[RobMunach]

I use 'em for going down grades. Not so much for general stopping. Brake pads have got to be cheaper than the wear items inside the trannie. Plus, you can just lift off the gas sooner, save gas, as well as brake pads. But that is just me.......

That is the correct way to use the tranny. This has been discussed before in great length. Anyone who downshifts all the time to slow the vehicle (Auto or Stick) is a fool. Going down long grades is another story. Brakes are cheap, clutches and trannys are not.

 

[RobMunach]

Down hill speed check down shift is actually a good idea especially with the CVT given its pretty slippery and the car will just rocket down hill unchecked.

Driving around town and down shifting as you approach stoplights? Brakes are a better idea cost less to service than a CVT and even the MT folks say down shifting past 3rd for regular use around town stuff is just shocking the running gear hard and adding wear to the transmission - and drive lines which really isn't worth the value add going below 3rd.

Exactly. FWIW, Most people don't keep their cars for the long haul anymore so they typically do not care.

 

[RobMunach]

Don't get me wrong, I don't actually do a lot of engine braking, just on long hills, and I'm pretty gentle on the brakes when I can be (traffic sometimes decides otherwise). I'm just wary of applying "common wisdom" on a fundamentally different transmission design without some data to back it up. I'd agree that in the absence of such data, that caution is probably due, but that's different from assuming the same rules apply, and using that as the reason for doing it that way.

Torque being applied in the "wrong direction" leading to additional wear makes some sense, depending on the design of the components. While it only needs to work in one direction, that doesn't mean that the design will wear out faster in the other, but it could. But the downshift itself shouldn't be the reason for the additional wear in a CVT design, not when the torque convertor should still be locked up through the whole engine braking maneuver.

Again, this is why I'd wish there was better data on it to research.

Anytime you drive your car there is wear and fatigue occurring in the drivetrain. It is hard to dispute that downshifting will increase that wear and fatigue. The question is weather it will cause a problem in your ownership period. Maybe, maybe not. It is still not a good practice unless necessary.

 

[RobMunach]

I downshift with the paddles only on long downhill slopes or aggressive stops. The paddles are right there and easily accessible.

Why on aggressive stops? Let the brake pedal and ABS do its job in those situations. Unless you feel like you are going to have to get on the gas real quickly soon after or during the stop - then it make sense.

 

[RobMunach]

Why? Because engine braking ADDS to the power of the hydraulic braking system, but does NOT pose a lockup risk.

LOL at all the people who think engine braking is bad for the engine. Do you all shift into neutral before letting your foot off the gas?

In a panic stop, the brakes are not an issue - tire traction is. Any modern braking system has plenty of power for a panic stop. There is no need to supplement them. I never said engine braking is bad for an engine, it just adds wear if it is used all the time to slow the car instead of letting the brakes do their job. My guess is that you have never done a track day in your or another car. You will quickly learn the only reason to downshift when on the brakes is to have your car in the proper gear when exiting the corner (heel-toe shifting if you have a stick). It is not to supplement the brakes and can upset the car if the downshifts are not done at the proper time. Probably not an issue on the street, but the concept is still the same.

 

[RobMunach]

Right, and I understand the additional wear side, but also think on the other side with the modern electronics governing the shifts and engine speed etc, the entire body of the car would rust out well before any tangible effects from downshifting to stop would ever show up in the cars lifetime for me at least. I'm hoping to have this car a long time which to me is 10 years / 120,000 miles.

I think I just want to hear it from the horses mouth at this point. I'm not planning to downshift every stop 100% of the time. I guess maybe if I'm coming in a little hot or light changes on me it comes in handy. Also coming from a lighter more sport oriented car (r32) so still probably adjusting my driving to the new ride. I'm anxious to hear their reply.

Same principals applied to your R32....

 

[RobMunach]

Doesn't that assume that the car isn't rev matching the downshifts? I'm not sure how it works in the 2.5 CVT, but I know in my GTI (and in the 3.6r), the dramatic increase to RPMs is done electronically before any load is placed on the transmission. I could be wrong, but it's worth the discussion. FWIW, if I put my car in Sport mode, the DSG pretty much downshifts to 4k RPM in every gear when coming to a stop.

Edited to add: less braking = less brake dust on your wheels!

That certainly minimizes the shock on the drive train, but still is pointless in everyday driving - except to limit brake dust.

