode with a wider rpm range compared to just auto mode. This allows me to downshift into 2nd gear with rpms shooting up +5000 in sequential mode where 2nd gear is locked out at the same mph in auto mode+paddles. I would play with all the different combos of sport, sport+, auto, and sequential mode to find the best settings for max performance.

B25Nut

We always drive in Sport mode. When we begin to coast down a local long, steep grade, I wait until we’re at 72 mph and push the D/S button once. For the next three minutes I don’t have to touch the brakes even though everyone around me are. Without the use of the paddles, the speed doesn’t get above 74 mph. At the bottom of the grade I press D/S again and it’s back to normal driving.

Madd Dog

I will often pop the left paddle a time or two, but this 4 doesn’t have a lot of compression. Sometimes I will gently brake for a couple of seconds.