 

[RobMunach]

I've heard a lot of 'blah blah' on this idea for years.
Of the vehicles I've had, downshifting to slow down didn't give me any unreasonable issues with durability vs not. Here's my experience to support why.

First vehicle to account for was a Plymouth Champ. That's the same as the Dodge Colt, made by Mitsubishi and sold as the Mirage. It was a front wheel drive compact. When I got it (used from in the family), it had the stock 3 speed automatic behind the 1.6L I4. I didn't bother downshifting it manually, and being a non-computer controlled automatic, it would downshift itself on longer, more drawn out decelerations. That transmission had gone out and been replaced before I got the car, and was in mega-slip mode when I rebuilt the engine @ ~100,000 miles. I looked at the other versions of the car, and found there was a 4 speed manual 'twin stick' (dual input ranges), and a plain 4 speed. The holes for mounting the hardware for a stick were all in my chassis, and the auto and stick shifters mounted in the same hole, the same way. I swapped for the plain 4 speed. I proceeded to flog it for over 125k miles and had loads of fun. I finally broke the clutch after burnouts and hard launches, and downshifting EVERY time, at that 125k mile mark. The friction material was still there, but one of the recoil springs on the friction disc finally gave out. Most people don't get that many miles out of driving a clutch 'normally', which usually means way too much slipping on 'normal' takeoffs and never downshifting. The car had no ABS, so without downshifting I had a choice of only so much braking or lockup, or the much more difficult mastery of modulating the braking myself, or adding in engine braking to compliment the regular brakes. My brakes lasted longer than normal, and make no mistake - I was (and really still am) a fairly aggressive driver.

I followed that car with an Astro van. Auto trans. Handled like a barn on wheels. Went through a trans mount, trans, U-joint, and a couple of sets of brakes in the same 125k mile span. Only engine braking used there was for long or exceptionally steep downhill grades, which was certainly less than 1k miles of that span.

ABS doesn't make your vehicle stop faster, it only maintains your ability to steer and control the vehicle. It also doesn't magically make your brakes bigger, which is the only way to make the brakes themselves really stop you faster. You're converting velocity (inertia) into heat, and it takes mass to absorb the heat, and surface area to apply friction to convert the inertia into heat. Engine braking compliments what your normal braking system does by basically bypassing it and directing some of that friction to the tires vs the road, and the rotating masses against the air being compressed in the engine. Oh, and if you think ABS wasn't designed and tested in situations where the engine was braking because of the gear it is in, you assume poorly. What do you think happens when people are still accelerating and need to perform a panic stop? Many won't remember to press in the clutch at such a panic, they'll just punch the brakes. Ever noticed how many people stall after a REAL panic stop? You can bet automakers considered this situation, and ABS will still do its best even when such is the case.

Maybe so, but the fact is that in a modern automobile, tires and/or traction available are your limiting factors in a panic stop, not the size of the brakes. If you have more traction, you will stop faster - period. The brakes do not need any assistance from the engine braking. The size of your brakes typically only typically affects brake fade on a long descent or on a racetrack (if you decide to take your OB there). Again, you do not see racecar drivers downshifting to help slow the car, they only use it to be in the proper gear for coming out of the next corner.

 

[RobMunach]

If the size of the brakes don't matter, why do race cars have serving platter sized rotors with massive calipers and heaps and tons of swept area? Yes, brake size DOES matter. My point was if you can't get bigger brakes, your only choice with what you have is engine braking. The gain is much less, but its more than nothing - and the added wear and tear is not the disaster some make it out to be. Also, don't compare a race car directly to a street car in all regards - most race cars aren't expected to keep brakes for 30k miles. You treat brakes as per race disposables. Race grade engines and transmissions are far less expendable. A street car's engine and trans are designed with much more long term durability, instead of outright performance. Costs a lot less in a race car to swap pads every race than to replace a high output but relatively fragile engine every few races.

You are talking race cars and not street cars. The brake sizes on modern street cars are plenty big to take care of a single panic stop - maybe not multiple ones in a row - but that does not happen on the street. The lawyers would not have it any other way. A car stops so quickly from 60 mph nowadays, I doubt the transmission will have time to downshift and have it have a whole lot of effect anyway. I'd also like to see you turn off you ABS (if possible) and see if you can stop your car faster using the brakes and downshifting - good luck :>